10-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)
x	ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
FOR THE FISCAL YEAR ENDED DECEMBER 31, 2005
o	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE TRANSITION PERIOD FROM                TO

Commission file number 1-8432

Mesa Offshore Trust

(Exact Name of Registrant as Specified in Its Charter)

Texas	76-6004065
(State or Other Jurisdiction of	(I.R.S. Employer
Incorporation or Organization)	Identification No.)
JPMorgan Chase Bank, N.A., Trustee
Institutional Trust Services
700 Lavaca Austin, Texas	78701
(Address of Principal Executive Offices)	(Zip Code)

Registrant’s telephone number, including area code: 1-800-852-1422

Securities registered pursuant to Section 12(b) of the Act:

Title of Each Class	Name of Each Exchange On Which Registered
None	None

Securities registered pursuant to Section 12(g) of the Act:

Units of beneficial interest

(Title of Class)

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes o No x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x  No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See definition of “accelerated filer and large accelerated filer” in Rule 12b-2 of the Exchange Act (Check one):

Large accelerated filer o Accelerated filer o Non-accelerated filer x

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes £  No x

The aggregate market value of 71,980,216 Units of Beneficial Interest in Mesa Offshore Trust held by non-affiliates of the registrant at the closing sales price on June 30, 2005, of $0.03 was approximately $2,159,000.

Indicate the number of shares outstanding of each of the registrant’s classes of common stock, as of the latest practicable date.

As of March 31, 2006, 71,980,216 Units of Beneficial Interest were outstanding in Mesa Offshore Trust.

DOCUMENTS INCORPORATED BY REFERENCE: None.

TABLE OF CONTENTS

		Page
	PART I	4
Item 1.	Business	4
	Description of the Trust	4
	Description of the Units	6
	Legal Proceedings and Status of the Trust	8
	Timing of Liquidation	10
	Description of Royalty Properties	12
	Contracts	23
	Regulation and Prices	24
Item 1A.	Risk Factors	26
Item 1B.	Unresolved Staff Comments	30
Item 2.	Properties	30
Item 3.	Legal Proceedings	30
Item 4.	Submission of Matters to a Vote of Security Holders	31
	PART II	32
Item 5.	Market for the Registrant’s Common Equity and Related Unitholder Matters	32
Item 6.	Selected Financial Data	32
Item 7.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	33
Item 7A.	Quantitative and Qualitative Disclosures About Market Risk	38
Item 8.	Financial Statements and Supplementary Data	39
Item 9.	Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	50
Item 9A.	Controls and Procedures	50
	PART III	51
Item 10.	Directors and Executive Officers of the Registrant	51
Item 11.	Executive Compensation	51
Item 12.	Security Ownership of Certain Beneficial Owners and Management	51
Item 13.	Certain Relationships and Related Transactions	51
Item 14.	Principal Accounting Fees and Services	52
	PART IV	52
Item 15.	Exhibits, Financial Statement Schedules	52
SIGNATURES		54

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Note Regarding Forward-Looking Statements

This Form 10-K includes “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements other than statements of historical facts included in this Form 10-K, including without limitation the statements under “Business—Termination of the Trust,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and Note 1 to the financial statements of the Trust regarding the future net revenues of the Trust, are forward-looking statements. Although Pioneer Natural Resources Company (“PNR”) has advised the Trust that it believes that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct. Important factors that could cause actual results to differ materially from expectations (“Cautionary Statements”) are disclosed in this Form 10-K, including, without limitation in conjunction with the forward-looking statements included in this Form 10-K. A consolidated summary description of principal risk factors that could cause actual results to differ is also set forth in this Form 10-K under “Item 1A. Risk Factors.” All subsequent written and oral forward-looking statements attributable to the Trust or persons acting on its behalf are expressly qualified in their entirety by the Cautionary Statements.

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PART I

Item 1.Business.

DESCRIPTION OF THE TRUST

The Mesa Offshore Trust (the “Trust”), created under the laws of the State of Texas, maintains its offices at the office of the Trustee, JPMorgan Chase Bank, N.A. (the “Trustee”), 700 Lavaca, Austin, Texas 78701. The telephone number of the Trust is 1-800-852-1422. JPMorgan Chase Bank, N.A. was formerly known as The Chase Manhattan Bank and is the successor by mergers to the original name of the Trustee, Texas Commerce Bank National Association.

The Trustee does not maintain a website for filings by the Trust with the U.S. Securities and Exchange Commission (“SEC”). Electronic filings by the Trust with the SEC are available free of charge through the SEC’s website at www.sec.gov.

The principal asset of the Trust consists of a 99.99% interest in the Mesa Offshore Royalty Partnership (the “Partnership”). The Trust was created on December 28, 1982, effective December 1, 1982, when Mesa Petroleum Co. conveyed to the Partnership certain overriding royalty interests (collectively, the “Royalty”) carved out of Mesa Petroleum Co.’s existing working interests in ten producing and non-producing oil and gas leases offshore Louisiana and Texas (the “Royalty Properties”). The Partnership was formed for the purpose of receiving and holding the Royalty, receiving the proceeds from the Royalty, paying the liabilities and expenses of the Partnership and disbursing remaining revenues to the Trustee and Mesa Offshore Management Co., the managing general partner of the Partnership at that time, in accordance with their interests. Until August 7, 1997, MESA Inc. owned and operated its assets through Mesa Operating Co. (“Mesa”), the operator and the managing general partner of the Royalty Properties. On August 7, 1997, MESA Inc. merged with and into Pioneer, formerly a wholly owned subsidiary of MESA Inc., and Parker & Parsley Petroleum Company merged with and into Pioneer Natural Resources USA, Inc. (successor to Mesa Operating Co.), a wholly owned subsidiary of Pioneer (“PNR” or “Pioneer”) (collectively, the mergers are referred to herein as the “Merger”). Subsequent to the Merger, Pioneer owns and operates its assets through PNR and is also the managing general partner of the Partnership. As hereinafter used in this report, the term PNR generally refers to the operator of the Royalty Properties, unless otherwise indicated. See “Legal Proceedings and Status of the Trust” on page 8 of this Form 10-K and “Timing of Liquidation” on page 10 of this Form 10-K for additional information regarding PNR and the Trust.

Units of beneficial interest (“units”) in the Trust were issued on December 28, 1982 to Mesa Petroleum Co. shareholders, who received one unit for each share of Mesa Petroleum Co. common stock held.

The terms of the Mesa Offshore Trust Indenture (the “Trust Indenture”) provide, among other things, that: (1) the Trust cannot acquire any asset other than its interest in the Partnership and cannot engage in any business or investment activity; (2) the Royalty can be sold in part or in total for cash upon approval of the unitholders or upon termination of the Trust; (3) the Trustee can establish cash reserves and borrow funds to pay liabilities of the Trust and can pledge the assets of the Trust to secure payment of the borrowing; (4) the Trustee will make quarterly distributions of cash available for distribution to the unitholders in January, April, July and October of each year; and (5) the Trust will terminate upon the first to occur of the following events: (i) the total amount of cash received per year by the Trust for each of three successive years commencing after December 31, 1987 is less than ten times one-third of the total amount payable to the Trustee as compensation for such three-year period (the “Termination Threshold”) or (ii) a vote by holders of a majority of the outstanding units in favor of termination. Amounts paid to the Trustee as compensation were approximately $204,000, $148,000, and $152,000, for the years 2005, 2004 and 2003, respectively. As described further in “Status of the Trust” on page 8 of this Form 10-K, the

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Termination Threshold was met in each of the three consecutive years ending December 31, 2005. Upon termination of the Trust, the Trustee will sell for cash all the assets held in the Trust estate and make a final distribution to unitholders of any funds remaining after all Trust liabilities have been satisfied.

The terms of the First Amended and Restated Articles of General Partnership of the Partnership (the “Partnership Agreement”) provide that the Partnership shall dissolve upon the occurrence of any of the following: (1) December 31, 2030; (2) the election of the Trustee to dissolve the Partnership; (3) the termination of the Trust; (4) the bankruptcy of the Managing General Partner; or (5) the dissolution of the Managing General Partner or its election to dissolve the Partnership; provided that the Managing General Partner shall not elect to dissolve the Partnership so long as the Trustee remains the only other partner of the Partnership.

Under the instrument conveying the Royalty to the Partnership (the “Conveyance”), the Trust is entitled to its share (99.99%) of 90% of the Net Proceeds, as hereinafter defined, realized from the sale of the hydrocarbons as, if and when produced from the Royalty Properties. See “Description of Royalty Properties” on page 12 of this Form 10-K. The Conveyance provides for a monthly computation of Net Proceeds. “Net Proceeds” means the excess of Gross Proceeds, as hereinafter defined, received by PNR during a particular period over operating and capital costs and an amount to be recovered for future abandonment costs during such period. “Gross Proceeds” means generally the amount received by PNR from the sale of its share of minerals covered by the Royalty, subject to certain adjustments. Operating costs means, generally, costs incurred by PNR in operating the Royalty Properties, including capital costs. If operating and capital costs exceed the Gross Proceeds for any month, the excess plus interest thereon at the prime rate of the Bank of America plus one-half percent is recovered out of future Gross Proceeds prior to the making of further payment to the Trust. The Trust is not liable for any operating costs or other costs or liabilities attributable to the Royalty Properties or minerals produced there from. PNR, as owner of the working interest in the Royalty Properties, is required to maintain books and records sufficient to determine the amounts payable under the Royalty. Additionally, in the event of a controversy between PNR and any purchaser as to the correct sale price for any production, amounts received by PNR and promptly deposited by it with an escrow agent are not considered as having been received by PNR and therefore are not subject to being payable with respect to the Royalty until the controversy is resolved; but all amounts thereafter paid to PNR by the escrow agent will be considered amounts received from the sale of production. Similarly, operating costs include any amounts PNR is required to pay whether as a refund, interest or penalty to any purchaser because the amount initially received by PNR as the sales price was in excess of that permitted by the terms of any applicable contract, statute, regulation, order, decree or other obligation. Within 30 days following the close of each calendar quarter, PNR is required to deliver to the Trustee a statement of the computation of Net Proceeds attributable to such quarter.

The Royalty Properties are required to be operated by PNR in accordance with reasonable and prudent business judgment and good oil and gas field practices. PNR has the right to abandon any well or lease if, in its opinion, such well or lease ceases to produce or is not capable of producing oil, gas or other minerals in commercial quantities. PNR markets the production on terms deemed by it to be the best reasonably obtainable in the circumstances. See “Contracts” on page 23 of this Form 10-K. The Trustee has no power or authority to exercise any control over the operation of the Royalty Properties or the marketing of production there from.

The discussions of terms of the Trust Indenture, the Partnership Agreement and the Conveyance contained herein are qualified in their entirety by reference to the Trust Indenture, the Partnership Agreement and the Conveyance themselves, which are exhibits to this Form 10-K and are available upon request from the Trustee.

The Trust has no employees. Administrative functions of the Trust are performed by the Trustee.

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DESCRIPTION OF THE UNITS

Each unit is evidenced by a transferable certificate issued by the Trustee. Each unit ranks equally as to distributions and has one vote on any matter submitted to unitholders. Each unit evidences an undivided interest in the Trust, which in turn owns a 99.99% interest in the Partnership.

Distributions

The Trustee determines for each month the amount of cash available for distribution for such month. Such amount (the “Monthly Distribution Amount”) is equal to the excess, if any, of the cash distributed by the Partnership to the Trust during such month, plus any other cash receipts of the Trust during such month (other than interest earned on the Monthly Distribution Amount for any other month), over the liabilities of the Trust paid during such month, and adjusted for changes made by the Trustee during such month in any cash reserves established for the payment of contingent or future obligations of the Trust. The Monthly Distribution Amount for each month is payable to unitholders of record on the monthly record date (the “Monthly Record Date”), which is the close of business on the last business day of such month, or such later date as the Trustee determines is required to comply with legal or stock exchange requirements. However, to reduce the administrative expenses of the Trust, the Trust Indenture provides that the Trustee does not distribute cash monthly, but rather, during January, April, July and October of each year, distributes to each person who was a unitholder of record on a Monthly Record Date during one or more of the immediately preceding three months, the Monthly Distribution Amount for the month or months that he was a unitholder of record, together with interest earned on such Monthly Distribution Amount from the Monthly Record Date to the payment date.

Liability of Unitholders

As regards to the unitholders, the Trustee is fully liable if the Trustee incurs any liability without ensuring that such liability will be satisfiable only out of the Trust assets (regardless of whether the assets are adequate to satisfy the liability) and in no event out of amounts distributed to, or other assets owned by unitholders. However, under Texas law, it is unclear whether a unitholder would be jointly and severally liable for any liability of the Trust in the event that all of the following conditions were to occur: (1) the satisfaction of such liability was not by contract limited to the assets of the Trust; (2) the assets of the Trust were insufficient to discharge such liability; and (3) the assets of the Trustee were insufficient to discharge such liability. Although each unitholder should weigh this potential exposure in deciding whether to retain or transfer his units, the Trustee is of the opinion that because of the passive nature of the Trust assets, the restrictions on the power of the Trustee to incur liabilities and the required financial net worth of any trustee, the imposition of any liability on a unitholder is extremely unlikely.

Federal Income Tax Matters

This section is a summary of certain federal income tax matters of general application as of the date of this report. Except where indicated, the discussion below describes general federal income tax considerations applicable to individuals who are citizens or residents of the United States. Accordingly, the following discussion has limited application to domestic corporations and persons subject to specialized federal income tax treatment, such as regulated investment companies and insurance companies. It is impractical to comment on all aspects of federal, state, local and foreign laws that may affect the tax consequences of the transactions contemplated hereby and of an investment in the units as they relate to the particular circumstances of every unitholder. Federal income taxation is a highly complex matter that may be affected by many considerations. Each unitholder is encouraged to consult its own tax advisor with respect to its particular circumstances and the advisability of its ownership of units.

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This summary is based on current provisions of the Internal Revenue Code of 1986, as amended (the Code), existing and proposed Treasury Regulations thereunder and current administrative rulings and court decisions, all of which are subject to changes that may or may not be retroactively applied. Some of the applicable provisions of the Code have not been interpreted by the courts or the Internal Revenue Service (the “IRS”). No assurance can be provided that the statements set forth herein (which do not bind the IRS or the courts) will not be challenged by the IRS or will be sustained by a court if so challenged.

Ownership of Units

The federal income tax consequences to the unitholders of owning units depend on whether the Trust is classifiable as a grantor trust, a non-grantor trust, or a corporation. The Trustee reports on the basis that the Trust is a grantor trust. Based on its recent audit policy, the IRS is expected to concur with such action. No IRS ruling has been received with respect to the Trust, however, and no court case has been decided involving identical facts and circumstances. It is possible, therefore, that the IRS will assert on audit that the Trust is taxable as a corporation and that a court might agree with that assertion.

Income and Depletion

Royalty income, net of depletion and severance taxes, is portfolio income. Subject to certain exceptions and transitional rules, Royalty income cannot be offset by passive losses. Additionally, interest income is portfolio income. Administrative expense is an investment expense.

Generally, prior to the Revenue Reconciliation Act of 1990, the transferee of an oil and gas property could not claim percentage depletion with respect to production from the property if it was “proved” at the time of the transfer. This rule is not applicable in the case of transfers of properties after October 11, 1990. Thus, eligible unitholders who acquired units after that date are entitled to claim an allowance for percentage depletion with respect to Royalty income attributable to these units to the extent that this allowance exceeds cost depletion as computed for the relevant period.

Backup Withholding

Distributions from the Trust are generally subject to backup withholding at a rate of 28% of these distributions. Backup withholding will not normally apply to distributions to a unitholder, however, unless the unitholder fails to properly provide to the Trust his taxpayer identification number or the IRS notifies the Trust that the taxpayer identification number provided by the unitholder is incorrect.

Sale of Units

Generally, except for recapture items, the sale, exchange or other disposition of a unit will result in capital gain or loss measured by the difference between the tax basis in the unit and the amount realized. Effective for property placed in service after December 31, 1986, the amount of gain, if any, realized upon the disposition of oil and gas property is treated as ordinary income up to the amount of intangible drilling and development costs incurred and depletion claimed to the extent it reduced the taxpayer’s basis in the property. Under this provision, depletion attributable to a unit acquired after 1986 will be subject to recapture as ordinary income upon disposition of the unit or upon disposition of the oil and gas property to which the depletion is attributable. The balance of any gain or any loss will be capital gain or loss if the unit was held by the unitholder as a capital asset, either long-term or short-term depending on the holding period of the unit. This capital gain or loss will be long-term if a unitholder’s holding period exceeds one year at the time of sale or exchange. A long-term capital gains rate of 15% applies to most capital assets sold or exchanged with a holding period of more than one year. Capital gain or loss will be short-term if the unit has not been held for more than one year at the time of sale or exchange.

