MarkWest Energy Partners, L.P. (NYSE: MWE) today announced the execution of long-term gathering and processing agreements with Anadarko Petroleum Corporation (NYSE: APC) that will support the recently announced 120 million cubic feet per day (MMcf/d) expansion of the Partnership’s cryogenic processing capacity in East Texas. MarkWest will provide gathering and processing services to support Anadarko’s liquids-rich development program within Panola County, Texas. To provide critical midstream services to Anadarko and other producer customers that are expanding their drilling programs in East Texas, including Chevron, PetroQuest Energy, and Samson Lone Star, LLC, MarkWest is constructing the Carthage East plant, with cryogenic processing capacity of 120 MMcf/d, increasing total processing capacity in East Texas to 400 MMcf/d. In addition, Carthage East will expand the Partnership’s gathering capacity in East Texas by 140 MMcf/d and residue gas outlet capacities by 60 MMcf/d. “We are very pleased to announce agreements with Anadarko, Chevron, PetroQuest, and Samson to support the expansion of our East Texas assets,” said Frank Semple, Chairman, President and Chief Executive Officer. “Providing best-of-class, fully integrated natural gas midstream services is essential to the success of our producer customers, and we are excited to continue to play a role in our customers’ ongoing success in East Texas.” MarkWest Energy Partners, L.P. is a master limited partnership engaged in the gathering, transportation, and processing of natural gas; the transportation, fractionation, marketing, and storage of natural gas liquids; and the gathering and transportation of crude oil. MarkWest has extensive natural gas gathering, processing, and transmission operations in the southwest, Gulf Coast, and northeast regions of the United States, including the Marcellus Shale, and is the largest natural gas processor and fractionator in the Appalachian region. This press release includes “forward-looking statements.” All statements other than statements of historical facts included or incorporated herein may constitute forward-looking statements. Actual results could vary significantly from those expressed or implied in such statements and are subject to a number of risks and uncertainties. Although MarkWest believes that the expectations reflected in the forward-looking statements are reasonable, MarkWest can give no assurance that such expectations will prove to be correct. The forward-looking statements involve risks and uncertainties that affect operations, financial performance, and other factors as discussed in filings with the Securities and Exchange Commission. Among the factors that could cause results to differ materially are those risks discussed in the periodic reports filed with the SEC, including MarkWest’s Annual Report on Form 10-K for the year ended December 31, 2011. You are urged to carefully review and consider the cautionary statements and other disclosures made in those filings, specifically those under the heading “Risk Factors.” MarkWest does not undertake any duty to update any forward-looking statement except as required by law.