Petroleum companies
- Agip
- Amadeus Petroleum NL
- Amerada Hess
- Amoco
- Anadarko - exploration and production company
- Aruba Petroleum Incorporated - oil and gas operating company based in Plano, Texas, with a field office and equipment yard in Jacksboro, Texas.
- Aspen Integrated Oil & Gas LLC - exploration and production company West Texas/SE New Mexico, Oklahoma (Anadarko Basin), IIllinois Basin, South Texas and Gulf Coast
- Belco Oil & Gas Corp. - exploration, development and production of natural gas and oil in four areas: Rocky Mountains, Permian Basin of West Texas, the Mid-Continent region in Oklahoma, North Texas and Southwest Kansas and Austin Chalk Trend in both Texas and Louisiana.
- Berry Petroleum Company
- Black Hills Exploration and Production
- Black Star Oil Company
- Bolt Energy Ltd. - Oil and Gas Exploration
- BRG Petroleum, Inc. - independent oil & gas exploration and production (E&P) company
- Brigham Exploration Company - innovative independent oil and gas exploration company focused on the implementation of state-of-the-art 3-D seismic imaging techniques to reduce finding and development costs
- Cabot Oil & Gas Corporation - maintains drilling, production, storage, gathering, pipeline and marketing operations in the Appalachian Region, and drilling, production and marketing operations in the Gulf Coast Region and Rocky Mountains and Mid-Continent areas.
- Callon Petroleum Company - exploration, development, acquisition and operation of oil and gas in Louisiana, Alabama and offshore Gulf of Mexico.
- Canada Southern Petroleum Ltd.
- Canadian Natural Resources Limited
- Century Exploration Company - independent privately held oil and gas company engaged in the acquisition, development, exploration and production of oil and gas
- Chaparral Resources - independent oil and gas exploration and production company
- Chevron
- Circumpacific Energy Corporation - Canadian oil and gas exploration company
- Compton Petroleum Corporation - Calgary-based company actively engaged in the exploration, development and production of natural gas, natural gas liquids and crude oil in Western Canada
- Conoco
- Credo Petroleum Corporation - explores for, purchases, develops, produces and sells crude oil and natural gas
- Cross Timbers Oil Company - one of the fastest growing and top performing independent oil and natural gas producers in the United States
- D & L Energy Group - independent natural gas and oil exploration, production and marketing group that develops and produces oil and natural gas wells in Ohio and Pennsylvania
- DayStar Oil & Gas Corp.- recovery of hydrocarbon reserves through acquisitions and project development with a major emphasis on mature and marginal field enhancement, developmental exploitation drilling and low-risk exploration opportunities.
- DevX Energy, Inc.
- DinoTech Corporation - Oil Technology Investments - Oil technology investments and investing in oil and gas recovery providing economic solutions, consulting experience in developing, marketing and manufacturing proprietary ultrasound technologies.
- Doreal Energy Corporation - independent energy company engaged in the exploration, development, exploitation and acquisition of oil and natural gas properties in on-shore, conventional producing areas of North America
- Dragon Oil - Oil & Gas Exploration
- Eurogas Corporation - independent oil and gas company engaged in exploration, developement, production and acquisition activities in Tunisia, Spain and Canada
- Fidelity Oil Group
- Givot Olam - Oil Exploration in Israel
- Husky Oil
- Lukoil
- Murphy - exploration and production company
- New Horizon Exploration Inc.
- Newfield Exploration Company - independent crude oil and natural gas exploration and production company
- NIS Jugopetrol (Serbia)
- NIS Naftagas (Serbia) - Company for exploration and production of crude oil, natural gas, ground water and geothermal energy
- Nitro Petroleum- Oil and Gas Exploration
- Occidental Petroleum Corp.
- Ocean Energy, Inc. - Oil and Gas Exploration and Production
- PanCanadian Petroleum Ltd.- Calgary, Alberta, one of Canada's largest producers and marketers of crude oil, natural gas and natural gas liquids. Its extensive operations stretch across Canada and include a variety of international interests.
- Petro-Canada
- Petrobras
- Pioneer Oil and Gas
- Robertson Research International Limited
- Shell Exploration & Production
- Statoil AS
- Texaco
- TotalFinaElf
- Turkish Petroleum Corp.
- WesternZagos - Kurdistan region of Iraq
- Zavanna, LLC, Home Page - Oil and Gas Exploration and Development