CO2注入岩体的热-气-应力耦合二维弹塑性有限元分析

目前国内关于CO2地质埋存课题的研究已经起步，其中与岩石力学有关的工作急需加强。为此，考虑到向含气地层中注入CO2时岩石、气体和温度的相互作用，将CO2视为理想气体，使用Drucker-Prager屈服准则和‘无拉应力’判据，建立了一个热-气-应力耦合模型并研制了相应的二维有限元程序。假定了一个由下部注入层和上覆冠石层组成的CO2埋存地质系统，以此为数值模拟的对象，分析了CO2在不同的注入速率和注入时间条件下岩体的中的位移、应力、受拉与塑性破坏区的变化和分布情况，结果显示，为保证CO2注入岩体的稳定，应优择最佳的注入速率和注入时间。

2D elastoplastic finite element analysis of coupled thermo-gas-mechanical process in CO2 injection in strata

In China, the researches on geological sequestration of CO2 are started, and the researches concerned with rock mechanics should be strengthened. For this reason, considering the reaction between gas, temperature and rock during CO2 injection in gas-bearing strata, a coupled thermo-gas-mechanical model is established in which CO2 is regard as a perfect gas, and Drucker-Prager yield criterion and non-tensile criterion are used; a relative two-dimensional FEM code is developed. A geological sequestration system which consists of an under-part reservoir and an upper-part caprock is assumed. Taking the system as the objective of numerical simulation, the changes and distributions of displacements, stresses, tensile and shear failure zones in the rock masses are analyzed under the conditions of different injection rates and different injection times. The results show that the optimal injection rate and injection time should be selected in order to ensure the stability of rock mass injected by CO2.