San Ardo Oil Field

A familiar sight to travelers on U.S. Highway 101 between Los Angeles and San Francisco, the oil field is located about midway between Paso Robles and King City, in the southern part of Monterey County, at the Alvarado Road exit from U.S. 101.

These sands are an average of about 700 feet (210 m) thick, contain an abundance of heavy crude oil, and overlie granodioritic basement rocks.

All of the productive units are of Miocene age, and the underlying basement rocks date to the Jurassic period.

[4] The Texas Company (later Texaco, and currently Chevron Corp.) discovered the field in November 1947 by drilling their "Lombardi 1" well to a depth of 2,158 feet (658 m).

[5] Since the oil is heavy crude, with API gravity of only 9-11 in the Lombardi Sands and 13 in the Aurignac, getting it to flow to production wells can be difficult.

[6] Fireflooding, a technology in which the oil is ignited by an electric coil in the presence of oxygen, with the combustion front moving towards a production well, and sometimes followed by water flooding as a further assist, has also been used in several of the San Ardo pools.