This is a selective list of oil and gas fields in California, organized by county, giving their date of discovery, size, principal operators as of 2009, and other notes. Some of the smallest and those long abandoned are not included. Nomenclature generally follows the California Department of Conservation, Division of Oil, Gas, and Geothermal Resources.

Fresno County

• Coalinga Oil Field By far the largest field in Fresno County, with 5.7 million barrels produced in 2008.
• Jacalitos Oil Field 56 wells remain active, and 3.3 million barrels are estimated to remain in reserve.
• Guijarral Hills Oil Field With only one active well remaining in 2010, and which produced only 1.4 barrels of oil per day in 2009, this may be the still-active field nearest death in California.
• Kettleman North Dome Oil Field

Kern County

• Ant Hill Oil Field
• Asphalto Oil Field
• Belgian Anticline Oil Field
• Buena Vista Oil Field Former Naval Petroleum Reserve
• Coles Levee Oil Field North and South -- maybe separate articles
• Cymric Oil Field
• Devils Den Oil Field
• Edison Oil Field
• Elk Hills Oil Field Former Naval Petroleum Reserve
• Fruitvale Oil Field Underneath parts of Bakersfield
• Greeley Oil Field
• Kern Bluff Oil Field
• Kern Front Oil Field Vintage Production
• Kern River Oil Field Chevron Corporation
• Lost Hills Oil Field
• McKittrick Oil Field
• Midway-Sunset Oil Field The largest oil field in California. Numerous operators, including Chevron, Aera, PXP
• Mountain View Oil Field
• Mount Poso Oil Field Vintage, MacPherson, and others
• North Belridge Oil Field Aera and Greka
• Palomas Oil Field
• Poso Creek Oil Field E&B, and others
• Railroad Gap Oil Field
• Rio Bravo Oil Field
• Round Mountain Oil Field MacPherson, JP Oil
• Semitropic Oil Field Currently operated mainly by Vintage Production. Formerly known as the Semitropic Gas Field (since the deeper oil-bearing formations were not discovered until the field had been in operation for two decades). This field contains the deepest once-productive oil well in California, which went to a depth of 18,876 feet.
• Sevier Prospect (or perhaps Sevier Oil Field). An active prospect being investigated by Venoco, drilling directionally from several contained drillsites, on the east slope of the Temblors overlooking the Midway-Sunset. Part of the huge "Monterey shale play" that's been receiving a lot of press, and the only one of Venoco's several prospects that is currently producing.
• South Belridge Oil Field
• Ten Section Oil Field
• Trico Gas Field
• Yowlumne Oil Field

Kings County

• Kettleman North Dome Oil Field (also partially in Fresno County)

Elsewhere (this one is giant):

• Rio Vista Gas Field

Los Angeles County

• Beverly Hills Oil Field Operated entirely from drilling islands hidden in large, soundproofed buildings. Venoco, PXP, BrietBurn
• Brea-Olinda Oil Field Discovered in 1880; 16th-largest in California. On the border with Orange County.
• Cheviot Hills Oil Field Produced from two drilling islands, both hidden in golf courses south of Pico (Rancho Park and Hillcrest). Clever.
• Dominguez Oil Field The 23rd largest field in the state (as of 2007), this field had only 3 active wells, and only 67,000 barrels of recoverable reserves remaining. It might be closed now; check.
• El Segundo
• Inglewood Oil Field PXP
• Long Beach Oil Field Signal Hill, the densest oil development in the history of the state and most productive per unit area, is part of this field.
• Los Angeles City Oil Field North of downtown; one of the first to be discovered
• Los Angeles Downtown Oil Field Relatively recently discovered; operated entirely from a drilling island near 14th and Broadway. St. James Oil Corp.
• Rosecrans Oil Field
• Salt Lake Oil Field Produced entirely from the Beverly Center drilling island (east of San Vicente Blvd between Beverly Blvd and West 3rd Street) PXP.
• Santa Fe Springs Oil Field 11th largest in California
• San Vicente Oil Field Also produced entirely from the Beverly Center drilling island.
• Sawtelle Oil Field
• Torrance Oil Field Continuation of Wilmington
• Whittier Oil Field
• Wilmington Oil Field

Monterey County

• San Ardo Oil Field Chevron, Aera. The most northerly of the large fields on the ocean side of the Coast Ranges.

Orange County

• Richfield Oil Field
• Huntington Beach Oil Field Both onshore and offshore
• West Coyote Oil Field The 25th largest field in the state, this is the biggest oil field to be completely abandoned in California, with zero remaining recoverable reserves in the official figures.^[1]

San Luis Obispo County

• Arroyo Grande Oil Field Recently acquired by Plains (from Aera).

Santa Barbara County

• Carpinteria Offshore Oil Field Operated from three oil platforms in Federal waters offshore Carpinteria. Two of the platforms are run by Carone Petroleum, and the other by DCOR.
• Summerland Oil Field Now abandoned. This field was the location of the world's first offshore oil wells.
• Ellwood Oil Field The onshore portion is abandoned. It was shelled unsuccessfully by the Japanese in World War II from a submarine; the Sandpiper Golf Course occupies the spot now.
• Mesa Oil Field Abandoned; the site is covered with residential development, with most of the houses built in the 1950s. Current property values hover around a million dollars for each house.
• Zaca Oil Field Operated by Greka Energy. Produces heavy oil in an area of vineyards and ranches, not far from Neverland Ranch.
• Barham Ranch Oil Field Small field southwest of Los Alamos.
• Casmalia Oil Field Primarily operated by Greka.
• Lompoc Oil Field Operated by PXP, who offered to donate it as public land in return for the right to produce from Tranquillon Ridge. The deal was rejected in 2010 by the State Lands Commission.
• Orcutt Oil Field Formerly known as the "Santa Maria Oil Field"; the name was changed in the late 1940s to distinguish it from the Santa Maria Valley field to the north. Operated by BreitBurn Energy and Santa Maria Pacific.
• Santa Maria Valley Oil Field Currently run by Greka and several small operators; enormously productive during the Second World War.
• Cat Canyon Oil Field Greka, Aera Energy, Venoco; Chevron recently sold all its assets here to ERG.
• South Cuyama Oil Field E&B Natural Resources
• Russell Ranch Oil Field E&B Natural Resources
• La Goleta Gas Field Mainly used as a gas storage field by the local utility.

Ventura County

• Bardsdale Oil Field Mostly Vintage, some Vaquero and Thompco
• Ojai Oil Field Now mostly Vintage
• Oxnard Oil Field Tri-Valley, Chase
• Rincon Oil Field Vintage, and Greka for the offshore part
• San Miguelito Oil Field Vintage Production
• Santa Clara Avenue Oil Field Venoco, Inc.
• Saticoy Oil Field Vintage Production
• Sespe Oil Field Mostly Seneca, a few Vaquero and others
• South Mountain Oil Field Vintage Production and The Termo Co.
• Ventura Oil Field Aera Energy LLC. One of the last coastal onshore fields run by a major.
• West Montalvo Oil Field Venoco

Federal Offshore

• Dos Cuadras Offshore Oil Field Where the 1969 oil spill occurred; once run by Unocal, now entirely operated by DCOR
• Tranquillon Ridge Oil Field Where Plains proposed a project, in collaboration with environmental groups, but was defeated by the State Lands Commission
• Hondo Oil Field Entirely produced from Platform Hondo
• Sacate Oil Field Has the highest rate of any field in California -- an incredible 665 bbl/day/well^[2]
• Point Pedernales Oil Field Entirely produced from Platform Irene
• Point Arguello Oil Field