MarkWest Running Ahead of Schedule on Woodford System

MarkWest Energy Partners, L.P. said that it has completed the initial phase of the gathering system and started operations in the Woodford Shale Play in the Arkoma Basin of southeastern Oklahoma. This initial phase was completed approximately 90 days ahead of schedule and was needed to support the significant drilling success that Newfield Exploration Company has experienced in the area.

MarkWest continues to construct the full gathering system ahead of schedule and has already committed or spent approximately $70 million. MarkWest expects to invest up to $175 million by the end of 2007 and to invest up to $350 million over the next four years to build gathering infrastructure over approximately 200-square miles in a four county region.

"We are very pleased to announce the early completion of this initial phase and are very encouraged by the drilling results to date," said Frank Semple, MarkWest Energy Partners' President and CEO. "Newfield and other producers in the Woodford continue to improve their drilling and completion techniques and continue to increase their production estimates. Our job is to ensure that the gas production from their very successful efforts is delivered to the marketplace as effectively and efficiently as possible."

MarkWest Energy Partners, L.P. is a publicly traded master limited partnership with a solid core of midstream assets and a growing core of gas transmission assets. It is the largest processor of natural gas in the Northeast and is the largest gas gatherer of natural gas in the prolific Carthage field in east Texas. It also has a growing number of other gas gathering and intrastate gas transmission assets in the Southwest, primarily in Texas and Oklahoma.