ATP Continues to Expand Liquidity

ATP Oil & Gas Corporation

today announced that it has closed the previously mentioned $100 million temporary overriding royalty interest transaction at its Clipper property. Located at Green Canyon 300 in the deepwater Gulf of Mexico, Clipper has two wells that were completed in 2011 and tested at a combined rate of 22 MBoe/d (16 MBoe/d net to ATP), 62% oil. The new $100 million transaction is designed to fund a portion of the capital program at Clipper. Overriding royalty interest payments will not occur until Clipper begins producing. Clipper is scheduled to commence production late 3Q 2012 or early 4Q 2012. On Friday, March 16, 2012, ATP increased its First Lien facility by $155 million and the interest rate was reduced from a fixed 9.00% to a floating 8.75% per annum. These transactions are in addition to the approximately $80 million of asset monetizations that closed earlier this month. In total, ATP has improved its liquidity by closing transactions totaling approximately $335 million during March 2012