Purpose. To determine the general patterns in the formation of the sorption capacity of coal and the natural regional methane content of coal beds using a quantitative indicator – the relative gradient of gas content. Methodology. To determine the sorption capacity of coal, the authors used the well-known “volumetric method” and the method of EPR-spectroscopy (electron paramagnetic resonance). We used the results obtained during geological exploration to analyze the natural gas content of coal beds. The determination of natural gas content was carried out using special gas-core-samplers and formation testers. Methods of mathematical statistics were used to process experimental data. Findings. According to experimental data regarding the sorption methane-bearing capacity and natural gas content of Donbas coal beds, we carried out the analysis, statistical processing, and generalization of the obtained results. A regular change in the relative gradient of coal beds’ methane content has been established for the entire Donbas as a whole. The values of relative gradients for coals of various grades naturally decrease with increasing stratification depth and also naturally decrease in each depth interval from low-metamorphosed (grade D) coal to highly-metamorphosed one. Based on the approximation results, the corresponding equations were obtained for each grade of coal metamorphism from gas to-anthracite (A). Originality. New indicators have been proposed – the relative gradient of sorption methane-bearing capacity and the relative gradient of gas content, which allow comparison of these characteristics measured in absolute values (cm3/g, m3/t) for individual coal beds of different grades of metamorphism, at different depths and lying in different geological conditions. It has been proven that the sorption capacity of coal matter determines the natural regional (background) methane content of coal beds, and naturally, according to a hyperbolic dependence, decreases with increasing stratification depth and also naturally decreases in each of the depth intervals from low-metamorphosed coal (grade D) to highly metamorphosed one (grade A), with a relative gradient that asymptotically approaches to 1 at pressures above 6 MPa. Practical values. The obtained dependences of the relative gradient of gas content on depth and gas pressure for various grades of metamorphism can be used to predict the natural regional (background) gas content of coal beds by determining the maximum sorption capacity and calculating the desired depth or pressure.

A new determination method for coal metamorphism degree

This article discusses processes of rock-mass geothermal and geomechanical energy transfer on the nanolevel and describes different mechanisms of potential energy absorption, distribution and usage by the molecular structure of the coal substance. We show that mechanical and thermal energies in the molecular structure of the coal substance are transformed into quantum-mechanical energy which feeds the structural transformations and generation processes in the substance. At the nanolevel, the energy inflow transforms the atomic-molecular structure, changes the physical and chemical properties of the coal and may cause fluid (including methane) emission. The availability of a general solution for energetic problems of different hierarchical levels is evidence of the possibility of using a fractal approach for researching the energy re-distribution in the system. Розглянуто процеси передачі геотермічної та геомеханічної енергії гірського масиву на нанорівень, а також показано можливі механізми поглинання, поширення і використання виниклого підвищеного енергетичного потенціалу молекулярною структурою вугільної речовини. Встановлено, що в молекулярній структурі вугільної речовини механічна і теплова енергії перетворюються на енергію квантово-механічної природи, що живить структурні трансформації та генераційні процеси в речовині. На нанорівні вступ енергії викликає трансформацію атомно-молекулярної структури, зміни фізико-хімічних властивостей вугілля з можливим виділенням флюїдів, у тому числі метану. Енергії різних ієрархічних рівнів функціонально пов'язані. Наявність загального розв’язання для енергетичних задач різних ієрархічних рівнів свідчить про можливість застосування фрактального підходу до вивчення перерозподілу енергії в системі.

Purpose. To establish the regularities of the influence of magnetic fields on the peculiarities of changing the chemical and structural characteristics of the coal substance according to the size of microparticles enriched with vitrinite. To formulate a new system of views on the mechanisms of structural and functional transformations of coal substance under the influence of weak external fields. Methodology. The authors used an electric furnace heating up to 320 K that creates a pulsation magnetic field with a strength of up to 4,000 A/m to process dispersed samples of hard coal with a weak magnetic field. The methods of infrared spectroscopy and electron paramagnetic resonance were used in the research. Findings. Experimental works were carried out to estimate the impact of weak fields on the state and properties of coal substance. It is shown that weak energy fields, and the electromagnetic one in particular, are able to reduce the energy barriers of reactions in coal substance due to spin-spin interaction, which leads to the activation of processes at the atomic-molecular level and interfacial interaction. Originality.It is experimentallyestablished that for coal micro-particles with sizes from 0.16 to 0.1 m, enriched with vitrinite, the coupling coefficient decreases after exposure to an external magnetic field, and for micro-particles with sizes less than 0.63 m, this indicator increases. Such changes are caused by the redistribution of hydrogen between aromatic and aliphatic components during free-radical reactions. Changes in the spectrum on vitrinite (0.160.10 mm), are more significant than on inertinite (0.063<0.05 mm). At the same time, the external action of the electromagnetic field has caused the opposite consequences. It is shownthat magnetically stimulated chemical reactions occurring in the coal substance are aimed at the recombination of free radicals with active surface states of the organic mass of coal into stable gas molecules. The results of laboratory studies using the methods of electron magnetic resonance and infrared spectroscopy and infrared spectroscopy allow assuming that the changes in structural characteristics recorded during experiments with low-energy impacts can be considered as intermediatorsfor the matter transformation or changes in the state of coal in preparation for structural and functional transformations.For example, to the sorption interaction or destructive processes with methane generation. Practical values.The magnetic field effect can be used to develop new research methods for the study on elementary processes by electron spin resonance; control spin-dependent phase transitions. The use of magnetic resonance methods allows the usage of magnetically field effects in the form of basic tools for the research on structural defects. The results obtained will be a scientific ground for the development of methods for estimating the parameters of electromagnetic processes in coal to develop new technologies for the extraction and processing of hydrocarbon energy carriers.