基于扩展有限元法的碳酸盐岩地热储层岩体裂缝扩展行为

水力压裂作为一种主要的地热能开采手段，其压裂效果除与岩体基本物理力学性质有关外，还与裂隙分布、地应力状态、压裂工程参数等密切相关.为了探究以上因素对水力压裂过程中裂缝扩展行为的影响，以冀中坳陷碳酸盐岩储层岩体为研究对象，基于扩展有限元法，建立裂缝扩展流固耦合模型，分析了水平应力差、射孔方位角、注入液排量和压裂液黏度等参数对裂缝扩展行为的影响.结果表明:单裂缝扩展时，射孔方位角越小、注入量越大、越有利于裂缝扩展；双裂缝扩展时，水平应力差增大，裂缝偏转程度变小；水力裂缝与天然裂缝相交时，较小水平应力差有利于天然裂缝开启. 

Crack Propagation Behavior of Carbonatite Geothermal Reservoir Rock Mass Based on Extended Finite Element Method

Hydraulic fracturing is one of the main geothermal energy exploitation methods, and its fracturing effect is not only related to the basic physical and mechanical properties of the rock mass, but also closely related to the distribution of fractures, the state of in-situ stress, and the engineering parameters of fracturing. To explore the influence of the above factors of the fracture propagation behavior in the process of hydraulic fracturing, in this paper it takes the carbonatite reservoir rock mass in Jizhong depression as the research object. Based on the extended finite element method, a fracture propagation fluid-solid coupling model is established and analyzed. The influence of parameters such as horizontal stress difference, perforation azimuth angle, injection fluid displacement, and fracturing fluid viscosity on fracture propagation behavior. The results show: When a single fracture propagates, the smaller the perforation azimuth angle and the larger the injection rate, the more conducive to fracture propagation. When double cracks propagate, the horizontal stress difference increases, and the degree of crack deflection decreases. When hydraulic fractures intersect with natural fractures, the smaller horizontal stress difference is beneficial to the opening of natural fractures.