Simulation of hydraulic fracturing and Darcy fluid flow in a porous medium using a coupled Discrete Element Method with fluid flow

Studying fluid penetration of the rock matrix during fracture propagation is one of the most difficult technical challenges of hydraulic fracture engineering. To deal with this issue, a coupled hydraulic-mechanical model was performed to simulate fracture propagation during hydraulic fracturing. For this purpose, a new discrete elements approach with a force-displacement law was used for simulating the fracturing process in a flow-coupled Discrete Element Method (DEM). A series of cases was simulated to evaluate the effect of different rates of injection and permeability. Good agreement was obtained between the numerical results of this study and the reported experimental results. The results of hydraulic fracture modeling indicated that a low fluid viscosity led to wider fluid penetration and simultaneous occurrence of failure phenomenon and penetration. In the case of high viscosity, the fracture is propagated beyond the fluid penetration zone, and higher fluid pressure for fracture creation was needed than was the case for a low viscosity fluid. The results of the simulations with different permeability and low viscosity of fluid revealed that when the permeability was high, the fluid penetration was faster relative to the case with low permeability. The growth pattern of fracture in low permeability is straight and branching, but in the case of high permeability, the fracture pathway was straight and thick. The pressurization rate affected the number of cracks and the geometry of the fracture in the hydraulic fracturing model. Finally, an increase in pressurization rate resulted in an increase in the number of tensile cracks.