Well Proximity Governing Stress Drop Variation and Seismic Attenuation Associated With Hydraulic Fracturing Induced Earthquakes
Hongyu Yu, R. M. Harrington, Honn Kao, Yajing Liu, Rachel E. Abercrombie, Bei Wang
Abstract
Abstract We use broadband seismic data collected within 3 km of a hydraulic fracturing (HF) well in northeast British Columbia, Canada, to estimate the stress drop values of HF‐induced earthquakes and their spatial variation. Applying both spectral ratio and clustered single‐spectra fitting methods to 484 induced earthquakes (M‐1.0 to 3.0), we find that earthquakes close to the injection well have lower stress drop values than those at greater distance. Stress drop values are generally invariant within clusters either proximal (~0.1–1 MPa) or distal (~1–10 MPa) to the well, suggesting that dynamic ruptures in rocks with similar rheological properties tend to have relatively constant stress drop values. Clustered single spectrum fitting also suggests that the seismic quality factor (Q) is lower proximal to the well. We interpret the lower stress drop values and higher seismic attenuation proximal to the well as a result of higher fracture density and/or elevated pore pressure in the rock matrix due to hydraulic stimulation.