Fluid-solid-phase multi-field coupling modeling method for hydraulic fracture of saturated brittle porous materials

Hydraulic fracturing of saturated brittle rock is a common discontinuous multi-physics phenomenon. The evolution and flow behavior of hydraulic fractures are the key to multi-field coupling in saturated brittle porous media. A fluid-solid-phase multi-field coupling modeling method for hydraulic fracturing is proposed and implemented by staggered algorithm in a commercial finite element software. In this method, the hydraulic fracture evolution is controlled by a unified fracture phase-field method, and the fluid flow in the cracked domain is equivalent to a Darcy-type flow whose flow property is dependent on the crack width. The crack width is derived according to the level-set method, and discretized into an equivalent form to determine the flow property in the cracked domain. The simulation results show that the proposed multifield coupling modeling method performs well in simulating the hydraulic fracturing of saturated brittle porous media under constant flow and constant injection pressure. A heterogeneous model is established by applying the multi-field coupling modeling method to mesostructured materials, which shows great potential in simulating irregular-shaped natural fractures.