Utah FORGE: Fault Shear Reactivation Experimental Data for Fluid Injection-Rate Controls on Seismic Moment

Description

Included are experimental data recorded from shear experiments that specifically explore the link between fluid-injection rate and seismic moment resulting from shear reactivation of laboratory faults. Raw mechanical data from three experiments are included alongside corresponding MATLAB scripts that import and plot the data, as well as use it to calculate shear and normal stress. Experiments are performed on 2.5-3 inch long granitoid cores from the Utah FORGE EGS demonstration site, containing a single inclined fracture with small-scale roughness added to the fracture surface. The raw data included here were recorded from an aluminum triaxial pressure vessel (TEMCO) configured with three independent servo-controlled pumps, with distilled water used as the working fluid. The pumps control confining pressure, upstream pore pressure, and axial pressure, with each pump connected to a LabView interface to record applied pressures, cumulative injected water volumes, and pump flow rates. The downstream outlet from the fracture is closed to allow pressurization, which is measured by an external pressure transducer. A linear variable differential transformer (LVDT) attached to the axial piston measures axial displacement, from which we calculate shear displacement along the fracture. Additionally, P-wave transducers are used to record acoustic signatures, where acoustic emission events and maximum amplitudes are compared against seismic moment and shear slip velocity. Fluid injection rates range between 0.05 mL/min, 0.25 mL/min, and 0.75 mL/min for each experiment. Along-fault pressure distributions are progressively less uniform as injection rates increase, representing a switch from steady-state to transient conditions. Triggered shear displacement is used as a proxy for seismic moment and is indexed against cumulative injection volume and rate. Each experiment is performed under constant shear stress conditions, and the sample is fully saturated with DI water. Axial and confining stresses are applied to 3 MPa through pressure-stepping in 500 kPa increments. The pore pressure is held constant at 200 kPa prior to initiating the experiment, and initial axial displacement is recorded. The axial stress is then increased to initiate shear mobilization during the loading phase (run-in) until a peak steady state is achieved. The initial shear stress is reduced to approximately 80% of the peak shear stress by decreasing the axial stress, then held constant for the duration of each experiment.

Resources

Name Format Description Link
0 MATLAB code for constant rate experiment #15, run 3, where injection rate was held at 0.05 mL/min. The script imports and plots data from Temco cell, as well as calculates shear stress and normal stress. To run, download the raw data file and ensure the file paths in the script are accurately updated. https://gdr.openei.org/files/1625/MR15_Granitoid_CR0p05_3.m
47 Raw data for experiment #15, run 3, where injection rate was held at 0.05 mL/min. The associated MATLAB code defines the columns in the files, as well as imports and plots the data. https://gdr.openei.org/files/1625/MR15_Granitoid_CR0p05_3.txt
47 Raw data for constant rate experiment #2, run 1, where injection rate was held at 0.75 mL/min. The associated MATLAB code defines the columns in the files, as well as imports and plots the data. https://gdr.openei.org/files/1625/MR2_Granitoid_CR0p75_1.txt
47 Raw data for constant rate experiment #1, run 1, where injection rate was held at 0.25 mL/min. The associated MATLAB code defines the columns in the files, as well as imports and plots the data. https://gdr.openei.org/files/1625/MR1_Granitoid_CR0p25_1.txt
0 MATLAB code for constant rate experiment #2, run 1, where injection rate was held at 0.75 mL/min. The script imports and plots data from Temco cell, as well as calculates shear stress and normal stress. To run, download the raw data file and ensure the file paths in the script are accurately updated. https://gdr.openei.org/files/1625/MR2_Granitoid_CR0p75_1.m
0 MATLAB code for constant rate experiment #1, run 1, where injection rate was held at 0.25 mL/min. The script imports and plots data from Temco cell, as well as calculates shear stress and normal stress. To run, download the raw data file and ensure the file paths in the script are accurately updated. https://gdr.openei.org/files/1625/MR1_Granitoid_CR0p25_1.m

Tags

  • shear-experiments
  • pore-pressure
  • shear-displacement
  • temco
  • geophysics
  • egs
  • confining-pressure
  • geomechanics
  • utah-forge
  • constant-shear-stress
  • matlab
  • axial-pressure
  • induced-seismicity
  • along-fault-pressure
  • core-experiment
  • code
  • fracture
  • shear
  • injection-rate
  • raw-data
  • geothermal
  • seismic-moment
  • energy

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