Regional distribution of hydrocarbon fluid inclusions in carbonate fracture filling cements: geohistory analysis and timing of oil migration, Oman foredeep
Fractured, reservoir limestones in Oman and the United Arab Emirates include the Shuaiba (lower Aptian) and Mauddud (upper Aptian-lower Cenomanian). Petrography and geohistory analysis reveals five stages of diagenesis, fracturing, and fluid migration. (1) Shelf emergence: early cementation associated with regional uncomformities overlying both limestones; (2) pre-orogenic shelf emergence, late Cenomanian to Turonian: fractures cutting Stage 1 cements are healed by very cloudy, cleaved, and twinned calcite containing microfractures with yellow-white fluorescent, hydrocarbon fluid inclusions; (3) initial foredeep downwarp of 0 to 800 m (0 to 2624 ft), Coniacian to early Campanian: fractures cross-cutting Stage 2 fratures are healed with cloudy, cleaved, and sometimes twinned calcite containing dull-blue fluorescent, hydrocarbon fluid inclusions; (4) rapid subsidence and deposition. Companian to Maestrichtian: burial and tectonic stylolites crosscut Stage 2 and 3 fractures; and (5) uplift of the Oman Mountains after 3900 + m (12,795 + ft) burial by early Tertiary: fractures crosscutting all diagenetic features are filled with clear untwinned and uncleaved calcite containing only nonfluorescent, aqueous fluid inclusions. If we can correlate earliest stylolite formation with a minimum burial load of -- 800 m (-- 2625 ft), then the hydrocarbon inclusions in Stage 2 fractures must predate all of Stage 4 and most of Stage 3. In the deepest portions of the foredeep, close to the Oman Mountain front, this limits the presence of oil in fracture porosity to late Turonian-early Campanian time. Farther to the west, in the shallower parts of the foredeep, this constraint relaxes, and oil migration occurred as late as early Tertiary.
- Research Organization:
- Gulf Science and Tech., Co., Pittsburgh, PA
- OSTI ID:
- 6183865
- Report Number(s):
- CONF-8304200-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:3; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ASIA
CARBONATE ROCKS
DEVELOPING COUNTRIES
DIAGENESIS
ENERGY SOURCES
FOSSIL FUELS
FRACTURED RESERVOIRS
FUELS
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGY
LIMESTONE
MIDDLE EAST
MIGRATION
MINERAL RESOURCES
OMAN
PETROLEUM
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
RESERVOIR ROCK
RESOURCES
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SEDIMENTARY ROCKS