Clayton Williams Energy, Inc. (CWEI) is an independent oil and gas company engaged in the exploration for and production of oil and natural gas primarily in Texas, Louisiana and New Mexico. The Company operates in two segments: oil and gas exploration and production and contract drilling services. As of December 31, 2012, its portfolio of oil and natural gas reserves is weighted in favor of oil, with approximately 77% of its proved reserves consisting of oil and natural gas liquids (NGLs) and approximately 23% consisting of natural gas. As of December 31, 2012, CWEI held interests in 3,031 gross (1749 net) producing oil and gas wells and owned leasehold interests in approximately 951,000 gross (471,000 net) undeveloped acres. On March 14, 2012, its wholly owned subsidiary, Southwest Royalties, Inc. (SWR), completed the mergers of each of the 24 limited partnerships, of which SWR is the general partner (SWR Partnerships) into SWR.