Stanford Geothermal WorkshopFebruary 9-11, 2026

In geothermal exploration and reservoir development understanding subsurface stress is critical — for prioritizing exploration efforts, assessing fault-controlled permeability, designing well and stimulation plans, and managing long-term field performance. A new workflow combining fault mapping and analysis, ground deformation analysis, and stress transfer modeling enables robust characterization of stress and strain that are primary permeability controls in geothermal systems. The workflow begins with evaluation of regional-scale faulting primarily using public source data and calculation of slip and dilation tendency. Using processed interferograms from the COMET-LiCS Sentinel-1 InSAR portal and LiCBAS processing tools allow measurement of surface deformation over large areas of the western USA. Using the USGS Quaternary fault database, and building 2.5km buffers around those faults, Python coding in QGIS has enabled evaluation of the difference in deformation across Quaternary faults in northwest Nevada where a COMET interferogram overlaps multiple geothermal power plants and numerous known geothermal systems. Operating fields and known geothermal systems are typically associated with higher differential deformation across nearby faults indicating a spatial relationship between geothermal systems and more active faults. This integrated regional-scale assessment of stress and strain directs geothermal explorers to the most promising locations with a robust assessment of fault-controlled permeability. At high priority target locations, structural mapping in the field and LiDAR topographic analysis augment published fault data, and these data are integrated with all available data into a 3-D geological model. Stress data come from regional datasets, fault kinematic data, and local wells. Using a modified USGS stress transfer modeling, stress change is modeled across 3-D arrays of observation points, enabling full-depth stress change analysis across the depth range of target faults. Investigating the spatial variation of changes in fault normal and shear stress and Coulomb stress change across the volume of rock associated with target faults provides information about where fracture permeability is likely to be developing, de-risking exploration and development drilling. Results can be integrated into iterative evaluations of fault geometries and stress transfer models to inform uncertainty analyses. The regional to project-scale workflow provides a robust targeting tool focused on fault-controlled subsurface permeability. Wells need to intersect natural permeability for conventional hydrothermal developments. Alternatively, natural permeability may need to be avoided in EGS development or well understood for effective design of well stimulations.

Topic: Geology