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Non-U.S. Unitholders

In general, a unitholder who is a nonresident alien individual or which is a foreign corporation, each a “non-U.S. unitholder” for purposes of this discussion, will be subject to tax on the gross income produced by the Royalty at a rate equal to 30% or, if applicable, at a lower treaty rate. This tax will be withheld by the Trustee and remitted directly to the United States Treasury. A non-U.S. unitholder may elect to treat the income from the Royalty as effectively connected with the conduct of a United States trade or business under provisions of the Code or pursuant to any similar provisions of applicable treaties. Upon making this election a unitholder is entitled to claim all deductions with respect to that income, but he must file a United States federal income tax return to claim these deductions. This election once made is irrevocable unless an applicable treaty allows the election to be made annually.

The Code and the Treasury Regulations thereunder treat the publicly traded Trust as if it were a United States real property holding corporation. Accordingly, non-U.S. unitholders may be subject to United States federal income tax on the gain on the disposition of their units.

Federal income taxation of a non-U.S. unitholder is a highly complex matter which may be affected by many other considerations. Therefore, each non-U.S. unitholder is encouraged to consult with its own tax adviser with respect to its ownership of units.

Tax-Exempt Organizations

The Royalty and interest income should not be unrelated business taxable income so long as, generally, a unitholder did not incur debt to acquire a unit or otherwise incur or maintain a debt that would not have been incurred or maintained if the unit had not been acquired. Legislative proposals have been made from time to time which, if adopted, would result in the treatment of Royalty income as unrelated business taxable income. Each tax-exempt unitholder should consult its own tax advisor with respect to the treatment of royalty income.

LEGAL PROCEEDINGS AND STATUS OF THE TRUST

Hurricane Operations Update

Hurricane Katrina struck the Gulf of Mexico in August 2005. PNR notified the Trust that it had received preliminary assessments regarding damages from Hurricane Katrina to the West Delta production facilities in which the Trust has an interest. The operator of the West Delta properties has informed PNR that the West Delta properties have been shut in since August 27, 2005 due to damage to the platform, the pipeline and the sales terminal. The operator has notified PNR that the pipeline has not been repaired and currently there is no estimate as to when the repairs will be completed. The operator does not have an estimate on when production at West Delta will resume.

Status of the Trust

The Trust Indenture provides that the Trust will terminate if the total amount of cash per year received by the Trust falls below certain levels for each of three successive years. As a result of continued declines in production on Royalty Properties nearing the end of their estimated productive lives, Royalty income received by the Trust in 2002, 2003 and 2004 fell below the Termination Threshold prescribed by the Trust Indenture. The Trustee has taken steps to begin the process of liquidating the Trust. See “—Timing of Liquidation” below in this Note. The Trustee, which has no authority or discretionary control over the timing of expenditures, production or income on the Royalty Properties, has no discretion regarding the occurrence of the Termination Threshold or its consequences.

The Trust Indenture provides the Trustee a two-year period during which it must sell all of the Trust properties. The Trust Indenture provides that such properties must be sold for cash and not for any other

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consideration. The Trustee expects that the sale process will be open to any persons desiring to participate, but, as is customary, access to information and participation may be limited to persons who execute confidentiality agreements regarding information provided by the working interest owners. The Trustee may also require bidders to identify themselves clearly and to represent or evidence sufficient financing in order to participate, as the Trustee expects payment will be required promptly after the close of bidding without any financing conditions. Accordingly, the auction may not be a “public” auction in the sense that it may not be open to anyone who does not satisfy these requirements. The Trustee is currently reviewing a potential online bidding process for participants in order to provide current public information on bidding to the marketplace. The Trustee will also determine a duration of bidding that it deems in the best interest of the Unitholders.

Legal Proceedings

On April 11, 2005, MOSH Holding, L.P. (MHLP) filed an Original Petition in the District Court of Travis County, Texas, 250th Judicial District, against Pioneer Natural Resources Company; Pioneer Natural Resources USA, Inc.; Woodside Energy (USA), Inc. (Woodside); and JPMorgan Chase Bank, N.A., as Trustee of the Mesa Offshore Trust (Case No. GN501113). On November 28, 2005, Plaintiff amended its petition. In the amended petition, MHLP asserts claims against Pioneer and Woodside for matters including (1) a wrongful farmout of Brazos A-39 by Pioneer, (2) a wrongful delay by Pioneer in producing Brazos A-39, (3) fraudulent accounting practices by Pioneer, (4) breach of fiduciary duty by Pioneer, (5) aiding and abetting breach of fiduciary duty by Woodside, (6) misapplication of Trust property by Pioneer, (7) conspiracy to misapply fiduciary property by Woodside and Pioneer, (8) common law fraud by Pioneer, (9) gross negligence by Pioneer, and (10) breach of the conveyance agreement by Pioneer. MHLP asserts claims for damages against the Trustee for (1) an accounting; and (2) breach of fiduciary duty. The plaintiff remedies being sought include (a) reconstruing the Trust Indenture to determine that the Trust is not terminated because there has or should have been production which would have generated revenues to extend the life of the Trust, (b) requiring the Trustee to pursue certain claims, or to allow plaintiff to pursue such claims, (c) setting aside any farmouts by Pioneer in which there have been conveyances to an affiliate of Pioneer in violation of the Trust’s Conveyance and as a self-dealing transaction, (d) removing JPMorgan Chase Bank, N.A. as Trustee; (e) seeking return or forfeiture of compensation to JPMorgan Chase Bank, N.A. (f) recovering monetary damages against Pioneer, Woodside and JPMorgan Chase Bank, N.A., and (g) pursuing exemplary damages against all defendants.

On November 30, 2005, JPMorgan Chase Bank, N.A. announced its intention to resign as Trustee of the Mesa Offshore Trustee effective January 31, 2006. Since that announcement, MHLP and others have sought a qualified institution willing to serve as successor Trustee. However, neither MHLP nor Pioneer have identified a willing qualified successor Trustee that is not also a lender under one of Pioneer’s credit facilities (which status MHLP contends is an alleged conflict of interest).

On Friday, January 27, 2006, a hearing was held in the 334th Judicial District Court of Harris County, Texas, regarding MHLP’s Verified Application for Emergency Appointment of a Temporary Trustee in Case No. 2006-01984, MOSH Holding, L.P. v. Pioneer Natural Resources Company; Pioneer Natural Resources USA, Inc; Woodside Energy (USA), Inc.; and JPMorgan Chase Bank, N.A., as Trustee of the Mesa Offshore Trust. This case follows the transfer of prior claims filed by the plaintiff in Case No. GN501113. At this hearing, the court declined to approve MHLP’s motion to appoint Timothy J. Roberson, a principal and affiliate of the plaintiff, as temporary Trustee and declined to appoint any other person as temporary or successor Trustee.

In light of this development, and the absence of an identified successor Trustee, JPMorgan Chase Bank, N.A. withdrew its resignation as Trustee. The Trustee continues to desire the appointment of a qualified successor Trustee.

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To date, the Trustee has allowed MHLP to proceed on the issue of whether the farmout by Pioneer was a valid farmout, and the lawsuit remains in a phase where the parties are attempting to discover information about the claims and allegations. While Pioneer has provided a reasoned analysis of why it believes the farmout was in fact valid under the terms of the conveyance, only a court, and not the Trustee, can make a final determination. Further, while the plaintiff’s claims on the farmout issue may merit adjudication, based on facts known to the Trustee at this time, the Trustee is unable to determine, even if the plaintiff prevailed on its uncertain liability claims, whether the Trust would realize any economic benefit. Based on information received to date, the Trustee has not concluded that it would be in the best interest of the unitholders to fund the MHLP claims directly with Trust funds. However, as noted above, the Trustee has not opposed the plaintiff’s pursuit of its claims on behalf of the unitholders at their own expense, which reasonable expenses would be subject to repayment if the claims proved successful and a benefit were conferred upon all Unitholders of the Trust. In connection with both the anticipated sale of Trust properties pursuant to the Trust’s termination and the pending litigation, the Trustee has (1) engaged an independent reserve engineer to review the estimated reserves and (2) had an independent joint venture auditor review certain historical expenditures and revenue receipts on Trust properties. The Trustee believes expenditures for these reviews were prudent and in the interest of the unitholder.

The Trustee will make the full detail of the underlying data of the December 31, 2005 reserve report available for use in connection with the sale of the Trust properties as part of the Trust termination. For more information regarding the estimated remaining life of each of the Royalty Properties, the estimated future net revenues of the Royalty Properties and information relating to farm-outs of interests on the Royalty Properties based on information provided by PNR to D&M, see pages 22 and 23 of this Form 10-K and Note 6 in the Notes to Financial Statements included elsewhere in this Form 10-K. The sale of the assets of the Trust estate will include the related rights to abandonment accruals made by PNR. As explained in “Regulation and Prices—Platform Abandonment and Removal” below, PNR withholds from the Trust a reserve to cover its share of those future abandonment and removal costs. To the extent a certain party is able to complete the abandonment for an amount less than the funds withheld by PNR, the related rights to the abandonment accrual are likely to be deemed marketable. The final distribution to unitholders will be an amount net of funds required to satisfy all Trust liabilities.

TIMING OF LIQUIDATION

In connection with this litigation, the Trustee has agreed that it will give MHLP at least 60 days notice prior to the sale of any Trust properties in connection with the termination of the Trust. As of the date of this filing, based on the information currently provided by Pioneer and the preliminary state of the proceeding, the Trustee has not made any definitive conclusions as to the validity of the claims asserted by MHLP. However, the review of reserves by the independent reserve engineer has not shown the existence of significant reserves not previously included in the reserve report prepared by Pioneer in quantities originally alleged in the plaintiff’s petition.

As part of the termination procedures, the Trustee engaged an independent joint venture auditor in October 2004 to review the Trust properties as part of the termination of the Trust. The joint venture auditor reviewed the periods from 2003 through 2004. The Trustee believed this engagement of an outside expert on these matters to be a prudent step to identify any potential benefits to the Trust, as well as any limitations on potential benefits, due to differing interpretations of accounting matters that commonly occur in the oil and gas production industry. The review of the independent joint venture auditor was completed in December 2005, and it was the joint venture auditor’s opinion that the charges and credits and revenue to the Trust were in accordance with the applicable agreements, except for certain items noted in the report. The report notes exceptions, which may or may not turn out to be meritorious, as to amounts due to the Trust of $204,219. PNR, Stone Energy (Stone) and Newfield  Exploration Company (Newfield) have received a copy of the report and have 180 days to respond to these findings. As of March 15, 2006, PNR, Stone and Newfield have not yet responded to the findings in this report.

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Due to the pending litigation, the Trustee cannot predict the timing of the sale of all or a portion of the Trust properties as part of the Trust Termination.

Assets and Liabilities in the Process of Liquidation

As a result of the contractual termination of the Trust effective January 1, 2005, the Trust is in the process of liquidation. The below table presents the assets of the Trust at their estimated fair value:

	December 31, 2005
ASSETS
Cash and short term investments		$	1,846,798
Interest receivable		1,582
Net overriding royalty interest in oil and gas properties		4,831,237
Total assets		6,679,617
LIABILITIES
Reserve for Trust expenses		$	1,848,380
Total liabilities		1,848,380
Net assets in process of liquidation		$	4,831,237

The net overriding royalty interest in oil and gas properties at December 31, 2005 reflect the Trustee’s estimate of value (in the absence of third-party appraisals or evaluations), based on the Trust’s share of future net revenues from the net overriding royalty interest in the properties as of December 31, 2005. This estimate is based on the Trustee’s current assessment of the impact of selling existing assets based on current market conditions, and includes the following assumptions:

·The Trust’s estimated share of oil and gas reserve volumes at December 31, 2005, were derived from the reserve report prepared by DeGolyer and MacNaugton (D&M). The Trust’s estimated share of oil and gas reserve volumes at December 31, 2005 include reserves related to the Midway Prospect.(1)

·Forward strip commodity prices on December 31, 2005 for the life of the reserves.

·Exclusion of estimated future abandonment costs.(2)

·Discount rate of 10%.

(1)As a result of the litigation described above, the Trust had been unable to obtain necessary information from the working interest owner regarding such owner’s own current estimate of the fair value of the proved reserves on the Midway Prospect. The Trustee engaged D&M, an independent reserve engineer, to review all oil and gas reserves pertaining to the Royalty, including the Midway Prospect reserves and the Trust’s interest in these reserves as of December 31, 2005.

(2)The sale of the assets currently owned by the Partnership will include the related rights to abandonment costs previously withheld by the working interest owner. The working interest owner has withheld funds to cover the Trust’s share of future abandonment and removal costs. To the extent the abandonment is completed for an amount less than the funds withheld by the working interest owner, those funds would be distributed to the Trust. Therefore, estimated future abandonment costs are not reflected as a reduction of future net revenue.

The actual net proceeds from the sales of oil and gas properties may vary substantially from these estimates in value due to changes in current and estimated future oil and gas prices, subsequent production, estimates of actual abandonment costs and other factors which may be applied by the buyers.

11

For all other assets presented in the above table, the Trustee believes that historical cost approximates fair market value due to the short-term nature of such assets. The Trustee will continue to reserve funds to recoup its previously established reserves to pay Trust expenses, which will primarily consist of expenses incurred by the Trustee to liquidate the Trust’s assets. Any funds remaining after all expenses have been paid will be distributed to the Unitholders.

For more information regarding the estimated remaining life of each of the Royalty Properties, the estimated future net revenues of the Royalty Properties and information relating to farm-outs of interests on the Royalty Properties based on information provided by PNR to D&M, see pages 22 and 23 of this Form 10-K and Note 6 in the Notes to Financial Statements included elsewhere in this Form 10-K. The sale of the assets of the Trust estate will include the related rights to abandonment accruals made by PNR. As explained in “Regulation and Prices—Platform Abandonment and Removal” on page 26 of this Form 10-K, PNR withholds from the Trust a reserve to cover its share of those future abandonment and removal costs. To the extent a certain party is able to complete the abandonment for an amount less than the funds withheld by PNR, the related rights to the abandonment accrual are likely to be deemed marketable. The final distribution to untiholders will be an amount net of funds required to satisfy all Trust liabilities.

DESCRIPTION OF ROYALTY PROPERTIES

Producing Acreage and Wells as of December 31, 2005

			Producing Wells(1)
	Producing Acres		Gross				Net
Property	Gross	Net(2)	Oil		Gas		Oil		Gas
Offshore Louisiana(3)—
West Delta 61	5,000	3,750		—		4		—		.5
Offshore Texas(4)—
Brazos A-7	5,760	2,160		—		1		—		.1
Brazos A-39	5,760	2,160		—		—		—		—
Total	16,520	8,070		—		5		—		.6

(1)Dual completions are counted as one well. For information regarding wells producing at December 31, 2005, see page 34 of this Form 10-K. As of January 31, 2006, only the wells on Brazos A-7 and West Delta 61 were producing.

(2)Net Producing Acres are calculated by multiplying gross producing acres by the net Royalty interest (as defined by the Trust Indenture) attributable to the Trust for each property.

(3)All wells on South Marsh Island 155 and 156 leases were plugged and abandoned in 2002. PNR abandoned the platform for these two properties in 2003. All wells were plugged and abandoned and the platform was abandoned on West Delta 62 during 2003 and the lease was relinquished.

(4)All wells were plugged and abandoned and the platform was abandoned on Matagorda Island 624 during 2003 and the lease was relinquished.

12

DEGOLYER AND MACNAUGHTON
5001 SPRING VALLEY ROAD
SUITE 800 EAST
DALLAS, TEXAS 75244

APPRAISAL REPORT
as of
DECEMBER 31, 2005
on
CERTAIN INTERESTS
owned by
MESA OFFSHORE TRUST
prepared for
JPMORGAN CHASE BANK, N.A.

13

TABLE of CONTENTS

	Page
FOREWORD		15
Scope of Investigation		15
Authority		16
Source of Information		16
CLASSIFICATION of RESERVES		16
ESTIMATION of RESERVES		17
VALUATION of RESERVES		18
SUMMARY and CONCLUSIONS		19
APPENDIX

14

DEGOLYER AND MACNAUGHTON
5001 SPRING VALLEY ROAD
SUITE 800 EAST
DALLAS, TEXAS 75244

APPRAISAL REPORT
as of
DECEMBER 31, 2005
on
CERTAIN INTERESTS
owned by
MESA OFFSHORE TRUST
prepared for
JPMORGAN CHASE, N.A.

