期刊
JOURNAL OF HYDROLOGY
卷 599, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.jhydrol.2021.126377
关键词
Sub-resolution pore; Permeability; X-ray CT image; BF-LBM; K-means clustering; Hidden Markov random field
资金
- National Research Foundation of Korea (NRF) - Korea government (MSIT) [2020R1A2C1014815]
- National Research Foundation of Korea [2020R1A2C1014815] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
The study proposed a method to evaluate local permeability using the hydraulic diameter of unresolved pores in CT images, achieving reliable ternary segmentation with HMRF. Permeability was computed using the BF-LBM method, showing accurate estimation of permeability in porous rocks.
Three-dimensional X-ray computed tomographic (CT) images of specimens often serve as a flow simulation domain for numerical analysis, particularly for permeability estimation, but there exists uncertainty in classifying image pixels into pore or solid structures due to the complex pore geometry and limited resolution of X-ray CT image. This limitation has been tackled by ternary segmentation of CT images into resolved pore, unresolved pore, and solid phases, but it is still challenging to segment each phase and estimate local permeability of unresolved pore. This study proposed the estimation of the hydraulic diameter of each unresolved pore voxel in CT images to evaluate the local permeability by a general porosity-permeability model. Hidden Markov random field (HMRF) was implemented to achieve reliable ternary segmentation of porous rock images with different resolutions by considering the statistical and spatial distribution of CT numbers. Brinkman-force lattice Boltzmann method (BF-LBM) was then used to compute permeability. The results showed that the estimated permeability of Berea sandstone and limestone was analogous to experimentally measured values. The proposed procedure, which does not require experimental characterization of the pore size distribution, can be used to nondestructively estimate the permeability of porous rocks using X-ray CT images while being less sensitive to image resolution.
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