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 multi-field 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.