Effect of CO2 injection rate and roughness on fracture activation mechanism
LI Man1, 2, LUO Zhixiong1, GUO Dianbin3, HU Dawei2, 4*, YANG Fujian2, 4, ZHOU Hui2
(1. Key Laboratory of Intelligent Health Perception and Ecological Restoration of Rivers and Lakers, Ministry of Educations, Hubei University of Technology, Wuhan, Hubei 430068, China; 2. State Key Laboratory of Geomechanics and Geotechnical Engineering Safety, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China; 3. State Key Laboratory of Deep Geothermal Enrichment Mechanisms and Efficient Development, Beijing 102206, China; 4. State Key Laboratory of Deep Geothermal Resources, School of Sustainable Energy, China University of Geosciences (Wuhan), Wuhan, Hubei 430074, China)
Abstract：Carbon dioxide (CO2) capture, utilization, and storage (CCUS) represent an effective decarbonization pathway that can accelerate achievement of dual-carbon targets. However, during geological CO2 storage, the injection rate and fault roughness are critical factors influencing the risk of fault activation, yet the underlying mechanisms remain unclear. To address this, this study simulated the fault activation process through shear slip of fractures in a laboratory setting, systematically conducting triaxial shear-seepage tests on sandstone fractures under varying CO2 injection rates and roughness conditions. The morphology of the fracture surfaces before and after the tests was reconstructed and analyzed using a 3D scanner. The results indicate that: (1) The critical activation pressure of the fracture increases with the CO2 injection rate but decreases with increasing fracture roughness. (2) As either the CO2 injection rate or roughness increases, the time required for fracture activation during the injection-driven phase decreases. The deformation mechanism gradually shifts from being predominantly governed by shear slip to being co-controlled by shear slip and normal displacement, with normal displacement occurring prior to shear slip. (3) For smooth fractures, changes in surface morphology post-activation are negligible, and permeability increases only slightly. In contrast, for rough fractures, surface roughness decreases significantly after activation; however, permeability increases substantially due to the dilation effect. The findings of this research provide a theoretical reference for optimizing injection strategies and warning against fault instability risks in CO2 geological storage.
李 满1，2，罗志雄1，国殿斌3，胡大伟2，4*，杨福见2，4，周 辉2. CO2注入速率及粗糙度对裂隙激活机制影响的试验研究[J]. 岩石力学与工程学报, 2026, 45(4): 1065-1078.
LI Man1, 2, LUO Zhixiong1, GUO Dianbin3, HU Dawei2, 4*, YANG Fujian2, 4, ZHOU Hui2. Effect of CO2 injection rate and roughness on fracture activation mechanism. , 2026, 45(4): 1065-1078.
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2026, Vol. 45 
