The Oxnard Oil Field is a large and productive oil field in and adjacent to the city of Oxnard, in Ventura County, California in the United States. Its conventional oil reserves are close to exhaustion, with only an estimated one percent of the original oil recoverable with current technology remaining: 434,000 barrels (69,000 m3) out of an original 43.5 million. However, the reservoir includes an enormous deposit of tar sands, ultra-heavy oil classed as an unconventional petroleum reserve, and potentially containing 600 million barrels (95,000,000 m3) of oil equivalent, should it become economically feasible to extract. [1] Present operators on the field include Tri-Valley Oil & Gas Co., Anterra Energy Services, Inc., Chase Production Co., and Occidental Petroleum through its Vintage Production subsidiary. [2] As of the beginning of 2009, there were 34 active wells on the field. [2]
The Oxnard Oil Field is one of several beneath the Oxnard Plain, an area mostly protected agricultural land with the communities of Ventura, Oxnard, and Camarillo separated by greenbelts. In the vicinity of the oil field, agriculture remains the predominant land use, and oil wells, processing facilities, and associated infrastructure are interspersed with fields planted with crops such as strawberries, broccoli, and onions. Parts of the field, particularly on the west, have been given over to light industrial and commercial development as the Oxnard metropolitan area expands to the east. U.S. Highway 101 bounds the field on the north; California State Route 34 (Oxnard's East 5th Street) cuts across it from east to west, and Rice Avenue crosses it from north to south. Most of the currently active oil wells are in the eastern portion of the field, west of the intersection of 5th Street and Pleasant Valley Road. Some active wells remain west of Rice Avenue, and a group of wells using directional drilling is clustered together in a drilling island near the northeast corner of the intersection of Rose Avenue and Wooley Road. The total productive area of the field projected to the surface is 1,350 acres (546 ha). [3]
The climate in the region is Mediterranean, with cool, rainy winters and warm, rainless summers, in which the heat is moderated by frequent morning coastal low clouds and fog. Annual precipitation is around 15 inches (380 mm), almost all in the winter, and all in the form of rain. The mean annual temperature is 56 to 60 °F (16 °C); freezes occur rarely. [4] Elevations on the field range from about 40 to 60 feet (18 m) above sea level. It is mostly flat, with a very gentle slope to the south-southeast; drainage is along Revolon Slough to Calleguas Creek to Mugu Lagoon, and then to the Pacific Ocean.
The Oxnard field is within the Ventura Basin Province of southern California. Geologically, this area is part of a structural downwarp that occurred during the late Pliocene. Rocks within the region are all sedimentary and mostly marine. Oil accumulations, of which there are many in the Ventura province, mainly occur in anticlinal settings modified by faulting; stratigraphy is also influential in creating traps for hydrocarbons. Where the sedimentary rocks are sandstones with high porosity, and the structure and stratigraphy allow hydrocarbons to be trapped on their upward migration, oilfields are found. [5]
As the oil field is in the center of a large flat alluvial floodplain, there is no surface expression of any anticlinal structure capable of holding oil. Under the surface alluvium, a series of relatively impermeable sedimentary units cap the petroleum-bearing formation. On top are the Pleistocene San Pedro and Pleistocene-upper Pliocene Santa Barbara formations; under that the Pico Sands, of Pliocene age, which contain areas of tar sands; under that, separated by an unconformity, the Monterey Formation, of Miocene age, which also contains tar sands (the Vaca Tar Sand); under that, again separated by an unconformity, the relatively impermeable Conejo-Topanga Formation, which caps the faulted anticlinal structure containing medium-grade oil about 6,500 feet (2,000 m) below ground surface. This producing horizon is named the "McInnes" pool, and is in the Oligocene-age Sespe Formation. [6]
The Oxnard field contains a large quantity of tar sand, a type of bitumen which is categorized as an unconventional oil deposit. The average depth below ground surface of the tar sands – both the Vaca Sand, and the Pico Sand – is about 2,500 feet (760 m), and their thickness ranges from 0 to 600 feet (180 m), representing a total volume of 405,000 acre-feet (500,000,000 m3), equivalent to approximately 565 million barrels (89,800,000 m3) of oil for both units, were it possible to recover their petroleum content. [1] Only a tiny fraction of this has been brought to the surface to date, although Tri-Valley Corporation is actively developing the unit by drilling horizontal wells through the sands and subjecting them to the cyclic steam process. According to Tri-Valley, some of the test wells have shown production rates of 1,000 barrels per day (160 m3/d), and can be brought online as soon as the steam generators and storage infrastructure are in place on the field. [7]
