Warren Resources, Inc., an independent energy company, engages in the exploration and development of onshore oil and gas reserves in the United States. It primarily develops coalbed methane and natural gas properties located in the Rocky Mountain region; and waterflood oil recovery programs in the Wilmington field within the Los Angeles Basin of California. As of December 31, 2009, Warren Resources owned natural gas and oil leasehold interests in approximately 160,053 gross acres; had estimated net proved reserves of 124 billion cubic feet equivalent of natural gas; and had interests in 449 gross producing wells. The company was founded in 1990 and is based in New York, New York.