The oil field at South Belridge was first discovered in 1911 by Belridge Oil Company. That group maintained control of the oil field and its operations until 1979 when Royal Dutch Shell purchased the company and many of the drilling rights to the field for $3.65 billion dollars. The field is now operated by Aera Energy LLC, a company that represents a joint effort by Shell and ExxonMobil. Aera sends all the oil collected from the South Belridge oil field to refineries in Martinez and Torrance where gasoline and other oil byproducts are produced.
The oil reserves in the South Belridge field are found grouped in pools within structural traps on the hills of the San Joaquin Valley. Over time, the oil moved up through the ground into structural pools where it became trapped. South Belridge is made up of six major pools of oil with the largest and most productive of these being Tulare and Diatomite. All six of the pools at South Belridge have different depths, reserves, and usage dates.
The largest pools exist at Tulare and Diatomite. These two pools were found in 1911 and were the only two pools with enough reserves to be subjected to advanced recovery techniques. Both pools have been subjected overtime to steamflooding, waterflooding, and fireflooding to push the oil closer to the surface and increase production rates. The pools at Diatomite and Tulare are the closest to the surface with depths around 1,000 feet and 400 feet respectively. Steamflooding remains the only advanced recovery technique in use at South Belridge.
The Antelope Shale and McDonald pools are the deepest active pools in South Belridge with depths of 4,000 feet and 6,700 feet respectively. The pool at Devilwater-Gould is the deepest at 8,200 feet and was found in 1980. Oil was collected from the pool for just nine months before it was abandoned.
The South Belridge oil field is estimated to have produced 2 billion barrels of oil since its discovery in 1911 and it is widely believed to have nearly 520 million barrels of oil remaining, as of 2006. The remaining reserves at South Belridge make it the second largest remaining reserve in California. There are currently 6,017 active wells at South Belridge and the oil field is the fourth largest in the state behind the oil fields at Midway-Sunset, Kern River, and Wilmington. The entire production operation at Belridge collects an estimated 140,000 barrels of oil per day with 93,000 of that coming from the pools at Tulare and Diatomite.