Integrated geological and geophysical workflow for structural modelling; case study from the contraction foothills zone of the Colombian Eastern Cordillera

Abstract

In fold-and-thrust belts where there is a high degree of structural complexity, artificial geometrical distortions are often present on seismic reflection profiles. They need to be minimized during modelling. We document a workflow in which depth-mapping, velocity model building, well calibration and cross-section balancing are integrated into the seismic interpretation process to generate trustworthy structural models in complex zones. The proposed methodology is exemplified by a case study from the foothills zone of the Colombian Eastern Cordillera. In addition, sequential kinematic restoration of the modelled structure allowed evaluation of hydrocarbon migration routes during the period between the Oligocene and the middle Miocene. Following the previously mentioned workflow, we document a failed exploratory case study where all elements of the petroleum system are present except the trap. In this context, the documented case is a typical velocity pull-up. From this and published case studies we conclude that in Andean settings and probably most on land contractional-foothill settings, seismic image only, does not provide enough evidence of the presence of the trap but additional surface geological signatures must be documented. The proposed workflow therefore appears to be a useful tool for evaluating the exploration risk in structurally-complex fold-and-thrust belt settings.