Fund to be invested in mature oil and gas properties in the United States

HOUSTON, August 8, 2007 -- Sheridan Production Partners today announced the final closing of Sheridan Production Partners, L.P., a specialized $1.3 billion fund that will invest in mature oil and gas assets located in diverse basins across the United States.

"We're pleased to have the resources of a dedicated fund at a time when there is an increased focus on energy operations and optimization and a particularly attractive supply and demand dynamic for mature properties,"said Lisa Stewart, Chief Executive Officer of Sheridan Production Partners. "We have a strong team of seasoned oil and gas executives with whom I have successfully worked for more than a decade. We look forward to working together to capture many of the opportunities in today's market."

Sheridan Production Partners was established by Lisa Stewart, former Executive Vice President of El Paso and President of El Paso Exploration & Production Company, and Warburg Pincus, the global private equity firm. Sheridan will benefit from Warburg Pincus' extensive network of relationships throughout the oil and gas industry, its investment experience in the energy industry and its deep understanding of and access to energy capital markets.

Jeffrey A. Harris, a Managing Director and partner at Warburg Pincus's energy practice, said: "Lisa Stewart and Sheridan's senior management team have an excellent track record and tremendous experience both in acquiring and operating mature oil and gas assets. The team's quality reputation and expertise position them to build a geographically diversified portfolio of oil and gas properties while generating superior risk-adjusted rates of return."

With the close of Sheridan Production Partners, L.P., the fund will seek to acquire a portfolio of mature properties across the United States and optimize operations through accelerated production, recovery enhancement and additional capital.

About Sheridan
Formed in 2007, Sheridan Production Partners is a Houston-based production company dedicated to building a balanced portfolio of mature oil and gas properties across diverse basins in the United States, including the Gulf of Mexico shelf. Established by a proven and talented management team, Sheridan will invest in mature oil and gas properties and operate the properties to enhance recovery through capital investments while focusing on cost structure. Sheridan will make acquisitions through its $1.3 billion fund, Sheridan Production Partners, L.P. Its strategy is to build value at the company level in order to maximize returns. For more information, please visit www.sheridanproduction.com.

About Warburg Pincus
Warburg Pincus has been a leading private equity investor since 1971. The firm currently has approximately $20 billion of assets under management for investment in a range of sectors including consumer and retail, industrial, healthcare, financial services, energy, real estate and technology, media and telecommunications.

Warburg Pincus has raised 12 private equity investment funds which have invested more than $26 billion in more than 575 companies in 30 countries. Since the late 1980s, the firm has invested approximately $1.5 billion in companies involved in oil and gas exploration and production, energy and power projects and oilfield and other services. Warburg Pincus has been the lead investor in more than a dozen oil and gas exploration companies, including: Antero Resources, Bill Barrett Corporation (NYSE: BBG), Encore Acquisition Company (NYSE: EAC), Kosmos Energy, Latigo Petroleum, Newfield Exploration Co. (NSE: NFX) and Spinnaker Exploration, Inc. (NYSE: SKE). An experienced partner to entrepreneurs seeking to create and build durable companies with sustainable value, the firm has offices in Beijing, Frankfurt, Hong Kong, London, Mumbai, New York, San Francisco, Shanghai and Tokyo. For more information, please visit www.warburgpincus.com.