In conjunction with the acquisition agreement, MarkWest will invest up to an additional $15 million in 2008 and $13 million in 2009 to support the development of Petroquest’s Woodford Shale and coal bed methane initiatives.

These gathering systems currently produce approximately 45 million cubic feet of gas per day. Petroquest has over 31,000 net acres dedicated to these gathering assets and currently has three drilling rigs operating in this area.

Frank Semple, president and CEO of MarkWest Energy Partners, said: This investment represents another high-quality expansion of our Woodford operation. We are excited about this agreement and the opportunity to support Petroquest’s very successful drilling program in southeast Oklahoma.