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Geology and geochemistry of crude oils, Bolivar Coastal Fields, Venezuela

Journal Article · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:6987885

The Bolivar Coastal Fields (BCF) are located on the eastern margin of Lake Maracaibo, Venezuela. They form the largest oil field outside of the Middle East and contain oil which is mostly heavy with a gravity less than 22/sup 0/ API. Lake Maracaibo is now in an intermontane basin enclosed on three sides by the Andes Mountains. The area has a complex history and tectonic movement continues today. In the Cretaceous, the area was part of the platform of a large geosyncline, but by the Eocene it was near a coast where a series of large sandy deltas was deposited, with terrestrial sediments on the south and thick marine shales on the north. At this time, conditions for oil generation in the shales and migration to the sands were established, but the subsequent Oligocene faulting, uplift, and erosion may have allowed meteoric water to penetrate into reservoirs. During the Miocene and Pliocene, the basin was tilted first west and then south, and filled with continental sediments from the rising Andes. Tilting is still continuing and oil is moving up along the Oligocene unconformity, forming surface seeps.

OSTI ID:
6987885
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:2; ISSN AAPGB
Country of Publication:
United States
Language:
English

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