Geomechanical analysis of the influence of CO2 injection location on fault stability  

作　　者：Victor Vilarrasa Roman Makhnenko Sohrab Gheibi 

机构地区：[1]école Polytechnique Fédérale de Lausanne,Lausanne,Switzerland [2]Institute of Environmental Assessment and Water Research(IDAEA-CSIC),Barcelona,Spain [3]Associated Unit:Hydrogeology Group(UPC-CSIC),Barcelona,Spain [4]Department of Civil&Environmental Engineering,University of Illinois at Urbana-Champaign,USA [5]Norwegian University of Science and Technology,Trondheim,Norway

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2016年第6期805-818,共14页岩石力学与岩土工程学报（英文版）

基　　金：the support from the"EPFL Fellows"fellowship program co-funded by Marie Curie,FP7(Grant No.291771);partial support from the"TRUST"project of the European Community's Seventh Framework Programme FP7/2007-2013(Grant No.309607);the"FracRisk"project of the European Community's Horizon 2020 Framework Programme H2020-EU.3.3.2.3(Grant No.640979);sponsored by SCCER-SoE(Switzerland)(Grant No.KTI.2013.288);Swiss Federal Office of Energy(SFOE)project CAPROCK(Grant No.810008154)

摘　　要：Large amounts of carbon dioxide(CO2) should be injected in deep saline formations to mitigate climate change,implying geomechanical challenges that require further understanding.Pressure build-up induced by CO2injection will decrease the effective stresses and may affect fault stability.Geomechanical effects of overpressure induced by CO2injection either in the hanging wall or in the foot wall on fault stability are investigated.CO2injection in the presence of a low-permeable fault induces pressurization of the storage formation between the injection well and the fault.The low permeability of the fault hinders fluid flow across it and leads to smaller overpressure on the other side of the fault.This variability in the fluid pressure distribution gives rise to differential total stress changes around the fault that reduce its stability.Despite a significant pressure build-up induced by the fault,caprock stability around the injection well is not compromised and thus,CO2leakage across the caprock is unlikely to happen.The decrease in fault stability is similar regardless of the side of the fault where CO2is injected.Simulation results show that fault core permeability has a significant effect on fault stability,becoming less affected for high-permeable faults.An appropriate pressure management will allow storing large quantities of CO2without inducing fault reactivation.Large amounts of carbon dioxide(CO_2) should be injected in deep saline formations to mitigate climate change,implying geomechanical challenges that require further understanding.Pressure build-up induced by CO_2 injection will decrease the effective stresses and may affect fault stability.Geomechanical effects of overpressure induced by CO_2 injection either in the hanging wall or in the foot wall on fault stability are investigated.CO_2 injection in the presence of a low-permeable fault induces pressurization of the storage formation between the injection well and the fault.The low permeability of the fault hinders fluid flow across it and leads to smaller overpressure on the other side of the fault.This variability in the fluid pressure distribution gives rise to differential total stress changes around the fault that reduce its stability.Despite a significant pressure build-up induced by the fault,caprock stability around the injection well is not compromised and thus,CO_2 leakage across the caprock is unlikely to happen.The decrease in fault stability is similar regardless of the side of the fault where CO_2 is injected.Simulation results show that fault core permeability has a significant effect on fault stability,becoming less affected for high-permeable faults.An appropriate pressure management will allow storing large quantities of CO_2 without inducing fault reactivation.

关 键 词：Carbon dioxide(CO_2) injection GEOMECHANICS Fault stability Induced seismicity Fault permeability 

分 类 号：X701[环境科学与工程—环境工程] X141