SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* OAS Holding Co LLC (Last) (First) (Middle) 1001 FANNIN STREET, SUITE 202 (Street) HOUSTON TX 77002 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Oasis Petroleum Inc. [ OAS ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 06/22/2010
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/22/2010		S		17,930,000(1)	D	$13.16	43,700,000	D(2)(3)(4)(5)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* OAS Holding Co LLC (Last) (First) (Middle) 1001 FANNIN STREET, SUITE 202 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* ENCAP ENERGY CAPITAL FUND VI L P (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EnCap VI-B Acquisitions, L.P. (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* ENCAP ENERGY CAPITAL FUND VII LP (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EnCap Equity Fund VI GP, L.P. (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EnCap Equity Fund VII GP, L.P. (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EnCap Investments L.P. (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EnCap Investments GP, L.L.C. (Last) (First) (Middle) 1100 LOUISIANA, SUITE 3150 (Street) HOUSTON TX 77002 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. OAS Holding Company LLC ("OAS Holdco") sold 11,630,000 shares of common stock to the public in connection with the initial public offering of the issuer on June 22, 2010 (the "IPO"). Pursuant to the underwriting agreement and in connection with the IPO, the underwriters exercised their option (the "Over-Allotment Option") to purchase additional shares of common stock from OAS Holdco. The Over-Allotment Option closed simultaneously with the IPO. OAS Holdco sold an additional 6,300,000 shares of common stock pursuant to the underwriters' exercise of the Over-Allotment Option.

2. EnCap Energy Capital Fund VI, L.P. ("EnCap Fund VI"), EnCap VI-B Acquisitions, L.P. ("EnCap VI-B") and EnCap Energy Capital Fund VII, L.P. ("EnCap Fund VII" and, together with EnCap Fund VI and EnCap VI-B, the "EnCap Funds") collectively own a 61% interest in OAS Holdco. The EnCap Funds may be deemed to beneficially own the reported securities.

3. The EnCap Funds are controlled indirectly by David B. Miller, D. Martin Phillips, Gary R. Petersen, and Robert L. Zorich which are members of RNBD GP LLC ("RNBD") and any action taken by RNBD to dispose or acquire securities has to be unanimously approved by all four members. RNBD is the sole member of EnCap Investments GP, L.L.C. ("EnCap Investments GP"), which is the general partner of EnCap Investments L.P. ("EnCap Investments LP"), which is the general partner of EnCap Equity Fund VI GP, L.P. ("EnCap Fund VI GP") and EnCap Equity Fund VII GP, L.P. ("EnCap Fund VII GP"). EnCap Fund VI GP is the sole general partner of each of EnCap Fund VI and EnCap VI-B, and EnCap Fund VII GP is the sole general partner of EnCap Fund VII. Therefore, Messrs. Miller, Phillips, Petersen and Zorich, RNBD, EnCap Investments GP, EnCap Investments LP, EnCap Fund VI GP and EnCap Fund VII GP may be deemed beneficially own the reported securities.

4. This report is filed in connection with the Form 4 filed jointly today by Messrs. Miller, Phillips and Petersen and RNBD and the Form 4 filed today by Mr. Zorich.

5. The reporting persons disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that the reporting persons are the beneficial owners of the reported securities for purposes of Section 16 or for any other purpose.

Remarks:

EnCap VI-B Acquisitions, L.P., By EnCap VI-B Acquisitions GP, LLC, its general partner, By EnCap Energy Capital Fund VI-B, L.P., its sole member, By EnCap Equity Fund VI GP, L.P., its general partner, By EnCap Investments L.P., its general partner, By EnCap Investments GP, L.L.C., its general partner, By /s/ D. Martin Phillips, Senior Managing Director

	OAS Holding Company LLC, By /s/ Thomas B. Nusz	06/24/2010
	EnCap Energy Capital Fund VI, L.P., By EnCap Equity Fund VI GP, L.P., its general partner, By EnCap Investments, L.P., its general partner, By EnCap Investments GP, L.L.C., its general partner, By /s/ D. Martin Phillips, Senior Managing Director	06/24/2010
	See Remarks	06/24/2010
	EnCap Energy Capital Fund VII, L.P., By EnCap Equity Fund VII GP, L.P., its general partner, By EnCap Investments L.P., its general partner, By EnCap Investments GP, L.L.C., its general partner, By /s/ D. Martin Phillips, Senior Managing Director	06/24/2010
	EnCap Equity Fund VI GP, L.P., By EnCap Investments, L.P., its general partner, By EnCap Investments GP, L.L.C., its general partner, By /s/ D. Martin Phillips, Senior Managing Director	06/24/2010
	EnCap Equity Fund VII GP, L.P. , By EnCap Investments L.P., its general partner, By EnCap Investments GP, L.L.C., its general partner, By /s/ D. Martin Phillips, Senior Managing Director	06/24/2010
	EnCap Investments L.P. , By EnCap Investments GP, L.L.C., its general partner, By /s/ D. Martin Phillips, Senior Managing Director	06/24/2010
	EnCap Investments GP, L.L.C., By /s/ D. Martin Phillips, Senior Managing Director	06/24/2010
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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