13. Subsequent Event

On May 7, 2012, we executed the First Amendment to the Fourth Amended And Restated Credit Agreement, which, among other things, increased the number of banks, increased the borrowing base from $575.0 million to $650.0 million and added a survivorship of security provision. The agreement is effective May 7, 2012. All other terms of the agreement remain substantially the same as the prior agreement, including the termination date of May 5, 2015, interest rate spreads and covenants.