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The Effect of Correlated Permeability on Fluid-Induced Seismicity

Description: 

Fluid-induced earthquakes are a side effect of industrial operations such as hydraulic fracturing and enhanced geothermal systems, where high-pressure fluids are pumped into the earth's crust to increase oil and/or gas flow to a well from petroleum-bearing rock formations or to improve permeability in underground geothermal reservoirs. One of the challenges associated with subsurface high-pressure fluid injections is the estimation
of the seismic hazard and its spatial footprint: how far away from the injection site can seismicity be induced? Field data have shown that the spatial footprint typically varies significantly between injections into the basement and injections above basement. If the fluids are pumped into the crystalline basement, the occurrence of the seismicity is typically very localized in space. Here, we show that varying degrees of spatial correlations in porosity or log(permeability) can explain this observation. By analyzing high-quality permeability data, we first directly show that the degree of correlations in the crystalline basement is indeed significantly different from formations above the basement. Then, using this in a novel conceptual model, we show that the degree of correlations controls the spatial footprint of fluid-induced seismicity explaining the field observations. Our findings are independent of the presence or absence of viscoelastic effects typically responsible for aftershocks. Our findings can be directly incorporated in any seismic hazard assessment.

Session: De-risking Deep Geothermal Projects: Geophysical Monitoring and Forecast Modeling Advances

Type: Oral

Date: 4/18/2023

Presentation Time: 08:15 AM (local time)

Presenting Author: Joern Davidsen

Student Presenter: No

Invited Presentation: 

Authors