Oil & Gas

Apache Corporation

Big Buckets Rathole

BP America Production, Inc.

Champlin Exploration

Chesapeake Energy Corporation

ConocoPhillips

Continental Resources, Inc.

D&P Tank Trucks

Dakota Energy, LLC

Dakota Exploration, LLC

Dominion Oklahoma Texas Exploration, Inc.

Dorado E&P Partners

Duke Energy Field Services

Exxon Corporation

HighMount Exploration & Production, LLC

Hiland Partners

Kirkpatrick Oil & Gas

Linn Energy

Logan Eldorado Drilling Co.

Mustang Fuel Corporation

Oxy USA, Inc.

Quad Drilling Co.

Range Resources, Inc.

SandRidge Energy, Inc.

Siosi Oil & Gas

Trinidad Drilling, L.P.

Wind River Exploration, Inc.

XTO Energy, Inc.