FOREWORD

Scope of Investigation

This report presents an appraisal, as of December 31,2005, of the extent and value of the proved and probable crude oil, condensate, and natural gas reserves of working and royalty interests in certain properties owned by the Mesa Offshore Trust (MOST) located offshore from Louisiana and Texas in the Gulf of Mexico. Also presented are estimates of the extent only of the possible oil, condensate, and gas reserves. The Managing General Partner is Pioneer Natural Resources USA Inc. (PNR). This report was prepared at the request of JPMorgan Chase Bank, N.A. (JPMorgan Chase), trustee for MOST.

Reserves estimated in this report are expressed as gross and net reserves. Gross reserves are defined as the total estimated petroleum to be produced from these properties after December 31,2005. Net reserves are defined as that portion of the gross reserves attributable to MOST’s interests after deducting royalties and interests owned by others.

This report presents values that were estimated for proved and proved-plus-probable reserves using initial prices provided by JPMorgan Chase and initial costs provided by PNR. Future price and cost assumptions were provided by JPMorgan Chase. A detailed explanation of the price and cost assumptions used herein is included in the Valuation of Reserves section of this report.

Values are expressed in terms of estimated future gross revenue, future net revenue, and present worth. Future gross revenue is that revenue which will accrue from the production and sale of the estimated net reserves. Future net revenue is calculated by deducting estimated operating expenses and capital costs from the future gross revenue. Operating expenses include field operating expenses and the estimated expenses of direct supervision but do not include that portion of general administrative costs sometimes allocated to production. Future income tax expenses were not taken into account in the preparation of these estimates. Present worth is defined as future net revenue discounted at a specified arbitrary discount rate compounded monthly over the expected period of realization. In this report, present worth values using a nominal discount rate of 10 percent are reported in detail and values using nominal discount rates of 5, 15, 20, and 25 percent are reported as totals in the appendix to this report.

Estimates of oil, condensate, and gas reserves and future net revenue should be regarded only as estimates that may change as further production history and additional information become available. Not only are such reserves and revenue estimates based on that information which is currently available, but

15

such estimates are also subject to the uncertainties inherent in the application of judgmental factors in interpreting such information.

Authority

This report was authorized by Mr. Mike Ulrich, Vice President, JPMorgan Chase.

Source of Information

Information used in the preparation of this report was obtained from PNR’sfiles on behalf of JPMorgan Chase, from records on file with the appropriate regulatory agencies, and from public sources. In the preparation of this report we have relied, without independent verification, upon such information furnished by PNR and JPMorgan Chase with respect to property interests, production from such properties, current costs of operation and development, current prices for production, the future plans for development of the properties, agreements relating to current and future operations and sale of production, and various other information and data that were accepted as represented. A field examination of the properties was not considered necessary for the purposes of this report.

CLASSIFICATION of RESERVES

Petroleum reserves are classified by degree of proof as proved, probable, or possible. Proved reserves are judged to be economically producible in future years from known reservoirs under existing economic and operating conditions and assuming continuation of current regulatory practices using conventional production methods and equipment. In the analyses of production-decline curves, reserves were estimated only to the limit of economic rates of production under existing economic and operating conditions using prices and costs as of the date the estimate is made, including consideration of changes in existing prices provided only by contractual arrangements but not including escalations based upon future conditions. The petroleum reserves are classified as follows:

Proved—Reserves that have been proved to a high degree of certainty by analysis of the producing history of a reservoir and/or by volumetric analysis of adequate geological and engineering data. Commercial productivity has been established by actual production, successful testing, or in certain cases by favorable core analyses and electrical-log interpretation when the producing characteristics of the formation are known from nearby fields. Volumetrically, the structure, areal extent, volume, and characteristics of the reservoir are well defined by a reasonable interpretation of adequate subsurface well control and by known continuity of hydrocarbon-saturated material above known fluid contacts, if any, or above the lowest known structural occurrence of hydrocarbons.

Developed—Reserves that are recoverable from existing wells with current operating methods and expenses.

Developed reserves include both producing and nonproducing reserves. Estimates of producing reserves assume recovery by existing wells producing from present completion intervals with normal operating methods and expenses. Developed nonproducing reserves are in reservoirs behind the casing or at minor depths below the producing zone and are considered proved by production from other wells in the field, by successful drill-stem tests, or by core analyses from the particular zones. Nonproducing reserves require only moderate expense to be brought into production.

Undeveloped—Reserves that are recoverable from additional wells yet to be drilled.

Undeveloped reserves are those considered proved for production by reasonable geological interpretation of adequate subsurface control in reservoirs that are producing or proved by other wells but are not recoverable from existing wells. This classification of reserves requires drilling of

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additional wells, major deepening of existing wells, or installation of enhanced recovery or other facilities.

Probable—Reserves susceptible of being proved that are based on reasonable evidence of producible hydrocarbons within the limits of a structure or reservoir above known or inferred fluid contacts but are defined to a lesser degree of certainty because of more limited well control and/or the lack of definitive production tests. Probable reserves may include extensions of proved reservoirs or other reservoirs that have not been tested at commercial rates of flow or reserves recoverable by enhanced recovery methods that have not yet been tested in the same reservoir or where there is reasonable uncertainty that the program will be implemented.

Possible—Reserves that may exist but are less well defined by well control than probable reserves. Possible reserves include those based largely on log interpretation and other evidence of hydrocarbon saturation in zones behind the pipe in existing wells, possible extensions to proved and probable reserves areas where indicated by geophysical or geological studies, and those to be recovered by enhanced recovery methods where the data are insufficient to classify the reserves as proved or probable.

The extent to which probable and possible reserves ultimately may be reclassified as proved reserves is dependent upon future drilling, testing, and well performance. The degree of risk to be applied in evaluating probable and possible reserves is influenced by economic and technological factors as well as the time element. Probable and possible reserves in this report have not been adjusted in consideration of these additional risks and therefore are not comparable with proved reserves.

ESTIMATION of RESERVES

Estimates of reserves were prepared by the use of standard geological and engineering methods generally accepted by the petroleum industry. The method or combination of methods used in the analysis of each reservoir was tempered by experience with similar reservoirs, stage of development, quality and completeness of basic data, and production history.

The volumetric method was used to estimate the original oil in place (OOIP) and original gas in place (OGIP). Structure maps were prepared to delineate each reservoir, and isopach maps were constructed to estimate reservoir volume. Electrical logs, radioactivity logs, core analyses, and other available data were used to prepare these maps as well as to estimate representative values for porosity and water saturation.

Estimates of ultimate recovery were obtained after applying recovery factors to OOIP or OGIP. These recovery factors were based on consideration of the type of energy inherent in the reservoirs, analyses of the petroleum, and the structural positions of the properties.

The rates used for future oil, condensate, and gas production are estimated to be within the capacity of a well or reservoir to produce. Data available from wells drilled on the appraised properties through December 31, 2005, were used to prepare the estimates shown herein. Gross production through December 31,2005, was deducted from the gross ultimate recovery to arrive at estimates of gross reserves. Production from the properties was halted in the third quarter of 2005 as a result of hurricanes. Production is expected to resume in the first quarter of 2006.

Gas volumes estimated herein are expressed as sales gas at a temperature base of 60 degrees Fahrenheit (°F) and a pressure base of 14.73 pounds per square inch absolute (psia). Sales gas is defined as the total gas to be produced from the reservoirs, measured at the point of delivery, after reduction for fuel usage, flare, and shrinkage resulting from field separation and processing. Condensate reserves estimated herein are those to be obtained by normal separator recovery.

17

Estimates of the gross and net proved, probable, and possible reserves, as of December 31,2005, of the properties appraised are presented as follows. Oil and condensate reserves are expressed in barrels (bbl) and gas reserves are expressed in thousands of cubic feet (Mcf).

	Oil and Condensate (bbl)		Sales Gas (Mcf)
Gross Reserves
Proved		141,777	7,083,449
Probable(1)		40,919	5,351,000
Possible(1)		25,590	8,530,000
Net Reserves
Proved		10,766	460,055
Probable(1)		2,818	293,244
Possible(1)		1,281	426,500

(1)Probable and possible reserves have not been risk adjusted.

VALUATION of RESERVES

This report has been prepared using initial prices provided by JPMorgan Chase and initial costs provided by PNR on behalf of JPMorgan Chase. Future prices were estimated using guidelines established by the United States Securities and Exchange Commission (SEC) and the Financial Accounting Standards Board (FASB). In this report, values for proved and proved-plus-probable reserves were based on projections of estimated future production and revenue prepared for these properties with no risk adjustment applied to the probable reserves. Probable reserves involve substantially higher risks than proved reserves. Revenue values for proved-plus-probable reserves have not been adjusted to account for such risks; this adjustment would be necessary in order to make values for proved-plus-probable reserves comparable with values for proved reserves.

Oil and Condensate Prices

Initial oil and condensate prices furnished by JPMorgan Chase, after adjustments for differentials, varied from $57.61 to $58.01 per barrel and were held constant for the producing lives of the properties.

Natural Gas Prices

The natural gas prices also furnished by JPMorgan Chase, after adjustments for differentials, varied from $7.31 to $9.86 per thousand cubic feet of gas and were held constant for the producing lives of the properties.

Operating Expenses and Capital Costs

Estimates of the operating expenses were provided by PNR and were held constant for the lives of the properties. Future capital expenditures were provided by PNR using current values and were held constant to the date of the expenditure.

Abandonment Costs and Salvage Value

Costs for abandonment of the working-interest well were offset by the salvage value estimated by PNR.

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The estimated future revenue to be derived from the production and sale of MOST’s net proved and proved-plus-probable reserves, as of December 31, 2005, under the economic assumptions furnished by JPMorgan Chase is summarized as follows:

	Proved ($)	Proved plus Probable(1) ($)
Future Gross Revenue	4,625,213		7,114,303
Operating Expenses	64,641		64,641
Capital Costs	0		0
Future Net Revenue(2)	4,560,572		7,049,662
Present Worth at 10 Percent(2)	3,821,991		5,745,130

(1)There has been no adjustment to the value of the probable reserves to account for risk.

(2)Future income tax expenses were not taken into account in the preparation of these estimates.

The appendix bound with this report presents tabulations and projections of revenue from the proved and non-risk-adjusted proved-plus-probable reserves for the interests appraised. Also included are summaries of the probable and possible reserves.

In our opinion, the information relating to estimated proved reserves, estimated future net revenue from proved reserves, and present worth of estimated future net revenue from proved reserves of oil, condensate, and gas contained in this report has been prepared in accordance with Paragraphs 10-13, 15 and 30(a)-(b) of Statement of Financial Accounting Standards No. 69 (November 1982) of the FASB and Rules 4-10(a) (1)-(13) of Regulation S-X and Rule 302(b) of Regulation S-K of the SEC; provided, however, that (i) certain estimated data have not been provided with respect to changes in reserves information and (ii) future income tax expenses have not been taken into account in estimated the future net revenue and present worth values set forth herein. Other rules and regulations of the SEC contain specific provisions that prohibit the reporting of probable and possible reserves; therefore, the reporting and filing with the SEC of the probable or possible reserves and the values based on proved-plus-probable reserves contained herein would not be in conformity with such rules and regulations and should not, under any circumstances, be used or relied upon to meet the requirements thereof.

To the extent the above-enumerated rules, regulations, and statements require determinations of an accounting or legal nature or information beyond the scope of our report, we are necessarily unable to express an opinion as to whether the above-described information is in accordance therewith or sufficient therefore.

SUMMARY and CONCLUSIONS

Evaluated herein are working and royalty interests in certain properties owned by MOST located offshore from Louisiana and Texas in the Gulf of Mexico. Estimates of MOST’s net proved, probable, and possible reserves, as of December 31, 2005, of the properties appraised are presented as follows. Oil and condensate reserves are expressed in barrels (bbl) and gas reserves are expressed in thousands of cubic feet (Mcf).

	Proved	Probable(1)		Possible(1)
Net Oil and Condensate, bbl	10,766		2,818		1,281
Net Sales Gas, Mcf	460,055		293,244		426,500

(1)Probable and possible reserves have not been risk adjusted.

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Revenue and costs attributable to MOST’s interests in the proved and proved-plus-probable reserves, as of December 31, 2005, of the properties evaluated under the aforementioned assumptions concerning future prices and costs are estimated as follows:

	Proved ($)	Proved plus Probable(1) ($)
Future Gross Revenue	4,625,213		7,114,303
Operating Expenses	64,641		64,641
Capital Costs	0		0
Future Net Revenue(2)	4,560,572		7,049,662
Present Worth at 10 Percent(2)	3,821,991		5,745,130

(1)There has been no adjustment to the value of the probable reserves to account for risk.

(2)Future income tax expenses were not taken into account in the preparation of these estimates.

20

Gas volumes estimated herein are expressed at a temperature base of 60 °F and a pressure base of 14.73 psia.

	Submitted,
	DeGOLYER and MacNAUGHTON
SIGNED: February 1, 2006
	Paul J. Szatkowski, P.E.
	Senor Vice President
	DeGolyer and MacNaughton

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Reserves

A study of the proved oil and gas reserves attributable to the Partnership as of December 31, 2005, has been made by D&M. The following letter (the “Reserve Report”) summarizes such reserve study. The Reserve Report reflects estimated reserve quantities and future net revenue based upon estimates of the future timing of actual production without regard to when received in cash by the Trust, which differs from the manner in which the Trust recognizes and accounts for its Royalty income. For further information regarding the Net Overriding Royalty Interest, the Basis of Accounting for the Trust and Supplemental Reserve Information, see Notes 2, 3 and 6, respectively, in the Notes to Financial Statements contained in Item 8 of this Form 10-K.

There are numerous uncertainties inherent in estimating quantities of proved reserves and in projecting the future rates of production and timing of development expenditures, including many factors beyond the control of the producer. The preceding reserve data in the Reserve Report represent estimates only and should not be construed as being exact. Reserve assessment is a subjective process of estimating the recovery from underground accumulations of gas and oil that cannot be measured in an exact way and estimates of other persons might differ materially from those of D&M. Accordingly, reserve estimates are often different from the quantities of hydrocarbons that are ultimately recovered.

Also, while estimates of reserves attributable to the Royalty Properties are shown in order to comply with requirements of the SEC, there is no precise method of allocating estimates of physical quantities of reserves between PNR and the Partnership, since the Royalty is not a working interest and the Partnership does not own and is not entitled to receive any specific volume of reserves from the Royalty. Reserve quantities in the previously mentioned reserve study have been allocated based on the method referenced in the Reserve Report. The quantities of reserves attributable to the Partnership will be affected by future changes in various economic factors utilized in estimating future gross and net revenues from the Royalty Properties. Therefore, the estimates of reserves set forth in the Reserve Report are to a large extent hypothetical and differ in significant respects from estimates of reserves attributable to a working interest.

Moreover, the discounted present values in the Reserve Report should not be construed as the current market value of the estimated gas and oil reserves attributable to the Royalty Properties or the costs that would be incurred to obtain equivalent reserves, since a market value determination would include many additional factors. In accordance with applicable regulations of the SEC, estimated future net revenues were based, generally, on current prices and costs, whereas actual future prices and costs may be materially greater or less. The estimates in the Reserve Report use market prices as of December 31, 2005. These prices (having weighted average year end prices of $57.61 to $58.01 per barrel and $7.31 to $9.86 per Mcf as of December 31, 2005) were held constant over the estimated life of the Royalty Properties. These prices were influenced by seasonal demand for natural gas and may not be the most appropriate or representative prices to use for estimating future revenues or related reserve data. The average price of natural gas sold from the Royalty Properties during 2005 was $7.01 per Mcf, representing a combination of contract prices and spot market prices, while the average price of crude oil, condensate and natural gas liquids was $48.97 per barrel.

22

The following is a summary of the estimated remaining life for each of the Royalty Properties provided to the Trustee by D&M as of December 31, 2005. There are numerous uncertainties present in estimating the remaining productive lives for the Royalty Properties. The following summary represents an estimate only and should not be construed as being exact. The estimated remaining productive life of each property varies depending on the recoverable reserves and annual production assumed by D&M. In addition, future economic and operating conditions may cause significant changes in these estimates.

