Calculating fault stability

With fault stability analysis you can estimate whether a fault is critically stressed, or quantify the potential for this. To understand a fault's potential to slip is vital when making decisions about optimal well placement and design, studying reservoir compartmentalization and drainage patterns, and enhanced recovery techniques. Although a fault may be inactive within a stable tectonic environment, changes in the subsurface conditions may impact the sealing capacity as well as the fault's stability. Examples of changed stress conditions are injection of highly pressurized mud into the fault during drilling operations and depletion or injection of fluids into the reservoir. If the fault may start to slip, this can be associated with seismicity, a loss in sealing capacity of the fault itself, or a top seal breach due to fault propagation.

With the Discrete Analysis workflow of the Fault Stability strip you analyze the stability of the faults represented by surfaces. Input to this calculation are the subsurface stress conditions and pore pressure in the context of the fault geometry and orientation to the stress field. At the end of this workflow, fault stability is estimated by means of various properties, such as Tau ratio (a relative property related to shear stress) and Coulomb failure criterion (CFF, an absolute measure of shear stress impact). With the Volume Analysis workflow in the same strip you can analyze the integrity of the caprock and regions with unknown fracture orientation. The Tools section contains tools to work on the input and output of the Discrete Analysis workflow, for example a tool to graphically display calculated stresses as arrows or in Mohr space, and a tool to analyze probabilities in case you incorporated uncertainty.