Systematic Pore Characterization of Sub-Bituminous Coal from Sohagpur Coalfield, Central India Using Gas Adsorption Coupled with X-ray Scattering and High-Resolution Imaging

Pore characterization helps to estimate the coalbed methane recovery and carbon storage potential of the reservoir. Earlier research on the characteristics of coal pores has shown that coal has high hydrocarbon storage potential in the adsorbed state, but few studies have shown the influence of chemical heterogeneities and depth on the adsorption potential of the coal. With the objective of studying the effect of chemical variation, depth, and surface roughness on gas adsorption potential, this study combines coal composition analysis and adsorption-based pore characterization of coal and shale samples coupled with high-resolution imaging and X-ray scattering measurements. Variation in pore features is correlated with varying depth and composition. A decrease in the mesopore volume and surface area is observed with an increase in the depth and total organic content and inverse behavior is observed for micropores. Scanning electron microscopy images depict the change in the pore shape from semi-spherical OM pores to elongated pores with depth, and samples with high mineral content show a dominance of inter- and intraparticle pores. Fractal dimension values estimated from SAXS are notably higher than N2-LPGA-derived values (i.e.,─DS > DN) due to the incorporation of inaccessible pores, which reflects an increase of up to 62% in SAXS estimated mesopore volume and surface area. This study will provide a better approach to understand the impact of composition, depth, and surface roughness over the gas storage potential in coal reservoirs.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work publicApplied Geophysics and Petrophysic

Geotechnical and geological investigation of slope stability of a section of road cut debris-slopes along NH-7, Uttarakhand, India

Slope stability is of significant importance for sustainable development in mining, civil-engineering, and urban planning. This paper attempted to assess the stability conditions of road cut debris slopes along the National Highway-7 (NH-7), Uttarakhand, India. The engineering parameters of the slope forming materials and other inputs used for slope stability analysis were evaluated based on different geotechnical tests such as direct shear strength, density analysis test, rock hardness tests, particle size analysis, Atterberg limits, and XRD analysis for the finer fraction of the slope materials. The slope stability was evaluated based on the limit equilibrium method (LEM) and finite-element methods based on strength reduction factor (FEM-SRF). The results showed that the slope materials are mainly comprised of well-graded sands, gravelly sands, with little or no plasticity and display no clay activity along with moderate cohesion (19.4–31.5 ​kPa) and internal friction angle (26.23° to 38.44°). The slope stability conditions based on LEM were consistent with the SRF-FEM and revealed that the slopes with the highest height and dip angle (L4 and L6) are critically stable with a strength reduction factor less than 1. Based on the above results, it is inferred that the slope geometry (overall slope angle and height) has the greatest effect on the stability conditions of the studied slopes rather than the activity of swelling clay minerals. Excavation at the crown part of the slope, installation of retaining and gabion walls along the toe and grass planting on the slope surface are possible stabilization measures to increase the stability of the slopes