United States

Amerada Hess Corporation

Nexen Petroleum U.S.A. Inc.

American Energy Group

Northern Border Pipeline

Anadarko

Nuevo Energy Group

BP Corporation (ARCO, Amoco)

Newfield Exploration Company

Central Resources, Inc.

Occidental Petroleum Corporation

ChevronTexaco

Petro-Hunt Corporation

Cortez Oil & Gas, Inc.

Phillips Petroleum Company

Denbury Management, Inc.

Pioneer Natural Resources USA

Devon Energy Corporation

Plains Resources, Inc.

Dominion Exploration & Production, Inc.

Prodigy Oil & Gas LLC

Eland Energy, Inc.

Rosewood Resources, Inc.

Encore Acquisitions Partners, Inc.

Samedan Oil Corporation

Energen Resources

Shell Oil Company

ExxonMobil

Syntroleum Corporation

Five States Energy Company

Tejas Gas Corporation

Foothill Capital

Texland Petroleum

Forest Oil Corporation

THUMS

Goldston Oil Corporation

Torch Energy Corporation

Halliburton Energy Services

TotalFinaElf (Fina Oil & Chemical Company)

Headington Oil Company

Triad Energy Corporation

Hunt Petroleum Corporation

UNOCAL Corporation/Spirit 76

Ironwood Resources

Verado Energy, Inc.

Kerr-McGee Corporation

Vintage Petroleum, Inc.

Koch Exploration Company

Weber Energy Corporation

Louis Dreyfus Natural Gas

Westport Resources Corporation

Lyco Energy Company

Williams Energy Group

Magnum Hunter Resources, Inc.

The Wiser Oil Company

Marathon Oil Company

Woodbine Petroleum, Inc.

Merit Energy Company

XTO Energy (Cross Timbers Oil Company)

Yates Petroleum Company

International

ADNOC (Abu Dhabi National Oil Company)

Production Company of Oman (Shell)

Caltex Petroleum Corporation (ChevronTexaco)

PDVSA (Venezuela)

Central Resources, Inc.

Perez Companc S.A. (Argentina, Peru)

Chevron San Jorge S.A. (Argentina)

Petrobras

COPI (Chevron Overseas Petroleum, Inc.)

Pioneer Natural Resources (South Africa)

Dalmine SPA

Pluspetrol

Ecopetrol (Colombia)

REPSOL-YPF (Argentina)

Esso Malaysia

Santos

Forest International (South Africa)

Syntroleum

HOCOL (Colombia)

TotalFinaElf (Elf Aquitaine Petroleum)

INA (Croatia)

UMIC Cote d’Ivoire Corporation (Ocean Energy)

Nexen, Inc. (Canada) (Wascana Energy, Inc.)

UNOCAL Corporation/Spirit 76

Northstar Energy (Ocean Energy)

UPR (Venezuela)

Oxy Oil & Gas International

YPF (Argentina)

Financial

Allied Irish Bank

NatWest Securities

American Bank of Texas

Northern Trust Bank

American Federal Bank

PNC Financial Services

ANZ Investment Bank

Price Waterhouse LLP

Bank of America

Prudential Capital Group

Bank One (now J.P. Morgan Chase)

R. Reid Investments, Inc.

Bank of Montreal

Royal Bank of Canada

BBVA Compass Energy Group

RZB Finance LLC

Coldwell Banker Commercial

Siemens Financial Services, Inc.

Comerica Bank Energy Finance

Standard Americas, Inc.

Credit Agricole Indosuez (Calyon)

Stratum Group Ltd.

DZ Bank AG

Sun Trust Robinson Humphrey

Fortis Capital Corporation

Texas Capital Bank

GE Capital Corporation

The Huntington National Bank

Guggenheim Partners

The Carlyle Group

Hibernia National Bank (now Capital One)

Wells Fargo Energy Group

Jefferies Finance LLC

World Bank

NATIXIS

UniCredit Bank AG

Governmental Agencies

Department of Energy (DOE)

Environmental Protection Agency (EPA)