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A 3D Stochastic Modelling Approach for Induced Seismicity Risk Mitigation

Session: Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip IV

Type: Oral

Date: 4/20/2021

Presentation Time: 05:45 PM Pacific

Description: 

Anthropogenic fluid injection into the subsurface is known to produce induced seismicity. Efforts to quantify induced-seismicity risk and to develop mitigation strategies are hampered by a dearth of numerical schemes that can accommodate realistic Earth models while capturing the full spectrum of applicable physics. Several models have been proposed to explain the mechanisms of fault activation by fluid injection. The most common is an increase in pore pressure within the fault zone, which leads to a reduction in effective normal stress acting on the fault. Alternatively, poroelastic coupling between hydraulic fractures and the rock matrix is capable of altering fault-loading conditions without any hydraulic connection. More recently, it has been recognized that aseismic slip triggered by the two mechanisms above may play a major in loading unstable regions of a fault. Here, we present a new 3D stochastic approach to modelling injection-induced seismicity, whereby each of these mechanisms are accounted for. Uncertainties in input parameters are addressed stochastically to provide a probabilistic assessment of induced-seismicity risk. Regions of modelled faults that exceed the assigned failure criteria are mapped and provide estimates for the magnitudes of any seismic events that may occur. Due to the stochastic approach, probabilities for the expected maximum magnitudes of events and the sensitivities of results to the different input parameters can be analyzed. This type of modelling can be used to give a site-specific assessment of how the probability of generating an induced event changes, based on different treatment designs. Case studies from western Canada are used to evaluate the applicability of this approach for unconventional oil and gas development; this methodology also has potential for other industries, including geothermal energy and gigatonne-scale carbon dioxide storage.

Presenting Author: Thomas S. Eyre

Student Presenter: No

Authors