TTI model interpretation when anisotropic migration velocity analysis is impossible: A case history from the Colombian Llanos Basin

The objective of the anisotropic depth imaging was to obtain a more accurate positioning of the events for an appropriate well trajectory. The original well location was determined from the isotropic depth migration, and it was clear from early in the drilling cycle that there were lateral-position errors on the seismic image. The TTI anisotropic depth migration project ran during drilling to refine the well trajectory. We used a collaborative, geologically constrained approach that integrates all available geologic information into the interpretation of the seismic velocity model. This area has interbedded siliciclastic rocks with high dips and vertical and lateral velocity contrasts, giving a considerable lateral movement in the images in depth when we correct for seismic anisotropy and lateral-velocity heterogeneity. The position of the structure and dips on the final depth image were confirmed by two wells drilled in the area.