| Description |
Fracture in porous media plays a critical role in our society and economies through applications in petroleum engineering, civil engineering, bioengineering, geoengineering, etc. Understanding fracture behavior in heterogeneous porous media is a challenging task as in most applications, various physical processes across multiple spatial and temporal scales dictate the fracture behavior. To break down barriers in understanding fracture behavior in heterogeneous porous media such as the role of nano/microscopic pore structure on fracture behavior, multiphysics interactions as well as the impact due to complex loading conditions, this dissertation presents a multiscale and multiphysics investigation of fracture in heterogeneous porous media. The overall research is classified into two thrust areas: i) Multiscale nature of fracture: Investigating fracture across scales from atomistic to macroscopic by developing novel multiscale numerical frameworks. ii) Multiphysics nature of fracture: Investigating fracture behavior under coupled processes by developing state-of-the-art multiphysics numerical modeling methods. Within the first thrust, we developed a novel computational homogenization framework for fracture modeling in heterogeneous porous media. This framework combined the finite element heterogeneous multiscale method (FE-HMM) and phase-field fracture technique. The multiscale method is used to generate elasticity tensor from microscopic domain and updates energy evolution in the phase-field fracture model, which ensures that the variation of microscopic pore structures can be considered in the strain energy-driven fracture propagation. Furthermore, we expanded the proposed multiscale framework to the atomistic level by using the combined molecular dynamic (MD) and phase-field approach, which captures more complicated interactions or relations between nano and macroscopic structures in porous media. For the first time, pore structure at the nanoscale is used in bridging the gap between two scales (e.g., nano and macro). Within the second thrust, for the first time, we proposed an ALE-DEM-peridynamic (Arbitrary Lagrangian-Eulerian-Discrete Element Method-peridynamic) modeling strategy to study the role of filling nanopartilces on fracture mitigation in wellbore cement. Within this fully-coupled multiphysics model, two-phase flow, nanoparticle clusters, and crack surfaces in cement interact concurrently. Secondly, for the first time, we established a two-phase flow-driven fracture model in porous media by using the phase-field fracture technique combined with the governing equations for two-phase flow. iv |