Property	Productive Life(1)(2)
West Delta 61		7 years
Brazos A-7		2 years
Brazos A-39		2 years

(1)The Trust will terminate in the event the total amount of cash received per year by the Trust falls below certain levels. Accordingly, it would be possible for the Trust to terminate even though some of the Royalty Properties continued to have remaining productive lives. See “Legal Proceedings and Status of the Trust” on page 8 of this Form 10-K and see “Timing of Liquidation” on page 10 of this Form 10-K.

(2)Estimates of remaining lives may vary significantly from year to year.

The future net revenues contained in the Reserve Report have not been reduced for future general and administrative costs and expenses of the Trust, which are expected to approximate $500,000 annually.

The general and administrative costs and expenses of the Trust may increase in future years, depending on the amount of royalty income, increases in accounting, engineering, legal and other professional fees and other factors.

CONTRACTS

General

PNR has advised the Trust that during 2005 its offshore gas production was marketed under short-term contracts at spot market prices primarily to TOTAL S.A. PNR has further advised the Trust that it expects to continue to market its production under short-term contracts for the foreseeable future. Spot market prices for natural gas in 2005 were generally higher than spot market prices in 2004.

Market for Natural Gas

The amount of cash distributions by the Trust is dependent on, among other things, the sales prices for natural gas produced from the Royalty Properties and the quantities of gas sold. The natural gas industry in the United States during the 1990’s was affected generally by a surplus in natural gas deliverability in comparison to demand. Demand for gas declined during this period due to a number of factors including the implementation of energy conservation programs, a shift in economic activity away from energy intensive industries and competition from alternative fuel sources such as residual fuel oil, coal and nuclear energy. In late 2001 and early 2002, demand for natural gas increased as a result of the increase in clean burning natural gas fired power generation, the increase in the usage of electrical power fueled by the expanding U.S. economy and a return to seasonally cold winters. Annual wellhead prices generally increased from $2.95 per Mcf in 2002, increased to $5.09 per Mcf in 2003, to $5.49 per Mcf in 2004 and increased to $5.65 in 2005 according to the Natural Gas Monthly published by the Energy Information Administration of the Department of Energy.

The seasonal nature of demand for natural gas and its effects on sales prices and production volumes may cause the amounts of cash distributions by the Trust to vary substantially on a seasonal basis. Generally, production volumes and prices are higher during the first and fourth quarters of each calendar

23

year due primarily to peak demand in these periods. Because of the time lag between the date on which PNR receives payment for production from the Royalty Properties and the date on which distributions are made to unitholders, the seasonality that generally affects production volumes and prices is generally reflected in distributions to unitholders in later periods.

Competition

The production and sale of gas from the areas in which the Royalty Properties are located is highly competitive and PNR has a number of competitors in these areas. PNR has advised the Trust that it believes that its competitive position in these areas is affected by price, contract terms and quality of service. PNR’s business is affected not only by such competition, but also by general economic developments, governmental regulations and other factors.

Marketing of Liquids

PNR generally reserves in its gas purchase contracts the right to extract condensate and other liquid and liquefiable hydrocarbons from all gas produced. PNR is currently selling the condensate and other liquids to various purchasers under contracts with terms of one year or less.

REGULATION AND PRICES

General

The production and sale of natural gas from the Royalty Properties are affected from time to time in varying degrees by political developments and federal, state and local laws and regulations. In particular, oil and gas production operations and economics are, or in the past have been, affected by price controls, taxes, conservation, safety, environmental and other laws relating to the petroleum industry, by changes in such laws and by constantly changing administrative regulations.

Operating Hazards and Uninsured Risks

PNR’s oil and gas activities are subject to all of the risks normally incident to exploration for and production of oil and gas, including blowouts, cratering and fires, each of which could result in damage to life and property. Offshore operations are subject to a variety of operating risks, such as hurricanes and other adverse weather conditions and lack of access to existing pipelines or other means of transporting production. Furthermore, offshore oil and gas operations are subject to extensive governmental regulations, including certain regulations that may, in certain circumstances, impose absolute liability for pollution damages, and to interruption or termination by governmental authorities based on environmental or other considerations. In accordance with customary industry practices, PNR carries insurance against some, but not all, of these risks. Losses and liabilities resulting from such events would reduce revenues and increase costs to the Trust to the extent not covered by insurance.

FERC Regulation

In general, the FERC regulates the transportation of natural gas in interstate commerce by interstate pipelines. Over the course of approximately the previous decade, the FERC adopted regulations resulting in a restructuring of the natural gas industry. The principal elements of this restructuring were the requirements that interstate pipelines separate, or “unbundle,” into individual components the various services offered on their systems, with all transportation services to be provided on a non-discriminatory basis, and the prohibition against an interstate pipeline providing gas sales services except through separately-organized affiliates. In various rulemaking proceedings following its initial unbundling requirement, the FERC has refined its regulatory program applicable to interstate pipelines in various respects, and it has announced that it will continue to monitor these regulations to determine whether

24

further changes are needed. As to these various developments, the working interest owners have advised the Trust that the on-going and evolving nature of these regulatory initiatives makes it impossible to predict their ultimate impact on the prices, markets or terms of sale of natural gas related to the Trust.

State and Other Regulation

State regulation of gathering facilities generally includes various safety, environmental, and in some circumstances, non-discriminatory take requirements. Some states have implemented more stringent legislation in recent years to regulate gathering rates charged by gas gathering companies, but to date the effect to PNR in connection with the Royalty Properties has been minimal.

Natural gas pipeline facilities used for the transportation of natural gas in interstate commerce are subject to Federal minimum safety requirements. These requirements, however, are not applicable to, inter alia,: (1) onshore gathering facilities outside: (i) the limits of any incorporated or unincorporated city, town, or village; and (ii) any designated residential or commercial area; or (2) pipeline facilities on the Outer Continental Shelf (“OCS”) upstream of the point at which operating responsibility transfers from a producing operator to a transporting operator. See 49 C.F.R. § 192.1(b). We are informed that the Royalty Properties are located in Federal waters on the OCS. The standards governing pipeline safety have undergone recent changes and it is possible that future changes in the regulations and statutes may occur which may increase the stringency of the standards or expand the applicability of the standards to facilities not currently covered.

Environmental

PNR’s operations are subject to numerous federal, state and local laws and regulations controlling the discharge of materials into the environment or otherwise relating to the protection of the environment, including the Comprehensive Environmental Response, Compensation and Liability Act (“CERCLA” or “Superfund”), the Solid Waste Disposal Act, the Clean Air Act, and the Federal Water Pollution Control Act. These laws and regulations, including their state counterparts, can impose liability upon the lessee under a lease for the cost of cleanup of discharged materials resulting from a lessee’s operations or can subject the lessee to liability for damages to natural resources. Violations of environmental laws, regulations, or permits can result in civil and criminal penalties as well as potential injunctions curtailing operations in affected areas and restrictions on the injection of liquids into the subsurface that may contaminate groundwater. PNR maintains insurance for costs of cleanup operations, but it is not fully insured against all such risks. A serious release of regulated materials could result in the U.S. Department of the Interior requiring lessees under federal leases to suspend or cease operations in the affected area. In addition, the recent trend toward stricter standards and regulations in environmental legislation is likely to continue. For example, legislation has been proposed in Congress that would reclassify certain oil and gas production wastes as “hazardous wastes” which would subject the handling, disposal and cleanup of these wastes to more stringent requirements and result in increased operating costs for the Royalty Properties, as well as the oil and gas industry in general. State initiatives to further regulate the disposal of oil and gas wastes are also pending in certain states, and these initiatives could have a similar impact on the Royalty Properties.

From time to time, federal and state environmental agencies propose regulations which could have a direct and material impact on PNR’s operations. For example, under the Oil Pollution Act of 1990, as amended by the Coast Guard Authorization Act of 1996 (collectively, “OPA”), parties responsible for offshore facilities must establish and maintain evidence of oil-spill financial responsibility (“OSFR”) for costs attributable to potential oil spills. OPA requires a minimum of $35 million in OSFR for offshore facilities located on the OCS. This amount is subject to upward regulatory adjustment up to $150 million. Responsible parties for more than one offshore facility are required to provide OSFR only for their offshore facility requiring the highest OSFR. In 1998, the Minerals Management Service (“MMS”)

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adopted regulations for establishing the amount of OSFR required for particular facilities. The amount of OSFR increases as the volume of a facility’s worst-case oil spill increases. Accordingly, for facilities with worst-case spills of less than 35,000 barrels, only $35 million in OSFR is required; for worst-case spills of over 35,000 barrels, $70 million is required; for worst-case spills of over 70,000 barrels, $105 million is required; and for worst-case spills of over 105,000 barrels, $150 million is required. In addition, all OSFR below $150 million remains subject to upward regulatory adjustment if warranted by the particular operational, environmental, human health or other risks involved with a facility. Under this regulation, PNR is required to maintain $35 million in OSFR for its offshore facilities. PNR is maintaining its OSFR in this amount by insurance. Although the working interest owners have advised the Trust that current environmental regulation has had no material adverse effect on the working interest owners’ present method of operations, the impact of the recently adopted regulatory changes, and of future environmental regulatory developments such as stricter environmental regulation and enforcement policies, cannot presently be quantified. By letter dated November 9, 1995, PNR was advised by the MMS that it does not qualify for a waiver from supplemental bond requirements and that PNR may be required to post supplemental bonds covering its potential obligations with respect to offshore operations. PNR executed a guaranty of abandonment liability (area wide) with the MMS on April 26, 1996, in satisfaction of these obligations.

PNR has advised the Trust that it is not involved in any administrative or judicial proceedings relating to the Royalty Properties arising under federal, state, or local environmental protection laws and regulations which would have a material adverse effect on the Trust’s financial position or results of operations.

Platform Abandonment and Removal

PNR is responsible for the abandonment and removal of its offshore drilling and production structures within one year after the cessation of production, although extensions can be requested. PNR withholds from the Trust a reserve to cover its share of those future abandonment and removal costs. See Item 7 and Note 3 in the Notes to Financial Statements for amounts withheld as of December 31, 2005 and amounts to be withheld in the future.

Item 1A.     Risk Factors.

Although risk factors are described elsewhere in this Form 10-K together with specific Cautionary Statements, the following is a summary of the principal risks associated with an investment in units in the Trust.

Natural gas and oil prices fluctuate due to a number of factors, and lower prices will reduce net proceeds available to the Trust and distributions to Trust unitholders.

The Trust’s quarterly distributions are highly dependent upon the prices realized from the sale of natural gas and oil. Natural gas and oil prices can fluctuate widely on a month-to-month basis in response to a variety of factors that are beyond the control of the Trust and the working interest owners. Factors that contribute to price fluctuation include, among others: political disruption, war, or other armed conflict in oil producing regions, in particular the war in Iraq; worldwide economic conditions; weather conditions; the supply and price of foreign natural gas and oil; the level of consumer demand; the price and availability of alternative fuels; the proximity to, and capacity of, transportation facilities; and the effect of worldwide energy conservation measures.

Moreover, government regulations, such as regulation of natural gas and oil transportation and price controls, can affect product prices in the long term.

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Lower natural gas and oil prices may reduce the amount of natural gas that is economic to produce and reduce net profits available to the Trust. The volatility of energy prices reduces the predictability of future cash distributions to unitholders. Substantially all of the natural gas and natural gas liquids produced from the Royalty Properties is being sold on the spot market or under short-term contracts.

Increased production and development costs for the Royalty will result in decreased Trust distributions.

Production and development costs attributable to the Royalty are deducted in the calculation of the Trust’s share of net proceeds. Accordingly, higher or lower production and development costs, without concurrent increases in revenues, directly decrease or increase the amount received by the Trust for the Royalty.

If development and production costs of the Royalty exceed the proceeds of production from the Royalty Properties, the Trust will not receive net proceeds for those properties until future proceeds from production exceed the total of the excess costs plus accrued interest during the deficit period. Development activities may not generate sufficient additional revenue to repay the costs.

Trust reserve estimates depend on many assumptions that may prove to be inaccurate, which could cause both estimates of reserves and estimated future revenues to be too high or too low.

The value of the units of beneficial interest of the Trust depends upon, among other things, the amount of reserves attributable to the Royalty and the estimated future value of the reserves. Estimating reserves is inherently uncertain. Ultimately, actual production, revenues and expenditures for the underlying properties will vary from estimates and those variations could be material. Petroleum engineers consider many factors and make assumptions in estimating reserves. Those factors and assumptions include:

·historical production from the area compared with production rates from similar producing areas;

·the assumed effect of governmental regulation; and

·assumptions about future commodity prices, production and development costs, severance and excise taxes, and capital expenditures.

Changes in these assumptions can materially change reserve estimates.

The reserve quantities attributable to the Royalty and revenues are based on estimates of reserves and revenues for the underlying properties. The method of allocating a portion of those reserves to the Trust is complicated because the Trust holds an interest, indirectly through the Partnership, in the Royalty and does not own a specific percentage of the natural gas reserves.

The Trustee also relies entirely on reserve estimates and related information prepared by PNR and the independent  reserve engineer engaged by the Trust. While the Trustee has no reason to believe the reserve estimates and related estimates of value included in this report are not accurate, to the extent additional information exists that could affect their reserve estimates, the estimated reserves in these reports and related estimates of value could also be too low.

Estimates and accruals of costs by PNR may be greater or lesser than future estimated or actual costs.

As discussed in Item 7 and Note 3 to the Notes to Financial Statements, at December 31, 2005 PNR has withheld approximately $348,066 for future abandonment costs. To the extent future estimated or actual abandonment costs exceed this amount, PNR would be entitled to withhold such amounts from payments with respect to the Royalty. Similarly, to the extent future estimated or actual abandonment

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costs are less than this amount, PNR may release such amounts. In connection with the termination of the Trust and sale of the Royalty Properties, the rights to these accrued abandonment costs will be included together with the other assets being sold. Only unitholders at the time of any such release or sale and the applicable distribution would be entitled to the distribution by the Trust.

Operating risks for the working interest owners’ interests in the Royalty Properties can adversely affect Trust distributions.

The occurrence of drilling, production or transportation accidents at any of the Royalty Properties will reduce Trust distributions by the amount of uninsured costs. These occurrences include blowouts, cratering, explosions and other environmental damage. Offshore activities are also subject to a variety of operating risks such as hurricanes and other weather disturbances. These accidents and other natural disasters may result in personal injuries, property damage, damage to productive formations or equipment and environmental damages. Any uninsured costs would be deducted as a production cost in calculating net proceeds payable to the Trust.

The operators of the working interests are subject to extensive governmental regulation.

Offshore oil and gas operations have been, and in the future will be, affected by federal, state and local laws and regulations and other political developments, such as price or gathering rate controls and environmental protection regulations. These regulations and changes in regulations could have a material adverse effect on Royalty income payable to the Trust.

None of the Trustee, the Trust nor its unitholders control the operation or development of the Royalty Properties and have little influence over operation or development.

Neither the Trustee nor the unitholders can influence or control the operation or future development of the underlying properties. The Royalty Properties are owned by PNR as an independent working interest owner. The working interest owner manages the underlying properties and handles receipt and payment of funds relating to the Royalty Properties and payments to the Trust for the Royalty.

PNR, as the current working interest owner, is under no obligation to continue operating the properties. Neither the Trustee nor the unitholders have the right to replace an operator.

The Trustee relies upon the working interest owners and managing general partner for information regarding the Royalty Properties.

The Trustee relies on the working interest owners and managing general partner for information regarding the Royalty Properties. The working interest owners alone control (i) historical operating data, including production volumes, marketing of products, operating and capital expenditures, environmental and other liabilities, effects of regulatory changes and the number of producing wells and acreage, (ii) plans for future operating and capital expenditures, (iii) geological data relating to reserves, as well as related projections regarding production, operating expenses and capital expenses used in connection with the preparation of the reserve report, (iv) forward-looking information relating to production and drilling plans and (v) information regarding the Royalty Properties responsive to litigation claims. While the Trustee requests material information for use in periodic reports as part of its disclosure controls and procedures, the Trustee does not control this information and relies entirely on the working interest owners to provide accurate and timely information when requested for use in the Trust’s periodic reports. The Trustee also relies on the managing general partner of the Partnership to collect certain information from the working interest owners and does not have any direct contact with the working interest owners other than the managing general partner. Under the terms of the Trust Indenture, the Trustee is entitled to rely, and in fact relies, on certain experts in good faith. While the Trustee has no reason to believe its reliance on experts is unreasonable, this reliance on experts and limited access to information may be viewed as a weakness as compared to the management and oversight of entity forms other than trusts.

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The owner of any Royalty Property may abandon any property, terminating the related Royalty.

