4D Electrical Resistivity Imaging of Stress Perturbations Induced During
High-Pressure Shear Stimulation Tests
Abstract
Fluid flow through fractured media is typically governed by the
distribution of fracture apertures, which are in turn governed by
stress. Consequently, understanding subsurface stress is critical for
understanding and predicting subsurface fluid flow. Although
laboratory-scale studies have established a sensitive relationship
between effective stress and bulk electrical conductivity in crystalline
rock, that relationship has not been extensively leveraged to monitor
stress evolution at the field scale using electrical or electromagnetic
geophysical monitoring approaches. In this paper we demonstrate the use
time-lapse 3-dimensional (4D) electrical resistivity tomography to image
perturbations in the stress field generated by pressurized borehole
packers deployed during shear-stimulation attempts in a 1.25 km deep
metamorphic crystalline rock formation.