Development & Contract History

The Wilmington Oil Field was discovered in 1932, and production from the Long Beach portion of the tidelands began in 1937. For more than a decade, it seemed like a straightforward success: the City was sitting on a fortune. Then the ground started moving.

By the late 1940s, engineers realized that extracting oil from underground reservoirs was causing the land above to sink. By 1951, the center of an elliptical subsidence bowl was dropping at an alarming rate. Infrastructure buckled. Flood damage mounted. Costs were enormous.

The City’s response transformed the entire field. Engineers developed a waterflooding program that injected water back into the reservoir, replacing the extracted fluids and halting the sinking. That program not only stopped the subsidence but increased oil production. It became a model for oilfields worldwide.

With subsidence under control, a 1962 public referendum authorized offshore development from four man-made islands. The Long Beach Unit was formed, the THUMS Long Beach Company consortium was created, and island construction began in 1966. Waterflooding was built into the Long Beach Unit from day one: a direct lesson from the tidelands experience.

The City has been the primary operator of both the West Wilmington and Long Beach Unit operations ever since, with a series of field contracts, unit agreements, and financial partnerships shaping operations across the decades. Today those operations are carried out by two field contractors: California Resources Corporation (CRC) on the THUMS Islands, and Tidelands Oil Production Company in the West Wilmington area.

Other City Oil Interest

In addition to the Wilmington operations, the City holds working interests and royalty interests in several smaller upland properties, including Signal Hill East and West Units, Recreation Park, and City Wasem. These smaller properties are not part of the main Wilmington field operations described here.