Paper contribution

Integrated Petrographic and Sorption Analysis of Pore Morphology in Sub-bituminous Coals

Ashutosh Tripathy; Madhurima Mazumder; T.N Singh

Proceedings
EUROCK 2026
Pages
303-308
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

The generation and migration of CBM occur in the nanoscale pore found in coals. Nonetheless, the extreme compactness and multifaceted characteristics of nanopores remain poorly understood in terms of their morphology. In this study, coal samples were collected from Jharia coalfield, India. 2D image analysis, geochemical analysis, and low-pressure N2 adsorption (LPNA) studies were used to examine the morphological parameters of the pore that influence it. According to the petrographic analysis, vitrinite is the dominant group among all macerals in samples (mean 62%), with a notable proportion of liptinite (24%) maceral group, whereas the concentration of inertinite group is the lowest (12.5%). Values of Vitrinite reflectance range from 0.54% to 0.61%, whereas ash content varies between 45.9 and 55.1%, volatile matter ranges from 31.1 to 37.1%, and moisture content varies from 7.1 to 9.2%, indicating that Jharia coal is of sub- bituminous ’B’ rank. The primary pore types identified by the microphotographic image observation are the interparticle pores, the intraparticle pores, and the microcracks. Volume of pore ranges from 0.000277 to 0.029754 cm3 /g, whereas values of SSA range between and m2/g. From rock-eval pyrolysis result, value of the HI ranges from 201 to 209 mg HC/g TOC, whereas the Tmax ranges from 423 to 429. HI vs. Tmax data indicates that samples are thermally mature and type II kerogen in nature. TOC varies from 63.59% to 66.8% wt%. From a rock mechanical standpoint, the heterogeneity in pore morphology and maceral composition indicates variable stress sensitivity and deformation behavior under in-situ conditions. From the above results, it can be shown that total organic carbon is positively and negatively related with pore parameters, indicating that TOC has the greatest influence on pore characteristics and suggesting a significant hydrocarbon potential. Our results strengthen the experimental basis for understanding coal nanopore structure.

Contributors

Authors

  1. Ashutosh Tripathy Indian Institute of Technology (Indian School of Mines), India ORCID 0000-0001-7253-2960
  2. Madhurima Mazumder Indian Institute of Technology (Indian School of Mines), India ORCID 0009-0005-6020-3656
  3. T.N Singh Indian Institute of Technology, Patna ORCID 0009-0005-7159-631X

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