An Integrated Method to Mitigate Hazards from Hydraulic Fracturing-Induced Earthquakes in the Duvernay Shale Play

Abstract

Abstract In recent decades, a remarkable increase in induced seismicity in the Western Canada Sedimentary Basin (WCSB) has been largely attributed to the hydraulic fracturing (HF) operations in unconventional plays. However, a mitigation strategy concerning geological, geomechanical, and operational susceptibilities to HF-induced seismicity has not been well understood. In this work, an integrated method is proposed to mitigate potential risks from HF-induced seismicity in the Duvernay play near Crooked Lake. The geological susceptibility to induced seismicity is evaluated first from site-specific formation pressure, a distance to the Precambrian Basement, and the existence of pre-existing faults. The regional in-situ stress and rock mechanics are then assessed to determine the geomechanical susceptibility to induced seismicity. Next, the operational susceptibility is determined by comparing induced seismicity with operational parameters such as total injection fluids and proppant mass. Finally, a multiple linear regression (MLR)-based approach is proposed by considering the feature importance of different parameters. It is found that regions with a low formation pressure (<60MPa), a great distance to the Precambrian Basement (>260m), a low minimum principal stress (<70MPa), and a low brittleness index (<0.62) tend to be seismicity-quiescent regions. Three new horizontal wells are drilled and fractured to validate the applicability of our MLR-based approach. High-resolution monitoring results indicated that 95% of the induced events had a magnitude of less than 2.0 during and after HF operations (three-month time window and five-kilometer well-event distance), among which the maximum magnitude reached M3.05 (<red light magnitude M4.0). Therefore, the MLR-based approach was successful in mitigating potential seismicity risks, which can be applied to other regions to guide seismicity-free fracturing operations in unconventional plays.