The working interest owner may at any time transfer all or part of the Royalty Property to another unrelated third party. Unitholders are not entitled to vote on any transfer, and the Trust will not receive any proceeds of any such transfer. Following any transfer, the Royalty Properties will continue to be subject to the Royalty, but the net proceeds from the transferred property would be calculated separately and paid by the transferee. The transferee would be responsible for all of the obligations relating to calculating, reporting and paying to the Trust the Royalty on the transferred portion of the Royalty Properties, and the current owner of the Royalty Properties would have no continuing obligation to the Trust for those properties.

The current working interest owner or any transferee may abandon any well or property if it reasonably believes that the well or property can no longer produce in commercially economic quantities. This could result in termination of the Royalty relating to the abandoned well. Please see “Business—Legal Proceedings and Status of the Trust and Timing of Liquidation” in Item 1 of this Form 10-K.

The Royalty will be sold and the Trust is being terminated.

The Trust is being terminated and the Trustee must sell the Royalty as the total amount of cash received per year by the Trust for each of three consecutive years ending December 31, 2004 was less than the Termination Threshold. Following this termination and liquidation, the net proceeds of any sale will be distributed to the unitholders and unitholders will receive no further distributions from the Trust. We cannot assure you that any such sale will be on terms acceptable to all unitholders. See Item 1 of this Form 10-K under “Business—Legal Proceedings and Status of the Trust and Timing of Liquidation.”

Trust assets are depleting assets and, if the working interest owners or other operators of the Royalty Properties do not perform additional development projects, the assets may deplete faster than expected.

The net proceeds payable to the Trust are derived from the sale of depleting assets. Accordingly, the portion of the distributions to unitholders attributable to depletion may be considered a return of capital. The reduction in proved reserve quantities is a common measure of depletion. Future maintenance and development projects on the Royalty Properties will affect the quantity of proved reserves. The timing and size of these projects will depend on the market prices of natural gas. If the operator of the Royalty Properties does not implement additional maintenance and development projects, the future rate of production decline of proved reserves may be higher than the rate currently expected by the Trust. For federal income tax purposes, depletion is reflected as a deduction, which is dependent upon the purchase price of a unit. Please see the section entitled “Business—Description of the Units—Federal Income Tax Matters” in Item 1 of this Form 10-K under “Business”.

Unitholders have limited voting rights.

Voting rights as a unitholder are more limited than those of stockholders of most public corporations. For example, there is no requirement for annual meetings of unitholders or for an annual or other periodic re-election of the Trustee. Unlike corporations which are generally governed by boards of directors elected by their equity holders, the Trust is administered by a corporate Trustee in accordance with the Trust Indenture and other organizational documents. The Trustee has extremely limited discretion in its administration of the Trust.

Unitholders have limited ability to enforce the Trust’s rights against the current or future owners of the Royalty Properties.

The Trust Agreement and related trust law permit the Trustees and the Trust to sue the working interest owner to compel it to fulfill the terms of the Conveyance of the Royalty. If the Trustee does not take appropriate action to enforce provisions of the Conveyance, the recourse of a unitholder would likely

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be limited to bringing a lawsuit against the Trustee to compel the Trustee to take specified actions. Unitholders probably would not be able to sue the working interest owner directly.

Item 1B.Unresolved Staff Comments.

There were no unresolved Securities and Exchange Commission comments as of December 31, 2005.

Item 2.Properties.

Reference is made to Item 1 of this Form 10-K.

Item 3.Legal Proceedings.

On April 11, 2005, MOSH Holding, L.P. (MHLP) filed an Original Petition in the District Court of Travis County, Texas, 250th Judicial District, against Pioneer Natural Resources Company; Pioneer Natural Resources USA, Inc.; Woodside Energy (USA), Inc.(Woodside); and JPMorgan Chase Bank, N.A., as Trustee of the Mesa Offshore Trust (Case No. GN501113). On November 28, 2005, Plaintiff amended its petition. In the amended petition, MHLP asserts claims against Pioneer and Woodside for matters including (1) a wrongful farmout of Brazos A-39 by Pioneer, (2) a wrongful delay by Pioneer in producing Brazos A-39, (3) fraudulent accounting practices by Pioneer, (4) breach of fiduciary duty by Pioneer, (5) aiding and abetting breach of fiduciary duty by Woodside, (6) misapplication of Trust property by Pioneer, (7) conspiracy to misapply fiduciary property by Woodside and Pioneer, (8) common law fraud by Pioneer, (9) gross negligence by Pioneer, and (10) breach of the conveyance agreement by Pioneer. MHLP asserts claims for damages against the Trustee for (a) an accounting; and (2) breach of fiduciary duty. The plaintiff remedies being sought include (a) reconstruing the Trust Indenture to determine that the Trust is not terminated because there has or should have been production which would have generated revenues to extend the life of the Trust, (b) requiring the Trustee to pursue certain claims, or to allow plaintiff to pursue such claims, (c) setting aside any farmouts by Pioneer in which there have been conveyances to an affiliate of Pioneer in violation of the Trust’s Conveyance and as a self-dealing transaction, (d) removing JPMorgan Chase Bank, N.A. as Trustee; (e) seeking return or forfeiture of compensation to JPMorgan Chase Bank, N.A. (f) recovering monetary damages against Pioneer, Woodside and JPMorgan Chase Bank, N.A., and (g) pursuing exemplary damages against all defendants.

On November 30, 2005, JPMorgan Chase Bank, N.A. announced its intention to resign as Trustee of the Mesa Offshore Trustee effective January 31, 2006. Since that announcement, MHLP and others have sought a qualified institution willing to serve as successor Trustee. However, neither MHLP nor Pioneer have identified a willing qualified successor Trustee that is not also a lender under one of Pioneer’s credit facilities (which status MHLP contends is an alleged conflict of interest).

On Friday, January 27, 2006, a hearing was held in the 334th Judicial District Court of Harris County, Texas, regarding MHLP’s Verified Application for Emergency Appointment of a Temporary Trustee in Case No. 2006-01984, MOSH Holding, L.P. v. Pioneer Natural Resources Company; Pioneer Natural Resources USA, Inc; Woodside Energy (USA), Inc.; and JPMorgan Chase Bank, N.A., as Trustee of the Mesa Offshore Trust. This case follows the transfer of prior claims filed by the plaintiff in Case No. GN501113. At this hearing, the court declined to approve MHLP’s motion to appoint Timothy J. Roberson, a principal and affiliate of the plaintiff, as temporary Trustee and declined to appoint any other person as temporary or successor Trustee.

In light of this development, and the absence of an identified successor Trustee, JPMorgan Chase Bank, N.A. withdrew its resignation as Trustee. The Trustee continues to desire the appointment of a qualified successor Trustee.

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To date, the Trustee has allowed MHLP to proceed on the issue of whether the farmout by Pioneer was a valid farmout, and the lawsuit remains in a phase where the parties are attempting to discover information about the claims and allegations. While Pioneer has provided a reasoned analysis of why it believes the farmout was in fact valid under the terms of the conveyance, only a court, and not the Trustee, can make a final determination. Further, while the plaintiff’s claims on the farmout issue may merit adjudication, based on facts known to the Trustee at this time, the Trustee is unable to determine, even if the plaintiff prevailed on its uncertain liability claims, whether the Trust would realize any economic benefit. Based on information received to date, the Trustee has not concluded that it would be in the best interest of the unitholders to fund the MHLP claims directly with Trust funds. However, as noted above, the Trustee has not opposed the plaintiff’s pursuit of its claims on behalf of the unitholders at their own expense, which reasonable expenses would be subject to repayment if the claims proved successful and a benefit were conferred upon all Unitholders of the Trust. In connection with both the anticipated sale of Trust properties pursuant to the Trust’s termination and the pending litigation, the Trustee has (1) engaged an independent reserve engineer to review the estimated reserves and (2) had an independent joint venture auditor review certain historical expenditures and revenue receipts on Trust properties. The Trustee believes expenditures for these reviews were prudent and in the interest of the unitholder.

The Trustee will make the full detail of the underlying data of the December 31, 2005 reserve report available for use in connection with the sale of the Trust properties as part of the Trust termination. For more information regarding the estimated remaining life of each of the Royalty Properties, the estimated future net revenues of the Royalty Properties and information relating to farm-outs of interests on the Royalty Properties based on information provided by PNR to D&M, see pages 22 and 23 of this Form 10-K and Note 6 in the Notes to Financial Statements included elsewhere in this Form 10-K. The sale of the assets of the Trust estate will include the related rights to abandonment accruals made by PNR. As explained in “Regulation and Prices—Platform Abandonment and Removal” on page 26 of this Form 10-K, PNR withholds from the Trust a reserve to cover its share of those future abandonment and removal costs. To the extent a certain party is able to complete the abandonment for an amount less than the funds withheld by PNR, the related rights to the abandonment accrual are likely to be deemed marketable. The final distribution to unitholders will be an amount net of funds required to satisfy all Trust liabilities.

Item 4.Submission of Matters to a Vote of Security Holders.

There were no matters submitted to a vote of unitholders during the fourth quarter of 2005.

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PART II

Item 5.   Market for the Registrant’s Common Equity and Related Unitholder Matters.

The units of beneficial interest of the Trust were delisted from the Pacific Exchange effective May 18, 2001. The Trust units are currently eligible for trading on the OTC Bulletin Board under ticker symbol MOSH. There was no distribution of income for the year ended December 2005. In 2005, the Trust had gross Royalty income of $2,356,256; however during 2005, PNR recouped deficit balances of  $71,342; net Royalty income to the Trust was $2,284,914 in 2005. No Royalty income will be distributed to the unitholders until the Trustee recoups Trust expenses being paid from the reserve that the Trustee has established for anticipated future expenses. The high and low sales prices and distributions per unit for each quarter in the two years ended December 31, 2005 were as follows:

	2005							2004
	High		Low		Distribution Paid			High		Low		Distribution Paid
First Quarter	$	0.04	$	0.02		$	—	$	0.05	$	0.03		$	—
Second Quarter	$	0.04	$	0.02		$	—	$	0.05	$	0.03		$	—
Third Quarter	$	0.07	$	0.03		$	—	$	0.04	$	0.02		$	—
Fourth Quarter	$	0.12	$	0.04		$	—	$	0.04	$	0.02		$	—

At March 14, 2006, the 71,980,216 units outstanding were held by 11,800 unitholders of record.

Item 6.   Selected Financial Data.

	2005		2004			2003			2002			2001
Royalty income	$	2,284,914	$	—		$	—		$	—		$	1,772,595
Distributable income	$	—	$	—		$	—		$	—		$	1,401,106
Distributable income per unit	$	—	$	—		$	—		$	—		$	0.0195
Accumulated deficit at year end	$	—	$	(59,035	)	$	(696,712	)	$	(825,616	)	$	(81,329	)
Total assets at year end.	$	1,851,428	$	387,986		$	951,557		$	1,497,883		$	2,153,070

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Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations.

The following review of the Trust’s financial condition and results of operations should be read in conjunction with the financial statements and notes thereto.

Critical Accounting Policies

The financial statements of the Trust are prepared on the following basis:

(a)   Royalty income recorded for a month is the Trust’s interest in the amount computed and paid by the working interest owner to the Partnership for such month rather than either the value of a portion of the oil and gas sold by the working interest owner for such month or the amount subsequently determined to be 90% of the net proceeds for such month;

(b)   Interest income, interest receivable and distributions payable to unitholders include interest to be earned on short-term investments from the financial statement date through the next date of distribution; and

(c)   Trust general and administrative expenses are recorded in the month they accrue and are recoupable from Royalty income.

This basis for reporting distributable income is considered to be the most meaningful because distributions to the unitholders for a month are based on net cash receipts for such month. However, it will differ from the basis used for financial statements prepared in accordance with accounting principles generally accepted in the United States of America because, under such accounting principles, royalty income for a month would be based on net proceeds from sales for such month without regard to when calculated or received and interest income for a month would be calculated only through the end of such month.

Status of the Trust

Hurricane Katrina struck the Gulf of Mexico in August 2005. PNR notified the Trust that it had received preliminary assessments regarding damages from Hurricane Katrina to the West Delta production facilities in which the Trust has an interest. The operator of the West Delta properties has informed PNR that the West Delta properties have been shut in since August 27, 2005 due to damage to the platform, the pipeline and the sales terminal. The operator has notified PNR that the pipeline has not been repaired and currently there is no estimate as to when the repairs will be completed. The operator does not have an estimate on when production at West Delta will resume.

The Trust Indenture provides that the Trust will terminate if the total amount of cash per year received by the Trust falls below certain levels for each of three successive years. As a result of continued declines in production on Royalty Properties nearing the end of their estimated productive lives, Royalty income received by the Trust in 2002, 2003 and 2004 fell below the Termination Threshold prescribed by the Trust Indenture. The Trustee has taken steps to begin the process of liquidating the Trust. See “Timing of Liquidation” below in this Note. The Trustee, which has no authority or discretionary control over the timing of expenditures, production or income on the Royalty Properties, has no discretion regarding the occurrence of the Termination Threshold or its consequences.

The Trust Indenture provides the Trustee a two-year period during which it must sell all of the Trust properties. The Trust Indenture provides that such properties must be sold for cash and not for any other consideration. The Trustee expects that the sale process will be open to any persons desiring to participate, but, as is customary, access to information and participation may be limited to persons who execute confidentiality agreements regarding information provided by the working interest owners. The Trustee may also require bidders to identify themselves clearly and to represent or evidence sufficient financing in order to participate, as the Trustee expects payment will be required promptly after the close of bidding without any financing conditions. Accordingly, the auction may not be a “public” auction in the sense that

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it may not be open to anyone who does not satisfy these requirements. The Trustee is currently reviewing a potential online bidding process for participants in order to provide current public information on bidding to the marketplace. The Trustee will also determine a duration of bidding that it deems in the best interest of the Unitholders.

Below is additional information regarding the Trust properties provided by D&M:

Properties producing as of December 31, 2005

Property	Number of Producing wells(1)		Estimated Productive Life(1)		Estimated Future Royalty Income(2)
West Delta No. 61		4		7 years	$	2,458,852
Brazos A-7		1		2 years	$	1,363,139

(1)Information obtained from December 31, 2005 reserve report prepared by D&M.

(2)Represents estimated future royalty income from the December 31, 2005, reserve report. Future royalty income was calculated using oil and gas spot prices in effect at December 31, 2005 of $57.61 to $58.01 per barrel and $7.31 to $9.86 per thousand cubic feet.

Properties abandoned or scheduled for abandonment as of December 31, 2005

Property	Status
Brazos A-7	Abandoned in 2005 (excluding producing well and platform)
Brazos A-39	Plug and abandonment procedures completed in 2005 (excluding Midway prospect)*
West Delta 62	Plug and abandonment procedures completed in 2003
South Marsh Island 155	Plug and abandonment procedures completed in 2002
South Marsh Island 156	Plug and abandonment procedures completed in 2002
Vermillion 381	Plug and abandonment procedures completed in 1989
South Pelto 12	Plug and abandonment procedures completed in 1986
Matagorda Island 624	Plug and abandonment procedures completed in 2003
High Island 567	Plug and abandonment procedures completed in 1992

*Midway prospect will be tied -back to an existing platform operated by a third party.

Financial and Operational Review

As discussed in Item 1 of this Form 10-K, PNR has advised the Trust that during 2005, its offshore gas production was marketed under short-term contracts at spot market prices primarily to TOTAL S.A. and that it expects to continue to market its production under short-term contracts for the foreseeable future. Spot market prices for natural gas were on the average higher in 2005 than spot market prices in 2004.

The amount of cash distributed by the Trust is dependent on, among other things, the sales prices and quantities of gas, crude oil, condensate and natural gas liquids produced from the Royalty Properties and the quantities sold. Substantial uncertainties exist with regard to future gas and oil prices, which are subject to fluctuations due to the regional supply and demand for natural gas and oil, production levels and other activities of the Organization of the Petroleum Exporting Countries (“OPEC”) and other oil and gas producers, weather, storage levels, industrial growth, conservation measures, competition and other variables.

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Below is a summary of Royalty income received on the Trust properties for each of the three years ending December 31, 2005:

	2005			2004			2003
Gross proceeds @ 90%	$	2,085,418		$	810,336		$	745,192
Operating expenditures @ 90%	(104,265		)	(172,594		)	(605,927		)
Capital expenditures @ 90%(1)	375,338			—			(10,348		)
Net proceeds (deficit)	2,356,491			637,742			128,917
Increase (decrease) in deficit	(71,349		)	(637,742		)	(128,917		)
Net proceeds after deficit recovery	2,285,142			—			—
Royalty income (99.99%)	$	2,284,914		$	—		$	—

(1)   PNR believes that the future abandonments have been fully funded, no such amounts were withheld in 2004 or 2005. In 2005, the Trust received gross proceeds of $375,338 from PNR related to the sale of the South Marsh Island 155 platform that was abandoned by PNR and for casings related to the PNR platform at Brazos A-39.

