Estimating the coulomb failure function using seismic velocities

Fault seal capacity is an important component in the conventional petroleum system. Assessing the capacity for a fault to seal or leak can be difficult, particularly where well constraint is lacking. In the frontier basin, in a marine setting, the only data available may be from a seismic survey. However, useful constraints on a faults sealing capacity can be extracted from this data alone. This study investigates the robustness of a number of empirical relations that can assist in extracting useful constraints from seismic velocities. Reliable estimates on maximum and minimum stress tensors and pore pressures can be calculated and combined with basic fault architecture analysis, to aid in placing some practical constraints on fault risk. In this study an area on the Rankin Trend, North West Shelf Australia, found good correlation between well-based and seismic velocity-based pore pressures and stress magnitudes allowing a coulomb failure function based only on stacking velocities to be calculated.