The quality of the oil from the lower pools is good and the gravity medium, at 24 to 38 API, while the oil from the tar sand is extremely heavy and of poor quality, with an extraordinarily high sulfur content – API gravity of 5-7, viscosity of 28,000 to 33,000 centipoise, and sulfur content of between 5 and 7.5 percent by weight. [3]
The field was discovered in January 1937 by Vaca Oil Exploration Co., which drilled into tar sands about 2,800 feet (850 m) below ground surface. In spite of the extremely viscous petroleum deposits in the producing formation, which they named after their firm – the Pliocene "Vaca" Tar Sand – they were able to produce about 50 barrels per day (7.9 m3/d). In May of that same year they discovered tar sands in the underlying Monterey Formation from which they were able to produce about 90 barrels (14 m3) of oil per day. [6]
More adventurous drillers found deeper producing horizons with lighter oil. In 1953 and 1954 the McInnes, Lucas, and Livingston pools were brought online, producing oil of API gravity 24, 32 and 25-36 respectively. [3] Waterflooding operations in these deeper reservoirs in the 1960s assisted production, but most wells in these horizons were abandoned as the last economically recoverable oil was extracted; a few remained as water disposal wells, as it is usually both economically and environmentally preferable to reinject wastewater back into a depleted reservoir than to treat and release it on the surface. In 2008 only two wells remained active in the deep McInnes reservoir; all the others were in the shallow tar sands. [8]
Under the California Department of Conservation well adoption rule, Tri-Valley Oil & Gas Company acquired 20 wells formerly operated by defunct GEO Petroleum, Inc., which filed for Chapter 11 bankruptcy protection in 1998. [9] Wells declared deserted by the State – typically due to the dissolution of the operator – are open to adoption and redevelopment under the "orphan well" rule, with the written consent of the owner of the mineral rights to the property as well as the State Department of Oil, Gas, and Geothermal Resources. In 2008 Tri-Valley began redeveloping these wells and bringing them back to production. [2]
Oil produced in the field goes to the small (2,800-barrel (450 m3)-per-day) Oxnard Refinery, owned by Tenby, Inc., in an unincorporated area south of Fifth Street near the eastern Oxnard city limit. This refinery also processes oil from the West Montalvo field on the coast directly west of the Oxnard field. [10]
Between 1950 and 1981 Mandalay Bay was a permitted oil field waste disposal site which caused the release of numerous hazardous chemicals. [11] The records of what was dumped were subsequently lost, resulting in calls for an investigation and millions of dollars in lawsuits from home buyers who were told the area was safe for habitation. [12]
Anterra operates the only commercial facility that disposes oil field waste through injection wells in the county. In 1998, Anadime Energy Services Inc. applied for permission from the county of Ventura to operate a commercial disposal site at 1933 E. Wooley Road near the Oxnard city limits. This Canadian firm accepted waste from other oil field operators, mostly brine, and injects it thousands of feet into the ground. This permit held by Anterra will expire in 2018 and the commercial oil disposal sites in agricultural land are no longer permitted by county zoning law. The county Board of Supervisors eliminated such a use in farmland two years after the 1998 permit was issued. [13] They also denied a zoning change in 2015 that would have allowed expansion of the facility citing the many places of open space and industrial zones where the oil field disposal sites are permitted. They were unconvinced by the testimony that Ventura County, as the third-largest oil-producing region in the state, needs to allow brines to be disposed of effectively and cheaply. Anterra can still apply to continue operations at the current level when the permit expires. [14] The Santa Clara Wastewater Facility, established in 1959 about 2 miles (3.2 km) southwest of Santa Paula, accepted such waste but without injection wells on site until it closed in 2014. [15]
The McKittrick Oil Field is a large oil and gas field in western Kern County, California. The town of McKittrick overlies the northeastern portion of the oil field. Recognized as an oil field in the 19th century, but known by Native Americans for thousands of years due to its tar seeps, the field is ranked 19th in California by total ultimate oil recovery, and has had a cumulative production of over 303 million barrels (48,200,000 m3) of oil. The principal operators of the field as of 2008 were Chevron Corp. and Aera Energy LLC, but many independent oil exploration and production companies were also active on the field. The California Department of Oil, Gas and Geothermal Resources (DOGGR) estimates approximately 20 million recoverable barrels of oil remain in the ground.
