Potapchuk I. Substantiation of parameters of the process of plasma expansion of downhole wells

The dissertation is aimed at solving an urgent scientific problem, which is to substantiate the parameters of the process of plasma expansion of downhole wells on the basis of defined patterns of changes in energy consumption, thermogasodynamic parameters of plasma - forming gas and geometric parameters of well and thermophysical parameters of massif, which is essential for mineral extraction. A mathematical model consisting of differential equations of mass conservation, amount of motion and energy and equations of dependence of thermal destruction of rock was developed in work for the first time, in which takes into account the relationship between gas-dynamic parameters of high-temperature coolant and thermostressed state of massif and dependence of physical properties of coolant and rocks from the temperature. The equations of the mathematical model are closed by the corresponding boundary conditions. The system of the differential equations is solved by a numerical method. The method was developed and equipment was created, on which was modeled the processes of heating and thermal destruction of the inner surface of well. A regularity for the temperature gradient on the lateral surface of the well from the thermo-gas-dynamic parameters of the plasma-forming gas and the geometric parameters of the well and the thermophysical properties of the massif has been established for the first time. A rational value of the duration of heat treatment of the inner surface of the well was established for the first time, which corresponds to the minimum energy intensity of the thermal destruction process and is determined by the temperature and thermophysical properties of the plasma-forming gas. When expanding a well with a plasma thermal tool, it was determined for the first time that the location of the maximum temperature on its surface, which corresponds to the coordinate of the beginning of rock destruction, moves away from the cut of the plasmatron nozzle with increasing heating time/ For the first time, the connection between the minimum specific energy consumption for well expansion with the initial temperature and consumption of plasma-forming gas was defined, as well as the final diameter of the well. At the same values of plasma thermal power, the use of an angular plasmatron allows to reduce the peeling time of rock compared to the axial, which, in turn, leads to increased productivity of the rock destruction process and a significant reduction in energy. The results of theoretical and experimental studies are the basis of "Methodological recommendations for the selection and justification of the parameters of the process of plasma expansion of downhole wells" with the economic effect of the introduction in the process of expansion of downhole wells 1617 UAH per well meter.