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Title: Geology and hydrocarbon accumulations, Columbus basin, offshore Trinidad

Journal Article · · Am. Assoc. Pet. Geol., Bull.; (United States)

The Columbus basin, situated on the eastern shelf of Trinidad, lies at the eastern extremity of a belt of severe deformation along the northern boundary of South America that has been affected by compressional and wrench tectonics in Pliocene-Pleistocene time. Two major structural trends are present in the Columbus basin: a series of east-nourtheast trending anticlines and north-nouthwest oriented normal faults. The basin was filled during late Moecene to Holocene time with sediments deposited by an ancestral Orinoco River draining a hinterland to the southwest. The Pliocene-Pleistocene section, which contains the hydrocarbon accumulations in the Columbus basin, was deposited in three coarsening-uppward sedimentary sequences followed by a late Pliestocene transgressive sequence. Traps for hydrocarbon accumulation were formed by an easterly trending Pliocene-Pleistocene wrench system with associated east-northeast-oriented anticlines combined with north-northwest-oriented normal faults. Oil was sourced in the late Miocene lower Cruse Formation, whereas gas was derived both from Pliocene-Pleistocene pro-delta shales and as a late high-temperature phase of lower Cruse hydrocarbon generation. The north-northwestern faults formed migrarion conduits form the oil source rock to Pliocene-Pleistocene reservoirs. The temporal relationship of faulting to oil generation is a major factor affecting the distribution of oil and gas. The size of hydrocarbon accumulations is limited to some extent by a lack of an effective hydrocarbon seal, particularly in the western half of the basin.

Research Organization:
Amoco Norway Oil Co., Stavanger, Norway
OSTI ID:
5635916
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:7
Country of Publication:
United States
Language:
English