Oil gravity segregation in the Monterey formation, California
- Mobil Exploration and Producing, Bakersfield, CA (United States)
The Monterey Formation is a fractured siliceous shale that is the principal reservoir and source rock for oil fields in the Santa Maria basin and the western Santa Barbara Channel. Monterey crudes in producing offshore fields are high-sulfur oils that range from 10[degrees] to 35[degrees] API. The oils in Monterey fractured reservoirs display a systematic increase in API gravity with increasing height above the oil-water contact. The rate of change in API gravity with depth in Monterey oil fields generally ranges from 0.5[degrees] to 1.2[degrees] API/100 ft. The oil-water contact usually occurs at an oil gravity of 10[degrees] API (the gravity at which the density of the oil and the water is equal). The maximum API gravity in a Monterey oil field is related to the level of thermal exposure experienced by the formation in the adjacent depocenter. Monterey oils are sourced by high-sulfur kerogens that generate heavy oils at low levels of thermal exposure, but generate progressively higher gravity oils at higher levels of thermal maturity. Comparison of the maximum API gravity found in 33 Monterey-sourced oil fields with the maximum temperature experienced by the Monterey Formation within three miles of the field (the most likely migration distance) suggests that a temperature of 260[degrees]F (127[degrees]C) is required to generate 20[degrees] API oil, and a temperature of 330[degrees]F (166[degrees]C) is required to generate 30[degrees] API oil.
- OSTI ID:
- 6833409
- Report Number(s):
- CONF-9404149--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 78:4; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
Similar Records
Controls on the variation of crude oil quality, Santa Maria basin, California
The nature and distribution of fluid inclusions in the Monterey Formation in the vicinity of the Santa Maria Basin, California: Implications for petroleum migration
Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
API GRAVITY
CALIFORNIA
COMPARATIVE EVALUATIONS
DENSITY
DEPTH
DEVELOPED COUNTRIES
DIMENSIONS
EVALUATION
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
HYDROGEN COMPOUNDS
INTERFACES
MINERAL RESOURCES
NORTH AMERICA
OFFSHORE SITES
OIL FIELDS
OXYGEN COMPOUNDS
PACIFIC OCEAN
PETROLEUM DEPOSITS
PHYSICAL PROPERTIES
RESERVOIR ROCK
RESOURCES
ROCKS
SANTA BARBARA CHANNEL
SEAS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
SULFUR CONTENT
SURFACE WATERS
TEMPERATURE DEPENDENCE
USA
WATER