Warren Resources, Inc. (Warren) is an independent energy company engaged in the exploration, development and production of domestic onshore crude oil and gas reserves. The Company focuses primarily on the exploration and development of its waterflood oil recovery properties in the Wilmington field within the Los Angeles Basin of California, and its coalbed methane (CBM) natural gas properties located in the Rocky Mountain region. The Company's properties are primarily located in California, Wyoming, New Mexico, North Dakota and Texas. As of December 31, 2011, it owned natural gas and oil leasehold interests in approximately 129,588 gross (69,641 net) acres, approximately 80% of which are undeveloped. As of December 31, 2011, Warren had interests in 414 gross (206 net) producing wells and are the operator of record or actively participate in the management and operations for 74% of these wells. Warren E&P, Inc. is its wholly owned subsidiary.