A petroleum seep is a place where natural liquid or gaseous hydrocarbons escape to the Earth's atmosphere and surface, normally under low pressure or flow. Seeps generally occur above either terrestrial or offshore petroleum accumulation structures. The hydrocarbons may escape along geological layers, or across them through fractures and fissures in the rock, or directly from an outcrop of oil-bearing rock.
The Midway-Sunset Oil Field is a large oil field in Kern County, San Joaquin Valley, California in the United States. It is the largest known oilfield in California and also the largest oil field in the country by total oil in place, though Alaska's Prudhoe Bay Oil Field and the East Texas Oil Field have larger total production values of over 13 billion barrels and 5.4 billion barrels respectively compared to Midway-Sunset which has produced nearly 4 billion barrels.
The South Belridge Oil Field is a large oil field in northwestern Kern County, San Joaquin Valley, California, about forty miles west of Bakersfield. Discovered in 1911, and having a cumulative production of over 2,000 million barrels (320,000,000 m3) of oil equivalent at the end of 2023, it is the fourth-largest oil field in California, after the Midway-Sunset Oil Field, Kern River Oil Field, and Wilmington Oil Field, and is the sixth-most productive field in the United States. Its estimated remaining reserves, as of the end of 2008, were around 494 million barrels (78,500,000 m3) out of approximately 10.2 billion barrels of original oil in place, and it had 6,253 active wells. The principal operator on the field was Aera Energy LLC, a joint venture between Royal Dutch Shell and ExxonMobil. Additionally, the field included the only onshore wells in California owned and operated by ExxonMobil.
The Elk Hills Oil Field 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 oil production of close to 1.5 billion barrels (240,000 dam3) and a cumulative barrel of oil equivalent production of 2.2 billion BOE at the end of 2023, it is the fifth-largest oil field in California, and the seventh-most productive field in the United States.
The Coalinga Oil Field is a large oil field in western Fresno County, California, in the United States. It surrounds the town of Coalinga, about halfway between Los Angeles and San Francisco, to the west of Interstate 5, at the foot of the Diablo Range. Discovered in the late 19th century, it became active around 1890, and is now the eighth-largest oil field in California, with reserves totaling approximately 58 million barrels (9,200,000 m3), and over 1,600 active oil wells. The principal operators on the field, as of 2008, were Chevron Corp. and Aera Energy LLC.
The Buena Vista Oil Field, formerly the Naval Petroleum Reserve No. 2 (NPR-2) is a large oil field in Kern County, San Joaquin Valley, California in the United States. Discovered in 1909, and having a cumulative production of approximately 686 million barrels (109,100,000 m3), it is the tenth-largest oil field in California as of 2024. Its annual production has remained constant for the past decade around 1,250,000 barrels (199,000 m3) after being revitalized in the late 2000s. Part of this revitalization involved Crimson Resources initiating a waterflood in the Etchegoin Formation. They saw good response and sold the asset to Occidental Petroleum. CRC continued the development of the waterflood, but also tested the viability of the Monterey Formation. The Monterey Formation at Buena Vista has proven to be a viable target and is currently being developed.
The Cymric Oil Field is a large oil field in Kern County, California, in the United States. While only the 14th-largest oil field in California in total size, in terms of total remaining reserves it ranks fifth, with the equivalent of over 119 million barrels (18,900,000 m3) still in the ground. Production at Cymric has been increasing faster than at any other California oil field.
The Lost Hills Oil Field is a large oil field in the Lost Hills Range, north of the town of Lost Hills in western Kern County, California, in the United States.
The Kettleman North Dome Oil Field is a large oil and gas field in Kings and Fresno counties, California. Discovered in 1928, it is the fifteenth largest field in the state by total ultimate oil recovery, and of the top twenty oil fields, it is the closest to exhaustion, with less than one-half of one percent of its original oil remaining in place.
The Mount Poso Oil Field is a large oil and gas field in the lower foothills of the Sierra Nevada in Kern County, California, United States. Discovered in 1926, it is the 21st largest field in California by total ultimate oil recovery, having a cumulative production of close to 300 million barrels (48,000,000 m3). The current principal operator of the field is California Resources Corporation; 652 wells remained active at the end of 2006, while production had dwindled to 554,000 barrels (88,100 m3) during that year, from a peak of over 9 million barrels (1,400,000 m3) in 1981.
The Kern Front Oil Field is a large oil and gas field in the lower Sierra Nevada foothills in Kern County, California. Discovered in 1912, and with a cumulative production of around 210 million barrels (33,000,000 m3) of oil, it ranks 29th in size in the state, and is believed to retain approximately ten percent of its original oil, according to the official estimates of the California Department of Oil, Gas, and Geothermal Resources (DOGGR). It is adjacent to the much larger Kern River Oil Field, which is to the southeast, and the Mount Poso Oil Field to the north.
