MarkWest Energy Partners, L.P. (NYSE: MWE) (“MarkWest”) (the “Partnership”) announced today an operational update regarding the development of midstream infrastructure projects in the liquids-rich areas of the Marcellus and Utica Shales. In the last four months, MarkWest has commenced operations of seven major infrastructure projects in the Northeast including five new cryogenic processing plants totaling 1 billion cubic feet per day (Bcf/d) of capacity and two fractionation facilities totaling 98,000 barrels per day (Bbl/d) of C2+ fractionation capacity. MarkWest continues to expand its leading midstream presence throughout the Northeast and currently has 17 major processing and fractionation projects under construction. These projects are occurring at nine locations in Ohio, Pennsylvania, and West Virginia and are expected to increase the Partnership’s total processing capacity to approximately 4.7 Bcf/d and total fractionation capacity in the region to over 400,000 barrels per day (Bbl/d). In the Marcellus Shale, the Partnership commenced operations of three new processing plants during the fourth quarter of 2013. These new plants were commissioned at the Majorsville, Mobley, and Sherwood complexes and have increased MarkWest’s total processing capacity in the liquids-rich corridor of the Marcellus to over 2.2 Bcf/d. At the Majorsville complex in Marshall County, West Virginia, MarkWest increased total capacity to 670 million cubic feet per day (MMcf/d) with the addition of Majorsville V, a 200 MMcf/d plant to support Chesapeake Energy Corporation (NYSE: CHK) and Statoil ASA (NYSE: STO). At the Mobley complex in Wetzel County, West Virginia, MarkWest increased total capacity to 520 MMcf/d with startup of Mobley III, a 200 MMcf/d plant to support rapidly growing rich-gas production from EQT Corporation (NYSE: EQT) and Magnum Hunter Resources Corporation (NYSE: MHR). At the Sherwood complex in Doddridge County, West Virginia, MarkWest expanded total capacity to 600 MMcf/d after bringing online Sherwood III, a 200 MMcf/d to support Antero Resources Corporation’s (NYSE: AR) (Antero) extensive Marcellus development program.