Petroleum

ANR Pipeline Co.

Abu Dhabi National Oil Company

Agway, Inc.

Alberta Energy Company Ltd.

Amerada Hess Corporation

Amoco Corporation

Anadarko Petroleum Corporation

Apache Corporation

Aral AG

Arctic Slope Regional Corporation

Ashland Inc.

Atlantic Richfield Company

BHP Billiton

BJ Services Company

BP p.l.c.

Baker Hughes Incorporated

Belco Oil & Gas Corp.

Benton Oil and Gas Company

Berry Petroleum Company

Bill Barrett Corporation

Blue Rhino Corporation

Boots & Coots International Well Control, Inc.

Brigham Exploration Company

British-Borneo Oil & Gas PLC

Broken Hill Proprietary Company Ltd.

Burlington Resources Inc.

Burmah Castrol PLC

CITGO Petroleum Corporation

CONSOL Energy Inc.

Callon Petroleum Company

Caltex Petroleum Corporation

Chevron Corporation

ChevronTexaco Corporation

Chiles Offshore Corporation

China National Petroleum Corporation

Chinese Petroleum Corporation

Cimarex Energy Co.

Compañia Española de Petróleos S.A. (Cepsa)

Comstock Resources, Inc.

Conoco Inc.

ConocoPhillips

Cosmo Oil Co., Ltd.

DeepTech International Inc.

Denbury Resources, Inc.

Devon Energy Corporation

Distrigaz S.A.

Dril-Quip, Inc.

Dynegy Inc.

E.On AG

ENI S.p.A.

ENSCO International Incorporated

Edge Petroleum Corporation

Egyptian General Petroleum Corporation

El Paso Corporation

Elf Aquitaine SA

Enbridge Inc.

Encore Acquisition Company

Energen Corporation

Enterprise Oil PLC

Enterprise Oil plc

Equitable Resources, Inc.

Exxon Corporation

Exxon Mobil Corporation

Ferrellgas Partners, L.P.

Flying J Inc.

Forest Oil Corporation

Giant Industries, Inc.

Global Industries, Ltd.

Global Marine Inc.

GlobalSantaFe Corporation

Grey Wolf, Inc.

Halliburton Company

Hanover Compressor Company

Helix Energy Solutions Group, Inc.

Hellenic Petroleum SA

Helmerich & Payne, Inc.

Holly Corporation

Hunt Consolidated, Inc.

Hunting plc

Hurricane Hydrocarbons Ltd.

Husky Energy Inc.

Idemitsu Kosan Co., Ltd.

Imperial Oil Limited

Indian Oil Corporation Ltd.

Input/Output, Inc.

Iogen Corporation

Ipiranga S.A.

Kerr-McGee Corporation

Kinder Morgan, Inc.

Koch Industries, Inc.

Koppers Industries, Inc.

Kuwait Petroleum Corporation

MOL Rt

McDermott International, Inc.

Meteor Industries Inc.

Mobil Corporation

Murphy Oil Corporation

NGC Corporation

Nabors Industries, Inc.

National Iranian Oil Company

National Oil Corporation

Newfield Exploration Company

Nexen Inc.

Nigerian National Petroleum Corporation

Nippon Oil Corporation

Noble Affiliates, Inc.

OAO Gazprom

OAO LUKOIL

OAO NK YUKOS

OAO Siberian Oil Company (Sibneft)

OAO Surgutneftegaz

OAO Tatneft

Occidental Petroleum Corporation

Odebrecht S.A.

Oil States International, Inc.

PTT Public Company Ltd.

Pacific Ethanol, Inc.

Pakistan State Oil Company Ltd.

Parker Drilling Company

Patterson-UTI Energy, Inc.

Pennzoil Company

Pennzoil-Quaker State Company

Pertamina

PetroFina S.A.

Petrobras Energia Participaciones S.A.

Petrohawk Energy Corporation

Petroleos Mexicanos

Petroliam Nasional Bhd (Petronas)

Petron Corporation

Phillips Petroleum Company

Pioneer Natural Resources Company

Pogo Producing Company

Polski Koncern Naftowy ORLEN S.A.

Premcor Inc.

Pride International, Inc.

Quaker State Corporation

RWE AG

Range Resources Corporation

Reliance Industries Ltd.

Repsol S.A.

Repsol-YPF S.A.

Resource America, Inc.

Rowan Companies, Inc.

Santa Fe International Corporation

Santos Ltd.

Sasol Limited

Saudi Arabian Oil Company

Schlumberger Limited

Seagull Energy Corporation

Seitel, Inc.

Shanghai Petrochemical Co., Ltd.

Shell Oil Company

Showa Shell Sekiyu K.K.

Smith International, Inc.

Sonatrach

Spinnaker Exploration Company

St. Mary Land & Exploration Company

Statoil ASA

Suburban Propane Partners, L.P.

Suncor Energy Inc.

Sunoco, Inc.

Superior Energy Services, Inc.

Swift Energy Company

TEPPCO Partners, L.P.

Talisman Energy Inc.

Texaco Inc.

The British Petroleum Company plc

The Coastal Corporation

The Williams Companies, Inc.

Tidewater Inc.

Tom Brown, Inc.

Tonen Corporation

TonenGeneral Sekiyu K.K.

TransMontaigne Inc.

Transocean Sedco Forex Inc.

Travel Ports of America, Inc.

Triton Energy Corporation

Ultra Petroleum Corporation

Ultramar Diamond Shamrock Corporation

Union Texas Petroleum Holdings, Inc.

Unit Corporation

Universal Compression, Inc.

Unocal Corporation

Valero Energy Corporation

Varco International, Inc.

Vastar Resources, Inc.

Vintage Petroleum, Inc.

Wascana Energy Inc.

Weatherford International, Inc.

Webber Oil Company

Western Atlas Inc.

Western Company of North America

Western Gas Resources, Inc.

Westport Resources Corporation

Whiting Petroleum Corporation

World Fuel Services Corporation

XTO Energy Inc.