ATP Oil Gas Corporation Denver Presentations September 16

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

Forward-looking Statement This presentation contains projections and other forward looking statements within the meaning of Section 27 A of the Securities Act of 1933 and Section 21 E 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

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

Company Profile • Ticker: ATPG • Production: • 2001 Actual: • 2002 Guidance: 25. 7 Bcfe 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

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

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

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

Recent Focus • 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 ATP Oil & Gas Corporation

2002 Development Activity Gulf of Mexico South Marsh Island 189 Projected start date Actual first production Eugene Island 71 Initial production Increased production West Cameron 101 Projected start date 13 workovers PDNP to PDP April 2002 March 18, 2002 PUD to PDP Feb 2002 June 2002 PUD to PDP 4 th Quarter PDNP to PDP ATP Oil & Gas Corporation

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

ATP Area of Operations Oil & Gas Corporation WC 101 11

West Cameron 101 Water Depth: Working Interest: Net Revenue Interest: Platform/Wells: First Production: Producing Sands: 43’ 100% 73. 33% One well caisson. 4 th Q 2002 (proposed) 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. ATP Oil & Gas Corporation

West Cameron 101 #2 Log ATP Oil & Gas Corporation

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

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

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

Helvellyn Water Depth: Working Interest: Net Revenue Interest: Platform/Wells: First Production: 90’ 100% Subsea Projected 2003 Producing Sands: Rotliegend/Carboniferous First well drilled: First well tested: 1985 47/10 -1 well tested at 29. 4 MMcfepd ATP proposed well: 2, 000 foot horizontal section through both producing sands ATP Oil & Gas Corporation

Helvellyn Development 2002 Projected production 2003 ATP Oil & Gas Corporation

Helvellyn Development August 2002 Pipeline Lay ATP Oil & Gas Corporation

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

Venture Development 2003 Projected production 2004 ATP Oil & Gas Corporation

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

ATP Oil & Gas Corporation Financial Overview

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

First Half 2002 Capital Liquidity Improvement Working Capital Increased $12. 2 million + Bank and Subordinated Debt Decreased $10. 0 million = Overall Capital Liquidity Improvement $22. 2 million ATP Oil & Gas Corporation

2002 Operating Performance ($ in millions) Gross Margin 87% 2 Q 02 Note: Revenue reflect the effects of settled hedging activity ATP Oil & Gas Corporation

Financial Strength • Long-term debt / proven reserves(1) $0. 38 / Mcfe • EBITDA / Interest(2) 7. 7 X • Bank credit facility(1) $62 million • 1 H 02 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 2 Q 02 results (3) Gulf of Mexico only ATP Oil & Gas Corporation

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

Our Peers ATP Oil & Gas Corporation

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

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

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

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

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

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

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

Rate of Return Focused Capital Efficiency ATP Oil & Gas Corporation

ATP Why Should ATP Be In Your Portfolio? 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

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

History of Producing Results 6 years of production and reserve growth GAS OIL Production (BCFE) Proven Reserves (BCFE) 2 Q 02 Production 71% natural gas 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 GU 1 1 UJ United Kingdom 44 (0) 1483 307200 www. atpog. com ATP Oil & Gas Corporation