Riverstone Holdings Reaches Agreement to Invest in Three Rivers Natural Resource Holdings LLC

Austin, TX and New York, NY (April 15, 2010) – The Riverstone/Carlyle Global Energy and Power Funds, a group of energy-focused private equity funds managed by Riverstone Holdings LLC (“Riverstone”), announced today that it will make a strategic investment in Three Rivers Operating Company LLC (“Three Rivers” or the “Company”), a private upstream oil & gas company based in Austin, Texas. Separately, Three Rivers will acquire certain assets of Chesapeake Energy Corporation (“Chesapeake”). The assets are primarily located in the Permian Basin of West Texas and Southeast New Mexico. Terms of the transaction were not disclosed.

Three Rivers will concentrate its efforts in the Permian Basin and will be managed by CEO Michael Wichterich, as well as Gabe Ellisor, Jim Keisling and Barry Smith. The leadership team has significant experience in managing exploration and production assets both in the Permian Basin and other regionsof the United States. Mr. Wichterich formerly served as the Chief Financial Officer of Mariner Energy, Inc. during Riverstone’s investment in that company.

Mr. Wichterich, CEO, said “Riverstone brings both capital and significant E&P experience to facilitate our strategic plans. We are excited to partner with them in pursuit of the ambitious goals we have set for Three Rivers.”

Pierre Lapeyre and David Leuschen, Co-Founders of Riverstone added, “We are excited to work again with Mike, as well as his team of experienced executives. This investment is consistent with Riverstone’s objective of partnering with proven management teams that possess strong track records with basinfocused operating expertise. We look forward to supporting the Company’s growth.”

About Riverstone Holdings LLC
Riverstone Holdings LLC, an energy and power-focused private equity firm founded in 2000, has approximately $17 billion under management across six investment funds, including the world’s largest renewable energy fund. Riverstone conducts buyout and growth capital investments in the midstream, exploration & production, oilfield services, power and renewable sectors of the energy industry. With offices in New York, London and Houston, the firm has committed approximately $13.6 billion to 69 investments in North America, Latin America, Europe and Asia. For more information, visit www.riverstonellc.com.

Contact:
For Riverstone Holdings LLC:
Jeffrey Taufield or Michael Freitag
Kekst and Company
212-521-4800