Long-term debt

Long-term debt at March 31, 2012 and December 31, 2011, consisted of the following:



	March 31, 2012			December 31, 2011
8.875% Senior Notes due 2017	$	325,000		$	325,000
9.875% Senior Notes due 2020	300,000			300,000
8.25% Senior Notes due 2021	400,000			400,000
Senior secured revolving credit facility	40,000			—
Real estate mortgage notes, principal and interest payable monthly, bearing interest at rates ranging from 3.50% to 5.46%, due January 2013 through December 2028; collateralized by real property	12,932			12,116
Installment notes payable, principal and interest payable monthly, bearing interest at rates ranging from 2.00% to 9.25%, due April 2012 through March 2017; collateralized by automobiles, machinery and equipment	6,039			5,546
Capital lease obligations	—			10
Discount on 8.875% Senior Notes due 2017	(1,593		)	(1,658		)
Discount on 9.875% Senior Notes due 2020	(6,327		)	(6,441		)
	1,076,051			1,034,573
Less current maturities	4,096			3,078
	$	1,071,955		$	1,031,495

In April 2010, we entered into our Eighth Restated Credit Agreement (our “senior secured revolving credit facility”), which is collateralized by our oil and natural gas properties and matures on April 1, 2016. Availability under our senior secured revolving credit facility is subject to a borrowing base which is set by the banks semi-annually on May 1 and November 1 of each year. In addition, the lenders may request a borrowing base redetermination once between each scheduled redetermination and in the event of early termination of our derivative contracts.

The Eighth Amendment to our senior secured revolving credit facility, effective April 30, 2012, amended our Asset Sale Covenant to permit the sale of certain oil and natural gas properties located in southern Oklahoma and increased our permitted ratio of Consolidated Net Debt to Consolidated EBITDAX from 4.25 to 4.50. It also reaffirmed the borrowing base at $375,000 through November 1, 2012. As of May 11, 2012, the balance outstanding under our senior secured revolving credit facility is $50,000.

Borrowings under our senior secured revolving credit facility are made, at our option, as either Eurodollar loans or Alternate Base Rate (“ABR”) loans. The entire balance outstanding at March 31, 2012 was a Eurodollar loan.

Interest on Eurodollar loans is computed at the Adjusted LIBO Rate, defined as the rate applicable to dollar deposits in the London interbank market with a maturity comparable to the interest period (one, two, three or six months, selected by us) times a Statutory Reserve Rate multiplier, as defined in our senior secured revolving credit facility, plus a margin where the margin varies from 1.75% to 2.75% depending on the utilization percentage of the conforming borrowing base. Interest payments on Eurodollar borrowings are due the last day of the interest period, if shorter than three months or every three months.

Interest on ABR loans is computed as the greater of (1) the Prime Rate, as defined in our senior secured revolving credit facility, (2) the Federal Funds Effective Rate, as defined in our senior secured revolving credit facility, plus 1/2 of 1%, or (3) the Adjusted LIBO Rate, as defined in our senior secured revolving credit facility, plus 1%; plus a margin where the margin varies from 0.75% to 1.75%, depending on the utilization percentage of the borrowing base.

Commitment fees of 0.50% accrue on the unused portion of the borrowing base amount and are included as a component of interest expense. We have the right to make prepayments of the borrowings at any time without penalty or premium.

Our senior secured revolving credit facility has certain negative and affirmative covenants that require, among other things, maintaining a Current Ratio, as defined in our senior secured revolving credit facility, of not less than 1.0 to 1.0 and a Consolidated Net Debt to Consolidated EBITDAX ratio, as defined in our senior secured revolving credit facility, of not greater than 4.50 to 1.0 for the four consecutive fiscal quarters ending on June 30, 2010 and for each period of four consecutive fiscal quarters ending on the last day of such applicable fiscal quarters thereafter.

We believe we were in compliance with all covenants under our senior secured revolving credit facility as of March 31, 2012.

Our senior secured revolving credit facility also specifies events of default, including non-payment, breach of warranty, non-performance of financial covenants, default on other indebtedness, certain adverse judgments, and change of control, among others. In addition, bankruptcy and insolvency events with respect to us or certain of our subsidiaries will result in an automatic acceleration of the indebtedness under our senior secured revolving credit facility. An acceleration of our indebtedness under our senior secured revolving credit facility could in turn result in an event of default under the indentures for our Senior Notes, which in turn could result in the acceleration of the Senior Notes.

If the outstanding borrowings under our senior secured revolving credit facility were to exceed the borrowing base as a result of a redetermination, we would be required to eliminate this excess. Within 10 days after receiving notice of the new borrowing base, we would be required to make an election: (1) to repay a portion of our bank borrowings in the amount of the excess either in a lump sum within 30 days or in equal monthly installments over a six-month period, (2) to submit within 30 days additional oil and natural gas properties we own for consideration in connection with the determination of the borrowing base sufficient to eliminate the excess or (3) to eliminate the excess through a combination of repayments and the submission of additional oil and natural gas properties within 30 days.