Below is a summary of distributable income for the years ended December 31, 2005, 2004 and 2003:

	Years Ended December 31,
	2005			2004			2003
Royalty income	$	2,284,914		$	—		$	—
Interest income	8,512			4,493			9,169
General and administrative expenses	(2,293,426		)	(4,493		)	(9,169		)
Distributable income	$	—		$	—		$	—
Distributable income per unit	$	—		$	—		$	—
Accumulated deficit (as of period end)	$	—		$	(59,035	)	$	(696,712	)

Below is a summary of general and administrative expenses and the adjustments made to the reserve for trust expenses:

	Years Ended December 31,
	2005		2004			2003
General and administrative costs incurred during the year	$	824,691	$	567,461		$	612,572
Adjustments to reserve for trust expenses	1,456,428		(562,968		)	(603,403		)
General and administrative costs as reported	$	2,281,119	$	4,493		$	9,169

General and administrative expenses of the Trust for 2005 increased 45% to $824,691 for 2005 as compared to $567,461 for 2004.  The increase in general and administrative expenses in 2005 is primarily due to an increase in legal fees as a result of pending litigation and the anticipated sale of Trust properties pursuant to the Trust’s termination.  In addition, the Trust incurred additional expenditures in 2005 for the independent reserve studies performed as of March 31, 2005 and December 31, 2005 and for the independent joint venture auditor to perform a review of certain historical expenditures and revenue receipts on Trust properties.

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Below is an operational review of the remaining producing Trust properties:

Brazos A-7 and A-39

	2005			2004			2003
Gross proceeds @ 90%	$	156,378		$	160,014		$	193,039
Operating expenditures @ 90%	(83,470		)	(171,043		)	(429,232		)
Capital expenditures @ 90%	6,750			—			2,481		)
Net proceeds (deficit)	$	79,658		$	(11,029	)	$	(233,712	)

Production Volumes and Average Prices:
Crude oil, condensate and natural gas liquids (Bbls)	52		36		348
Average sales price per Bbl	$	52.59	$	35.78	$	27.42
Natural gas (Mcf)	23,928		29,145		35,644
Average sales price per Mcf	$	6.42	$	5.45	$	5.15
Producing wells	1		1		1

The Brazos A-7 and A-39 blocks continued to experience a decrease in natural gas production due to natural production decline. As of December 31, 2005, these two blocks had one well producing, the Brazos A-7 No. B-1 well which is operated by Newfield Exploration Company. The Brazos A-39 No. A-3 well ceased production during the fourth quarter of 2003. PNR entered into farmout agreements for the Trust’s interest in both of these blocks so that two exploration prospects could be drilled and in which the Trust will retain an overriding royalty interest. The first prospect on Brazos A-7 was drilled during 2003 and was determined to be a dry hole. As such, the well was plugged and abandoned. In 2005, PNR has performed abandonment procedures at the PNR operated Brazos A-7 and the A-39 blocks, with minor sitework clearance remaining. In 2005, the Trust received a $6,750 credit for casings related to the PNR platform at Brazos A-39.

The second exploration prospect was drilled on Brazos A-39, which PNR has announced as a discovery. A production test was completed during the first quarter of 2005. PNR, the operator on this property, has informed the Trustee that the lower horizon of the prospect was determined to be non-commercial, while the middle horizon produced at 10 million cubic feet of gas per day during a seventeen hour flow test. There is no assurance that these flow rates will continue, as offshore oil and gas properties often experience stronger initial flow rates and more rapid declines than onshore properties. PNR expects to tie-back this prospect into an existing platform, operated by a third party, with first production expected to commence in the first half of 2006. Under the terms of a Farmout Agreement between PNR and Woodside Energy (USA) Inc., PNR farmed out to Woodside the undivided one-half interest previously burdened by the Trust’s net profits interest, but expressly providing that the farmed out interest would not be subject to the Trust’s net profits interest. PNR reserved a 10% overriding royalty interest, proportionately reduced to the interest conveyed, which interest, upon Woodside’s recoupment of specified costs and expenses, would increase to 12.5%, proportionately reduced to the interest conveyed. The Trust’s net profits interest burdens the overriding royalty interest reserved by PNR. PNR has informed the Trustee that it believes this process is consistent with the terms of the original conveyance and with the handling of other farmout transactions involving lands burdened by the Trust’s net profits interest.

PNR continues to own the undivided one-half interest not burdened by the Trust’s net profits interest and will participate in and operate the well as owner of that undivided one-half interest (subject to an agreement with Woodside to grant Woodside such interest in PNR’s remaining undivided one-half interest to equalize those parties participation in the well).

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PNR has noted to the Trustee that the Farmout Agreement enabled the drilling costs of these prospects to be carried on the Trust’s interest in part by Woodside. PNR further noted that the Trust’s net profits interest would not have entitled the Trust to payment until drilling costs and applicable interest were recovered, whereas the overriding royalty interest retained under the Farmout Agreement entitles the Trust to payments prior to the recoupment of expenses incurred by Woodside and PNR. As noted above, the first prospect on Brazos A-7 was determined to be a dry hole. Under the Farmout Agreement and related agreements, those drilling and abandonment costs have been born entirely by PNR and Woodside and are not subject to recoupment from any proceeds otherwise payable to the Trust. Similarly, the Trust’s current interest in the “Midway” prospect on Brazos A-39 will be entitled to payment prior to PNR’s and Woodside’s recovery of expenses for drilling, completion, sub-sea tie backs and other costs.

The Brazos A-7 and A-39 blocks also experienced a significant decrease in operating expenditures due to the Brazos A-39 No. A-3 well no longer producing.

West Delta 61 and 62

	2005			2004			2003
Gross proceeds @ 90%	$	1,929,040		$	650,322		$	552,153
Operating expenditures @ 90%	(20,795		)	(1,551		)	(176,695		)
Capital expenditures @ 90%	—			—			(12,829		)
Net proceeds (deficit)	$	1,908,245		$	648,771		$	362,629
Production Volumes and Average Prices:
Crude oil, condensate and natural gas liquids (Bbls)	12,261			9,596			7,266
Average sales price per Bbl	$	48.96		$	32.55		$	27.92
Natural gas (Mcf)	185,769			63,109			52,401
Average sales price per Mcf	$	7.09		$	5.35		$	7.26
Producing wells	4			4			3

Hurricane Katrina struck the Gulf of Mexico in August 2005. PNR notified the Trust that it had received preliminary assessments regarding damages from Hurricanes Katrina to the West Delta production facilities in which the Trust has an interest. The operator of the West Delta properties has informed PNR that the West Delta properties have been shut in since August 27, 2005 due to damage to the platform, the pipeline and the sales terminal. The operator has notified PNR that the pipeline has not been repaired and currently there is no estimate as to when the repairs will be completed. The operator does not have an estimate on when production at West Delta will resume.

The West Delta 61 and 62 blocks experienced an increase in oil and natural gas production in 2005 as compared to the same period in 2004 due to production from new wells that came online in the third quarter of 2004. The PNR-operated wells ceased production in 2002, and the wells were plugged and abandoned by year-end with the facilities being completely abandoned during 2003. The only remaining wells on this block are in West Delta 61. PNR farmed out a portion of West Delta 61 to Stone retaining a 12.5% (11.25% net to the Trust) overriding royalty interest.

Capital Expenditures

In 2005, the Trust received, from PNR, net proceeds of $375,300 related to the sale of the South Marsh Island 155 platform that was abandoned by PNR and for casings related to the PNR platform at Brazos A-39. PNR does not anticipate any significant capital expenditures on the Royalty Properties in the future. Due to the limited financial capacity of the Trust, PNR has advised that it intends to farm out the

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Trust’s interest in the blocks it believes may be produced economically, retaining an overriding royalty interest for the Trust.

Abandonment Expenditures

The below table provides a rollforward of the abandonment and removal costs cash reserve that PNR has withheld from the Trust since January 1, 2003:

Balance, January 1, 2003	$	5,640,443
Abandonment cost incurred (Mat. Is. 624 & WD 62)	(2,839,800		)
Balance, December 31, 2003	2,800,643
Abandonment cost incurred (Mat. Is. 624 & WD 62)	(124,492		)
Balance, December 31, 2004	$	2,676,151
Abandonment cost incurred (Brazos A-7A, A-7#4,A-39A1A,A-2 and A-3A)	(2,328,085		)
Balance, December 31, 2005	$	348,066

Liquidity and Capital Resources

In accordance with the provisions of the Trust conveyance, generally all revenues received by the Trust, net of Trust administrative expenses and any cash reserves established for the payment of contingent or future obligations of the Trust, are distributed currently to the unitholders.

The Trust’s source of cash is the Royalty income received from its share of the net proceeds from the Royalty Properties. Reference is made to Note 6 in the Notes to Financial Statements under Item 8 of this Form 10-K for estimates of future Royalty income attributable to the Partnership, of which the Trust has a 99.99% interest.

Production and Price Review

Production volumes for natural gas increased to 209,697 Mcf in 2005 as compared with 92,254 Mcf in 2004. The average sales price received for natural gas in 2005 was $7.01 per Mcf as compared with $5.38 per Mcf in 2004. Crude oil, condensate and natural gas liquids production volumes increased to 12,313 barrels in 2005 as compared to 9,632 barrels in 2004. The average sales price in 2005 for crude oil, condensate and natural gas liquids was $48.97 per barrel as compared with $32.57 per barrel in 2004.

Production volumes for natural gas increased to 92,254 Mcf in 2004 as compared with 88,045 Mcf in 2003. The average sales price received for natural gas in 2004 was $5.38 per Mcf as compared with $6.05 in 2003. Crude oil, condensate and natural gas liquids production volumes increased to 9,632 barrels in 2004 as compared to 7,614 barrels in 2003. The average sales price in 2004 for crude oil, condensate and natural gas liquids was $32.57 per barrel as compared with $27.90 per barrel in 2003.

Item 7A.Quantitative and Qualitative Disclosures About Market Risk.

Not applicable.

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Item 8.Financial Statements and Supplementary Data.

MESA OFFSHORE TRUST
STATEMENTS OF DISTRIBUTABLE INCOME

	Years Ended December 31,
	2005			2004			2003
Royalty income	$	2,284,914		$	—		$	—
Interest income	8,512			4,493			9,169
General and administrative expenses	(2,293,426		)	(4,493		)	(9,169		)
Distributable income	$	—		$	—		$	—
Distributable income per unit	$	—		$	—		$	—

STATEMENTS OF ASSETS, LIABILITIES AND TRUST CORPUS

	December 31,
	2005			2004
ASSETS
Cash and short-term investments	$	1,846,798		$	376,599
Interest receivable	1,582			250
Net overriding royalty interest in oil and gas properties	380,905,000			380,905,000
Less: accumulated amortization	(380,901,952		)	(380,893,873		)
Total assets	$	1,851,428		$	387,976
LIABILITIES AND TRUST CORPUS
Reserve for trust expenses	$	1,848,380		$	376,849
Distributions payable	—			—
Trust corpus (71,980,216 units of beneficial interest authorized and outstanding)	3,048			11,127
Total liabilities and trust corpus	$	1,851,428		$	387,976

STATEMENTS OF CHANGES IN TRUST CORPUS

	Years Ended December 31,
	2005			2004		2003
Trust corpus, beginning of year	$	11,127		$	11,127	$	11,127
Distributable income	—			—		—
Distributions to unitholders	—			—		—
Amortization of net overriding royalty interest	(8,079		)	—		—
Trust corpus, end of year	$	3,048		$	11,127	$	11,127

The accompanying notes are an integral part of these financial statements.

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MESA OFFSHORE TRUST
NOTES TO FINANCIAL STATEMENTS

(1)Trust Organization and Provisions

The Trust

The Mesa Offshore Trust (the “Trust”) was created effective December 1, 1982. On that date, Mesa Petroleum Co., predecessor to Mesa Limited Partnership, which was predecessor to MESA Inc., transferred to the Trust a 99.99% interest in the Mesa Offshore Royalty Partnership (the “Partnership”). The Trust is an independent trust administered by JPMorgan Chase Bank, N.A., as trustee (the “Trustee”). JPMorgan Chase Bank, N.A., was formerly known as The Chase Manhattan Bank and is the successor by mergers to the original name of the Trustee, Texas Commerce Bank National Association.

The terms of the Mesa Offshore Trust Indenture (the “Trust Indenture”) provide, among other things, that:

(a)   the Trust cannot engage in any business or investment activity or purchase any assets;

(b)   the interest in the Partnership can be sold in part or in total for cash upon approval of the unitholders;

(c)   the Trustee can establish cash reserves and borrow funds to pay liabilities of the Trust and can pledge the assets of the Trust to secure payment of the borrowings;

(d)   the Trustee will make cash distributions to the unitholders in January, April, July and October of each year as discussed more fully in Note 4; and

(e)   the Trust will terminate upon the first to occur of the following events: (i) the total amount of cash received per year by the Trust for each of three successive years commencing after December 31, 1987 is less than ten times one-third of the total amount payable to the Trustee as compensation for such three-year period (the “Termination Threshold”) or (ii) a vote by holders of a majority of the outstanding units in favor of termination. Amounts earned by the Trustee as compensation were approximately $204,000 $148,000 and $152,000 for the years 2005, 2004 and 2003, respectively. As described further in “Legal Proceedings and Status of the Trust” on page 8 of this Form 10K and “Timing of Liquidation” on page 10 of this Form 10-K, the Termination Threshold was met in the three consecutive years ending December 31, 2004. Upon termination of the Trust, the Trustee will sell for cash all the assets held in the Trust estate and make a final distribution to unitholders of any funds remaining after all Trust liabilities have been satisfied.

The Partnership

The Partnership was created to receive and hold a net overriding royalty interest (the “Royalty”) in ten producing and non-producing oil and gas properties located in federal waters offshore Louisiana and Texas (the “Royalty Properties”). MESA Inc. created the Royalty out of its working interest in the Royalty Properties and transferred it to the Partnership. Until August 7, 1997, MESA Inc. owned and operated its assets through Mesa Operating Co. (“Mesa”), the operator and the managing general partner of the Royalty Properties. On August 7, 1997, MESA Inc. merged with and into Pioneer Natural Resources Company (“Pioneer”), formerly a wholly owned subsidiary of MESA, Inc., and Parker & Parsley Petroleum Company merged with and into Pioneer Natural Resources USA, Inc. (successor to Mesa), a wholly owned subsidiary of Pioneer (“PNR”) (collectively, the mergers are referred to herein as the “Merger”). Subsequent to the Merger, Pioneer owns and operates its assets through PNR and is also the managing general partner of the Partnership.

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The Partnership is owned 99.99% by the Trust and 0.01% by PNR. PNR serves as the managing general partner of the Partnership. PNR receives no compensation for serving as managing general partner other than the income it receives attributable to its interest in the Partnership.

Legal Proceedings and Status of the Trust

Hurricane Katrina struck the Gulf of Mexico in August 2005. PNR notified the Trust that it had received preliminary assessments regarding damages from Hurricane Katrina to the West Delta production facilities in which the Trust has an interest. The operator of the West Delta properties has informed PNR that the West Delta properties have been shut in since August 27, 2005 due to damage to the platform, the pipeline and the sales terminal. The operator has notified PNR that the pipeline has not been repaired and currently there is no estimate as to when the repairs will be completed. The operator does not have an estimate on when production at West Delta will resume.

The Trust Indenture provides that the Trust will terminate if the total amount of cash per year received by the Trust falls below certain levels for each of three successive years. As a result of continued declines in production on Royalty Properties nearing the end of their estimated productive lives, Royalty income received by the Trust in 2002, 2003 and 2004 fell below the Termination Threshold prescribed by the Trust Indenture. During 2005, the Trustee has taken steps to begin the process of liquidating the Trust. See “__Timing of Liquidation” below in this Note. The Trustee, which has no authority or discretionary control over the timing of expenditures, production or income on the Royalty Properties, has no discretion regarding the occurrence of the Termination Threshold or its consequences.

