Insights of Cleat Attribute of Barakar Coal Deposits of Son Valley Basin, India: Implication for Coal Bed Methane Exploration

Cleat attributes and coal quality have been evaluated through field observation, SEM images analysis and proximate-ultimate analyses on representative coal samples collected from four different underground coal mines of Son-Valley coal Basin of central India for the characterization of coal bed methane prospective. The coal samples were characterized as durainic-clarodurainic-vitrainic type to durocalrainic-clarainic type based on litho-type composition. Cleats were identified as face cleat and butt cleat range 5-10 cm-1 to 2–3 cm-1 depending on the litho-types whereas, cleat density ranges 7-16 cm-2 revealed that cleat development is influenced by litho-types. The cleat orientation shows two main strikes almost NW-SE to NNW-SSE and NE-SW to ENE-WSW elucidates the face cleat and butt cleats are perpendicular to each other. SEM images for coal samples were analysed to validate the cleat geometry at micro-scale, illustrates that face cleat and butt cleats are orthogonal to each other. The technological properties viz. moisture (Wa), volatile matter yield (VMdaf) ash yield (Ad) of coal samples are placed in the range of 0.66–11.80, 32.0–50.05 and 13.23–43.73 wt.% respectively. The fuel ratios of all the samples varied from 1.05–2.35 indicating that coal samples were of sub-bituminous to bituminous rank. The carbon and hydrogen (Cdaf, Hdaf) content of samples ranges from 68.89–86.08 and 5.22–6.60 wt.% respectively. The atomic ratio H/C and O/C through van-Krevelen diagram demonstrate the predominance of type-III/IV kerogens usually derived from terrestrial source in studied coal belongs to the gas genesis window.