The Role of Vertical Mechanical Heterogeneity in Predicting Fault Zone Architecture

The modeling of flow across faults in reservoir simulation and in exploration is based often on the permeability distribution. Detailed observations of faults across a range of stratigraphic facies, however, show that this simplification is likely to miss some of the fault zone architectural complexity that can play a significant role in the modeled flow. With over 10 years mapping the details in fault zones from a range of different tectonic and stratigraphic environments, RDR has compiled a unique set of observations that show the importance of the vertical mechanical heterogeneity (VMH) at the time of deformation. In our model for fault evolution, we define an incipient shear zone across which the layers and multilayers are sheared by brittle faulting and ductile folding. This incipient shear zone has been defined as a premonitory shear zone (PSZ) that “forecasts” the position of a fault with discrete offset. The complexity of the fault zone increases with an increase in the VMH with both discrete fault offsets and smearing of the ductile layers. A simple fault zone develops with a lower VMH. These conceptual models, combined with mechanical modeling, describe the process, which improves the prediction of the fault zone architecture.