Advanced PP and PS Model Building – An Offshore Mexico Example

Model building and depth imaging with PS converted-wave data is more complicated than with P-wave data alone. We must determine appropriate compressional and shear velocities such that PP and PS sections match, and accuracy of anisotropic parameters is crucial to minimize residual moveout on both data types. Fortunately, recent technological developments, notably joint PP-PS tomography, allow us to produce excellent PS depth-imaged results with reasonable turnaround time. In this case study we describe the application of PP-PS model building and depth imaging to an OBC seismic survey. The area is characterized by complex structure combined with large velocity contrasts, both of which cause problems for PS model building. A state-of-the-art workflow was applied that included joint PP-PS tomography, maximum use of well data, and minimal interpretation. High-quality PP and PS results were produced in a reasonable timeframe.