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Coupled Thermo-Hydro-Mechanical Effects on Injection-Induced Seismicity in Fractured Reservoirs
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  • Victor Vilarrasa,
  • Ahmad Zareidarmiyan,
  • Roman Makhnenko,
  • Francesco Parisio
Victor Vilarrasa
Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Institute of Environmental Assessment and Water Research (IDAEA-CSIC)

Corresponding Author:[email protected]

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Ahmad Zareidarmiyan
Spanish National Research Council, Spanish National Research Council
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Roman Makhnenko
University of Illinois, University of Illinois
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Francesco Parisio
Freiberg University of Mining and Technology, Freiberg University of Mining and Technology
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Abstract

With the urgent necessity of geo-energy resources to achieve carbon neutrality, fluid injection and production in the fractured media will significantly increase. Applications such as enhanced geothermal systems, geologic carbon storage, and subsurface energy storage involve pressure, temperature, and stress changes that affect fracture stability and may induce microseismicity. To eventually have the ability to control induced seismicity, it is first necessary to understand its triggering mechanisms. To this end, we perform coupled thermo-hydro-mechanical (THM) simulations of cold water injection and production into a rock containing two fracture sets perpendicular between them. The permeability of fractures being four orders of magnitude higher than the one of the rock matrix leads to preferential pressure and cooling advancement, which induce stress changes that affect fracture stability. We find that the fracture set that is oriented favorably to undergo shear slip in the considered stress regime becomes critically stressed, inducing microseismicity. In contrast, the fracture set that is not favorably oriented for shear remains stable. These results contrast with those obtained for an equivalent porous media that does not explicitly include fractures in the model, which fails to reproduce the direction-dependent stability of fractures present in the subsurface. We contend that fractures should be directly embedded in the numerical models when inhomogeneities are of the spatial scale of the reservoir to enable reproducing the THM coupled processes that may lead to induced microseismicity.