California-based Aera Energy ranks first among largest US private oil producers

According to the IPAA, about 90% of US oil and gas production comes from independent operators. A large number of those operators are privately-held companies ranging in size from those with a dozen or so producing wells to the largest private firm, Bakersfield, Calif.-based Aera Energy LLC, which operates more than 12,000 wells.

Private companies keep their books closed to the public, so the preferred method of ranking them is by production (barrels of oil equivalent). This is how we have ranked the 20 largest private US producers for this article.

No. 1 Aera Energy is one of California's largest oil and gas producers, accounting for roughly 30% of the state's total production. Most of Aera's production is in the San Joaquin Valley, but the company also has operations in the LA Basin and in Ventura and Monterey counties. Aera produces about 160,000 barrels of oil and 50 million cubic feet of natural gas each day and has proved oil and gas reserves equivalent to approximately 800 million barrels of oil.

Aera is jointly owned by Shell and ExxonMobil and is operated as a stand-alone company with its own board of directors. The company employs 1,200 people as well as hundreds of contractor companies.

Dallas-based Merit Energy Co. is No. 2 on our list. Founded in 1989, Merit acquires, operates, and develops mature, producing properties within the United States, Canada, and the Gulf of Mexico. Merit owns an interest in over 12,500 wells with net production in excess of 94,000 boe/day. The company employs a field staff of 450 people who operate out of 15 field offices. All pumpers and field operations people are Merit employees. The company's Canadian operations are headquartered in Calgary.

No. 3-ranked Samson Lone Star LLC, based in Tulsa, Okla., is engaged in oil and gas exploration, acquisition, and production operations in 18 states in the USA, Canada, and the North Sea. The company's international and offshore divisions are headquartered in Houston.

Yates Petroleum Corp., based in Artesia, NM, is No. 4 on the list. It is the seventh-largest oil producer and sixth-largest natural gas producer in New Mexico. The family-owned company has been in business 75 years and has over 600 employees in three states. Yates maintains field offices in Denver; Gillette, Wyo.; and Rock Springs, Wyo.

Samson Resources is No. 5. Samson is active in most major oil and gas regions in North America as well as interests in Australia. Some key producing regions and basins for Samson are East Texas, Texas Gulf Coast, Anadarko, Permian, San Juan, Green River, and the Williston Basin. The company is active in resource plays such as the Bakken, Haynesville, and Marcellus and also drills in more conventional areas, such as along the Texas Gulf Coast.

Headquartered in Houston, No. 6-ranked Hilcorp Energy Company's primary operating areas are the US Gulf Coast and Wyoming's Powder River Basin. Hilcorp likes to say it started out in 1989 as "three guys and a telephone" and grew to become one of the largest privately-held E&P companies in the US. The company's business model – acquire and exploit – hasn't changed significantly since the company was founded.

John B. Walker is president and CEO of the No. 7 company, Houston-based Enervest Operating LLC and also serves as the top executive for several affiliated companies, including EV Energy Partners LP and EnerVest Management Partners Ltd. The company operates in 12 states, including Arkansas, Colorado, Kansas, Louisiana, Michigan, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, Texas, and West Virginia.

Ray Hunt is CEO of Dallas-based Hunt Oil Co., No. 8 on the list. Founded in 1934, Hunt Oil has been in the petroleum business for 74 years. Hunt Oil Company, its subsidiaries and affiliated entities, engage in oil and gas exploration and production activities in the United States, Canada, Yemen, Peru, and a number of other countries. In addition, Hunt is integrally involved in the start-up of major LNG projects in Yemen and Peru.

No. 9 Mewbourne Oil Co. is headquartered in Tyler, Tex. The company has operations in the Permian Basin of West Texas and Southeast New Mexico and the Anadarko Basin of Western Oklahoma and the Texas Panhandle. Curtis W. Mewbourne, a native of Shreveport, La. and a petroleum engineering graduate of the University of Oklahoma, founded the company in 1965. In recognition of his longtime support, the University of Oklahoma named the Mewbourne School of Petroleum and Geological Engineering in his honor in May of 2000, and granted him the honorary degree of Doctor of Humane Letters in 2002. In 2007, the Mewbourne College of Earth & Energy was named in his honor.

Houston-based Walter Oil & Gas Corp. is No. 10 in our private company rankings. Walter Oil & Gas has operations in Texas, Louisiana, and the Gulf of Mexico. The company was founded in 2001 and is led by Joseph Walter, who serves as chairman, president, and CEO.

Bringing up the next 10 are Citation Oil & Gas Corp., Houston; Endeavor Energy Resources LP, Midland, Tex.; BOPCO LP, Fort Worth; LLOG Exploration Co., Metairie, La.; J-W Operating Co., Addison, Tex.; Red Willow Production Co., Ignacio, Colo.; Milagro Exploration LLC, Houston; Valence Operating Co., Houston; Ballard Exploration Co. Inc., Houston; and Kaiser-Francis Oil Co., Tulsa, Okla.