Hydromechanical behaviors of andesite under different stress states during fluid injection  

作　　者：Miao He Qi Li Xiaying Li Liang Xu Michael Kühn 

机构地区：[1]State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,430071,China [2]University of Chinese Academy of Sciences,Beijing,100049,China [3]Fluid Systems Modelling Section,GFZ German Research Centre for Geosciences,Potsdam,Germany [4]Institute of Earth and Environmental Science,University of Potsdam,Potsdam,Germany

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2021年第4期727-744,共18页岩石力学与岩土工程学报（英文版）

基　　金：funded by the National Natural Science Foundation of China(Grant Nos.41872210 and 41902297);IRSMGFZ Subsurface Utilization of Captured Carbon and Energy Storage System and the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering(Grant No.Z018004).

摘　　要：Water reinjection into the formation is an indispensable operation in many energy engineering practices.This operation involves a complex hydromechanical(HM)coupling process and sometimes even causes unpredictable disasters,such as induced seismicity.It is acknowledged that the relative magnitude and direction of the principal stresses significantly influence the HM behaviors of rocks during injection.However,due to the limitations of current testing techniques,it is still difficult to comprehensively conduct laboratory injection tests under various stress conditions,such as in triaxial extension stress states.To this end,a numerical study of HM changes in rocks during injection under different stress states is conducted.In this model,the saturated rock is first loaded to the target stress state under drainage conditions,and then the stress state is maintained and water is injected from the top to simulate the formation injection operation.Particular attention is given to the difference in HM changes under triaxial compression and extension stresses.This includes the differences in the pore pressure propagation,mean effective stress,volumetric strain,and stress-induced permeability.The numerical results demonstrate that the differential stress will significantly affect the HM behaviors of rocks,but the degree of influence is different under the two triaxial stress states.The HM changes caused by the triaxial compression stress states are generally greater than those of extension,but the differences decrease with increasing differential stress,indicating that the increase in the differential stress will weaken the impact of the stress state on the HM response.In addition,the shear failure potential of fracture planes with various inclination angles is analyzed and summarized under different stress states.It is recommended that engineers could design suitable injection schemes according to different tectonic stress fields versus fault occurrence to reduce the risk of injection-induced seismicity.

关 键 词：Water reinjection Stress state Hydromechanical(HM)coupling Injection-induced seismicity Numerical modeling 

分 类 号：P315.9[天文地球—地震学]