The fracture network in shale gas reservoirs has a plurality of extending frontiers and the propagation paths of fractures are difficult to predict in advance. When the network fracturing is simulated by the extended finite element method (XFEM) based on stress intensity factors, the computation is arduous and time-consuming, which limits the application of XFEM in field fracturing design. Therefore, a simulating method of crack propagation based on energy criterion is proposed. Based on the principle of energy balance, the energy criterion for controlling crack frontiers extending is established by the fluid injection energy, the rock strain energy, the surface energy, the seismic energy and the friction loss energy. The criterion only needs to calculate the energy distribution in the crack frontiers to judge whether the fracture could expand, avoiding the fussy calculation of the stress intensity factor. Based on the proposed energy criterion, the fluid solid coupling effect and the fractures interaction, an energy method is established for network fracturing simulation in shale gas horizontal well. The results show that the fracture network morphology obtained by simulation is basically consistent with micro-seismic monitoring result, and the computational efficiency of this simulation method is 10000 times higher than that of XFEM. The energy method provides an idea and basis for the simulation and design of shale reservoir fracturing.

页岩气储层中的裂缝网络具有多个延伸边界，裂缝的传播路径难以事先预测。在基于应力强度因子的扩展有限元方法（XFEM）对网络裂缝进行模拟时，计算量大且费时，这限制了XFEM在现场裂缝设计中的应用。因此，提出了一种基于能量准则的裂纹扩展模拟方法。基于能量平衡原理，通过流体注入能量，岩石应变能，表面能，地震能和摩擦损失能建立了控制裂纹前沿扩展的能效准则。该标准只需要计算裂纹边界处的能量分布即可判断裂缝是否会扩展，避免对应力强度因子进行繁琐的计算。基于提出的能量准则，流固耦合效应和裂缝相互作用，建立了一种能量方法，用于页岩气水平井网络压裂模拟。结果表明，通过仿真得到的裂缝网络形态与微震监测结果基本吻合，该仿真方法的计算效率比XFEM高10000倍。能量法为页岩储层压裂模拟与设计提供了思路和依据。建立了页岩气水平井网压裂模拟能量方法。结果表明，通过仿真得到的裂缝网络形态与微震监测结果基本吻合，该仿真方法的计算效率比XFEM高10000倍。能量法为页岩储层压裂模拟与设计提供了思路和依据。建立了页岩气水平井网压裂模拟能量方法。结果表明，通过仿真得到的裂缝网络形态与微震监测结果基本吻合，该仿真方法的计算效率比XFEM高10000倍。能量法为页岩储层压裂模拟与设计提供了思路和依据。