Modeling of sandstone microscopic pore structure and numerical analysis of carbon dioxide seepage paths
Sandstone is a potential rock for CO2 geological sequestration.In order to analyze the flow of CO2 in sandstone and to explore the pore network characteristics of rock at the microscopic scale as the basis for CO2 migration and diffusion,this paper studies two types of sandstone through pore media modeling and numerical analysis of seepage paths.Through the excursion set theory on Gaussian random field,the two-phase rock model with random morphology is generated.Using the mathematical morphology image analysis method,the seepage paths are extracted and the related parameters are analyzed.The results show that the pore network morphology of Mt.Simon sandstone and Berea sandstone is complex,and there are multiple tortuous gas-liquid seepage paths at the microscopic scale.Within a cube with a side length of 600 μm,the seepage path length is 1 341-2 514 μm and 1 302-2 328 μm,the tortuosity is 2.24-4.19 and 2.17-3.88,and the pore throat diameter locates in the range of 2-14 μm and 2-10 μm respectively.The sandstone pore network has good connectivity,and the connected porosity accounts for 81.5％and 76.6％of the total porosity,which can provide a good environment for the diffusion and migration of CO2.This is one of the important reasons why sandstone becomes a potential rock for CO2 underground reservoirs.
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