Predicting the regional distribution of fracture networks using the distinct element numerical method

Abstract

Previous research has shown the importance of understanding the relationship between fault geometry and current applied tectonic stresses in the prediction of critically stressed faults and their propensity for fluid flow via generated fracture networks along and/or around the fault plane. This article summarizes research aimed at increasing this understanding by applying the distinct element method (DEM) to predict stress within a rock mass generated by far-field stress on seismically resolvable faults within a modeled area. We showed that increases in differential over regional stress can be correlated with the presence of fractured rock as detected by petrophysical logs and core and drilling data. A case study example is used to illustrate the methodology from the Penola Trough, Otway Basin, South Australia, modeled using two-dimensional DEM. Assuming a reasonable understanding of (1) rock properties, (2) structure, and (3) far-field or regional stress, then the technique described in this article provides a valid workflow to increase confidence in the prediction of the generation of fractures and their spatial distribution.