ATP Announces Success at Shimshon Well in the Mediterranean Sea

ATP Oil & Gas Corporation (NASDAQ: ATPG) and its wholly-owned subsidiary ATP East Med B.V. (“ATP East Med”) today announced success at the Shimshon well in the Levant Basin of offshore Israel. The Shimshon well encountered more than 62 feet (19 meters) of natural gas pay in the Bet Guvrin sands. The Shimshon well is in a water depth of 3,622 feet (1,104 meters) and was drilled to a subsea depth of 14,445 feet (4,403 meters). ATP expects to provide additional information about the discovery during the third quarter of 2012. ATP East Med operates with a 40% working interest. Other interest owners in the well are Isramco Negev 2 LP (39%), Naphtha Exploration Limited Partnership (10%), INOC Dead Sea LP (10%) and I.O.C.-Israel (1%).

About ATP Oil & Gas Corporation

ATP Oil & Gas is an international offshore oil and gas development and production company with operations in the Gulf of Mexico, Mediterranean Sea and the North Sea. The company trades publicly as ATPG on the NASDAQ Global Select Market. For more information about ATP Oil & Gas Corporation, visit www.atpog.com.

Forward-looking Statements

Certain statements included in this news release contain "forward-looking statements" within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934. ATP cautions that assumptions, expectations, projections, intentions, plans, beliefs or similar expressions used to identify forward-looking statements about future events may, and often do, vary from actual results and the differences can be material from those expressed or implied in such forward looking statements. Some of the key factors which could cause actual results to vary from those ATP expects include, without limitation, volatility in commodity prices for crude oil and natural gas, the condition of the capital markets generally, as well as ability to access them, the timing of planned capital expenditures, uncertainties in estimating reserves and forecasting production results, operational factors affecting the commencement or maintenance of producing wells, and uncertainties regarding environmental regulations or litigation and other legal or regulatory developments affecting its business. ATP assumes no obligation and expressly disclaims any duty to update the information contained herein except as required by law. While ATP does not file reports with the SEC containing probable and possible reserve quantities, ATP occasionally will include them in news releases, presentations and discuss such reserves publicly. ATP and its independent third party reservoir engineers use the term “probable” to describe volumes of reserves potentially recoverable through additional drilling or recovery techniques that, by their nature, are more speculative than estimates of proved reserves. Any estimates of reserves in this news release have been prepared by our independent third party engineers. More information about the risks and uncertainties relating to ATP's forward-looking statements is found in the company's SEC filings or website, www.atpog.com.