| 3-M Energy Corporation |
| Abraxas Petroleum Corporation |
| Addax Operating, LLC. |
| Aera Energy LLC |
| Alta Mesa Service, LP |
| Anadarko Petroleum Corporation |
| Anschutz Exploration Corporation |
| Antero Resources Corporation |
| Apache Corporation |
| Apollo Operating, LLC |
| Approach Resources |
| ARES Energy, LTD |
| Argent Energy (US) Holdings, Inc. |
| Arrington Oil & Gas Operating, LLC |
| Aruba Petroleum, Inc. |
| Athlon Energy Operating LLC |
| Atlantic Operating, Inc. |
| Atlas Resource Partners, LP |
| Atlas Energy, L.P. |
| Augustus Energy Partners, LLC |
| AWP Operating Company |
| Axia Energy, LLC |
| Axis Energy Corporation |
| Aztec Drilling & Operating, LLC |
| BASA Resources, Inc. |
| Bayswater Exploration & Production, LLC |
| Baytex Energy USA Ltd. |
| BC Operating, Inc. |
| Berry Petroleum |
| Best Petroleum Explorations, Inc. |
| BG Group plc |
| BHP Billiton Petroleum (Fayetteville) LLC |
| Big Star Oil & Gas, LLC |
| Bill Barrett Corporation |
| Black Brush O & G, Inc. |
| Black Diamond Minerals, LLC |
| Black Hills Exploration and Production |
| Black Raven Energy, Inc. |
| BLS Production Co., Inc. |
| Bluestem Energy Holdings, LLC |
| BlueStone Natural Resources II, LLC |
| BLX, Inc. |
| Boaz Energy, LLC |
| Bold Operating , LLC |
| Bonanza Creek Energy, Inc. |
| Borderline Operating Corp. |
| BP America Production Company |
| Brammer Engineering, Inc. |
| Breck Operating Corp. |
| Breitling Oil and Gas |
| Bridwell Oil Company |
| Brigham Oil & Gas, L.P. |
| BTA Oil Producers LLC |
| Burk Royalty Co., LTD. |
| Burleson Petroleum, Inc. |
| Burnett Oil Co., Inc. |
| BVX Operating Inc. |
| C & J Energy Services |
| Cabot Oil & Gas Corporation |
| Callon Petroleum Operating Company |
| Capstone Natural Resources, LLC |
| Carrizo (Marcellus) LLC |
| Carrizo Oil & Gas, Inc. |
| Caraway Operating Company |
| Chalker Energy Partners, III |
| Chaparral Energy, LLC |
| Chesapeake Operating, Inc. |
| Chevron USA, Inc. |
| Cheyenne Petroleum Co. |
| Chief Oil & Gas LLC |
| Cimarex Energy Co. |
| Cimarex Energy Co. of Colorado |
| Cinco Natural Resources Corporation |
| Cirque Resources LP |
| Citation Oil and Gas Corp. |
| Citrus Energy Corporation |
| Clayton Williams Enerby, Inc. |
| Clear Fork Inc. |
| CML Exploration, LLC |
| Cobra Oil & Gas Corporation |
| COG Operating LLC |
| Columbus Oil Company |
| Comstock Oil & Gas |
| Condor Energy Technology, LLC |
| ConocoPhillips Company |
| CONSOL Energy, Inc. |
| Continental Resources |
| Cordillera Energy Partners, III |
| Corinthian Exploration (USA) Corp. |
| Corlena Oil Company |
| Crescent Point Energy |
| Crest Resources, Inc. |
| Crimson Exploration Oper., Inc. |
| Crockett Operating LLC |
| Crossroads Energy Partners, LLC |
| Crown Equipment Co. |
| CrownQuest Operating, LLC |
| The Cumming Company, Inc. |
| DEEN DRILLING COMPANY |
| Delta CO2, LLC |
| Delta Oil & Gas Ltd. |
| Denali Oil & Gas Management |
| Denbury Onshore, LLC |
| Devon Energy |
| Diamondback Resources, LLC |
| Discovery Operating, Inc. |
| DTE Gas Resources, LLC |
| E&B Natural Resources Management Corporation |
| Eagle Ridge Energy, LLC |
| Eagle Ridge Operating, LLC |
