Coupling 2D Numerical Kinematic and Thermal Maturity Modelling in Fold and Thrust Belt and Foreland Basin: Implications for the Petroleum System in the Eastern Venezuelan Basin

Vargas F, Adrián E.¹, Asbrúbal J. Bernal P¹ (1) PDVSA - Intevep, Los Teques, Venezuela

The maturity of source rocks responds to time an temperature state in the basin, which is controlled by to the interplay between stratigraphic and tectonic processes in three-dimensions. In structural complex areas, the majority of current numerical techniques generally employ one-dimensional modelling or an oversimplification of tectonic processes in two and three dimensions to investigate the petroleum system processes. In this study, the modelling of source rock generation and expulsion and fluid flow in two-dimensional compressional structures is achieved through use of a forward numerical approach. Structural deformation is described by fault-related folding and the thermal evolution of the source rock is described by the Arrhenius equation. This approach is used to investigate the petroleum system in an area of the Eastern Venezuelan Basin.

Modelling results highlight the impact of different kinematic models in the generation and expulsion of hydrocarbons and suggest that the level of thermal maturity of the source rock can be used to constrained the kinematic evolution of structures in fold and thrust belts. The stratigraphic and tectonic evolution in this area comprises periods of sequence and out-of-sequence deformation, which is supported by seismic data interpretation. Due this variable basin evolution, various episodes of source rock generation and expulsion are interpreted. The geometry of the basin at the time of occurrence of these episodes is interpreted to be responsible for accumulations showing hydrocarbon mixing. Furthermore, post accumulation processes (e.g. biodegradation, evaporative fractionation) contribute to modify the physical and chemical properties of the hydrocarbon in the reservoirs.