Abstract

RANGEL, Antonio V.; GONCALVES, Félix T. T.  and  ESCALANTE, Carlos E.. ORGANIC GEOCHEMICAL EVALUATION OF THE PATÍA BASIN, COLOMBIA: ASSESSING THE PETROLEUM SYSTEM OF A FRONTIER AREA. C.T.F Cienc. Tecnol. Futuro [online]. 2002, vol.2, n.3, pp.83-95. ISSN 0122-5383.

The Patia basin is an exploration frontier area of approximately 5000 km² located in southwestern Colombia. Seventy samples from 6 outcrop sections and one oil sample from the Matacea Creek seep were submitted for geochemical analyses. These analyses provide a basis to better assess the petroleum potential of this frontier area. Organic carbon content and Rock-Eval pyrolysis indicate that the Chapungo Sequence of Late Cretaceous age and the Chimborazo Formation of Eocene age have the higher petroleum source potential among the studied units. Petrographic evidence suggests that the heat effect of igneous intrusions account for the high maturity of some of the sampled intervals. Bulk and molecular parameters indicate that the oil sample of the Matacea Creek seep has been biodegraded, but there is also evidence of a recharge of the oil to the surface. Biomarker data indicates that the Chimborazo Formation is the unit that displays the best correlation with the Matacea Creek oil. The lack of a perfect match between the oil seep and the Chimborazo extracts might be the result of biodegradation or the existence of more proximal facies of the Chimborazo Formation, not sampled in this survey. The Matacea Creek oil seep is proof of a petroleum system.

Keywords : Patía Basin; oil seep; organic geochemistry; biomarker.

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