ATP Begins 2008 with Record Reserves and Production

Business Wire, Feb 21, 2008

HOUSTON -- ATP Oil & Gas Corporation (NASDAQ:ATPG) today announced record reserves in all categories, an annual production increase of 26% and a reserve replacement ratio of 223%.

Reserves and Production

ATP reported independent third-party year-end 2007 total proved plus probable reserves of 181.7 MMBoe with a pre-tax PV-10 value of approximately $5.3 billion. Proved reserves were 119.3 MMBoe, an increase of 13.1 MMBoe ( 12%), with a pre-tax PV-10 value of approximately $3.5 billion. Equally important was the growth in proved developed reserves, increasing 5.7 MMBoe ( 16 %) to 41.3 MMBoe. ATP's 181.7 MMBoe of proved and probable reserves are located 57% in the Gulf of Mexico Deepwater, 4% on the Gulf of Mexico Shelf and 39% in the North Sea.

ATP achieved a 223% reserve replacement ratio for 2007 with additions of 23.8 MMBoe to its proved reserves. Acquisitions resulted in 5.2 MMBoe, while revisions, extensions and discoveries to properties previously owned accounted for 18.6 MMBoe. ATP coupled these additions with record production of 10.7 MMBoe, including 8.6 MMBoe in the Gulf of Mexico and 2.0 MMBoe in the North Sea.

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All reserves and hydrocarbons included in this release are shown net to ATP's working interest. On or about March 3, ATP will post copies of certification letters from its independent third-party reservoir engineers under the Investor Info-Annual/Quarterly Reports section of its website at www.atpog.com.

Top 5 Properties

Based on proved and probable reserves, ATP's top five properties are listed below. Collectively, the top five properties, all of which are operated by ATP, represent 80% of proved and probable reserves.

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Reserve Reports

ATP's 2006 and 2007 proved and probable reserve reports were prepared by independent third-party reservoir engineers. ATP's Gulf of Mexico reserves were prepared by Ryder Scott Company, L.P., Collarini Associates and DeGolyer and MacNaughton. ATP's U.K. reserves were prepared by RPS Energy and ATP's Netherlands reserves were prepared by Ryder Scott Company, L.P.

The proved reserve quantities and classifications contained in the reports prepared by the independent third-party reservoir engineers conform to the definition as set forth in accordance with parameters established by the Securities and Exchange Commission ("SEC") Regulation S-X Part 210.4-10 (a) as clarified by subsequent Commission Staff Accounting Bulletins.

About ATP Oil & Gas

ATP Oil & Gas is an international offshore oil and gas development and production company with operations in the Gulf of Mexico 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 are "forward-looking statements" under the Private Securities Litigation Reform Act of 1995. ATP cautions that assumptions, expectations, projections, intentions, or beliefs about future events may, and often do, vary from actual results and the differences can be material. Some of the key factors which could cause actual results to vary from those ATP expects include changes in natural gas and oil prices, the timing of planned capital expenditures, availability of acquisitions, uncertainties in estimating proved reserves and forecasting production results, operational factors affecting the commencement or maintenance of producing wells, the condition of the capital markets generally, as well as our ability to access them, and uncertainties regarding environmental regulations or litigation and other legal or regulatory developments affecting our business. The SEC has generally permitted oil and gas companies, in filings made with the SEC, to disclose only proved reserves that a company has demonstrated by actual production or conclusive formation tests to be economically and legally producible under existing economic and operating conditions. ATP and its independent third-party reservoir engineers use the terms "probable" and "possible" and ATP uses the term "recoverable hydrocarbons" to describe volumes of reserves potentially recoverable through additional drilling or recovery techniques that the SEC's guidelines may prohibit ATP from including in filings with the SEC. These estimates are by their nature more speculative than estimates of proved reserves. All estimates of probable and possible reserves in this news release have been prepared by ATP's independent third-party reservoir engineers and all estimates of recoverable hydrocarbons have been prepared by management. More information about the risks and uncertainties relating to ATP's forward-looking statements are found in the company's SEC filings.