Induced Seismicity Driven by Fluid Diffusion Revealed by a Near-Field Hydraulic Stimulation Monitoring Array in the Montney Basin, British Columbia

This study presents observations using new data from a deployment of eight broadband seismometers surrounding a horizontal well pad at distances of similar to 1-3 km for the period before, during, and after a hydraulic fracturing treatment in the Montney Basin, British Columbia, Canada. We use a multistation-matched filter detection and double-difference earthquake relocation to develop a catalog of 350 events associated with hydraulic fracturing stimulation, with magnitudes ranging from -2.8 to 1.8 and estimated catalog completeness of approximately -0.2. The seismicity distribution suggests a statistically significant association with injection, and event migration can be described by a hydraulic diffusivity of similar to 0.2 m(2)/s. A comparison between daily seismicity rate and analytical stress evolution inferred from daily injection volumes implies that pore pressure diffusion largely controls earthquake nucleation at distances less than 1 km, whereas poroelastic stress transfer likely dominates at intermediate distances of similar to 1-4 km at time scales shorter than diffusion. Both mechanisms likely have a limited effect on stress perturbation at distances over 5 km.