A review of petroleum systems and hydrocarbon potential in the Eastern Cordillera and eastern foothills belt, Colombia

In this review, we propose a hypothesis to explain the contrasting petroleum exploration success rates of four structural domains within the Eastern Cordillera and eastern foothills plays of Colombia. Recently published case studies suggest that the observation regarding the central eastern foothills plays (Nunchia syncline) being the most prolific trend is not related to exploration well density. Instead, it is a function of the Nunchia syncline having the most complete Neogene depositional record which resulted in an almost continuous overburden during deformation. The result is that the producing structures in the southern segment of the Nunchia syncline and the similar, yet unexplored trend in the northern segment of the Nunchia syncline, are associated with pods of active source rocks in the backlimbs of those structures. In contrast, the early (Late Paleogene) maturation due to thicker Paleogene overburden caused most of the hydrocarbon generation in the Axial Zone of the Eastern Cordillera to occur before the Late Oligocene–Early Miocene formation of the structures. Nevertheless, further petroleum systems modelling may help identify areas where pods of active source rocks could exist adjacent to major structures. In all scenarios, the remaining prospectivity of the Axial Zone of the Eastern Cordillera is much lower than in the northern segment of the Nunchia syncline. Finally, the presence of thick overburden and even the potential seismic expression of the trap are not sufficient to reduce uncertainties regarding future discoveries. We document a case study where a sub-thrust pull-up led to failure of a prospect. After years of exploration, we consider that all successful discoveries in the foothills of the Eastern Cordillera are related to the surface expression of the deeper subsurface structural traps.