--> ABSTRACT: Apiay Petroleum Province: Hydrocarbon Pools in Southern Llanos Basin of Columbia, by E. Castro; #91022 (1989)

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Apiay Petroleum Province: Hydrocarbon Pools in Southern Llanos Basin of Columbia

E. Castro

The discovery of Apiay field in August 1981 represents the successful effort of the Empresa Colombiana de Petroleos in its exploration program in the Llanos basin of eastern Colombia. Ecopetrol subsequently found nine oil fields in Upper Cretaceous sandstone reservoirs similar to the Apiay discovery. The recoverable hydrocarbon reserves attributed to this trend are over 100 million bbl of oil and 60 billion ft3 of gas. As of July 1988, thirty producing wells and four dry holes have been completed in the area.

The stratigraphic section of the Apiay area consists of metasediments and sedimentary sequences of early Paleozoic through Quaternary age. The hydrocarbon reservoirs were deposited in a continental to littoral environment.

Two main reservoirs are found in the Upper Cretaceous clastic system. The lower accumulation is structurally controlled and produces 18°-24° API oil from a water-drive reservoir. The upper producing zone is a strato-structural accumulation of 32°-34° API oil in a gas-expansion reservoir. A gas reservoir is present in lower Tertiary sandstones.

Different styles of structuring have been active through time; an extensional system prevailed from the late Paleozoic to Late Cretaceous and a compressional system dominated during the Tertiary, with a thrust belt being established during late Miocene-Pliocene. Hence, the inversion of early established tectonic and structural features is an important factor in the accumulation of hydrocarbons. Production has been established on four structural trends in the Apiay area: from east to west, Apiay-Guatiquia, Austral-Tanane, Ocoa-Guayuriba, and Libertad-Reforma.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.