Prediction of static and dynamic fluid pathways within and around dilational jogs

The distribution of stresses around a fault controls the development of second order fractures and influences fluid migration pathways. This paper demonstrates how the regions of enhanced fracture-induced permeability and fluid migration pathways, in both static and dynamic situations, can be predicted for dilational jogs subjected to simple shear. Mean stress is one of several key factors influencing the migration of fluids through a system. By combining mean stress data with second order fracture predictions obtained from experimentally determined stress trajectory and differential stress data around fault geometries, it is possible to derive predictions for the fluid pathways associated with a static (homogenous) system. Superimposing the mean stress states obtained for the same jog at different applied loads enables the changes in mean stress (and hence fluid migration) associated with the cyclical loading of a fault during stick-slip faulting to be studied. In addition, the mean stress patterns associated with successive stages in the jog’s evolution have been studied and the variations in these patterns, and therefore of the associated fluid migration pathways, mapped in order to track the change in these pathways that occurs as the overlap of the jog-defining faults increases.