The Elk Hills Oil Field (formerly the Naval Petroleum Reserve No. 1) is a large oil field in western Kern County, in the Elk Hills of the San Joaquin Valley, California in the United States, about 20 miles (32 km) west of Bakersfield. Discovered in 1911, and having a cumulative production of close to 1.3 billion barrels (210,000 dam3) of oil at the end of 2006, it is the fifth-largest oil field in California, and the seventh-most productive field in the United States.