Gulfport Energy Corp.
Gran Tierra Energy, Inc.
Imperial Oil Ltd.
Exxon Mobil Corp.
GeoPark Ltd.
Sabine Royalty Trust
Chevron Corp.
Penn Virginia Corp.
SRC Energy, Inc.
Ecopetrol SA
Targa Resources Partners LP
QEP Resources, Inc.
Hess Corp.
Talos Energy, Inc.
WPX Energy, Inc.
Valero Energy Corp.
Crescent Point Energy Corp.
Cloud Peak Energy, Inc.
Legacy Reserves, Inc.
PermRock Royalty Trust
Apache Corp.
Contango Oil & Gas Co.
Unit Corp.
Centennial Resource Development, Inc.
Foresight Energy LP
SunCoke Energy, Inc.
EQT Corp.
Abraxas Petroleum Corp.
Denbury Resources, Inc.
Enerplus Corp.
Devon Energy Corp.
CNOOC Ltd.
Andeavor Logistics LP
PDC Energy, Inc.
Ring Energy, Inc.
Northern Oil & Gas, Inc.
Lilis Energy, Inc.
Bonanza Creek Energy, Inc.
Enservco Corp.
TransAtlantic Petroleum Ltd.
