Reservoir and source-bed history of Great Valley, California

Journal Article · Mon May 01 00:00:00 EDT 1978 · Am. Assoc. Pet. Geol. Bull.; (United States)

OSTI ID:6984192

Zieglar, D L ^[1]; Spotts, J H

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1. Chevron U.S.A., San Francisco

The application of geochemical concepts and relations of reservoir porosity-permeability-depth helps focus exploratory efforts on the favorable parts of geologic trends in partially explored basins. Porosity data from 165 producing reservoirs ranging in age from Late Cretaceous to Pleistocene show that the best reservoirs lose porosity at a rate of approximately 1.52% per 1,000 ft of burial. Reservoirs on the large-amplitude folds on the west side of the San Joaquin Valley have a more rapid porosity loss with depth. A crossplot of porosity-permeability indicates a ''best reservoir''relation of a tenfold decrease in permeability for each decrease of seven porosity units. Within the Great Valley, four major depocenters are definable by use of isopach data. Each has had a different source-bed history. Continental margin sedimentary rocks of Late Cretaceous age contain organic material that generally is structured and is believed to be the source of gas in the Scaramento Valley. Although a Tertiary depocenter exists in the Delta area, subsidence has failed to place Paleocene and Eocene source beds into the thermal zone thought to be required for oil and gas generation. Gas trapped in Paleocene and Eocene reservoirs must have migrated from more deeply buried Cretaceous source beds. Tertiary beds in the Buttonwillow and Tejon depocenters in the southern San Joaquin Valley contain large amounts of sapropelic organic material which is believed to be the source of the oil and gas found there. Source beds in the Buttonwillow depocenter have been in the thermal zone for generation for only about 5 My. Source beds in the Tejon depocenter started subsiding into the thermal zone more than 15 My ago.

• OSTI ID: 6984192
• Journal Information: Am. Assoc. Pet. Geol. Bull.; (United States), Vol. 62:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
CALIFORNIA
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
RESERVOIR ROCK
GEOCHEMISTRY
CRETACEOUS PERIOD
PERMEABILITY
POROSITY
QUATERNARY PERIOD
RESERVOIR ENGINEERING
SANDSTONES
TERTIARY PERIOD
CENOZOIC ERA
CHEMISTRY
ENGINEERING
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MESOZOIC ERA
NORTH AMERICA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA
WESTERN REGION
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration