Hydrocarbon Potential Evaluation of the Southern Llanos Basin and the Western Margin of the Barbados Accretionary Prism, Caribbean Region

Abstract

Summary This study implements 2D basin modeling and petroleum system assessment in two Caribbean basins to test new geological models recently proposed. The basin modeling integrates existing and new geochemical data to evaluate the hydrocarbon potential of these basins. The southern Llanos basin contains rocks with two different degrees of thermal maturity. Locally, the hydrocarbon generation for possible Lower Paleozoic source rocks started in the Silurian and by the Permian they had reached transformation ratio of 100%. The petroleum expelled was likely accumulated in pre-existing structures that were later uplifted up to 2200m, inducing destruction of the traps and losses of hydrocarbons. Towards the southern area, Paleozoic rocks are less thermally matured and may preserve higher hydrocarbon potential. Cretaceous/Cenozoic rocks are immature for hydrocarbon generation. Possible Upper Cretaceous source rocks located on buried half-graben structures within the Tobago basin are suggested to have started to expel hydrocarbons in the Oligocene and have reached transformation ratio of 70%. The petroleum expelled during the Oligocene-Eocene, was likely accumulated in deeply-buried thrusts formed during the early development of the Barbados accretionary prism, while later structures were charged by remigration from the older structures and younger hydrocarbons. Paleogene source rocks are starting to generate hydrocarbons.