The Fruitvale Oil Field is a large oil and gas field in the southern San Joaquin Valley, California, within and just northwest of the city of Bakersfield, along and north of the Kern River. It is one of the few oil fields in the California Central Valley which is mostly surrounded by a heavily populated area. Discovered in 1928, and with a cumulative total recovery of more than 124 million barrels (19,700,000 m3) of oil at the end of 2006, it is 41st in size among California oil fields, and according to the California Department of Oil, Gas, and Geothermal Resources (DOGGR) its total reserve amounts to a little less than ten percent of its original oil.
The Round Mountain Oil Field is a large oil and gas field in the foothills of the Sierra Nevada, about 10 miles (16 km) northeast of Bakersfield, California, United States. It is east of the giant Kern River Oil Field, one of the largest in the United States, and also close to the Mount Poso Oil Field and Kern Front Oil Field. With a cumulative total recovery of more than 110 million barrels (17,000,000 m3) of oil, it is the 48th largest oil field in California, but remains relatively productive with still about ten percent of its reserves remaining in the ground, according to the California Department of Oil, Gas, and Geothermal Resources (DOGGR).
The North Belridge Oil Field is a large oil field along California State Route 33 in the northwestern portion of Kern County, California, about 45 miles west of Bakersfield. It is contiguous with the larger South Belridge Oil Field to the southeast, in a region of highly productive and mature fields. Discovered in 1912, it has had a cumulative production of 136,553,000 barrels (21,710,200 m3) of oil, and retains 27,443,000 barrels (4,363,100 m3) in reserve, as of the end of 2006, making it the 40th largest oil field in the state.
The Guijarral Hills Oil Field is a formerly-productive oil and gas field near Coalinga on the western side of the Central Valley in central California in the United States. Discovered in 1948, and having produced 5.4 million barrels (860,000 m3) of oil during its peak year in 1950, it now has but one active oil well producing a little over a barrel of oil a day, and is very near to exhaustion, with only 343,000 recoverable barrels of oil remaining throughout its 2,515-acre (10.18 km2) extent according to the official California State Department of Conservation estimate. As of 2010, the only active operator was Longview Production Company.
The McKittrick Tar Pits are a series of natural asphalt lakes situated in the western part of Kern County in southern California. The pits are the most extensive asphalt lakes in the state.
The Mountain View Oil Field is a large, mature, but still-productive oil field in Kern County, California, in the United States, in the extreme southern part of the San Joaquin Valley southeast of Bakersfield. It underlies the town of Arvin, as well as some smaller agricultural communities. The field is spread out across a large area, covering just under 8 square miles (21 km2), with wells and storage facilities widely dispersed throughout the area, scattered among working agricultural fields of broccoli and carrots as well as citrus orchards. Discovered in 1933, it has produced over 90 million barrels (14,000,000 m3) of oil in its lifetime, and although declining in production is one of the few inland California fields in which new oil is still being discovered.
The Edison Oil Field is a large oil field in Kern County, California, in the United States, in the southeastern part of the San Joaquin Valley and adjacent foothills east-southeast of Bakersfield. The field has a total productive area of over 8,000 acres (32 km2), most of which is intermingled with agricultural land uses; oil pumps and storage tanks are surrounded with row crops and orchards in much of the field's extent. Discovered in 1928, and with a cumulative production of 149 million barrels (23,700,000 m3) of oil as of 2008, and having over 6 million barrels (950,000 m3) in reserve, it is ranked 38th among California's oil fields by total ultimate recovery. It is a mature field in decline, and is run entirely by small independent operators. As of 2008, there were 40 different oil companies active on the field, one of the most in the state for a single field. 914 wells remained active on the field, averaging only two barrels of oil per well per day from the dwindling reservoirs.
The Los Angeles City Oil Field is a large oil field north of Downtown Los Angeles. Long and narrow, it extends from immediately south of Dodger Stadium west to Vermont Avenue, encompassing an area of about four miles long by a quarter-mile across. Its former productive area amounts to 780 acres (3.2 km2).
The California oil and gas industry has been a major economic and cultural component of the US state of California for over a century. Oil production was a minor factor in the 19th century, with kerosene replacing whale oil and lubricants becoming essential to the machine age. Oil became a major California industry in the 20th century with the discovery on new fields around Los Angeles and the San Joaquin Valley, and the dramatic increase in demand for gasoline to fuel automobiles and trucks. In 1900 California pumped 4 million barrels (640,000 m3), nearly 5% of the national supply. Then came a series of major discoveries, and the state pumped 100 million bbl (16 million m3) in 1914, or 38% of the national supply. In 2012 California produced 197 million bbl (31 million m3) of crude oil, out of the total 2,375 million bbl (378 million m3) of oil produced in the US, representing 8.3% of national production. California drilling operations and oil production are concentrated primarily in Kern County, San Joaquin Valley and the Los Angeles basin.
