Silica phase changes: Diagenetic agent for oil entrapment, Lost Hills field, California

Conference · Fri Feb 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5220713

Julander, D R; Szymanski, D L ^[1]

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1. Chevron USA, Inc., Bakersfield, CA (United States)

The siliceous shales of the Monterey Group are the primary development target at Lost Hills. Silica phase changes have influenced the distribution and entrapment of hydrocarbons. With increasing temperature, opal A phase diatomite is converted to opal CT and finally quartz phase rock. All phases are low in permeability. The opal A diatomite is characteristically high in oil saturation and productive saturation. Productivity from this phase is dependent on structural position and fieldwide variations in oil viscosity and biodegradation. The deeper chert reservoir coincides with the opal CT to quartz phase transition. Porosity is again reduced in this transition, but saturations in the quartz phase rocks increase. Tests in the chert reservoir indicate a single, low-permeability system, suggesting the importance of matric contribution. resistivity and porosity in the diatomite, and resistivity and velocity in the chert, are the physical properties which best reflect saturation. Methods exploiting these properties (FMS, BHTV, borehole, and surface shear wave studies) should be helpful in further characterizing the reservoirs and identifying future pay.

• OSTI ID: 5220713
• Report Number(s): CONF-9103128--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CALIFORNIA
CHALCOGENIDES
CHERT
DEVELOPED COUNTRIES
DIAGENESIS
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MINERAL RESOURCES
MINERALOGY
NORTH AMERICA
OIL SATURATION
OPALS
OXIDES
OXYGEN COMPOUNDS
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SATURATION
SEDIMENTARY ROCKS
SHALES
SILICON COMPOUNDS
SILICON OXIDES
USA