水力压裂扩展特性的数值模拟研究

采用ABAQUS建立了水力压裂计算模型，模拟了地应力、岩石力学特性、压裂液流体特性等各种复杂因素对水力压裂扩展的影响。通过计算分析得到一些有益结论：（1）在注入压力一定的情况下起裂压力与最小水平地应力、临界应力、初始孔隙压力成正比，而与压裂液黏度、最大水平地应力、弹性模量无关；（2）裂缝扩展长度和最大缝宽与最小水平地应力、初始孔隙压力、弹性模量成反比，而与最大水平地应力无关；（3）水力压裂作业中，缝长的扩展过程可分为无扩展阶段、快速扩展阶段、稳定扩展阶段以及缓慢扩展阶段等4个阶段。研究结论对于水力压裂作业优化具有参考价值。

Simulation study of characteristics of hydraulic fracturing propagation

simulation model of hydraulic fracturing propagation is proposed by using the software of ABAQUS. The key factors of geotectology such as in-situ stress distribution, mechanical properties, fracturing fluid properties etc, which affect on the characteristics of fracturing propagation, are studied with the model. Several conclusions are drawn from the simulation results. When injecting pressure is constant, the fracture initiation pressure is proportional to the magnitude of minimal horizontal stress, critical stress and initial pore pressure, elastic modules, and is independent of fracturing fluid viscosity and maximal horizontal stress. The fracture length and maximal fracturing width are inversely proportional to the minimal horizontal stress, initial pore pressure and elastic modules. Further more they are independent of maximal horizontal stress. The process of hydraulic fracturing may be divided into four stages, namely no growth, quick growth, steady growth and slow growth stages. The obtained conclusions are of much significance for the perforation parameter optimization and design of hydraulic fracturing treatments.