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Development of deep shelf or onshore gas hydrate fields involves drilling wells with subsequent thermal, decompression or chemical action on the bed. In this case, the radius of thermal or decompression action is limited. As the field develops, recovery efficiency decreases, and necessity arises for drilling a new well that influences the cost of the technology. To determine the rational wells location, it is necessary to predict the advance of the phase transformation rate front into the depth of the bed. In this work, to study the movement dynamics of the gas hydrates dissociation front in a porous layer of rock, the Stefan problem solution is used. The method adequacy is substantiated by comparing the calculated results with known experimental data. The temperature fields are modelled in a porous bed during the methane hydrate dissociation. The temperature field dynamics for 200 days in a porous bed during the methane hydrate dissociation caused by thermal action is shown. The influence of porosity and excess temperature on the dissociation front movement rate is revealed.

Gas hydrate is a new clean energy resource with polar molecule. However due to the change of temperature and pressure during extraction process, there will be secondary formation of gas hydrate, which usually occurs in reservoirs or pipelines near the wellhead. It is significance to prevent secondary formation of hydrate because of safety issues or production rate reduction caused by it. Theoretically, microwave heating can accelerate the decomposition of gas hydrate. Therefore, it is possible to use microwave radiation to prevent secondary formation of hydrate. In this paper, a microwave antenna with special shaped coaxial-slots was designed. Based on electromagnetics and antenna transmission theories, the key parameters of the coaxial-slot antenna were calculated. The frequency is 2.45 GHz, the impedance is 50 ohms, and ratio of outer to inner conductor radius is 3.32. The slots were designed as ‘H’-shape with the width is 2 mm, the radial length is 12mm, the axial length is 14 mm and the interval is 35 mm. Teflon was used as filling material and the radome. Then the software HFSS and ANSYS were used to analyze the electromagnetic field and temperature field to further optimize the parameters. It will be proved that the microwave antenna can heat gas hydrate and prevent the secondary formation.

The mechanism of gas hydrates formation in coal seams is studied in the paper, as well as their involvement is hypothesized in the sudden outbursts of coal and gas during underground mining of coal deposits. It has been substantiated and proved that one of the real reasons for subsequent outbursts is the formation of gas hydrates in coal as a type of secondary gas hydrate deposits. It has been also substantiated that, as a result of coal metamorphism, a large amount of gaseous hydrocarbons, mainly methane, is formed in the seam, which under certain thermobaric conditions leads to the gas hydrates formation. It has been experimentally proved that the mechanism of such inclusions formation between gas hydrate and coal is a result of strong chemisorption, which, when disturbing thermobaric conditions, leads to gas-dynamic activity of coal seams. It has been revealed that during the dissociation of gas hydrates, obtained in a medium of activated coals, twice as much gaseous methane is released. The research analysis indicates that the formation of natural gas solid solutions in coal pores under certain thermodynamic conditions and the natural humidity, characteristic of coal seams, is one of the causes of sudden coal and gas outbursts. The gas hydrates dissociation influences on the gas-dynamic activity of a coal seam and the formation of an outburst hazardous situation.

The growth of prices for traditional energy sources prompts Ukraine to seek new approaches to solving energy problems. Today, the country has intensified its work in this direction, in particular, legislative support is being developed and improved, and the investment climate for alternative energy projects is improving. In many countries of the world, it has long been understood how serious and necessary is the development of alternative energy. At present, in the face of various gas contradictions and unstable oil prices, the need for energy carriers is constantly increasing, which makes it necessary to seek the latest solutions to the energy problem. Many leading countries in the world are engaged in the search for alternative sources of energy, one of which is natural gas hydrates. This relatively new resource offers great opportunities both for economic growth and stability of states, and for the development of scientific institutions in this field. Flagships in the study and development of gas-hydrated deposits are the United States, China, Japan and Canada. Along with them should be noted the achievements of scientists in India, EU countries, Ukraine, Russia and Bulgaria.