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Ingrid Kristine Jacobsen & Omar Yesid Duran Triana
January 11, 2023 @ 12:00 pm - 1:00 pm
Exploitation of energy from enhanced geothermal systems is performed by injecting fluid at high pressure into the reservoir such that faults are deliberately opened. The fault opening causes enhancement of the fluid flow, which is favorable for exploitation of the geothermal energy, but also fault slip, which may be of the unstable kind that results in induced seismicity.
In this talk I will first present a mathematical model for fault deformation in a mixed-dimensional setting. Then I will move on to talk about the concepts behind the rate and state friction (RSF) models which are widely used in simulations regarding seismicity. Briefly explained, RSF models consider the coefficient of friction to be dependent on both slip rate and the state of the contacting rock surfaces, and parameters appearing in its model equations can tell us about whether fault slip will be unstable (seismic) or stable (aseismic).
Omar Yesid Duran Triana (and here)- abstract:
This research was inspired and intended as an extension to the mixed-dimensional poromechanical models for fractured media presented in [1]. There the classical continuum mechanics is considered in the context of finite and infinitesimal strain. We addressed fracture mechanics from a different perspective by considering the linear theory of the Cosserat (micropolar, asymmetric) continuum. We considered an conforming-H1 method for the resulting set equations. Extra regularity can be achieved on the asymmetric component of the stress tensor and fracture tractions through the angular momentum balance defined on surfaces. We addressed the second-order formulation and present numerical results for the adopted model.
[1] W.-M. Boon and J.-M. Nordbotten. Mixed-dimensional poromechanical models of fractured porous media. Acta Mech (2022).