--> Pore Pressure Diffusion Model to Simulate Triggering of Microearthquakes in the Cardium Formation, West-Central Alberta
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Pore Pressure Diffusion Model to Simulate Triggering of Microearthquakes in the Cardium Formation, West-Central Alberta

Abstract

Fluid-Previous HitinducedNext Hit Previous HitseismicityNext Hit resulting from hydraulic fracturing has become a mounting public concern in Western Canada. Understanding of the physics of Previous HitinducedNext Hit and triggered Previous HitseismicityTop is still in its infancy and this limits our ability to predict the magnitude of ground motions and the probability of their occurrence. Our work aims to address this uncertainty using a numerical modeling approach. For this project, it is assumed that linear pore pressure relaxation in porous media of the Cardium Formation is the main triggering mechanism for potential microearthquakes. Analytical solutions of the linear pore pressure diffusion equation are well established by previous authors. We have used these solutions for a heterogeneous and anisotropic medium to analytically and numerically simulate linear spatial-temporal pore pressure diffusion during injection and post-injection. The pore pressure diffusion model is coupled with the Mohr-Coulomb failure criterion to estimate the probability of triggering microseimic events. The preliminary results reveal that the probability of triggering microseimic events is enhanced in areas with lower rock cohesion due to the presence of pre-existing fractures, and also in areas with higher deviatoric stress related to higher elastic heterogeneity of the medium. Previous, similar studies have failed to accurately define the rock properties in their reservoir of interest. Our model will ultimately integrate an upscaled static geological model of stratigraphically-controlled poroelastic properties in the Cardium Formation, based on core and petrophysical analyses from the Pembina Halo tight oil play area. The resulting model will be better able to estimate critical parameters such as injection volume and rate, pressure, and time of the events prior to stimulation of the reservoir.