The research is aimed to study the process of change in temperature mode dynamics for the Earth subsurface layer when heat is extracted with geothermal heat pump systems, reveal and disclose specifics of effect on the ecology caused by technologies using geothermal resources and give practical recommendations regarding further development of methods for designing heat pumps using low potential heat energy of soil based on the long-term forecast and efficacy assessment. Mathematical statistics and mathematical model methods were applied for assessment of economic and environmental effects. Methods based on principles of the theory of thermal conductivity, hydromechanics, theory of differential equations and mathematical analysis were applied for calculation of proposed systems and review of field observation findings. The authors had developed for research purposes an experimental geothermal heat pump system consisting of four structurally connected geothermal wells, each with installed U-shaped twin collectors of 200 m overall length, and a heat pump of 14 kW capacity with a heat energy battery for 300 L connected to the building heat-supply system. They also created a computer data archivation and visualisation system and devised a research procedure. The paper provides assessment of the effect caused by changes in the process operation mode of the heat pump system on the soil temperature near the geothermal well. As a result, the authors have found that the higher the intensity of heat energy extraction, the lower the soil temperature near the geothermal heat exchanger, in proportion to the load on the system. Moreover, it has been determined by experimental means that at critical loads on the geothermal heat exchanger the soil temperature is unable to keep up with regeneration and may reach negative values. The research also determined relation between inservice time and season of the system operation and temperature fluctuations of geothermal field. For example, it has been found by experimental means that the heat flow from the well is spread radially, from the well axis to its borders. Additionally, it has been proved that depending on the heat load value, the bed temperature is changed after the time of the first launch. For example, the geothermal field temperature has changed from the time of the first launch during 1-year operation by 0.5 °С in average. The research has proved that depending on the heat load value, under seasonal operation (heating only or cooling only) of the system, the soil temperature has decreased for five years by 2.5 °С and switched to quasi-steady state, meanwhile, stabilisation of the geothermal field in the state under 1-year operation (heating and cooling) occurred yet in the 2nd year of operation. In conclusion, the paper reasonably states that geothermal heat pump systems using vertical heat exchangers installed into the wells put no significant human-induced load on the environment. At the same time, still relevant are issues of scientific approach to development of the required configuration of the geothermal collector, methodology for its optimal placement and determination of efficacy depending on operation conditions.

In the bowels of the Earth and in the oceans of the World Ocean, there are practically unlimited resources of natural gas in the solid hydrate state, available to most countries of the world community. The development of gas hydrate deposits is based on the process of dissociation (separation), in which the gas hydrates break down into gas and water. In these technologies, three methods for the development of gas hydrate deposits are proposed: pressure reduction, heating and inhibitor input. Based on the systematized data, the above methods are suggested to be attributed to traditional methods, as the most studied and classical ones. It is proposed to identify a number of methods that imply the same results, but use other physical approaches and designate them as unconventional. 1. Decomposition of methane hydrates by nanoparticles. In this method, the use of nanoparticles commensurate with the gas hydrate cell (supplied as part of a hydrodynamic jet) is proposed for efficient and safe destruction of the gas hydrate. The application of nanotechnology provides effective and consistent study of the entire surface of the aquatic deposit of gas hydrates, with the necessary rate of their destruction and the production of planned volumes of methane. 2. Decomposition of methane hydrates by microorganisms (bacteria). In this process, in the process of the life of the bacteria, a gas must be released, replacing in the clathrate structure a molecule of methane per molecule of the given gas. In addition, the process must be controlled by the use of external factors that provide nutrition to the bacteria and at the same time, light, chemicals, electromagnetic radiation, etc. can be stopped at any time, which is absent in the natural conditions of formation of the gas hydrate.

The literature sources dealing with the history of gas hydrate studies and discovery of possible existence of gas hydrate deposits in natural conditions were analyzed. They contain facts proving that within 1966 and 1969 the conditions for formation of hydrates in porous medium were researched at the Department of Gas and Gas Condensate Deposits Development and Exploitation of Gubkin Russian State University of Oil and Gas. The first experiments were set up by the Ukraine-born Yurij F. Makogon, Department Assistant Professor. The results proved possibility of formation and stable existence of gas hydrates in earth’s crust and became a scientific substantiation of natural gas hydrate deposits discovery. In 1969 the exploitation of Messoyakha deposits in Siberia started and it was the first time when the natural gas was derived directly from hydrates. The same year that invention was officially recognized and registered. Following the comprehensive international expert examination the State Committee on Inventions and Findings of the USSR Council of Ministers assumed that the citizens of the USSR Yurij F. Makogon, Andrej A. Trofimuk, Nikolaj V. Cherskij and Viktor G. Vasilev made a discovery described as follows: “Experiments proved previously unknown ability of natural gas to form deposits in the earth’s crust in solid gas hydrate state under definite thermodynamic conditions (Request dated March 19, 1969)”. The authors were presented with diplomas on March 4, 1971. From then onwards the issue of natural gas hydrates existence was widely researched all around the world. In 1985 Yurij F. Makogon became a Professor. Since 1973 he was a head of the gas hydrate laboratory in the All-Russian Scientific Research Institute of Natural Gases and Gas Technologies. Within 1974–1987 he was a head of the gas hydrate laboratory in Oil and Gas Research Institute RAS. In 1992 he was invited by one of the largest universities of the USA to arrange modern laboratory for gas hydrate study. The laboratory was created in the Texas University, USA and in 1995 Yurij Makogon became its head. As far as interest in gas hydrates increases Yurij F. Makogon reports at 27 international congresses and conferences, gives lectures in 45 world leading universities, functions as an academic adviser and participates in different international programs on research and exploitation of gas hydrate deposits in USA, Japan and India. The heritage of the scientist includes 27 patents, eight monographs (four of them were translated and published in the USA and Canada) and more than 270 scientific articles.

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