The Wilmington Oil Field is a prolific petroleum field in Los Angeles County in southern California in the United States. Discovered in 1932, it is the third largest oil field in the United States in terms of cumulative oil production. The field runs roughly southeast to northwest through the Los Angeles Basin, stretching from the middle of San Pedro Bay through Long Beach and east of the Palos Verdes Peninsula. The field originally contained approximately 3 billion barrels (480,000,000 m3) of reserves. In 2013, the USGS estimated future potential production from the combined Wilmington-Belmont oilfield could be around 900 million barrels (140,000,000 m3).

The Los Angeles Basin is a sedimentary basin located in Southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the Transverse Ranges. The present basin is a coastal lowland area, whose floor is marked by elongate low ridges and groups of hills that is located on the edge of the Pacific Plate. The Los Angeles Basin, along with the Santa Barbara Channel, the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, lies within the greater Southern California region. The majority of the jurisdictional land area of the city of Los Angeles physically lies within this basin.