Regional caprock-destroying dolomite on the middle jurassic to early cretaceous Arabian shelf
Massive, stratigraphically-discordant dolomite occurs on the late Mesozoic Arabian Shelf in the northern portion of Aramco's main producing area. This dolomite is associated with solution-collapse of Hith-Arab anhydrite seals and with enhancement of porosity and permeability in tight limestone seals within the region. By destroying regional caprocks, dolomitization has had an adverse effect on oil accumulation. The spatial extent of this dolomite was determined by the examination of Formation Density/Compensated Neutron wireline logs and sample description logs from 50 onshore and offshore wells. Fluid inclusion geothermometry reveals that baroque dolomite precipitated from brine with salinities of 223,000 to 249,000 ppm TDS at temperatures of 102 to 134/sup 0/C onshore and 131 to 155/sup 0/C offshore. Petroleum fluid inclusions within the baroque dolomite indicate hydrocarbon migration contemporaneous with dolomitization. Carbon and oxygen isotope data suggest that that brine which precipitated baroque dolomite was also responsible for the massive recrystallization of shelf limestone to form host dolomite. Chemical analyses of formation waters suggest that brine which migrated out of halite deposits during burial was the dolomitizing fluid. The geological and geochemical attributes of Arabian Shelf dolomites strongly resemble those reported for dolomite associated with Alpine and Mississippi Valley-type carbonate-hosted lead-zinc deposits in Europe and North America.
- Research Organization:
- Arabian American Oil Co
- OSTI ID:
- 5161254
- Journal Information:
- Soc. Pet. Eng. AIME, Pap.; (United States), Vol. SPE13697
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARABIAN SEA
CONTINENTAL SHELF
GEOCHEMISTRY
GEOTHERMOMETRY
PETROGRAPHY
CAP ROCK
CRETACEOUS PERIOD
DOLOMITE
JURASSIC PERIOD
NEUTRON LOGGING
OIL WELLS
RESERVOIR ENGINEERING
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
CONTINENTAL MARGIN
ENGINEERING
GEOLOGIC AGES
INDIAN OCEAN
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MESOZOIC ERA
MINERALS
OXYGEN COMPOUNDS
RADIOACTIVITY LOGGING
SEAS
SURFACE WATERS
WELL LOGGING
WELLS
020300* - Petroleum- Drilling & Production