破坏引起的白滨砂岩的渗透性变化及其对CO2含水层隔离的意义

Abstract The long-term safety assessment of CO_2 aquifer storage requires a deep understanding of permeability evolutionduring inelastic deformations in sedimentary rocks. The permeability change has been measured in the entire process fromelastic, plastic, post-failure to axial stress unloading for Shirahama sandstone subjected to triaxial compressions undervarious confining pressures. The measurements revealed that the confining pressure plays an important role in controllinginelastic deformation behavior and the tendency of the permeability evolution. In the brittle faulting regime under a lowconfining pressure, significant increase in permeability accompanied by dilatancy can be observed. In brittle-ductile transition

FAULTING-INDUCED PERMEABILITY CHANGE IN SHIRAHAMA SANDSTONE AND IMPLICATION FOR CO2 AQUIFER STORAGE

The long-term safety assessment of CO2 aquifer storage requires a deep understanding of permeability evolution during inelastic deformations in sedimentary rocks. The permeability change has been measured in the entire process from elastici plastic, post-failure to axial stress unloading for Shirahama sandstone subjected to triaxial compressions under various confining pressures. The measurements revealed that the confining pressure plays an important role in controlling inelastic deformation behavior and the tendency of the permeability evolution. In the brittle faulting regime under a low confining pressure, significant increase in permeability accompanied by dilatancy can be observed. In brittle-ductile transition regime and ductile regime, faulting or inelastic deformation does not necessarily and significantly enhance the permeability, and the permeability during deformation is lower than their corresponding initial values. Microscopic observations revealed that the two mechanisms: (1) shear-enhanced cracking, and (2) grain crushing, are responsible for these inelastic deformation and permeability evolution tendency. The presented results suggested that storing CO2 in those sites where ductile deformation prevails may be more safe.