Microseismicity and Dry Shear-Slip in the Stimulated Rock Volume during Fracture Treatment in Shale Wells: Analyzing Data from the Hydraulic Fracture Test Site (Permian Basin) with the Linear Superposition Method (LSM)

This study analyzes 130,286 microseismic events recorded during treatment of 434 fracture stages in the Wolfcamp Shale Formation at the DOE Hydraulic Fracture Test Site (Reagan County, West Texas). Three principal results are presented: (1) Detailed LSM models of the shear-slip and tensile failure regions, near the advancing fracture tips, are developed for both single and multiple hydraulic fractures. These models give comprehensive insight in the extent and migration of active shear-slip zones in the stimulate rock volume (SRV) during fracture treatment. (2) The HFTS microseismic data is analyzed in detail to characterize the dimensionless moment magnitudes (Mw). Probabilistic mean values of Mw are used to estimate the seismic moment, M0, which is useful to constrain the upper limits for the amount of slip on the micro-fractures responsible for the microseismicity in individual stages. (3) A final discussion is included on the critical assumptions underlying a prior notion that microseismic monitoring would provide a poor characterization tool for the hydraulic fracturing process and the associated fracture network development - because only a minuscule fraction of the injection energy would be represented by the recorded microseismic energy.