| Eagle Rock Mid-Continent Operating, LLC |
| Eagle Rock Operating Company, LLC |
| Eckard Global, LLC |
| Eclipse Resources I, LP |
| E C Stryker, Inc. |
| Edge Barnett Operating Company LLC |
| EdgeMarc Energy Holding, LLC |
| EF Energy, LLC |
| E.G.L. Resources, Inc. |
| El Paso E&P Company |
| Element Petro Operating II, LLC |
| Element Petroleum Operating, LLC |
| Elm Ridge Exploration Co. LLC |
| Empresa Energy, LLC |
| Encana Oil & Gas (USA) Inc. |
| Encana_RCP |
| Endeavor Energy Rsources |
| Enduring Resources LLC |
| Energen Resources Corporation |
| Energy Corporation of America |
| Enerplus Resources (USA) Corporation |
| EnerVest, Ltd. |
| Entek GRB LLC |
| EOG Resources, Incorporated |
| EP Energy |
| EQT Production |
| Estancia Oil & Gas, LLC |
| Evertson Operating Company, Inc. |
| Exaro Energy II, LLC |
| EXCO Resources, Inc. (Joint Venture w/ BG Group plc) |
| ExL Petroleum, LP |
| Extex Operating Company |
| ExxonMobil Upstream Research Company |
| Fair Oil, Ltd. |
| Fairways Exploration & Production, LLC |
| Fairway Resources Op. LLC |
| Fasken Oil and Ranch, Ltd. |
| Fidelity Exploration & Production |
| FIML Natural Resources, LLC |
| Finley Resources, Inc. |
| Fivestones Energy LLC |
| Foree Oil Company |
| Foreland Operating, LLC |
| Forest Oil Corporation |
| Forge Energy, LLC |
| Foundation Energy Management, LLC |
| Franks Exploration Company, LLC |
| Future Petroleum Company, LLC |
| FX Drilling Company, Inc. |
| G3 Operating, LLC |
| GPII Energy, Inc. |
| Gasco Energy, Inc. |
| Gastar Exploration Texas LP |
| GeoSouthern Energy Corporation |
| GMX Resources |
| Goodrich Petroleum Co. LLC |
| Gordon Creek, LLC. |
| Gosney & Sons, Inc. |
| Great Plains Operating, LLC |
| Great Western Drilling |
| Great Western Oil & Gas Company, LLC |
| Gunnison Energy Corporation |
| Gunn Oil Company |
| H&L Exploration Company, LLC |
| Halcon Resources Corporation |
| Hannathon Petroleum, LLC |
| Heartland Solutions, Inc. |
| Helis Oil & Gas Company, L.L.C. |
| Henry Resources LLC |
| Hess Corporation |
| Hibernia Resources, LLC |
| HighMount Exploration & Production LLC |
| Hilcorp Energy Company |
| Holmes Exploration, LLC |
| HRM Resources LLC |
| Hungtington Energy, LLC |
| Hunt Marcellus Operating Company |
| Hunt Oil Company |
| Imperial Gas Resources, LLC |
| Incline Energy |
| Indigo II Louisiana Operating, LLC |
| Indigo Minerals |
| Ironwood Oil and Gas, LLC |
| J Cleo Thompson |
| JAMEX, Inc |
| JDL Operating, LLC |
| Jetta Operating Company, Inc. |
| Johanson Oil |
| Johnson & Ernst Operating Co. |
| Jones Energy Ltd. |
| Juno Operating Company II, LLC |
| J-W Operating Company |
| K.P. Kaufman Company, Inc. |
| Kaler Energy Corp. |
| Keith F. Walker Oil & Gas Co., LLC |
| Killam Oil Co., Ltd. |
| Kindee Oil & Gas Texas, LLC |
| Kinder Morgan |
| Kodiak Oil & Gas Corp. |
| Lane Operating Company |
| Laramie Energy II, LLC |
| Laredo Petroleum, Inc. |
| LaVernia Oil |
| Layline Petroleum |
| LCS Production Company |
| LeClair Operating Co., Inc. |
| Legacy Reserves Operating LP |
| Legado Permian, LLC |
| Legend Natural Gas, LLC |
| L.E. Jones Operating, Inc. |
| LeNorman Operating LLC |
| Lewis Energy Group |
