Technical and Economical Evaluation of an Over-pressured Prospect in Columbus Basin

A. O. Adebayo1, G. B. Egbeyale1 and O. S. Bamigboye

Department of Physics and Materials Science, Kwara State University, Malete., Nigeria.
Department of Chemical Engineering, Kwara State University, Malete., Nigeria.
University of the West Indies, Trinidad and Tobago.

Keywords: overpressure, amplitude, evaluation. modeling, prospect, technical

Abstract

Technical and economical evaluation of an over-pressure prospect in the Columbus Basin, Trinidad was conducted in an area covered by 3D seismic volume and characterized by high amplitude, continuous seismic anomaly. The area is covered by 3D pressure volumes and nearby well data comprising of 6 wells with a total depth of 73,248 feet. A challenge with the prospect is the presence of high pore pressures and abnormal pore pressures which are widespread in the tertiary offshore South-East (SE) Trinidad. The prospect was some distance from well control in this area. Due to the lack of well data present within the prospected area, rock physics modeling was used to understand the seismic amplitudes and anomaly present at the interested depth. The -3 -1 - results obtained for sand and shale acoustic impedance are 8070.8 gcm ms and 11615.03 gcm 3ms-1 respectively; for density, velocity of primary wave and secondary wave - 2589 gcm-3, 4304 ms- 1, 902 ms-1 and 3284 gcm-3, 2090 ms-1, 2457 ms-1 respectively. Rock physics, acoustic impedance calculations and AVO modeling showed that the anomaly could be attributed to gas sand. The prospect was fully mapped and depth converted. After volumetric calculations, reserve estimates and risk assessments were completed, an economic evaluation was performed based on a proposed development plan. Taking into account the results from the studies, a recommendation was made to drill the prospect.