16 | OPERATING AREAS AMERICA’S PREMIER  ENERGY RESOURCE BASE  » Chesapeake is the second-largest producer of U.S. natural gas and a Top 15 producer of U.S. oil and natural gas liquids. The company has  built a large resource base of high-quality U.S. assets in the Barnett, Haynesville, Bossier, Marcellus and Pearsall natural gas shale plays and in the Granite Wash, Cleveland, Tonkawa, Mississippian, Bone Spring, Avalon, Wolfcamp, Wolfberry, Eagle Ford, Niobrara and Utica unconventional liquids plays. In 2010 Chesapeake increased its focus on applying the geoscientific and horizontal drilling expertise gained from developing unconventional natural gas shale plays to unconventional liquids-rich plays. Our goal is to reach a balanced mix of natural gas and liquids revenue as quickly as possible through organic drilling. We invested approximately $4.7 billion in 2010, net of divestitures, primarily in liquids-rich acreage to provide the foundation for this shift toward more profitable plays. We own interests in approximately 46,000 producing natural gas and oil wells, and in 2010 we produced approximately 1.035 trillion cubic feet of natural gas equivalent (tcfe) for an average of 2.8 billion cubic feet of natural gas equivalent (bcfe) per day. At year-end 2010, our proved reserves were 17.1 trillion cubic feet of natural gas equivalent, of which 90% were natural gas and all were onshore in the  U.S. We have also captured an inventory of up to 115,000 unrisked net future drilling opportunities — almost 50 years worth of drilling opportunities — on approximately 13.2 million net leasehold acres in the U.S. The following highlights Chesapeake’s ownership position  in our key operating areas. Natural Gas Shale Areas Liquids-Rich Areas  Operating States  Anadarko  Basin Permian Basin Eagle Ford Shale Barnett Shale Haynesville  Shale Bossier Shale Marcellus Shale Rockies 4 8 5 7 1 3  6 2