State-based peridynamics simulation of hydraulic fracture phenomenon in geological media

Tight shale reservoirs have recently emerged as potential game changers in oil and gas and energy sectors worldwide. Consequently, exploration and exploitation of unconventional reservoirs has significantly increased over the last decade. Currently used stimulation designs are based on conventional planar fracture models that cannot realistically simulate the geometry and the extent of hydraulically induced fractures. For that reason, developing models that can thoroughly and accurately describe fracture network initiation and propagation plays a significant role in evaluating well production.;The main goal of this work is to evaluate the utility of the peridynamic theory (PD) in modeling the process of hydraulic fracturing. Peridynamics is a nonlocal theory of continuum media that can facilitate a direct coupling between classical continuum mechanics and molecular dynamics. A linear-viscoelastic PD model was applied to a three-dimensional domain that was discretized with cubic lattices of particles. Damage in the model is represented by the bond breakage; as the stretch between two lattices reaches its critical limit, s_0, the bond breaks.;The validity of the peridynamic simulation was tested by comparing results obtained in this project against the results obtained in a study performed by Zhou et al. Therefore, six sets of experimental tests were conducted to simulate hydraulic fracturing based on the peridynamic method. Five sets of the simulation results produced in this work were in good agreement with the experimental results. The investigation examined the influences of the differential horizontal stress and preexisting fracture, along with different approach angles, on the geometry of the hydraulic fracture.;Different injection rates were applied to the model in order to compare the fractured area that resulted from different injection rates. The simulation showed that the maximum dilatation and fractured zone occurred at the injection rate of 0.61 m3/min. The 0.61 m3/min injection rate caused the highest complete damage (0.9--1) with 5.24 % of the total number of atoms. As a result, the peridynamic approach presents promising results in predicting fracture propagation and damage area.