Integrated studies of the hydrocarbon system in frontier areas are important to assess exploration risk. The Rubio block located in the Tchira Depression has been the focus of various geological studies, yet very few studies of its petroleum system have been published. Based on seismic, surface geologic, and geochemical data, a study of the petroleum system has been developed.

We have identified, based on quality limited seismic and surface data, at least three major periods of deformation in the study area, ranging from the Upper Cretaceous to the present. The first event is of Late Cretaceous age and is characterized by compression. The second period is characterized by extension and took place at least during the Paleocene. Both events may be related to the development of the Colombian Central Cordillera and the flexure caused by its tectonic load, which affected western Venezuela from the Upper Cretaceous to the Paleocene. The third event is characterized by compression that has occurred quite recently, and it may be associated with the development of the Mrida Andes. This last event is responsible for the development of the major structures in the Rubio block. It is worth noting that western Venezuela also was affected by a Jurassic extensional event that is not illuminated by the seismic data of the study area but has been amply shown in both surface and seismic data in the surrounding areas.

According to the 1-D and 2-D geochemical modeling results, we propose that maturity of the source rock (the La Luna Formation) is greater to the west than to the east. Hydrocarbon expulsion from the source rock started in the western portion of the area 25 m.y. This local kitchen stopped expelling because of its uplift, which was caused by the latest compression. On the other hand, the La Luna Formation in the eastern portion started to expel hydrocarbon very recently, which is still ongoing. This active oil kitchen may be feeding the oil seeps in the eastern part of the study area.