Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2020, Vol. 31 ›› Issue (10): 105 doi: 10.1007/s41365-020-00810-w

• NUCLEAR CHEMISTRY,RADIOCHEMISTRY,RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE • Previous Articles    

3D characterization of porosity and minerals of low permeability uranium-bearing sandstone based on multi-resolution image fusion

Bing Sun 1, Shan-Shan Hou 1, Sheng Zeng 2, Xin Bai 2, Shu-Wen Zhang 2, Jing Zhang 3   

  1. 1School of Civil Engineering, University of South China, Hengyang 421001, China
    2School of Resource Environment and Safety Engineering, University of South China, Hengyang 421001, China
    3School of Resources and Safety Engineering, Central South University, Changsha 410083, China
  • Received:2020-05-13 Revised:2020-09-03 Accepted:2020-09-09
  • Contact: Sheng Zeng E-mail:usczengs@126.com
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (No.11775107) and the Key Projects of Education Department of Hunan Province of China (No. 16A184).
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Bing Sun, Shan-Shan Hou, Sheng Zeng, Xin Bai, Shu-Wen Zhang, Jing Zhang. 3D characterization of porosity and minerals of low permeability uranium-bearing sandstone based on multi-resolution image fusion.Nuclear Science and Techniques, 2020, 31(10): 105     doi: 10.1007/s41365-020-00810-w
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Abstract: In the process of in situ leaching of uranium, the microstructure controls and influences the flow distribution, percolation characteristics, and reaction mechanism of lixivium in the pores of reservoir rocks, and directly affects the leaching of useful components. In this study, the pore throat, pore size distribution, and mineral composition of low-permeability uranium-bearing sandstone were quantitatively analyzed by high pressure mercury injection (HPMI), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and wavelength dispersive X-ray fluorescence (WD-XRF). The distribution characteristics of pores and minerals in the samples were qualitatively analyzed using energy dispersive scanning electron microscopy (EDS-SEM) and multi-resolution CT images. Image registration with the landmarks algorithm provided by FEI Avizo was used to accurately match the CT images with different resolutions. The multi-scale and multi-mineral digital core model of low-permeability uranium-bearing sandstone is reconstructed through pore segmentation and mineral segmentation of fusion core scanning images. The results show that the pore structure of low-permeability uranium-bearing sandstone is complex and has multi-scale and multi-crossing characteristics. The intergranular pores determine the main seepage channel in the pore space, and the secondary pores have poor connectivity with other pores. Pyrite and coffinite are isolated from the connected pores and surrounded by a large number of clay minerals and ankerite cements, which increases the difficulty of uranium leaching. Clays and a large amount of ankerite cement filled in the primary and secondary pores and pore-throats of the low-permeability uranium-bearing sandstone, which significantly reduces the porosity of the movable fluid and results in low overall permeability of the cores. The multi-scale and multi-mineral digital core proposed in this study provides a basis for characterizing macroscopic and microscopic pore-throat structures and mineral distributions of low-permeability uranium-bearing sandstone, and can better understand the seepage characteristics.

Key words: Low permeability uranium-bearing sandstone, Digital core, Micro-CT, SEM-EDS, Image fusion