Geology and oil and gas exploration in California's offshore basins
California's continental shelf contains 12 large pull-apart basins that formed by transtensional extension during Neogene transform margin tectonics. Most are elongate basins, subparallel to regional dextral strike-slip fault zones, and contain from 5000 to 30,000 ft of Neogene sediments. The common Neogene stratigraphic sequence consists of a relatively thin, transgressive, shallow marine sand and a shelf to slope succession that is overlain by thick basin-plain deposits of middle and upper Miocene age. Only three of the twelve major offshore basins have been actively explored in recent years; each is an extension of a producing onshore basin. The Santa Barbara and Los Angeles basins contain all of California's current offshore production, presently at 191,000 BOPD and 140,000 MCFGD. From their 29 fields, 2.23 billion bbl of oil and 1.7 tcf of gas have been produced, and remaining proven reserves are 873 million bbl of oil and 544 bcf of gas (January 1, 1985). In the Santa Barbara Channel, seven new fields or major extensions await development platforms, from which an additional combined peak production of 205,000 BOPD and 210,000 MCFGD is planned. Since 1981, exploration efforts in the offshore Santa Maria basin have resulted in the discovery of seven new oil fields, all with Monterey Formation reservoirs. Development plans for four of these fields currently include seven platforms, with an anticipated combined peak production of 210,000 BOPD and 117,000 MCFGD. Twenty wells were drilled between 1963 and 1967 in five of the central and northern California offshore basins. They yielded encouraging oil shows, but additional exploration activity was curtailed due to poor then-current economics. Recent exploration efforts benefit greatly from advanced logging technologies, developing stimulation and artificial lift methods for heavy oil, and much improved seismic data.
- Research Organization:
- Chevron U.S.A. Inc., San Francisco, CA
- OSTI ID:
- 7247675
- Report Number(s):
- CONF-8608105-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 70:7; Conference: 4. circum-Pacific energy and mineral resource conference, Singapore, China, 17 Aug 1986
- Country of Publication:
- United States
- Language:
- English
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