MarkWest Energy Partners (NYSE: MWE) (MarkWest) announced today the commencement of operations of the first Mobley processing facility located in Wetzel County, West Virginia. The 200 million cubic feet per day (MMcf/d) plant supports the development of rich-gas from the Marcellus Shale by EQT Corporation (NYSE: EQT), Magnum Hunter Resources Corporation (NYSE: MHR) and other producers. The Mobley facility is currently operating at approximately 60% utilization and will continue to experience accelerated volume growth due to the ongoing drilling success of MarkWest’s producer customers operating in the area. MarkWest expects to complete construction of its second Mobley facility, a 120 MMcf/d plant, during the first quarter of 2013, and by the fourth quarter of 2013 bring online a third facility with 200 MMcf/d of processing capacity. Once these announced projects are operational, the Mobley complex will have approximately 520 MMcf/d of processing capacity in the significant wet-gas fairway of northern West Virginia. The natural gas liquids (NGLs) recovered at Mobley are being transported via MarkWest’s NGL pipeline gathering network to the 60,000 barrels per day (Bbl/d) Houston fractionation complex in Washington County, PA, where they are separated into valuable purity products and marketed on behalf of producer customers. “The initial Mobley project presented a significant challenge because of the remote location and mountainous terrain,” said Frank Semple, Chairman, President and Chief Executive Officer of MarkWest. “With the initial plant now online and expansions well underway, our producer customers now have the infrastructure needed to efficiently develop their prolific Marcellus Shale acreage in northern West Virginia.” 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.