The Trust Indenture provides the Trustee a two-year period during which it must sell all of the Trust properties. The Trust Indenture provides that such properties must be sold for cash and not for any other consideration. The Trustee expects that the sale process will be open to any persons desiring to participate, but, as is customary, access to information and participation may be limited to persons who execute confidentiality agreements regarding information provided by the working interest owners. The Trustee may also require bidders to identify themselves clearly and to represent or evidence sufficient financing in order to participate, as the Trustee expects payment will be required promptly after the close of bidding without any financing conditions. Accordingly, the auction may not be a “public” auction in the sense that it may not be open to anyone who does not satisfy these requirements. The Trustee is currently reviewing a potential online bidding process for participants in order to provide current public information on bidding to the marketplace. The Trustee will also determine a duration of bidding that it deems in the best interest of the Unitholders.

On April 11, 2005, MOSH Holding, L.P. (MHLP) filed an Original Petition in the District Court of Travis County, Texas, 250th Judicial District, against Pioneer Natural Resources Company; Pioneer Natural Resources USA, Inc.; Woodside Energy (USA), Inc.(Woodside); and JPMorgan Chase Bank, N.A., as Trustee of the Mesa Offshore Trust (Case No. GN501113). On November 28, 2005, Plaintiff amended its petition. In the amended petition, MHLP asserts claims against Pioneer and Woodside for matters including (1) a wrongful farmout of Brazos A-39 by Pioneer, (2) a wrongful delay by Pioneer in producing Brazos A-39, (3) fraudulent accounting practices by Pioneer, (4) breach of fiduciary duty by Pioneer, (5) aiding and abetting breach of fiduciary duty by Woodside, (6) misapplication of Trust property by Pioneer, (7) conspiracy to misapply fiduciary property by Woodside and Pioneer, (8) common law fraud by Pioneer, (9) gross negligence by Pioneer, and (10) breach of the conveyance agreement by Pioneer. MHLP asserts claims for damages against the Trustee for (a) an accounting; and (2) breach of fiduciary duty. The plaintiff remedies being sought include (a) reconstruing the Trust Indenture to determine that the Trust is not terminated because there has or should have been production which would have generated revenues to extend the life of the Trust, (b) requiring the Trustee to pursue certain claims, or to allow plaintiff to pursue such claims, (c) setting aside any farmouts by Pioneer in which there have been conveyances to an affiliate of Pioneer in violation of the Trust’s Conveyance and as a self-dealing transaction, (d) removing JPMorgan Chase Bank, N.A. as Trustee; (e) seeking return or forfeiture of

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compensation to JPMorgan Chase Bank, N.A. (f) recovering monetary damages against Pioneer, Woodside and JPMorgan Chase Bank, N.A., and (g) pursuing exemplary damages against all defendants.

On November 30, 2005 JPMorgan Chase Bank, N.A. announced its intention to resign as Trustee of the Mesa Offshore Trustee effective January 31, 2006. Since that announcement, MHLP and others have sought a qualified institution willing to serve as successor Trustee. However, neither MHLP nor Pioneer have identified a willing qualified successor Trustee that is not also a lender under one of Pioneer’s credit facilities (which status MHLP contends is an alleged conflict of interest).

On Friday, January 27, 2006, a hearing was held in the 334th Judicial District Court of Harris County, Texas, regarding MHLP’s Verified Application for Emergency Appointment of a Temporary Trustee in Case No. 2006-01984, MOSH Holding, L.P. v. Pioneer Natural Resources Company; Pioneer Natural Resources USA, Inc; Woodside Energy (USA), Inc.; and JPMorgan Chase Bank, N.A., as Trustee of the Mesa Offshore Trust. This case follows the transfer of prior claims filed by the plaintiff in Case No. GN501113. At this hearing, the court declined to approve MHLP’s motion to appoint Timothy J. Roberson, a principal and affiliate of the plaintiff, as temporary Trustee and declined to appoint any other person as temporary or successor Trustee.

In light of this development, and the absence of an identified successor Trustee, JPMorgan Chase Bank, N.A. withdrew its resignation as Trustee. The Trustee continues to desire the appointment of a qualified successor Trustee.

To date, the Trustee has allowed MHLP to proceed on the issue of whether the farmout by Pioneer was a valid farmout, and the lawsuit remains in a phase where the parties are attempting to discover information about the claims and allegations. While Pioneer has provided a reasoned analysis of why it believes the farmout was in fact valid under the terms of the conveyance, only a court, and not the Trustee, can make a final determination. Further, while the plaintiff’s claims on the farmout issue may merit adjudication, based on facts known to the Trustee at this time, the Trustee is unable to determine, even if the plaintiff prevailed on its uncertain liability claims, whether the Trust would realize any economic benefit. Based on information received to date, the Trustee has not concluded that it would be in the best interest of the unitholders to fund the MHLP claims directly with Trust funds. However, as noted above, the Trustee has not opposed the plaintiff’s pursuit of its claims on behalf of the unitholders at their own expense, which reasonable expenses would be subject to repayment if the claims proved successful and a benefit were conferred upon all Unitholders of the Trust. In connection with both the anticipated sale of Trust properties pursuant to the Trust’s termination and the pending litigation, the Trustee has (1) engaged an independent reserve engineer to review the estimated reserves and (2) had an independent joint venture auditor review certain historical expenditures and revenue receipts on Trust properties. The Trustee believes expenditures for these reviews were prudent and in the interest of the unitholder.

The Trustee will make the full detail of the underlying data of the December 31, 2005 reserve report available for use in connection with the sale of the Trust properties as part of the Trust termination. For more information regarding the estimated remaining life of each of the Royalty Properties, the estimated future net revenues of the Royalty Properties and information relating to farm-outs of interests on the Royalty Properties based on information provided by PNR to D&M , see pages 22 and 23 of this Form 10-K and Note 6 in the Notes to Financial Statements included elsewhere in this Form 10-K. The sale of the assets of the Trust estate will include the related rights to abandonment accruals made by PNR. As explained in “Regulation and Prices—Platform Abandonment and Removal” on page 26 of this Form 10-K and Note 3 in the Notes to the Financial Statements included elsewhere in this Form 10-K, PNR withholds from the Trust a reserve to cover its share of those future abandonment and removal costs. To the extent a certain party is able to complete the abandonment for an amount less than the funds withheld by PNR, the related rights to the abandonment accrual are likely to be deemed marketable. The final distribution to unitholders will be an amount net of funds required to satisfy all Trust liabilities.

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Timing of Liquidation

In connection with this litigation, the Trustee has agreed that it will give MHLP at least 60 days notice prior to the sale of any Trust properties in connection with the termination of the Trust. As of the date of this filing, based on the information currently provided by Pioneer and the preliminary state of the proceeding, the Trustee has not made any definitive conclusions as to the validity of the claims asserted by MHLP. However, the review of reserves by the independent reserve engineer has not shown the existence of significant reserves not previously included in the reserve report prepared by Pioneer in quantities originally alleged in the plaintiff’s petition. Due to the pending litigation, the Trustee cannot predict the timing of the sale of all or a portion of the Trust properties as part of the Trust Termination.

As part of the termination procedures, the Trustee engaged an independent joint venture auditor in October 2004 to review the Trust properties as part of the termination of the Trust. The joint venture auditor reviewed the periods from 2003 through 2004. The Trustee believed this engagement of an outside party on these matters to be a prudent step to identify any potential benefits to the Trust, as well as any limitations on potential benefits, due to differing interpretations of accounting matters that commonly occur in the oil and gas production industry. The review of the independent joint venture auditor was completed in December 2005, and it was the joint venture auditor’s opinion that the charges and credits and revenue to the Trust were in accordance with the applicable agreements, except for certain items noted in the report. The report notes exceptions which may or may not turn out to be meritorious, as to amounts due to the Trust of $204,219. PNR, Stone Energy (Stone) and Newfield  Exploration Company (Newfield) have received a copy of the report and have 180 days to respond to these findings. As of March 15, 2006, PNR, Stone and Newfield have not yet responded to the findings in this report. Any proceeds received as a result of the joint venture audit will be included as Royalty income in the period in which the proceeds are received.

(2)Net Overriding Royalty Interest

The instruments conveying the Royalty to the Partnership provide that PNR will calculate and pay to the Partnership each month an amount equal to 90% of aggregate net proceeds for the preceding month. Generally, net proceeds means the excess of the amounts received by PNR from sales of its share of oil and gas from the Royalty Properties (gross proceeds) over the operating and capital costs incurred. Costs exceeding gross proceeds for any month are recovered by PNR, with interest thereon at the prime rate of the Bank of America plus one-half percent, out of future gross proceeds prior to making further royalty payments to the Partnership.

Amortization of the Royalty, which is calculated on the basis of current royalty income in relation to estimated future royalty income, is charged directly to trust corpus since such amounts do not affect distributable income.

(3)Basis of Accounting

The financial statements of the Trust are prepared on the following basis:

(a)   Royalty income recorded for a month is the Trust’s interest in the amount computed and paid by the working interest owner to the Partnership for such month rather than either the value of a portion of the oil and gas produced by the working interest owner for such month or the amount subsequently determined to be 90% of the net proceeds for such month;

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(b)   Interest income, interest receivable and distributions payable to unitholders include interest to be earned on short-term investments from the financial statement date through the next date of distribution; and

(c)   Trust general and administrative expenses are recorded in the month they accrue and are recoupable from Royalty income.

This basis for reporting distributable income is considered to be the most meaningful because distributions to the unitholders for a month are based on net cash receipts for such month. However, it will differ from the basis used for financial statements prepared in accordance with accounting principles generally accepted in the United States of America because, under such accounting principles, royalty income for a month would be based on net proceeds from production for such month without regard to when calculated or received and interest income for a month would be calculated only through the end of such month.

The instruments conveying the Royalty provide that the working interest owner will calculate and pay the Partnership each month an amount equal to 90% of the net proceeds for the preceding month. Generally, net proceeds means the excess of the amounts received by the working interest owner from sales of oil and gas from the Royalty Properties plus other cash receipts over operating and capital costs incurred. For the twelve months ending December 31, 2004, operating and capital costs incurred exceeded proceeds from oil and gas sales; accordingly, no Royalty income was reported.

For the twelve months ended December 31, 2005, the Trust had Royalty income of $2,284,914. However, no Royalty income will be distributed to unitholders until the Trustee recoups Trust expenses being paid from the reserve that the Trustee has established for anticipated future general and administrative expenses. As of December 31, 2005, $151,620 will be recouped by the Trustee from future Royalty income before Trust distributions will resume. The unexpended amount withheld by PNR for future abandonment costs at December 31, 2005 was $348,066.

Assets and Liabilities in the Process of Liquidation

As a result of the contractual termination of the Trust effective January 1, 2005, the Trust is in the process of liquidation. The below table presents the assets of the Trust at their estimated fair value:

	December 31, 2005
ASSETS
Cash and short term investments		$	1,846,798
Interest receivable		1,582
Net overriding royalty interest in oil and gas properties		4,831,237
Total assets		6,679,617
LIABILITIES
Reserve for Trust expenses		$	1,848,380
Total liabilities		1,848,380
Net assets in process of liquidation		$	4,831,237

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The net overriding royalty interest in oil and gas properties at December 31, 2005 reflect the Trustee’s estimate of value, (in the absence of third-party appraisals or evaluations) based on the Trust’s share of future net revenues from the net overriding royalty interest in the properties as of December 31, 2005. This estimate is based on the Trustee’s current assessment of the impact of selling existing assets based on current market conditions, and includes the following assumptions:

·  The Trust’s estimated share of oil and gas reserve volumes at December 31, 2005, were derived from the reserve report prepared by DeGolyer and MacNaugton (D&M). The Trust’s estimated share of oil and gas reserve volumes at December 31, 2005 include reserves related to the Midway Prospect.(1)

·  Forward strip commodity prices on December 31, 2005 for the life of the reserves.

·  Exclusion of estimated future abandonment costs.(2)

·  Discount rate of 10%.

(1)   As a result of the litigation described above, the Trust had been unable to obtain necessary information from the working interest owner regarding such owner’s own current estimate of the fair value of the proved reserves on the Midway Prospect. The Trustee engaged D&M, an independent reserve engineer, to review all oil and gas reserves pertaining to the Royalty, including the Midway Prospect reserves and the Trust’s interest in these reserves as of December 31, 2005.

(2)   The sale of the assets currently owned by the Partnership will include the related rights to abandonment costs previously withheld by the working interest owner. The working interest owner has withheld funds to cover the Trust’s share of future abandonment and removal costs. To the extent the abandonment is completed for an amount less than the funds withheld by the working interest owner those funds would be distributed to the Trust. Therefore, estimated future abandonment costs are not reflected as a reduction of future net revenue.

The actual net proceeds from the sales of oil and gas properties may vary substantially from these estimates in value due to changes in current and estimated future oil and gas prices, subsequent production, estimates of actual abandonment costs and other factors which may be applied by the buyers.

For all other assets presented in the above table, the Trustee believes that historical cost approximates fair market value due to the short-term nature of such assets. The Trustee will continue to reserve funds to recoup its previously established reserves to pay Trust expenses, which will primarily consist of expenses incurred by the Trustee to liquidate the Trust’s assets. Any funds remaining after all expenses have been paid will be distributed to the Unitholders.

(4)Distributions to Unitholders

Under the terms of the Trust Indenture, the Trustee must distribute to the unitholders all cash receipts, after paying liabilities and providing for cash reserves as determined necessary by the Trustee. The amounts distributed are determined on a monthly basis and are payable to unitholders of record as of the last business day of each month. However, cash distributions are made quarterly in January, April, July and October, and include interest earned from the monthly record dates to the dates of distribution.

(5)Federal Income Taxes

The Trustee reports on the basis that the Trust is a grantor trust. Based on its previous audit policy, the Internal Revenue Service (the “IRS”) is expected to concur with such action. No IRS ruling has been received or requested with respect to the Trust, however, and no court case has been decided involving

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identical facts and circumstances. It is possible, therefore, that the IRS would assert upon audit that the Trust is taxable as a corporation and that a court might agree with such assertion.

As a grantor trust, the Trust will incur no federal income tax liability. In addition, it will incur little or no federal income tax liability if it is held to be a non-grantor trust. If the Trust were held to be taxable as a corporation, it would have to pay tax on its net taxable income at the corporate rate.

(6)Supplemental Reserve Information (Unaudited)

Estimates of the proved oil and gas reserves attributable to the Royalty as of December 31, 2005, are based on a report prepared by DeGolyer and MacNaughton (D&M). The 2004 and 2003 reports are based on a report prepared by PNR. The estimates were prepared in accordance with guidelines established by the Securities and Exchange Commission (the “SEC”). Accordingly, the estimates were based on existing economic and operating conditions. The reserve volumes and revenue values contained in the reserve report for the Partnership interest were estimated by allocating to the Partnership a portion of the estimated combined net reserve volumes of the Royalty Properties based on future net revenue. Production volumes are allocated based on royalty income. Because the net reserve volumes attributable to the Partnership interest are estimated using an allocation of reserve volumes based on estimates of future net revenue, a change in prices or costs will result in changes in the estimated net reserve volumes. Therefore, the estimated net reserve volumes attributable to the Partnership interest will vary if different future price and cost assumptions are used. Only costs necessary to develop and produce existing proved reserve volumes were assumed in the allocation of reserve volumes to the Royalty.

Future prices for natural gas were based on prices in effect as of each year end and existing contract terms. Prices being received as of each year end were used for sales of oil, condensate and natural gas liquids. Operating costs, production and ad valorem taxes and future development and abandonment costs were based on current costs as of each year end, with no escalation.

There are numerous uncertainties inherent in estimating the quantities and value of proved reserves and in projecting the future rates of production and timing of expenditures. The reserve data below represent estimates only and should not be construed as being exact. Moreover, the discounted values should not be construed as representative of the current market value of the Royalty. A market value determination would include many additional factors including: (i) anticipated future oil and gas prices; (ii) the effect of federal income taxes, if any, on the future royalties; (iii) an allowance for return on investment; (iv) the effect of governmental legislation; (v) the value of additional reserves, not considered proved at present, which may be recovered as a result of further exploration and development activities; and (vi) other business risks.

Estimates of reserve volumes attributable to the Royalty are shown in order to comply with requirements of the SEC. There is no precise method of allocating estimates of physical quantities of reserve volumes between PNR and the Partnership, since the Royalty is not a working interest and the Partnership does not own and is not entitled to receive any specific volume of reserves from the Royalty. The quantities of reserves attributable to the Partnership have been and will be affected by changes in various economic factors utilized in estimating net revenues from the Royalty Properties, as well as any exploration activities which may be conducted by PNR. Therefore, the estimates of reserve volumes set forth below are to a large extent hypothetical and differ in significant respects from estimates of reserves attributable to a working interest.