| Liberty Resources LLC |
| Limestone Exploration II, LLC |
| Linn Energy, LLC |
| Llewellin Operating Company, LLC |
| LP Operating, LLC |
| Magnet Oil LP |
| Magnum Hunter Resources Corp. |
| MAK-J Energy |
| Marlin Energy Southwest GP, L.L.C. |
| Matador Production Company |
| Matrix Energy, LLC |
| McClure Oil Co. |
| McElvain Energy, Inc. |
| MDS Energy, Ltd |
| Medders Oil Company, Inc. |
| Merit Energy Company |
| Meritage Energy Company, LLC |
| Mesa-Energy Partners, LLC |
| Mestana Operating, L.L.C. |
| Metano Energy III, LP |
| Mewbourne Oil Company |
| Mid-Con Energy Operating, Inc. |
| Mid-States Operating Company |
| Midenergy Operating, LLC |
| Midland Oil and Gas, Inc. |
| Milagro Exploration, LLC |
| Mohican Operating |
| Molopo Energy Texas, LLC |
| Muirfield Exploration, Ltd. |
| Murex Petroleum Corp. |
| Murphy Exploration and Production USA |
| Muskegon Development Company |
| MWS Producing, Inc. |
| NMR Energy LLC |
| Navidad Resources, LLC |
| Newark E&P Operating, LLC |
| New Gulf Resources, LLC |
| Newfield Exploration Company |
| NFR Energy LLC |
| Noble Energy, Inc. |
| NOC |
| Novus Operating, LLC |
| Oasis Petroleum |
| O’Benco, Inc. |
| Occidental Oil and Gas |
| O.H.B., Inc. |
| Omni Oil & Gas |
| Opal Resources Operating Company |
| Osborn Heirs Company |
| Overland Resources, LLC |
| Pacesetter Energy, LLC. |
| Palmco LLC |
| Paloma Resources, LLC |
| Parsley Energy Operations, LLC |
| Parallel Petroleum LLC |
| Partee Drilling, Inc. |
| Parten Operating, Inc. |
| Patara Oil & Gas, LLC |
| Patriot Resources, Inc. |
| PDC Energy |
| Peak Permian, LLC |
| Peak Powder River Resources, LLC |
| Peak Texas Resources, LLC |
| Pecos Operating Company, LLC |
| Penn Virginia Oil & Gas Corporation |
| Pennsylvania General Energy |
| Peregrine Petroleum |
| Peterson Energy Operating, Inc. |
| PETEX |
| Petroglyph Operating Company, Inc. |
| Petrohawk Energy Corporation |
| Petro Hunt, L.L.C. |
| PetroQuest Energy LLC |
| Piedra Operating, LLC |
| Pioneer Natural Resources |
| Pitts Energy Co. |
| Plains Exploration & Production Company |
| Platinum Energy Solutions |
| PMO |
| P. O. & G. Operating, LLC |
| PPC Operating Company, LLC |
| Premier Natural Resources |
| Price Operating, LLC |
| Prima Exploration, Inc. |
| Prime Operating Company |
| Primexx Operating Corporation |
| Probity Operating, LLC |
| Propel Energy, LLC |
| QEP Resources, Inc. |
| Quantum Resources Management, LLC |
| Quest Energy Management Group, Inc. |
| Quicksilver Resources, Inc. |
| Ram Operating Company, Inc. |
| Range Resource Corporation |
| Ray Richey Management Company, Inc. |
| Red Willow Production Co. |
| Red Willow Production, LLC |
| Reliance Energy, Inc. |
| Renegade Oil & Gas Company, LLC. |
| Resolute Natural Resources |
| Rex Energy |
| Rice Drilling B, LLC |
| Riley Exploration, LLC |
| RIM Operating, Inc. |
| RK Petroleum Corp. |
| RKI Exploration & Production |
| RLU Operating, LLC |
| Roff Operating Company |
| Rosetta Resources |
| Rosewood Resources |
| Royalty Land & Dev. Co., Inc. |
| RSP Permian, LLC |
| S.B. Street Operating, Inc. |
| Sahara Operating Company |
| Samson |
| Samson Exploration, LLC |
