Oil has been known in the Santa Barbara Channel since prehistoric times; the native Chumash people used tar from the numerous natural seeps as a sealant, and tar regularly washes up on the beaches from the offshore seeps. The world's first offshore oil drilling took place at the
Summerland Oil Field in 1896, only five miles north of the Dos Cuadras field. Those wells were put in from piers in shallow water. Technology for drilling in deeper water from platforms did not come about until the middle of the 20th century. While the existence of the field was suspected in the 1950s, the field was not discovered until 1968. Unocal and several other oil companies took out leases on the field in February 1968, and put in the first well, and the first platform, that same year. Data regarding the four platforms are as follows: . Unocal succeeded in installing the first four wells from its Platform A by January 1969, but their attempt to install the fifth well was catastrophic, and resulted in one of the most notorious environmental disasters in United States history. 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 – 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. After the disaster and cleanup, Unocal continued drilling wells from the two platforms that were already in place ("A" and "B", began producing from them in March 1969, and installed two more platforms ("C" and "Hillhouse"). Production from the field peaked quickly, reaching a maximum in 1971, during which year almost 28 million barrels of oil were extracted. The field experienced a gradual decline in production afterwards, approximately 8 percent per year, as is typical of fields when the reservoir pressure declines, and in the absence of
secondary recovery technologies (such as water or gas injection). 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. In 1997 Nuevo took over the operations of the four platforms directly, and in 2004 passed them on to
Plains Exploration & Production on that firm's acquisition of Nuevo. Plains only ran the platforms for a little more than four months, selling the operation to DCOR in March 2005. As of 2009, DCOR retains operational control of the Dos Cuadras field. According to the Minerals Management Service (MMS), the field retains about 11.4 million barrels of oil in reserves recoverable with current technology. At the beginning of 2008, there were 145 producing oil wells distributed between the four platforms. ==References==