The future net revenues contained in the previously mentioned reserve report have not been reduced for future general and administrative expenses of the Trust, which are expected to approximate $500,000 annually. The general and administrative expenses of the Trust may increase in future years, depending on the amount of royalty income, increases in accounting, engineering, legal, and other professional fees and other factors.

46

The following schedules set forth (i) the estimated net quantities of proved and proved developed oil, condensate and natural gas liquids and natural gas reserves attributable to the Royalty, and (ii) the standardized measure of the discounted future royalty income attributable to the Royalty and the nature of changes in such standardized measure between years. These schedules are prepared on the accrual basis, which is the basis on which PNR maintains its production records and is different from the basis on which the Royalty is computed.

Estimated Quantities of Proved and Proved Developed Reserves (Unaudited)

	Oil and Condensate			Natural Gas
	(Bbls)			(Mcf)
Proved Reserves:
December 31, 2002		16,661		432,442
Revisions of previous estimates		(5,550	)	237
Extensions, discoveries and other additions		—		—
Production		—		—
December 31, 2003		11,111		432,679
Revisions of previous estimates		(5,151	)	(258,169
Extensions, discoveries and other additions		—		—
Production		—		—
December 31, 2004		5,960		174,510
Revisions of previous estimates		16,613		326,093
Extensions, discoveries and other additions		507		169,150
Production		(12,314	)	(209,698	)
December 31, 2005		10,766		460,055
Proved Developed Reserves:
December 31, 2002		16,661		432,442
December 31, 2003.		11,111		432,679
December 31, 2004.		5,960		174,510
December 31, 2005.		10,766		460,055

(See Notes on following page.)

Standardized Measure of Future Royalty Income from
Proved Oil and Condensate and Gas Reserves, Discounted at 10% Per Annum (Unaudited)

	December 31,
	2005			2004			2003
	(In thousands)
Ninety percent of future gross proceeds	$	4,625		$	1,808		$	3,584
Less ninety percent of—
Future operating costs	(65		)	(469		)	(640		)
Future capital costs, net of amounts previously accrued	—			—			—
Deficit due PNR	—			(59		)	(697		)
Future Royalty income	4,560			1,280			2,247
Discount at 10% per annum	(738		)	(176		)	(674		)
Standardized measure of future Royalty income from proved oil and gas reserves	$	3,822		$	1,104		$	1,573

47

Changes in the Standardized Measure of Future Royalty Income from
Proved Oil and Gas Reserves, Discounted at 10% Per Annum (Unaudited)

	Years Ended December 31,
	2005		2004			2003
	(In thousands)
Standardized measure at beginning of year	$	1,104	$	1,573		$	1,670
Revisions of previous estimates	3,311		(752		)	(675		)
Net changes in prices and production costs	422		126			411
Extensions, discoveries and other additions	1,160		—			—
Royalty income	(2,285)		—			—
Accretion of discount	110		157			167
Net changes in standardized measure	2,718		(469		)	(97
Standardized measure at end of year	$3,822		$	1,104		$	1,573

·The estimated quantities of proved reserves, standardized measure of future Royalty income and changes in the standardized measure represent 100% of amounts for the Partnership in which the Trust has a 99.99% interest.

(7)Selected Quarterly Financial Data (Unaudited)

	Summarized Quarterly Results
	Three Months Ended
	March 31		June 30		September 30			December 31
2005:
Royalty income	$	173,460	$	505,409		$	288,534	$	1,317,512
Distributable income	$	—	$	—		$	—	$	—
Distributable income per unit	$	—	$	—		$	—	$	—
2004:
Royalty income	$	—	$	—		$	—	$	—
Distributable income	$	—	$	—		$	—	$	—
Distributable income per unit	$	—	$	—		$	—	$	—

48

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

JPMorgan Chase Bank, N.A. (Trustee)
and the Unitholders of the Mesa Offshore Trust:

We have audited the accompanying statements of assets, liabilities and trust corpus of Mesa Offshore Trust as of December 31, 2005 and 2004, and the related statements of distributable income and changes in trust corpus for each of the years in the three-year period ended December 31, 2005. These financial statements are the responsibility of the Trustee. Our responsibility is to express an opinion on these financial statements based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit also includes assessing the accounting principles used and significant estimates made by the Trustee, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

These financial statements were prepared on the basis of accounting described in Note 3, which is a comprehensive basis of accounting other than accounting principles generally accepted in the United States of America.

In our opinion, the financial statements referred to above present fairly, in all material respects, the assets, liabilities and trust corpus of Mesa Royalty Trust as of December 31, 2005 and 2004, and the distributable income and changes in trust corpus for each of the years in the three-year period ended December 31, 2005, in conformity with the basis of accounting described in Note 3.

The accompanying financial statements have been prepared assuming that the Trust will continue as a going concern. As discussed in Note 1 to the financial statements, as a result of continued declines in production on Royalty Properties nearing the end of their estimated productive lives, Royalty income received by the Trust during 2002, 2003 and 2004 fell below the Termination Threshold prescribed by the Trust Indenture, resulting in the contractual termination of the Trust effective after December 31, 2004. The Trust Indenture provides the Trustee a two-year period during which it must sell all of the Trusts properties. Accordingly, there exists substantial doubt about the Trust’s ability to continue as a going concern. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

KPMG LLP

Houston, Texas
March 31, 2006

49

Item 9.Changes in and Disagreements with Accountants on Accounting and Financial Disclosure.

None.

Item 9A.Controls and Procedures

Evaluation of Disclosure Controls and Procedures.The Trustee maintains disclosure controls and procedures designed to ensure that information required to be disclosed by the Trust in the reports that it files or submits under the Exchange Act of 1934, as amended, is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and regulations. Disclosure controls and procedures include controls and procedures designed to ensure that information required to be disclosed by the Trust is accumulated and communicated by Pioneer, as the managing general partner of the Partnership, and the working interest owners to JPMorgan Chase Bank, N.A., as Trustee of the Trust, and its employees who participate in the preparation of the Trust’s periodic reports as appropriate to allow timely decisions regarding required disclosure.

As of the end of the period covered by this report, the Trustee carried out an evaluation of the Trust’s disclosure controls and procedures. Mike Ulrich, as Trust Officer of the Trustee, has concluded that the controls and procedures are effective.

Due to the contractual arrangements of (i) the Trust Indenture, (ii) the Partnership Agreement and (iii) the rights of the Partnership under the Conveyance regarding information furnished by the working interest owners, the Trustee relies on:  (A) information provided by the working interest owners, including (i) the status of litigation, (ii) historical operating data, plans for future operating and capital expenditures, reserve information, as well as (iii) information relating to projected production; (B) information provided by the managing general partner of the Partnership that is collected by the managing general partner from the working interest owners; and (C) conclusions regarding reserves by reserve engineers or other experts in good faith. See Item 1A. Risk Factors “—None of the Trust nor its unitholders control the operation or development of the Royalty Properties and have little influence over operation or development” and “—The Trustee relies upon the working interest owners and managing general partner for information regarding the Royalty Properties” in this form 10-K for a description of certain risks relating to these arrangements and reliance.

Changes in Internal Control over Financial Reporting..In connection with the evaluation by the Trustee of changes in internal control over financial reporting of the Trust that occurred during the Trust’s last fiscal quarter, no change in the Trust’s internal control over financial reporting was identified that has materially affected, or is reasonably likely to materially affect, the Trust’s internal control over financial reporting. The Trustee notes for purposes of clarification that it has no authority over, has not evaluated and makes no statement concerning, the internal control over financial reporting of the working interest owners or the managing general partner of the Partnership.

50

PART III

Item 10.Directors and Executive Officers of the Registrant.

There are no directors or executive officers of the Registrant. The Trustee is a corporate trustee that may be removed by the affirmative vote of a majority of the units then outstanding at a meeting of the holders of units of beneficial interest of the Trust at which a quorum is present.

The Trust does not have a principal executive officer, principal financial officer, principal accounting officer or controller and, therefore, has not adopted a code of ethics applicable to such persons. However, employees of the Trustee must comply with the bank’s code of ethics.

The Trust does not have a board of directors, and therefore does not have an audit committee, an audit committee financial expert or a nominating committee.

Item 11.Executive Compensation.

Not applicable.

Item 12.Security Ownership of Certain Beneficial Owners and Management.

(a)Security Ownership of Certain Beneficial Owners.

Title and Class of Voting Securities	Name and Address of Beneficial Ownership	Amount and Nature of Beneficial Ownership(1)			Percent of Class
Units of Beneficial Interest	MOSH Holding, L.P.		7,332,887	(2)(3)		10.2	%
	Nine Greenway Plaza
	Suite 3040
	Houston, Texas 77046

(1)Under applicable regulations of the Securities and Exchange Commission, securities are deemed to be “beneficially” owned by a person who directly or indirectly holds or shares of voting power with respect thereto.

(2)Based on information contained in the Form 4 filed on December 23, 2003 and Schedule 13D/A filed on December 16, 2003. These units of beneficial interest of the Issuer (the “Units”) are owned directly by MOSH Holding, L.P., a Texas limited partnership (“MHLP”). MOSH Holding I, L.L.C., a Texas limited liability company (“MOSHLLC”) is the sole general partner of MHLP and has sole investment discretion and voting authority with respect to the Units. Charles A. Sharman, Joseph F. Langston, Jr. and Timothy M. Roberson are the sole managers and members of MOSHLLC, in which capacity they may be deemed to share voting control and dispositive power over the Units.

(3)MOSHLLC and Messrs. Sharman, Langston and Roberson disclaim beneficial ownership of the reported Units except to the extent of their respective pecuniary interest therein.

(b)Security Ownership of Management. Not applicable.

(c)Changes in Control. Registrant knows of no arrangement, including the pledge of securities of the Registrant, the operation of which may at a subsequent date result in a change in control of the Registrant.

Item 13.Certain Relationships and Related Transactions.

See Item 3. Legal Proceedings and Item 1. Business “—Legal Proceedings and Status of the Trust” and “—Timing of Liquidation” for a description of legal proceedings and related transactions among the Trustee, the Trust and a 10% beneficial owner of units of the Trust.

51

Item 14.Principal Accounting Fees and Services

The Trust does not have an audit committee. Any pre-approval and approval of all services performed by the principal auditor or any other professional services firms and related fees are granted by the Trustee.

The following table presents fees for professional audit services rendered by KPMG LLP for the audit of the Mesa Offshore Trust financial statements for 2005 and 2004 and fees billed for other services rendered by KPMG LLP.

	2005		2004
Audit fees(1)	$	100,000	$	90,000
Audit-related fees	—		—
Tax fees(2)	25,000		25,000
All other fees	—		—
Total fees	$	125,000	$	115,000

(1)Audit fees consist of fees for the audit of the Mesa Offshore Trust financial statements and reimbursement for travel-related expenses.

(2)Tax fees consist of fees related to the Mesa Offshore Trust’s tax information for its unitholders paid in 2005 related to 2004 tax work and paid in 2004 related to 2003 tax work.

PART IV

Item 15. Exhibits, Financial Statement Schedules.

(a)(1)Financial Statements

The following financial statements are set forth under Part II, Item 8 of this Annual Report on Form 10-K on the pages indicated.

	Page in this Form 10-K
Statements of Distributable Income		39
Statements of Assets, Liabilities and Trust Corpus		39
Statements of Changes in Trust Corpus		39
Notes to Financial Statements		40
Report of Independent Registered Public Accounting Firm—KPMG LLP		49

(a)(2)   Schedules

Schedules have been omitted because they are not required, not applicable or the information required has been included elsewhere herein.

(a)(3)Exhibits

(JPMorgan Chase Bank, N.A., is successor by mergers to the original name of the Trustee, Texas Commerce Bank National Association)

52

		SEC File or Registration Number		Exhibit Number
4(a)	*Mesa Offshore Trust Indenture between Mesa Petroleum Co. and Texas Commerce Bank National Association, as Trustee, dated December 15, 1982		2-79673	10(gg)
4(b)	*Overriding Royalty Conveyance between Mesa Petroleum Co. and Mesa Offshore Royalty Partnership, dated December 15, 1982		2-79673	10(hh)
4(c)	*Partnership Agreement between Mesa Offshore Management Co. and Texas Commerce Bank National Association, as Trustee, dated December 15, 1982		2-79673	10(ii)
4(d)	*Amendment to Partnership Agreement between Mesa Offshore Management Co., Texas Commerce Bank National Association, as Trustee, and Mesa Operating Limited Partnership, dated December 27, 1985 (Exhibit 4(d) to Form 10-K for year ended December 31, 1992 of Mesa Offshore Trust)		1-8432	4(d)
4(e)	*Amendment to Partnership Agreement between Texas Commerce Bank National Association, as Trustee, and Mesa Operating dated as of January 5, 1994 (Exhibit 4(e) to Form 10-K for year ended December 31, 1993 of Mesa Offshore Trust)		1-8432	4 (e)
31	Certification furnished pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
32	Certification furnished pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

53

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	MESA OFFSHORE TRUST
	By	JPMORGAN CHASE BANK, N.A., TRUSTEE
	By:	/s/ MIKE ULRICH
		Mike Ulrich
		Vice President & Trust Officer
March 31, 2006

The Registrant, Mesa Offshore Trust, has no principal executive officer, principal financial officer, board of directors or persons performing similar functions. Accordingly, no additional signatures are available and none have been provided.

54

EXHIBIT INDEX

EXHIBIT NUMBER				SEC File or Registration Number		Exhibit Number
	4	(a)	*Mesa Offshore Trust Indenture between Mesa Petroleum Co. and Texas Commerce Bank National Association, as Trustee, dated December 15, 1982		2-79673		10	(gg)
	4	(b)	*Overriding Royalty Conveyance between Mesa Petroleum Co. and Mesa Offshore Royalty Partnership, dated December 15, 1982		2-79673		10	(hh)
	4	(c)	*Partnership Agreement between Mesa Offshore Management Co. and Texas Commerce Bank National Association, as Trustee, dated December 15, 1982		2-79673		10	(ii)
	4	(d)	*Amendment to Partnership Agreement between Mesa Offshore Management Co., Texas Commerce Bank National Association, as Trustee, and Mesa Operating Limited Partnership, dated December 27, 1985 (Exhibit 4(d) to Form 10-K for year ended December 31, 1992 of Mesa Offshore Trust)		1-8432		4	(d)
	4	(e)	*Amendment to Partnership Agreement between Texas Commerce Bank National Association, as Trustee, and Mesa Operating dated as of January 5, 1994 (Exhibit 4(e) to Form 10-K for year ended December 31, 1993 of Mesa Offshore Trust)		1-8432		4	(e)
	31		Certification furnished pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
	32		Certification furnished pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

*Previously filed with the Securities and Exchange Commission and incorporated herein by reference.

EX-31

Exhibit 31

CERTIFICATION

I, Mike Ulrich, certify that:

1.      I have reviewed this annual report on Form 10-K of Mesa Offshore Trust, for which JPMorgan Chase Bank, N.A., acts as Trustee;

2.      Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.      Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, distributable income and changes in trust corpus of the registrant as of, and for, the periods presented in this report;

4.      I am responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)), or for causing such controls and procedures to be established and maintained, for the registrant and I have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under my supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to me by others within those entities, particularly during the period in which this report is being prepared;

(b)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report my conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(c)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.      I have disclosed, based on my most recent evaluation, to the registrant’s auditors:

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting, which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

In giving the foregoing certifications in paragraphs 4 and 5, I have relied to the extent I consider reasonable on information provided to me by the working interest owners and the managing general partner of the Mesa Offshore Trust Partnership, in which the registrant owns a 99.99% interest.

Date: March 31, 2006	/s/ MIKE ULRICH
	Mike Ulrich,
	Vice President and Trust Officer
	JPMorgan Chase Bank, N.A.

EX-32

Exhibit 32

March 31, 2006

Via EDGAR

Securities and Exchange Commission
Judiciary Plaza
450 Fifth Street, N.W.
Washington, D.C. 20549

Re:Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Ladies and Gentlemen:

In connection with the Annual Report of Mesa Offshore Trust (the “Trust”) on Form 10-K for the year ended December 31, 2005 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, not in its individual capacity but solely as the trustee of the Trust, certifies pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to its knowledge:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Trust.

The above certification is furnished solely pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C. 1350) and is not being filed as part of the Form 10-K or as a separate disclosure document.

JPMORGAN CHASE BANK, N.A.
Trustee for Mesa Offshore Trust
By:	/s/ MIKE ULRICH
	Mike Ulrich
	Vice President and Trust Officer