Gulf of Mexico: Ship Shoal
The study area in the Gulf of Mexico is located off the coast of Louisiana in the Ship Shoal and South Timbalier area. The data available for the study includes a 3D seismic volume, electric logs, and paleostratigraphic picks (courtesy of WesternGeco, Schlumberger, and IHS Energy). The Gulf of Mexico is known to be a challenging area for seismic technology because of development of overpressure due to disequilibrium compaction that, for the most part, lowers the seismic velocities.
Basin modeling can be a powerful tool to investigate pore pressure, particularly related to disequilibrium compaction. Calibration is critical for building robust basin models that accurately map pore pressure changes. Seismic attributes can be powerful calibration tools for that purpose given their spatial extent. Also, background models of seismic impedance or velocity models for depth conversion can be problematic due to velocity decrease caused by the overpressure if the well-log data coverage is sparse. Basin modeling can then be used to map the overpressure distribution, while the velocity estimates based on basin modeling can be used to constrain the background models of seismic impedance or seismic velocity. Obtaining basin modeling estimates of seismic velocities requires combining basin modeling outputs with appropriate rock physics models.
Graduate student Wisam AlKawai established rock physics models that relate seismic velocities to porosity and effective stress. He examined the impact of using these models to estimate seismic velocities from basin modeling outputs. Finally, basin modeling velocity estimates based on different rock physics models were combined with the basin modeling density outputs to test the background models of the near angle elastic impedance. Some of these models were used in the inversion process to see how the quality of the inversion results obtained using background models was constrained. See also the Links with Seismic Data