Multiscale pore/throat characterization in tight sandstone formation with multi-threshold image segmentation algorithm
IntroductionPore space in tight sandstone formation is very complex with micro-scale and nano-scale pores/throats, the multi-scale characteristics needs to be considered for the construction of microscopic pore model accurately.MethodsIn this paper, micro-CT is used to obtain the representative 3D m...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2025-05-01
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| Series: | Frontiers in Earth Science |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2025.1576484/full |
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| Summary: | IntroductionPore space in tight sandstone formation is very complex with micro-scale and nano-scale pores/throats, the multi-scale characteristics needs to be considered for the construction of microscopic pore model accurately.MethodsIn this paper, micro-CT is used to obtain the representative 3D micro-scale gray image, and nano-CT is used to obtain the representative 3D nano-scale gray image based on the representative nano subsample. Then, the multi-threshold image segmentation algorithm is introduced to segment the micro-scale and nano-scale gray image respectively. Three distinct phases are identified in microscale images: (1) micro pore/throat phase, (2) micro-particle phase, and (3) a transitional matrix phase exhibiting intermediate grayscale values. This matrix phase represents unresolved nano-porosity and nano-particles beyond micro-CT resolution limits. Conversely, nanoscale images reveals two discrete phases: well-defined nanopore/throat phase and nano-particle phase. The micro-pore/throat and nano-pore/throat digital rocks are constructed respectively, and the corresponding pore network model in tight sandstone are extracted, the porosity and pore/throat size distribution at micro scale and nano scale is calculated respectively.Results and discussionMoreover, the nano pore/throat characteristics in nano-pore/throat digital rock is upscaled into the matrix phase of micro-pore/throat digital rock, which could calculate the total porosity and multiscale pore/throat size distribution in tight sandstone formation accurately. The digital rock analysis results are verified correctly with the comparison of the lab test results, which provides a fundamental platform for multiscale pore/throat characterization and formation evaluation in tight sandstone formation with important academic and application value. |
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| ISSN: | 2296-6463 |