1. 1 ATP Oil & Gas Corporation Denver Presentations September 16-17, 2002 ATP Oil & Gas Corporation

2. 2 Forward-looking Statement This presentation contains projections and other forward looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These projections and statements reflect the Company’s current view with respect to future events and financial performance. No assurances can be given, however, that these events will occur or that these projections will be achieved, and actual results could differ materially from those projected as result of certain factors. A discussion of these factors is included in the Company documents filed with the Securities and Exchange Commission. This presentation does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy or an attempt to influence any voting of securities, by any person. ATP Oil & Gas Corporation

3. Area of Operations Over 50 blocks in Gulf of Mexico 7 blocks in North Sea ATP Oil & Gas Corporation

4. 4 Company Profile Ticker:ATPG Production: 2001 Actual:25.7 Bcfe 2002 Guidance:26.5 Bcfe Proven reserves 2001: 235 Bcfe 3-year reserve replacement:374% 3-year F&D costs:$0.96/Mcfe ATP Oil & Gas Corporation

5. 5 Company Overview Development and production company Offshore solution provider for exploration oriented majors and independents Unique, repeatable strategy ATP Oil & Gas Corporation SMI 189/190

6. 6 Our D&P Strategy Works ATP Oil & Gas Corporation For the Sellers Eliminates future capital risk Allows them to recover some sunk costs Diverts capital to other core projects For ATP Eliminates exploration risk Reduces acquisition & development costs Shortens duration of risked capital

7. 7 Company History ATP Oil & Gas Corporation 1995 2002 1997 1991 ATP incorporated on August 8th ATP completes its first sub-sea development ATP acquires all Statoil’s properties on the Outer- Continental Shelf ATP is one of the first companies to utilize horizontal drilling offshore 1998 ATP awarded UKCS Blocks by DTI in a rare Out- of-Round license ATP was founded in 1991 and completed an initial public offering in February 2001

8. 8 Recent Focus ATP Oil & Gas Corporation Increasing financial flexibility –Reduced debt $28 million –Increased liquidity $22 million Exceeding operating goals –Decreased second quarter LOE / Mcfe 17% –Beat first half 2002 production guidance by 17% Developing North Sea reserves –Pipeline installed and well drilling at Helvellyn –First production in 2003 Making money –Discretionary cash flow increased from $4 to $48 million (‘97-’01) –Profitable in second quarter 2002

9. 9 2002 Development Activity ATP Oil & Gas Corporation Gulf of Mexico South Marsh Island 189PDNP to PDP Projected start dateApril 2002 Actual first productionMarch 18, 2002 Eugene Island 71PUD to PDP Initial productionFeb 2002 Increased productionJune 2002 West Cameron 101PUD to PDP Projected start date4 th Quarter 13 workoversPDNP to PDP

10. 10 Development Activity Gulf of Mexico ATP is moving 32 Bcfe from non-producing to proven developed producing properties (PDP) for less than $20 million, while increasing total PDP reserves 15% to 42 Bcf. ATP Oil & Gas Corporation

11. Area of Operations ATP Oil & Gas Corporation WC 101

12. 12 West Cameron 101 ATP Oil & Gas Corporation Water Depth: 43’ Working Interest: 100% Net Revenue Interest: 73.33% Platform/Wells:One well caisson. First Production:4 th Q 2002 (proposed) Producing Sands: Miocene Marg A 53 thru 55 Sands at 13,000’ TVD Current Status: Caisson waiting on completion Location: Offset Mobil L-2 well -555 MBO 2 BCFG Superior C-3, C-7 wells also prod. 53 and 55 sands.

