基于水平集法的三维非均质岩石建模及水力压裂特性

摘要 采用水平集法(LSM)描述非均质岩石的静态材料边界特性，探讨分层特性、含有随机分布包裹体特性和具有Weibull分布特性的三种非均质岩石材料有限元建模方法，并与基于完全流-固耦合弹塑性理论的弥散裂缝模型相结合进行水力压裂过程的模拟. 在水力压裂模型中通过Corey关系和相对渗透率计算压裂液与原有液体混合的特性. 最后进行符合Weibull分布的非均质岩石材料的水力压裂传播特性的计算，给出了等效开裂区域的发展过程、注水点处水压力与注水时间变化曲线和有效应力路径. 模拟结果表明，采用水平集法能够有效地描述岩石材料的非均质特性，同时该法能够与弥散裂缝模型很好地结合，实现三维非均质岩石的建模与水力压裂过程的模拟.
Abstract：The level set method(LSM)was introduced to describe the static material interface in a rock material. The finite element modeling procedures for the three-dimensional rock sample with the layered feature， randomly distributed inclusions and statistical Weibull distribution heterogeneity were given via the LSM. To study the propagation of hydraulic fracture， a smeared crack model based on the fully coupled， elasto-plastic， pore pressure-solid phase interaction theory was coupled to the LSM. The Corey relation and relative permeability were adopted to calculate the viscosity and permeability of mixture in the smeared cracked hydraulic fracture model. Finally， a case study that simulating hydraulic fracture propagation was carried out in a heterogeneous rock sample following Weibull distribution. The development of equivalent crack zone， pore pressure versus injection time and the effective stress path in the injected element were discussed. The simulation results indicate that the LSM coupling with smeared crack model can be well used for modeling the heterogeneity of three-dimensional rock material and simulating the hydraulic fracturing.