Utah FORGE: Fluid Injection-Rate Controls on Seismic Moment from Laboratory Fault Reactivation Experiments

This dataset contains experimental and acoustic data from shear reactivation tests that investigate the relationship between fluid-injection rate, pore pressure distribution, and seismic moment during laboratory fault slip. It includes raw mechanical data and acoustic emission recordings from fifteen experiments performed on 2.5-3 inch granitoid cores from the Utah FORGE enhanced geothermal systems (EGS) site. Each sample contains a single inclined fracture with small-scale surface roughness.

Experiments were conducted in an aluminum triaxial pressure vessel (TEMCO) equipped with three independently servo-controlled pumps using distilled water as the working fluid. The pumps regulated confining, upstream pore, and axial pressures, with each connected to a LabView interface to record applied pressures, cumulative injected volumes, and flow rates. The downstream outlet was closed to allow pressurization, monitored by an external pressure transducer. Axial displacement was measured by a linear variable differential transformer (LVDT) attached to the axial piston and converted to shear displacement along the fracture. Acoustic emissions were recorded using P-wave transducers, with event timing, amplitude, and cumulative amplitude compared against seismic moment and shear slip velocity.

Fluid injection rates of 0.05, 0.25, and 0.75 mL/min were applied under constant shear stress conditions, with both uniform and non-uniform along-fault pressure distributions. Samples were fully saturated with deionized water. Axial and confining stresses were increased to 3 MPa in 500 kPa increments, while pore pressure was held at 200 kPa prior to initiating shear mobilization. Axial stress was then increased to induce shear slip and subsequently reduced to approximately 60%, 80%, or 90% of the peak shear stress, depending on the experiment. The raw mechanical data files include time-series measurements of confining, pore, and axial pressures; pump volumes and flow rates; time (in hours:minutes:seconds); axial displacement (in millimeters); and downstream pressure (in psi).