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 South Cuyama Oil Field is a large oil and gas field in the Cuyama Valley and the adjacent northern foothills of the Sierra Madre Mountains in northeastern Santa Barbara County, California. Discovered in 1949, and with a cumulative production of around 225 million barrels (35,800,000 m3) of oil, it ranks 27th in size in the state, but is believed to retain only approximately two percent of its original oil, according to the official estimates of the California Department of Oil, Gas, and Geothermal Resources (DOGGR). Of the top forty onshore oil fields in California, it is the most recent to be discovered, but by the end of 2008 only 87 wells remained in production.
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 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 Beverly Hills Oil Field is a large and currently active oil field underneath part of the US cities of Beverly Hills, California, and portions of the adjacent city of Los Angeles. Discovered in 1900, and with a cumulative production of over 150 million barrels of oil, it ranks 39th by size among California's oil fields, and is unusual for being a large, continuously productive field in an entirely urban setting. All drilling, pumping, and processing operations for the 97 currently active wells are done from within four large "drilling islands", visible on Pico and Olympic boulevards as large windowless buildings, from which wells slant diagonally into different parts of the producing formations, directly underneath the multimillion-dollar residences and commercial structures of one of the wealthiest cities in the United States. Annual production from the field was 1.09 million barrels in 2006, 966,000 barrels in 2007, and 874,000 in 2008, and the field retains approximately 11 million barrels of oil in reserve, as estimated by the California Department of Conservation. The largest operators as of 2009 were independent oil companies Plains Exploration & Production and BreitBurn Energy.
The Ventura Oil Field is a large and currently productive oil field in the hills immediately north of the city of Ventura in southern California in the United States. It is bisected by California State Route 33, the freeway connecting Ventura to Ojai, and is about eight miles (13 km) long by two across, with the long axis aligned east to west. Discovered in 1919, and with a cumulative production of over 1 billion barrels (160,000,000 m3) of oil as of 2023 out of its original 3.3 billion. It is the tenth-largest producing oil field in California, retaining approximately 50 million barrels in reserve, and had 423 wells still producing. As of 2009 it was entirely operated by Aera Energy LLC.
The Dos Cuadras Offshore Oil Field is a large oil and gas field underneath the Santa Barbara Channel about eight miles southeast of Santa Barbara, California. Discovered in 1968, and with a cumulative production of over 260 million barrels of oil, it is the 24th-largest oil field within California and the adjacent waters. As it is in the Pacific Ocean outside of the 3-mile tidelands limit, it is a federally leased field, regulated by the U.S. Department of the Interior rather than the California Department of Conservation. It is entirely produced from four drilling and production platforms in the channel, which as of 2009 were operated by Dos Cuadras Offshore Resources (DCOR), LLC, a private firm based in Ventura. A blowout near one of these platforms – Unocal's Platform A – was responsible for the 1969 Santa Barbara oil spill that was formative for the modern environmental movement, and spurred the passage of the National Environmental Policy Act.
The Orcutt Oil Field is a large oil field in the Solomon Hills south of Orcutt, in Santa Barbara County, California, United States. Discovered in 1901 by William Warren Orcutt, it was the first giant field to be found in Santa Barbara County, and its development led to the boom town of Orcutt, now the major unincorporated southern suburb of Santa Maria. With a cumulative production in 2008 of 870,000 barrels (138,000 m3) of oil, it is the largest onshore producing field in Santa Barbara County.
The Brea-Olinda Oil Field is a large oil field in northern Orange County and Los Angeles County, California, along the southern edge of the Puente Hills, about four miles (6 km) northeast of Fullerton, and adjacent to the city of Brea. Discovered in 1880, the field is the sixteenth largest in California by cumulative production, and was the first of California's largest 50 oil fields to be found. It has produced over 430 million barrels of oil in the 130 years since it was first drilled, and retains approximately 20 million barrels in reserve recoverable with current technology. As of the beginning of 2009, 475 wells remained active on the field, operated by several independent oil companies, including Linn Energy, BreitBurn Energy Partners L.P., Cooper & Brain, and Thompson Energy.
