Denver-based MarkWest Energy Partners LP (NYSE: MWE) has announced the completion of long-term, fee-based agreements with Antero Resources (NYSE: AR) for the development of an additional cryogenic gas processing plant at the Partnership’s Sherwood complex in Doddridge County, W.Va. Under terms of the agreements, MarkWest will construct a fifth 200 million cubic feet per day (MMcf/d) processing facility that is expected to begin operations in the third quarter of 2014. Upon completion of the new plant, the Sherwood complex will have 1 billion cubic feet per day (Bcf/d) of total processing capacity.

Antero is a premier producer in the Northeast and is aggressively developing their acreage position throughout the rich-gas Marcellus. The Sherwood complex currently consists of two plants with 400 MMcf/d of capacity and is operating near full utilization. By the end of this year, MarkWest will bring online a third 200 MMcf/d plant at the complex and is quickly moving forward with the construction of a fourth plant by the second quarter of 2014.

Antero’s natural gas liquids (NGLs) recovered at the Sherwood complex are currently being delivered to MarkWest’s Houston complex in Washington County, Pennsylvania for fractionation and marketing. The Houston complex is the largest fractionation facility in the Northeast and provides extensive logistics services, including storage and the delivery of purity products to market by truck, rail and pipeline. In addition, the Houston complex offers Marcellus producers the first large-scale de-ethanization facility in the Northeast capable of producing purity ethane for delivery to Mariner West, and ultimately to the ATEX and Mariner East projects.

“We are delighted to further expand our strong relationship with Antero and develop additional processing capacity at the Sherwood complex to support their highly successful drilling program,” said Frank Semple, chairman, president and chief executive officer of MarkWest. “The ability to offer producers fully integrated midstream services throughout northern West Virginia and southwest Pennsylvania is critical to unlocking the abundant rich-gas reserves of the Marcellus shale. MarkWest is committed to providing Antero and its other customers with unique solutions that are backed by our best-in-class customer service.”

MarkWest is a master limited partnership engaged in the gathering, processing and transportation of natural gas; the gathering, transportation, fractionation, storage and marketing of natural gas liquids; and the gathering and transportation of crude oil. MarkWest has a leading presence in many unconventional gas plays including the Marcellus shale, Utica shale, Huron/Berea shale, Haynesville shale, Woodford shale and Granite Wash formation.