Modelling the Bohemian Earthquake Swarms: Application of a poro-thermo-elastic plastic model with weakening, damage and multiphase flow in GPU

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We propose to apply a newly developed model to numerically investigate earthquake swarms in general and the Bohemian swarms in particular. The model simulates a pore-elastic plastic rheology coupled with a non-linear diffusion model for pressure propagation, where the nonlinearity arises through the effective stress-dependence of the permeability. A two-phase (water and gas) flow model is currently being implemented. Numerical cracks in the model nucleate and grow in response to; i) far-field stresses developed at the boundaries, ii) stress perturbations arising from internal crack growth, and iii) poro-elastic stressing. Recent developments that include hardening, softening, and a damage growth model reproduce the entire (load-failure-unload) stress-strain curve observed in laboratory rock experiments. In this project, we propose to: 1) Include a heat flow model and introduce thermo-elasticity; 2) extend the model to 3-dimensions, 3) implement the model on the Graphics Processing Unit (GPU) platform, and 4) apply the model to the Bohemian swarms. The GPU platform allows fast and very high-resolution simulations in comparison to the standard CPU architecture. The numerical model is ideally suited to study the Bohemian swarms because the dominant physics of the Bohemian earthquake swarms are simulated, namely the complex interactions and feedbacks of CO2 injection, seismic slip (with the concomitant permeability enhancement) fluid flow, and advective heat flow. The model will be used to address: a) triggering mechanisms that generate swarm-earthquake activity, b) characterize fault-related fluid transport processes and effects of the fluid/rock interaction during migration, and c) investigate the system’s dependence on pressure and temperature.