f Turning-Ray Tomography Velocity Analysis: A Case History from Southern Trinidad

Turning-ray tomography is a method for estimating near-surface velocity structure using first-break arrival times in areas where conventional refraction statics techniques fail due to poor data or lack of a smooth refractor/velocity structure. We applied this technique to an exploration area of onshore southern Trinidad. The velocity estimates correlate accurately with both sonic logs and near-surface geologic features, and they accurately predicted near-surface velocities which were later confirmed by drilling. We save combined the shallow tomographic velocity information with deeper velocity information from well and seismic data to construct velocity models for ray-trace modeling and depth migration. As a result of this work, we believe that the refraction tomographic method is a viable technique for deriving useful velocity information from first-break arrival time data.