流‒固‒相多场耦合数值方法及水力压裂模拟

Multiphysics Coupled Numerical Method for Fluid-Solid-Phase Interaction and Hydraulic Fracturing Simulation

摘要:

基于统一断裂相场理论，提出了流?固?相多场耦合数值方法，并将其用于探究赋存地应力和天然裂缝对水力压裂及其裂缝形态的影响。数值模拟研究表明：流?固?相多场耦合数值方法能准确预测拉、剪和拉?剪复合等水力压裂的裂缝形态；起裂所需的压力水头与赋存地应力水平正相关，且水力压裂的裂缝形态受侧压力系数影响明显；天然裂缝改变了孔压的分布，进而影响水力压裂裂缝的分叉和交汇，形成不同的裂缝形态。

Abstract:

Based on a unified fracture phase-field theory， a fluid-solid-phase multiphysics coupling numerical method is developed and applied to investigate the influence of in-situ stress and natural fractures on hydraulic fracturing and fracture morphology. Numerical simulation studies demonstrate that the fluid-solid-phase coupling numerical method can accurately predict fracture morphologies under tension， shear， and combined tension-shear hydraulic fracturing. The pressure head required to initiate fractures is positively correlated with the in-situ stress level， while the fracture morphology is significantly influenced by the lateral pressure coefficient. Natural fractures alter the distribution of pore pressure， which in turn affects the branching and intersection of hydraulic fractures， leading to diverse fracture morphologies.