The development of 3-D basin models with complex structural features, fully coupled fluid-flow computations, and network compositional kinetics is just becoming a reality. The new basin models not only reduce exploration risk on a basinwide scale but also prioritize blocks of interest on subbasin or smaller scales. However, the models must be robust and easy to use to be effective in a competitive oil-exploration environment.

In many cases, faults are petroleum migration conduits, especially at depths less than a few kilometers. This is clearly indicated by observations in extensional basins with high deposition rates, such as the Gulf of Mexico and the Niger Delta. Model stability largely involves the handling of faults in 3-D. Most gridding schemes either superimpose a regular grid on complex depositional patterns and structures or capture some or all of the geologic complexity with disjointed grids or grids that are highly deformed in fault zones. A practical alternative to these two extremes is to capture the geology accurately away from faults and regrid inside faults to avoid grid distortion. This approach allows for easy implementation of a broad set of algorithms for fault permeability, such as controlling permeability by the smear-gouge ratio, when the fault is active or when fluid pressure exceeds a critical level.

The philosophy and essential elements of our approach to modeling 3-D fluid-flow in faults are illustrated with examples from the Gulf of Mexico and then applied in an exploration context in the Niger Delta.