Pioneer Southwest Energy Partners L.P. (the Partnership) is formed, by Pioneer Natural Resources Company (Pioneer), to own and acquire oil and gas assets in the Partnership's area of operations. The Partnership's area of operations consists of onshore Texas and eight counties in the southeast region of New Mexico. As of December 31, 2011, Pioneer owned a 52.4% limited partner interest in the Partnership and Pioneer owns and controls Pioneer Natural Resources GP LLC (the General Partner), which manages the Partnership. All of the Partnership's properties are located in the United States and all of the related oil, natural gas liquids (NGL) and gas revenues are derived from purchasers located in the United States. During the year ended December 31, 2011, the Company drilled 74 gross (71 net) wells, of which 73 gross wells were completed as productive wells.