Well-seismic Tie in the Green Canyon, Deep-water Area in the Gulf of Mexico – A Valuable Indicator of Anisotropy

The quality of synthetic seismograms depends on the quality of the seismic data, well data and the time-depth relationship. Recently, the final product from seismic data processing is delivered in the depth. However, well depth and seismic depth can be different, so there are unique issues that must be addressed to bring the two results together. Migration velocity is the one of the most important variables affecting the well-to-seismic tie, because incorrect velocities result in lateral and vertical mispositioning of reflections. One factor that can significantly affect the velocities is the presence of anisotropy. Incorrectly accounting for anisotropy manifests itself as an incorrect vertical seismic velocity, causing the data to mistie. The seismic-well tie is conducted in time, and then converted back to depth. However, this process can introduce additional uncertainty from the fact that the velocities used to transform each dataset to depth can be different. In this paper, we address how to identify seismic anisotropy to match those data, hence, using that information to re-image the seismic data. Rock-physics modelling can be incorporated into the well-seismic tie process to assist anisotropy estimation. We show examples of how to use mis-tie and rock-property analysis to account for anisotropy.