Dos Cuadras Offshore Oil Field

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.

[4] The Dos Cuadras field is a faulted anticlinal structure which plunges at both ends, thereby forming an ideal trap for hydrocarbon accumulation.

[5] The Repetto Sands unit consists of layers of mudstone, siltstone, and shale, and due to its depositional environment the general grain size and porosity increase towards the east.

Because the drillers were using an insufficient length of protective casing, when the well hit a high-pressure zone in the field, it blew out, spewing enormous quantities of oil and gas into the water from the sea floor.

While crews were able to cap the wellhead and relieve the pressure there, the adjacent geologic formations were not strong enough to contain the pressure, and lacking a steel protective casing, the reservoir fluid and gas ripped through the sedimentary sand layers directly on the ocean floor; the result was the 1969 Santa Barbara oil spill of 80,000 to 100,000 barrels, which eventually coated over 40 miles of southern California coastline with oil, an ecological disaster which killed upward of 10,000 birds and numerous sea mammals and other creatures.

Following the spill, the Secretary of the Interior ended all offshore oil drilling in the Outer Continental Shelf (OCS) until measures for better oversight were put in place, which happened in 1970 with the passage of the federal National Environmental Policy Act (NEPA), and in California, with the California Environmental Quality Act (CEQA).

Opposition to oil drilling was nothing new in Santa Barbara – local residents, led by a newspaper publisher, objected enough to the expansion of the Summerland field in the 1890s to organize a late-night derrick-destroying party near the present-day Miramar Hotel[12] – but the spill intensified the local hostility to oil drilling to the point that few new platforms were installed, and none at all within the 3-mile limit.

In 1985, Unocal tried waterflooding, and then polymer flooding, to improve production rates, and then in 1990 they began a horizontal drilling program to reach reservoirs impractical to exploit any other way.

[14] According to the Minerals Management Service (MMS), the field retains about 11.4 million barrels of oil in reserves recoverable with current technology.