| ExxonMobil Production Company | ChevronTexaco | BP America Production Company |
| Aka Energy | P-L Propylene LLC | TexStar Medstream |
| Total Energy | El Paso Field Services | Tesoro Refining |
| Duke Energy Field Services | Crosstex Energy Services | Flatrock Compression Company, Ltd |
| Sid Richardson Energy Services | Energy Transfer Corp. | EOG Resources |
| Aquila Gas Pipeline Corporation | Enbridge (U. S.), Inc. | Energy Production Corp. |
| Northcrest Resources | Midwest Steel Company | EPC Ltd. |
| Northwest Fuels Corp. | Orient Petroleum, Ltd. | Merit Energy |
| Weatherford Compression | Owel Holdings, Ltd | El Paso Production |
| Oxy Permian, Ltd | Kinder Morgan Pipeline | Momentum Energy |
| Enterprise Products | Copano Processing, L.P. | Chaparral Energy |
| Williams Field Services | Regency Gas Services | TexStar Pipeline |
| Frontier Refining | Cerrito Gathering Company | Sagebrush Pipeline, LLC |
| Valero Energy | Bearcub Energy | Marlin Midstream, LLC |
| Ventech Process Equipment | Lumen Midstream | Citation Oil & Gas |
| Superior Pipeline Company | Chesapeake Energy Corp. | Targa Resources |
| Nuevo Midstream LLC | ARC Energy Equipment | Hilcorp Energy |
| Rino-K&K Compression | Patara Oil & Gas | Saddle Butte Pipeline |
| Caiman Energy, LLC | Energy XXI | Chevron Midstream Pipelines |
Gas Processing
Refining