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Advanced characterization of pores and fractures in coals by nuclear magnetic resonance and X-ray computed tomography

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Abstract

This paper demonstrates capabilities of low-field nuclear magnetic resonance (NMR) and microfocus X-ray computed tomography (μCT) in advanced, nondestructive, and quantitative characterization of pore types, producible porosity, pore structure, and spatial disposition of pore-fractures in coals. Results show that the NMR transverse relaxation time (T 2) at 0.5–2.5, 20—50, and >100 ms correspond to pores of <0.1 μm, >0.1 μm, and fractures, respectively. A much higher T 2 spectrum peak reflects a much better development of pores (or fractures) corresponding to the T 2, and vice versa. Three basic components in coals, i.e., the pores (or fractures), coal matrix, and minerals have their distinctive range of CT numbers. Among these, the CT number of pores is commonly less than 600 HU. The producible porosity, which is a determination of permeability, can be calculated by T 2 cutoff value (T 2C) of coal NMR. The coal pore structure can be efficiently estimated by the newly proposed “T 2C based model”. Finally, μCT scan was proven capable of modeling and spatial visualization of pores and fractures.

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Authors and Affiliations

  1. School of Energy Resources, China University of Geosciences, Beijing, 100083, China

    YanBin Yao, DaMeng Liu, YiDong Cai & JunQian Li

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  1. YanBin Yao
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  2. DaMeng Liu
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  3. YiDong Cai
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  4. JunQian Li
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Correspondence to YanBin Yao.

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Yao, Y., Liu, D., Cai, Y. et al. Advanced characterization of pores and fractures in coals by nuclear magnetic resonance and X-ray computed tomography. Sci. China Earth Sci. 53, 854–862 (2010). https://doi.org/10.1007/s11430-010-0057-4

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  • DOI: https://doi.org/10.1007/s11430-010-0057-4

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