High Quality Content by WIKIPEDIA articles! The Semitropic Oil Field is an oil and gas field in northwestern Kern County in California in the United States, within the San Joaquin Valley. Formerly known as the Semitropic Gas Field, it was discovered by the Standard Oil Company of California in 1935, and first understood to be primarily a natural gas reservoir; however, in 1956 a much deeper oil-bearing zone was discovered. The field contains the deepest oil well ever drilled in California, at 18,876 feet (5,753 m). At the end of 2008 the field still had 56 active oil wells, most of which were owned by Occidental Petroleum, and the field had an estimated 343,000 barrels of oil still recoverable with current technology.