ARB Midstream
Alta Mesa Services, LP - O&G
Alyeska Pipeline Service Company
American Midstream Partners, LP
American Transmission Company
Amplify Energy
Anadarko Petroleum Corporation
Apache Corporation
Apex International Energy
Ascent Resources Management Services, LLC
Aux Sable Liquid Products, Inc.
Aux Sable Midstream
BASF Corporation
BHP Billiton Petroleum (Americas), Inc.
BP Exploration & Production, Inc.
BW Offshore USA Management, Inc.
Black Hills Energy
Black Stone Minerals Company, L.P.
Blue Racer Midstream, LLC
Buckeye Partners, L.P.
CHS, Inc.
CITGO Petroleum Corporation
CNOOC Petroleum U.S.A., Inc.
CNX Resources Corporation
COG Operating, LLC
CVR Energy, Inc.
Caerus Operating LLC
California Resources Corporation
Calpine Corporation
Chesapeake Energy Corporation
Chevron North America Exploration & Production
Chief Oil & Gas, LLC
Cimarex Energy Co.
Citation Oil & Gas Corp.
City Utilities of Springfield, MO
Colonial Pipeline Company
ConocoPhillips
Continental Resources, Inc.
Crescent Point Energy US Corp.
Crestwood Equity Partners, LP
Delta Air Lines, Inc. - MIPC, LLC
Delta Air Lines, Inc. - Monroe Energy, LLC
Denbury Resources, Inc.
Devon Energy Corporation
Diamondback Energy
Dominion Energy Gas Marketing, Inc (formerly SCANA Energy Marketing, Inc.)
Dominion Energy Southeast Services, Inc.
Dominion Energy, Inc.
Dominion Energy, Inc. - Gas Infrastructure
EOG Resources, Inc.
EP Energy
EnLink Midstream, LLC
Enable Midstream Partners, LP
Enbridge, Inc.
Encana Services Company, Ltd.
Encino Energy, LLC
Endeavor Energy Resources, LP
EnerVest, Ltd.
Enerflex Services, Inc.
Energy Transfer Partners, LP
Enerplus Resources (USA) Corporation
Equinor US Operations LLC
Explorer Pipeline, Inc.
Fieldwood Energy, LLC
Fleur de Lis Energy, LLC
Flint Hills Resources, LP
Fluor Federal Petroleum Operations, LLC
FourPoint Energy. LLC
Freeport LNG Development, L.P.
Goodnight Midstream, LLC
Hess Corporation
Hilcorp Energy Company
Hilcorp Energy Company - Harvest Pipeline Company
Hunt Oil Company
INPEX Americas, Inc.
ITC Holdings Corp.
Inflection Energy, LLC
Invenergy LLC
Keyera Corp. (USA)
Kinder Morgan, Inc.
Kosmos Energy, Gulf of Mexico
Kosmos Energy, LLC
LOOP, LLC
Laredo Petroleum, Inc.
Legacy Reserves, LP
Loews Corporation - Boardwalk Pipeline Partners, LP
LyondellBasell Industries
MD America Energy, LLC
MDU Resources Group, Inc. - Montana Dakota Utilities
Mach Resources LLC
Magellan Midstream Partners, L.P.
Marathon Oil Corporation
Merit Energy Company
Midcoast Energy, LLC
Mitsui & Co. Energy Marketing and Services (USA), Inc.
Mitsui E&P USA, LLC
Motiva Enterprises, LLC
Murphy Oil Corporation
National Fuel Gas Distribution Corporation
National Fuel Gas Supply Corporation
National Grid
NextDecade
NextEra Energy, Inc. - Nextera Energy Gas Producing, LLC
Noble Energy, Inc.
OGE Energy Corp.
Oak Ridge Natural Resources
Oasis Petroleum Inc.
Occidental Petroleum Corporation (Oxy)
Oil Search (Alaska), LLC
PDC Energy, Inc.
Pacific Drilling Services, Inc.
Pilot Flying J
Pioneer Natural Resources Co.
Plains All American Pipeline, L.P.
Port Houston
QEP Resources, Inc.
RKI Energy Resources, LLC
Range Resources Corp.
Red Bluff Resources Operating, LLC
Repsol Oil Gas USA, LLC
Repsol Services Company
SGC
Sable Permian Resources, LLC
San Joaquin Facilites Management, Inc.
SandRidge Energy, Inc.
Secure Energy Services USA, Inc.
SemGroup Corporation
SemGroup Corporation - SemGas
Sentinel Peak Resources, LLC
Sinclair Services Company
Southern Company - Georgia Power
Southern Company - Southern Power Company
Southwestern Energy Company
Suncor Energy (U.S.A) Marketing, Inc.
Tapstone Energy, LLC
Tellurian, Inc.
The University of Texas System - Oil & Gas Division
The Williams Companies, Inc.
Total E&P USA, Inc.
Total Petrochemicals & Refining USA, Inc.
TransCanada Corporation (US)
TransCanada Corporation - PipeLines, LP
Unit Corporation - Superior Pipeline Company, LLC
Unit Corporation - Unit Drilling Company
Unit Corporation - Unit Petroleum Company
Urban Oil and Gas Group
Venari Resources, LLC
Vermilion Energy USA
Vine Oil & Gas, LP
WGL Holdings, Inc. - Washington Gas
WPX Energy, Inc.
White Rock Oil & Gas, LLC
Whiting Petroleum Corporation
Xcel Energy, Inc.
Xcel Energy, Inc. - Northern States Power Company, a Wisconsin Corporation
Yokogawa Corporation of America