AKG Companies
Allegro Investments, Inc.
Alta Mesa Resources
Anadarko Canada Corporation
Anadarko Petroleum Corporation
Apache Corporation
Asher Resources
Barnes & Lewis, P.C.
Bass Enterprises Production Company
Bean Resources, Inc.
Bear Mountain Resources, LLC
Beartooth Oil and Gas Company
BEUSA Energy, Inc.
Bissell Operating, Inc.
Black Hills Exploration and Production Company
Bold Energy II, LP
BOPCO, L.P.
Brighton Energy, LLC
BTA Oil Producers
Burnett Oil Company, Inc.
C&E Operating, Inc.
C&J Energy Services
CEI Petroleum, Inc.
Chesapeake Energy Corporation
Cheyenne Petroleum Company
Cholla Petroleum, Inc.
Citrus Energy Corporation
Classic Hydrocarbons, Inc.
Devon Energy Corporation
Duncan Oil Properties, Inc.
Enerplus Resources (USA)
EnerQuest Oil and Gas, LLC
EOG Resources, Inc.
EXCO Operating Company, LP
EXCO Resources - Winchester
EXCO Resources, Inc.
Exoma Energy Limited
Fidelity Exploration and Production Company
Forest Oil Corporation
GLB Exploration, Inc.
Greystone Oil & Gas LLP
Gunnison Energy Corporation
Hadaway Engineering, Inc.
Harding & Shelton, Inc.
Helis Oil & Gas Company, LLC
Hinkle Oil & Gas, Inc.
Hunter Energy
JUNEX, Inc.
Keystone Exploraton, Ltd.
King Operating
Kirkpatrick Oil Company
Kodiak Oil & Gas Corporation
Laredo Petroleum, Inc.
Layline Petroleum LLC
LCS Production Company
Legado Resources

Legend Natural Gas II, LP
Legend Natural Gas III
Linn Operating, Inc.
Lone Star Land & Energy, LLC
Marion Energy, Inc.
McClesky Operating, Inc.
McKool Smith, P.C.
Mississippi Resources, LLC
Noble Energy Production, Inc.
Parten Operating, Inc.
Peak Energy Resources, LLC
Penn Virginia MC Energy, LLC
Petro-Hunt, LLC
Petrolera El Trebol SA
Petrolia Inc.
PetroSpirit Resources LTD
Philcon Development Company
Phoenix PetroCorp, Inc.
Plano Petroleum
Plantation Petroleum Company
Provident/Arkanova Energy
Pure Energy
Quantum Resource Management, LLC
Range Resources Corporation
Raydon Exploration
Red Willow Production Company
Reliance Energy, Inc.
Resolute Energy Corporation
RKI Exploration & Production, LLC
SandRidge Energy
Sequel Energy, LLC
SFC Energy Partners
Simray GP, LLC
Sojourner Drilling Company
Spooner Petroleum Company
Spyglass Cedar Creek, LP
Stetson Oil and Gas, LTD
Stonegate Production Company, LLC
Tarco Resources, Inc.
Tipperary Corporation
Trail Ridge Energy Partners, LLC
Unit Petroleum Corporation
URSA Resources Group, LLC
US Enercorp, LLC
Vanguard Natural Resources, LLC
Viking Energy
Voyager Exploration, Inc.
Wagner and Brown, Ltd
Westside Corporation Ltd.
White Oak Energy, LLC
Whitecap Resources, Inc.
Whiting Petroleum Corporation
Wiepking-Fullerton Energy, LLC
Wind River Hydrocarbons, Inc.
Wolverine Gas & Oil Corporation
Yuma Exploration and Production Company