砂岩是CO2含水层封存中重要岩石类型，其中的黏土矿物吸附CO2或H2O后会发生膨胀，影响岩石的力学性质，进而可能威胁储层的力学稳定性。以一种低黏土含量的石英胶结砂岩为研究对象，分别在干燥、饱和超临界CO2（supercriticalCO2，简称scCO2）和饱和H2O条件下进行了三轴压缩试验（孔隙压力恒定为10 MPa），对比分析了不同流体对砂岩的峰值强度、黏聚力、摩擦角及宏微观破坏特征的影响。结果显示，相比于干燥状态，超临界CO2和H2O的存在最大降低了砂岩试样7.61%、18.02%的峰值强度，不同围压水平下超临界CO2对砂岩峰值强度的削弱程度几乎为定值，而H2O的削弱程度随围压先升高后降低。砂岩的黏聚力在饱和超临界CO2和H2O条件下分别降低了12.11%、16.03%，而摩擦角几乎不受流体影响。超临界CO2和H2O都降低了砂岩的破坏角。Sandstoneis a crucial rock type for CO2 aquifer storage. The clay mineralswithin it expand upon adsorbing CO2 or H2O

which affectsthe rock’s mechanical properties and may threaten the reservoir’s mechanicalstability. A type of quartz-cemented sandstone with low clay content wasstudied. Triaxial compression experiments were performed under dry

H2O

and supercritical CO2 (scCO2) saturation conditions

maintaining a constant pore pressure of 10 MPa. The effects of various fluidson the peak strength

cohesion

friction angle

and both macroscopic andmicroscopic failure characteristics of sandstone were compared and analyzed. Resultsindicated that

compared to dry conditions

scCO2 and H2Opresence significantly reduced the peak strength of sandstone samples by 7.61%and 18.02%

respectively. Under different confining pressure levels

theweakening effect of scCO2 on sandstone peak strength remained nearlyconstant

whereas the weakening effect of H2O first increased andthen decreased with rising confining pressure. The cohesion of sandstonedecreased by 12.11% and 16.03% under scCO2 and H2O saturation

respectively

while the friction angle was remained nearly unaffected by thefluids. Both scCO2 and H2O reduce the failure angle of sandstone.