| Samson Oil and Gas Montana, Inc. |
| Sanchez Oil & Gas Corporation |
| Sandalwood Exploration, LP |
| SandRidge energy, Inc. |
| Sanguine Gas Exploration |
| Schlachter Operating Corp. |
| Seaboard Operating Co. |
| Seneca Resources Corporation |
| SG Interest I Ltd. |
| Sharp Image Energy |
| Shelby Operating Company |
| Shell Oil Company affiliate |
| Silver Creek Oil & Gas, LLC |
| Sinclair Oil & Gas Company |
| Slawson Exploration Company, Inc. |
| SM Energy |
| Snyder Brothers, Inc. |
| Sojourner Drilling Corporation |
| Southern Bay Operating, L.L.C. |
| Southwest Royalties, Inc. |
| Southwestern Energy |
| Stanolind Operating LLC |
| Steller Energy & Investment Corp. |
| Stephens & Johnson Operating Co. |
| Stokes & Spiehler |
| Stone Energy Corporation |
| Strat Land Exploration Co |
| Suemaur Expl. & Prod., LLC |
| Summitt Petroleum LLC |
| Sundance Energy |
| Swan PC, LP |
| Swift Energy Operating, LLC |
| Sydson Energy, Inc. |
| Synergy Offshore, LLC |
| Synergy Resources Corporation |
| TACOR Resources, Inc. |
| TAQA North USA, Inc. |
| Talisman Energy USA Incorporated |
| Tanos Exploration, LLC |
| Tecpetrol Operating, LLC |
| Tekton Energy |
| Telesis Operating Co., Inc. |
| Tema Oil and Gas Company |
| Tenaska Resources, LLC |
| Terrace Energy |
| Texakoma Operating LP |
| Texas Alliance of Energy Producers |
| Texas Energy Holdings, Inc. |
| Texas International Energy Partners |
| Texas Royalty Corp. |
| Texas Secondary Oil Corporation |
| Texland Petroleum, LP |
| Texon Oil Company, Inc. |
| The George R. Brown Partnership LP |
| The Termo Company |
| Thompson Engineering and Production Corp. |
| Three Rivers Operating Company, LLC |
| Titan Operating, LLC |
| Treadstone Energy Partners, LLC |
| Tracker Resource Dev III, LLC |
| Trap Rock Oil, LTD |
| Trey Resources, Inc. |
| Triana Energy |
| Triangle USA Petroleum Corporation |
| Tri-C Resources, LLC |
| Trilogy Resources |
| Trio Consulting & Management, LLC |
| True Oil LLC |
| Tug Hill Operating, LLC |
| TXON Partners LLC |
| TXP, Inc. |
| U.S. Enercorp, Ltd. |
| Ultra Petroleum |
| Unit Petroleum |
| Ute Energy Upstream Holdings, LLC |
| Vaalco Energy (USA), Inc. |
| Valence Operating Company |
| Vanguard Permian LLC |
| Vantage Energy Appalachia II, LLC |
| Vantage Energy Appalachia LLC |
| Vantage Fort Worth Energy LLC |
| Vantage- Uinta LLC |
| Venado Oil & Gas, LLC. |
| Venoco Inc. |
| Verado Energy, Inc. |
| Veritas Energy, LLC |
| Viejo Energy I, LLC |
| W & T Offshore, Inc. |
| Walsh Petroleum, Inc. |
| Walsh & Watts, Inc. |
| Walter Exploration Company |
| Wapiti Operating, LLC |
| Ward Petroleum |
| Warren American Oil Company |
| Weatherford International |
| Wellstar Corporation |
| Western Chief Operating, LLC |
| Wexpro Company |
| WG Operating, Inc. |
| Whiting Petroleum Corporation |
| Williams Oil Company |
| Willowbend Investments, Inc. |
| Windsor Permian LLC |
| Wolverine Gas & Oil Company of Utah, LLC |
| Woodbine Acquisitions, LLC |
| Woolsey Operating Co. LLC |
| WPX Energy |
| W.T. Waggoner Estate |
| Xstar Resources, LLC |
| XTO Energy/ ExxonMobil |
| Zargon Oil & Gas, LTD. |
| Zavanna, LLC |
| ZaZa Energy |
| Zenergy, Inc. |
