Subthrust imaging in the foothills of the Llanos Basin, Colombia

Abstract

The foothills of the Llanos Basin is an area of rough terrain and complex geology. Different post and pre-stack-time and depth migration algorithms were tested to improve seismic imaging, and reduce the effects of seismic anisotropy caused by dipping shales in the overburden. Raytracing modeling was a useful tool to identify shortcomings in the seismic acquisition parameters. Reprocessing of a seismic line using the new FRP anisotropic pre-stack depth migration from topography code gave excellent results in improving the seismic imaging in the subthrust areas. The APSDM let to new insights into the structural style of the area and gave an incentive to re-evaluate the exploration potential of the area. This thesis shows that the frontal thrust in the northern part of the Eastern Cordillera is an area of low angle thrust faults with the incipient formation of a triangle zone as opposed to previous workers who proposed inverted normal faults.