Experiment on nano-SiO2 enhancing sealing capacity of shale caprocks for CO2 geological storage
Shale is a common type of caprock for geological storage of CO2 in brine aquifers,and the enhancement of the ca-prock sealing capacity is beneficial to improve the storage safety.In this study,in order to investigate the effectiveness and feasibility to enhance the sealing capacity with mixed injection of CO2 and nano-SiO2(SNPs),three reaction experiments of shale caprock samples and supercritical CO2 were conducted under reservoir conditions,including the basic experiment group for reactions between shale sample and formation water,the control experiment group for reactions among shale sample,for-mation water and supercritical CO2,and the optimization group for reactions among shale sample,formation water,SNPs,and supercritical CO2.The pore structure,surface morphology,mineral composition and mechanical properties of shale sam-ples before and after the three reaction experiments were evaluated using NMR,field emission scanning electron microscope visual observation,X-ray diffraction and rock mechanics testing techniques.The results show that the increasements of macro pore components,porosity and permeability in the optimization group were lower than those in the control group after the re-action experiments.Compared with the control group,the relative content loss of clay and carbonate minerals in the optimiza-tion group was also less,indicating that CO2 mixed with SNPs can weaken the internal acid erosion of rock samples.SNPs can be adsorbed and accumulated on the end face of the pores and enter the pore throats,which can lessen mechanical and chemical damage of shale samples,demonstrating that SNPs mixed with CO2 can be beneficial for enhancing the caprock̍s sealing capacity for CO2 geological storage in brine aquifers.
CO2 geological storagenano-SiO2supercritical CO2caprock sealing capacity
李颖、李茂茂、李海涛、周军平、LEONHARD Ganzer、罗红文、康夫馨
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西南石油大学油气藏地质及开发工程国家重点实验室,四川成都 610500
重庆大学资源与安全学院,重庆 400030
Institute of Subsurface Energy Systems, Clausthal University of Technology, Agricolastraße 10, Clausthal-Zellerfeld 38678
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