13. 13 West Cameron 101 #2 Log ATP Oil & Gas Corporation

14. 14 Future Development (2003 – 2005) Future developments 100% of properties ATP operated ATP Oil & Gas Corporation

15. ATP Oil & Gas Corporation North Sea Developments ATP Oil & Gas Corporation

16. 16 Southern Gas Basin of North Sea ATP Oil & Gas Corporation The Tors Helvellyn Venture

17. 17 Helvellyn ATP Oil & Gas Corporation Water Depth: 90’ Working Interest: 100% Net Revenue Interest: 100% Platform/Wells:Subsea First Production:Projected 2003 Producing Sands: Rotliegend/Carboniferous First well drilled:1985 First well tested:47/10-1 well tested at 29.4 MMcfepd ATP proposed well:2,000 foot horizontal section through both producing sands

18. 18 Helvellyn Development ATP Oil & Gas Corporation Development 2002 Projected production 2003

19. 19 Helvellyn Development August 2002 Pipeline Lay ATP Oil & Gas Corporation

20. 20 Helvellyn Development Wellhead Protection Structure ATP Oil & Gas Corporation Well Spudded September 8, 2002

21. 21 Venture ATP Oil & Gas Corporation Development 2003 Projected production 2004

22. 22 The Tors ATP Oil & Gas Corporation 10km Development 2004 Projected production 2005

23. 23 Financial Overview ATP Oil & Gas Corporation

24. 24 Debt Reduction Program ATP Oil & Gas Corporation ($ in millions)

25. 25 First Half 2002 Capital Liquidity Improvement ATP Oil & Gas Corporation Working Capital Increased $12.2 million + Bank and Subordinated DebtDecreased $10.0 million = Overall Capital Liquidity Improvement $22.2 million

26. 26 2002 Operating Performance ATP Oil & Gas Corporation ($ in millions) Gross Margin 87% 2Q02 Note: Revenue reflect the effects of settled hedging activity

27. 27 Financial Strength ATP Oil & Gas Corporation Long-term debt / proven reserves (1) $0.38 / Mcfe EBITDA / Interest (2) 7.7X Bank credit facility (1) $62 million 1H02 Discretionary cash flow$29 million Capex (3) 1 st half 2002$12 million 2002 E$20 million (1)At June 30, 2002 (2)Based on 2Q02 results (3)Gulf of Mexico only

28. 28 Why Should ATP Be In Your Portfolio? ATP Oil & Gas Corporation Comparable to larger Gulf of Mexico operators

29. 29 Our Peers ATP Oil & Gas Corporation

30. 30 Why Should ATP Be In Your Portfolio? ATP Oil & Gas Corporation Comparable to larger Gulf of Mexico operators Attractive valuation

31. 31 Attractive Valuation P/CFPS significantly below peers ATP Oil & Gas Corporation

32. 32 Attractive Valuation EV trades at a discount to NAV ATP Oil & Gas Corporation

33. 33 Why Should ATP Be In Your Portfolio? ATP Oil & Gas Corporation Comparable to larger Gulf of Mexico operators Attractive valuation Efficient Gulf of Mexico operator

34. 34 Efficient Gulf of Mexico Operator Lowest production costs in the group ATP Oil & Gas Corporation

35. 35 Why Should ATP Be In Your Portfolio? ATP Oil & Gas Corporation Comparable to larger Gulf of Mexico operators Attractive valuation Efficient Gulf of Mexico operator Rate of return focused

36. 36 Rate of Return Focused 3-year F&D costs under $1/Mcf ATP Oil & Gas Corporation

37. 37 Rate of Return Focused Capital Efficiency ATP Oil & Gas Corporation

38. 38 Why Should ATP Be In Your Portfolio? ATP Oil & Gas Corporation Comparable to larger Gulf of Mexico operators Attractive valuation Efficient Gulf of Mexico operator Rate of return focused History of producing results

39. 39 History of Producing Results 6 years of cash flow and revenue growth ATP Oil & Gas Corporation Discretionary Cash Flow Revenue ($ in millions)

40. 40 ATP Oil & Gas Corporation Production (BCFE)Proven Reserves (BCFE) 2Q02 Production 71% natural gas History of Producing Results 6 years of production and reserve growth OIL GAS

41. 41 ATP Oil & Gas Corporation ATP Oil & Gas Corporation NASDAQ: ATPG ATP Oil & Gas Corporation 4600 Post Oak Place, Suite 200 Houston, TX 77027-9726 713-622-3311 ATP Oil & Gas (UK) Limited Victoria House, London Square, Cross Lanes Guildford, Surrey GU1 1UJ United Kingdom 44 (0) 1483 307200 www.atpog.com