Gas generation by coal matter in contemporary conditions

Abstract

A new approach for the study of processes at the atomic-molecular level occurring in the current situation in fossil carbonized organics was proposed. A new phenomenological model of physicochemical transformations in a metastable coal substance with the emission of fluids has been developed. The proposed physic/chemical model is based on the genetic connection of coal methane with fossil organic matter and determines the conditions for the activation of structural transformations in coalmines. This model describes the possible options for the coal/gas system development in the current situation. The accumulation of thermal and mechanical energy by coal in the form of structural stresses in an amount, sufficient to activate free-radical reactions, was experimentally established. In the undisturbed coalrock massif the processes of the coal molecular structure transformation have the relaxation character. The result of relaxation of the accumulated energy in the conditions of a gas-saturated coalrock massif is the methane generation by coal. Gas generation in the process of coalification, in its essence, is the energy response of the system to the action of external geomechanical options (temperature and pressure), by the way of releasing the accumulated additional energy with the emission of gaseous products and the destruction of the solid phase in the organic matter of the coal.

Redistribution and realization of energy at different scale-hierarchical levels of coalrock massif

“…The transfer of energy throughout the structure of the molecule is accompanied by the execution of work (the formation of defects and micro dislocations, generation of methane and the structuring of solid organic matter). Therefore, in coal of the same degree of metamorphism and age after the inversion of the tectonic regime due to the redistribution of the energy of external forces, aromaticity of the coal substance in individual areas, beds, horizons or sites may change [9].…”

“…Obviously, at all hierarchical levels, the type of dislocations significantly affects the conditions of energy accumulation and realization: less energy is accumulated in tensile zones than in compression zones. Relaxation of accumulated energy leads to the separation of low molecular weight compounds by the free-radical mechanism according to the physicochemical model of transformations proposed in [9,[12][13][14]. Therefore, in a fractal geological environment, disturbed by a hierarchical system of raptures of different genesis and sizes, energy redistribution and usage also occurs unevenly, which determines the specificity of permanent accumulation, absorption and displacement of it at all scale levels, from the atomic-molecular to coalrock massif as a whole.…”

“…For example, at the l 3 and k 4 beds of the South Wing of the Main Anticline, all outbursts are recorded in areas of the increased capacity of the contorted patch of coal, but the greater the coal fracture in the bed is, the lower the outburst intensity is. Obviously, the energy accumulated in the molecular structure of the disturbed coal, under certain geological conditions, instantly activates the physico-chemical processes, in the form of chain free-radical reactions, which leads to the grinding of coal and the release of methane [9,[12][13][14].…”