Potential petroleum reservoir rocks of north-central Oregon

Conference · Sat Aug 01 04:00:00 EDT 1987 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:5863898

Riddle, A J; Fisk, L H

The petroleum potential of north-central Oregon has been interpreted by many to be low. One of the dominant factors contributing to this interpretation is the assumption of poor reservoir rock quality. Their porosity and permeability measurements, scanning electron microscopy (SEM) studies, and petrographic analyses instead indicate that potentially good reservoir rocks exist. Well log responses also indicate that some subsurface sandstones have excellent porosities. Cretaceous turbidite sandstones of the Mitchell Formation in outcrop are poorly sorted, clay rich, tightly cemented, and have low porosities and permeabilities (range 3 to 11%, average 7%, and 0.01-9.8 md, average 1 md). However, in the subsurface where not tightly cemented with calcite, such as in reservoirs that accumulated petroleum prior to cementation, these submarine-fan sandstones may contain adequate porosity and permeability. Important secondary porosity could also be present, created by dissolution of calcite cement and detrital framework grains and by fracturing. Volcanic rocks and associated lithic sandstones make up most of the Tertiary stratigraphic sequence in the area. Fluvial channel sandstones of the Paleocene-Eocene Herren Formation are potentially excellent petroleum reservoirs, exhibiting good porosities (range 8 to 21%, average 12%) and permeabilities (up to 21 md, average 5 md). Low permeabilities in most samples are a result of authigenic clays plugging pore throats but this may be largely a surface weathering effect. Porosities of volcaniclastic sandstones in the Clarno Formation are surprisingly high (range 4 to 38%, average 17.5%). Permeabilities average 8 md and range from .01 to 43 md. Secondary porosity in these sandstones is a natural consequence of thermal maturation of associated kerogen-rich source of rocks and the production of organic acids.

• Research Organization: Loma Linda Univ., Riverside, CA
• OSTI ID: 5863898
• Report Number(s): CONF-870915-
• Conference Information: Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 71:8
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALLUVIAL DEPOSITS
CRETACEOUS PERIOD
ELECTRON MICROSCOPY
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MATURATION
MESOZOIC ERA
MICROSCOPY
MINERAL RESOURCES
NORTH AMERICA
OREGON
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCE POTENTIAL
RESOURCES
ROCKS
SANDSTONES
SCANNING ELECTRON MICROSCOPY
SEDIMENTARY ROCKS
SOURCE ROCKS
USA