The San Miguelito Oil Field is a large and currently productive oil field in the hills northwest of the city of Ventura in southern California in the United States. The field is close to the coastline, with U.S. Highway 101 running past at the base of the hills and is sandwiched between the larger Ventura Oil Field to the east and the Rincon Oil Field, which is partially offshore, to the north and northwest. Discovered in 1931, and with about 125 million barrels of cumulative production out of its original 520 million, it ranks 44th in the state by size. It is currently operated by CalNRG Operating LLC which acquired ownership of the field in 2021 after the bankruptcy of California Resources Corporation, a former subsidiary of Occidental Petroleum.
The West Montalvo Oil Field is a large and productive oil field on the coast of Ventura County, California, in the United States, in and adjacent to the city of Oxnard, California. Discovered in 1947, it has produced approximately 50 million barrels (7,900,000 m3) of oil, and originally contained up to 650 million barrels of oil in both the onshore and offshore areas. The offshore portion of the field is exploited from wells directionally drilled from onshore near McGrath Lake, from within an enclosure above the high-tide line at McGrath State Beach.
The Saticoy Oil Field is an oil and gas field in Ventura County, California, in the United States. The field is a long narrow band paralleling the Santa Clara River near the town of Saticoy. Discovered in 1955, it is one of the smaller but productive fields found in the region after most of the large fields had already been operational for decades. At the beginning of 2009 it still contained an estimated 387,000 barrels (61,500 m3) of recoverable oil out of its original 23.5 million, and had 15 wells remaining in operation. Vintage Production, a subsidiary of Occidental Petroleum, was the primary operator on the field as of 2009.
The South Mountain Oil Field is a large and productive oil field in Ventura County, California, in the United States, in and adjacent to the city of Santa Paula. Discovered in 1916, and having a cumulative production of over 165 million barrels (26,200,000 m3) of oil out of its original 630 million, it is the 37th largest oil field in California and the second largest in Ventura County. As of the beginning of 2009, it retains 316 active wells, and has an estimated 1.4 million barrels (220,000 m3) of oil remaining recoverable with current technology. Vintage Production, a subsidiary of Occidental Petroleum, was the largest operator as of 2009.
The Russell Ranch Oil Field is an oil and gas field in the Cuyama Valley of northern Santa Barbara and southern San Luis Obispo Counties, California, in the United States. Discovered in 1948, and reaching peak production in 1950, it has produced over 68 million barrels (10,800,000 m3) of oil in its lifetime; with only an estimated 216,000 barrels (34,300 m3) of recoverable oil remaining, and having produced around 66,000 in 2008, it is considered to be close to exhaustion. The primary operator on the field as of 2010 is E&B Natural Resources, which also runs the nearby South Cuyama Oil Field.
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 Carpinteria Offshore Oil Field is an oil and gas field in Santa Barbara Channel, south of the city of Carpinteria in southern California in the United States. Discovered in 1964, and reaching peak production in 1969, it has produced over 106 million barrels of oil in its lifetime, and retains approximately 2 million barrels in reserve recoverable with present technology, according to the California State Department of Natural Resources. Currently the field is produced from three drilling platforms four to five miles offshore, within Federal waters outside of the tidelands zone. Two of the platforms are operated by Pacific Operators Offshore LLC (PACOPS), the operating arm of Carpinteria-based Carone Petroleum; the other platform is operated by Dos Cuadras Offshore Resources (DCOR). The Carpinteria field is the 50th largest field in California by total original oil in place, as of the end of 2008.
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 Santa Clara Avenue Oil Field is an oil field in Ventura County, California, about six miles southeast of the city of Ventura and four miles northeast of Oxnard. It is produced entirely from two walled drilling islands along Santa Clara Avenue, each containing multiple directionally drilled wells. The field is within an agricultural area being encroached on several sides by urban development. As of 2010 the field reported 1,335,000 barrels of recoverable oil remaining, and had 18 active oil wells.