Implications from a study of the timing of oil entrapment in Monterey siliceous shales, Lost Hills, San Joaquin Valley, California
- Chevron USA, Bakersfield, CA (United States)
The oil and gas-rich upper Miocene siliceous shales of the Monterey Group are the primary development target in the Lost Hills Oil Field, San Joaquin Valley, California. As a result of diagenesis, the siliceous shales can be subdivided by opal phase into three sections (from shallow to deep): the Opal-A diatomites which are rich in oil saturation; the Opal-CT porcellanites which are predominantly wet but include pockets of moderate oil saturation; and the Quartz cherts and porcellanites which in some places are highly oil saturated immediately below the Opal CT section. Productivity trends in each of the three sections have been established through drilling and production testing, but a predictive model was not available until a study of the timing of oil entrapment at Lost Hills was recently completed. The study included an analysis of the depositional history of the siliceous shales and timing of: (1) structural growth of the Lost Hills fold, (2) source-rock maturation, and (3) development of the opal-phase segregation of the Monterey shales. The study led to enhanced understanding of the known oil saturation and production trends in the three opal-phase sections and yielded a predictive model that is being used to identify areas in the field with remedial or delineation potential. The study also produced evidence of fold axis rotation during the Pliocene and Pleistocene that helps explain differences in fracture orientations within the Monterey shales.
- OSTI ID:
- 5699460
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
CALIFORNIA
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
MATURATION
MINERAL RESOURCES
NORTH AMERICA
OIL SATURATION
PETROLEUM DEPOSITS
RESOURCES
SATURATION
SOURCE ROCKS
TECTONICS
USA