The objective of the work is to substantiate the actualization of the problem of obtaining geothermal energy from oil and gas wells of oil and gas production facilities in the central-eastern part of the Dnieper-Donetsk Depression (DDD). The research methodology is based on the collection and statistical processing geophysical data of the DDD oil and gas deposits, the use of balance equations for energy and substance matter. The main result of the work is that the principal technological scheme of the geothermal system has been developed and the geothermal potential of oil and gas wells in the experimental zone has been analyzed. There have been considered the technological and ecological aspects of geothermal heat usage from depleted deposits of the DDD wells, which were disclosed into Carboniferous deposits productive horizons.

Authors proposed analytical and algorithmic additions to the mathematical model of the prediction of the work of a gas­condensate field in the gas regime. The developed technique of improved calculations of the gas­dynamic parameters was verified by the actual history of a number of real fields in Ukraine. It demonstrated good results by accuracy in the course of medium­term prediction, which is important for estimating the efficiency of the measures for the intensification of well production. The new analytical construction of the systems of equations of the plane­radial inflow of gas to the well bottom and transport of gas by the vertical column allowed us to make the algorithm of iterative calculations more universal. The universality consists, in particular, in the possibility to predict the results of thermobaric changes in the gas flow and changes in the design parameters of a well after technological measures for the intensification of well production. The unique difference is the possibility of rapid evaluation of the prediction of intensification of a well with the interference into both the productive layer and the downhole equipment. Authors emphasized the need for a similar further improvement of the technological­mathematical model taking into account the new technologies of intensification, including innovative technological schemes of constructing the downhole equipment, equipment for the column of wells, wellhead equipment, multi­bottom and multi­row systems of extraction, extraction of gas with injection into the layer of special chemical agents.The certain properties of the adaption correction of parameters made it possible to use the program realization of the developed technological­mathematical model at the Ukrainian­Swedish gas­extraction company TOV “Karpatygaz”.

A review has been conducted of key trends in the development of geometric topology of geothermal heat exchangers. Authors proposed approaches to improving the designs and network structures for heat-transfer media circulation in the bottom-hole space of oil-and-gas reservoirs. Four geometric topologies of geothermal heat exchangers have been analysed: І – ІІ – rectilinear vertical smooth and finned pipelines; ІІІ – IV – a cluster in the form of a set of smooth and finned single-pipe elements, representing a figure of “squirrel wheel” or “meridian sphere” type. It is shown that the most effective technical solution, which ensures the increase in the coefficient of performance (COP) of bore-hole geothermal systems is finning the heat exchanging pipes. For the heat exchangers of І – ІІ type, the calculated increase in COP in comparison with smooth pipes is 40%, and for ІІІ – IV type – 95%. The key parameters influencing the COP of a geothermal heat exchanger are: the radius of fluids draining out during the heat exchange process, the radius of pipelines with circulating heat-transfer medium, the diameter of a cluster heat exchanger, the heat exchange area, the parameters of rocks thermal resistance in the bottom-hole zone of heat-receiving.