Advanced Geomechanical Analysis for Fault Slip due to Injection for Cases Identified as Higher Risk by the Screening Level FSP Tool
Abstract
Injection of produced water for disposal in an aquifer layer leads to increase in pressure in that layer, and a corresponding decrease in effective stress. This reduction in effective stress can make faults in critical orientations more likely to slip, and may lead to induced seismicity. Stanford University has released a screening level tool, the Fault Slip Potential Tool (FSP), developed in collaboration with ExxonMobil Upstream Research Company, to evaluate the induced seismicity risk for injection wells. The tool is based on several simplifying assumptions to make it easy to use and allow it to run quickly on standard computers. For wells with negligible predicted risk, for example when existing faults orientations are not favorable for slip, no additional action may be necessary. However, if an injection well is shown to be higher risk for induced seismicity using this screening level tool, advanced geomechanical analysis approach may be needed to better characterize and understand the risk. The present study analyzes (i) poroelastic effects, (ii) slip in a layer other than the injection aquifer layer due to pressure transmission along a high permeability fault gouge zone, (iii) the effect of a finite aquifer size and reservoir property anisotropy on the magnitude of pressure increase, and (iv) the effect of interaction between multiple injection/production layers. Approach for further refinement of the modeling approach, if necessary, such as inclusion of non-uniform horizons and non-planar fault surfaces based on seismic data, is also discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S31A..08L
- Keywords:
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- 4475 Scaling: spatial and temporal;
- NONLINEAR GEOPHYSICSDE: 7215 Earthquake source observations;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGYDE: 8164 Stresses: crust and lithosphere;
- TECTONOPHYSICS