oa High Resolution time-to-depth conversion using 3D Grid Tomography

A simple and fast method to perform the final time-to- depth conversion is to use 3D grid tomography, in which the inversion aims only at minimizing the misties between wells and seismic data. In the tomography only the normal ray needs to be shot, making the process very fast so that it can easily be run on a single workstation. This methodology avoids lengthy processes of correction using externally derived functions and/or transformation of velocities from interval to average and back.

The proposed workflow is applied to the PSDM data from the Pluto field, in the Australian North-West shelf. The input data had large residual misties with important lateral variability. The final results were robust, with tomography producing a smooth model which tied all the markers for all wells within a velocity depth sample.