MarkWest Energy Partners, L.P. is a master limited partnership engaged in the gathering, compressing, treating, processing and transportation of natural gas; the transportation, fractionation, storage, and marketing of natural gas liquid (NGLs), and gathering and transportation of crude oil. The Company operates in three segments: southwest segment, gulf coast segment and northeast segment. On February 21, 2008, MarkWest Energy Partners, L.P. completed its plan of redemption and merger (the Merger) with MarkWest Hydrocarbon, Inc. and MWEP, L.L.C., a wholly owned subsidiary of the Partnership, pursuant to which MarkWest Hydrocarbon, Inc. was merged into the partnership. On January 22, 2009, the Company entered into an agreement to form a joint venture with an affiliate of NGP Midstream and Resources, L.P. During the year ended December 31, 2008, the Company acquired the subsidiary of PetroQuest Energy, L.L.C. (PetroQuest).