2010 ANNUAL REPORT | 11 in cash and drilling carries. This was CNOOC’s second investment with  Chesapeake and its second investment in the U.S. onshore E&P industry.  We are currently drilling with five rigs in this play and expect to acceler- ate our drilling to 15 rigs by year-end 2013. We believe our leasehold  position could support the drilling of up to 7,600 additional net wells. Cleveland, Tonkawa and Mississippian Plays  — These three liquids-rich  plays of the Anadarko Basin should become significant contributors to  our growth in the years ahead. The Cleveland and Tonkawa plays are  tight sandstones located in western Oklahoma and the eastern Texas  Panhandle, and they provide returns that are some of the very best in  the company. We have acquired approximately 600,000 net leasehold  acres prospective for these plays and have drilled 75 net wells to date.  We are currently using eight rigs and believe our leasehold could sup- port the drilling of up to an additional 3,700 net wells.  The Mississippian fractured carbonate is primarily an oil play and is  located on the Anadarko Basin shelf of northern Oklahoma and southern  Kansas. We have acquired approximately 900,000 net leasehold acres  prospective for this play and have drilled 40 net wells to date. We are  currently using four rigs and believe our leasehold could support the  drilling of up to an additional 6,000 net wells. This is an area where we  anticipate bringing in a joint venture partner later in 2011 or in early 2012.  Bone Spring, Avalon, Wolfcamp and Wolfberry Plays — These four  liquids-rich plays of the Permian Basin should also become significant  contributors to our growth in the years ahead. To date, we have acquired  approximately 560,000 net leasehold acres that we believe are prospec- tive for these plays and have drilled 155 net wells. We are currently using  eight rigs and believe our leasehold could support the drilling of up to an additional 4,400 net wells.  Utica Shale  — Chesapeake has high hopes for this emerging shale play  in eastern Ohio, especially because it would become the fourth large  unconventional play (along with the Haynesville and Bossier shales  and the Mississippian carbonate) that Chesapeake has discovered. In  addition, we believe the play will have three distinct components (oil,  Natural gas and oil operations continue to grow and ex-  pand across the country as vast new resources are un-  locked through the process of hydraulic fracturing, or  “fracking,” a proven technology that has been used safely  and successfully in the completion of more than 1 million  U.S. wells since 1949. In our continuing efforts to educate the public and  alleviate common misconceptions about hydraulic  fracturing, Chesapeake became one of the first  energy companies to disclose the additives used  in the process. We are actively participating in a  national, publicly accessible web-based registry  developed by the Ground Water Protection Council  and the Interstate Oil and Gas Compact Commission,  with support of the U.S. Department of Energy. The  registry allows for fracking additives to be reported  on a well-by-well basis and offers public access to  that material on its website. Chesapeake began  loading well completion data onto the registry on  February 15, 2011, for wells where completion reports  have been filed with the appropriate state agencies.  During the fracking process, a mixture of approximately  99% water and sand, combined with a small amount of  chemical additives, is pumped at high pressure into a  targeted formation to create small fissures or fractures in  the surrounding rock or shale. These fractures are  kept propped open by the sand to allow the natural  gas or oil to freely flow into a wellbore. To view the listings and learn more about the fracking  process, the additives used and measures taken to protect  fresh ground water aquifers, visit www.fracfocus.org. Fracking Operations Transparency A prime example of Best Management Practices for fracture stimulation, this  well in Bradford County, Pennsylvania, is now producing natural gas from the Marcellus Shale. A closely regulated completion technique, fracking is  necessary to allow natural gas or oil to freely flow into the wellbore.