Building a model with realistic pore pressures: Modifying the SEAM Phase I subsalt model

Abstract

Predrill pore-pressure prediction, particularly in overpressured reservoirs, is of paramount importance for hazard avoidance in deepwater basins like those in the Gulf of Mexico. The SEG Advanced Modeling (SEAM) Pore Pressure Prediction project has been developing a model for a region of the Gulf of Mexico that can be used for seismic simulation to generate a seismic data set for use in testing pore-prediction methodologies. The approach was to modify the deepwater model developed for the SEAM Phase I project to include a realistic pore-pressure distribution. The methodology for determining the pore pressures was to use basin simulation with the Phase I model as a basis. We experimented with a range of parameters and pore-pressure-generation mechanisms to better understand their impact on the final distribution of predicted pore pressures. The experiments and results obtained from them will be described. Following completion of the basin simulation, a rock-physics model was developed to transform the geology and derived pore pressures into anisotropic elastic values that were then used for seismic simulation.