Gd2O2S:Tb phosphors with different terbium content are prepared in a reducing atmosphere at various synthesis conditions. The effect of an activator and Na4P2O7 flux concentrations upon photo-and X-ray induced luminescence of the synthesized samples as well as on their acid-base properties and morphology is studied. The addition of Na4P2O7 flux into the charge mixture leads to a significant increase of the phosphor particle size. A positive correlation is found between the particle size and pH value of the phosphor aqueous slurry. The photoluminescence intensity is found to mostly depend on the activator concentration, while X-ray luminescence intensity primarily depends on the particle size and crystal structure perfectness of the phosphor matrix. Charge mixture compositions and synthesis conditions providing Gd2O2S:Tb phosphors with the highest photo-and X-ray luminescence intensity are determined. A Gd2O2S:Tb phosphor with X-ray luminescence intensity exceeding the values for the commercial phosphor KEP-45 of a similar composition is developed. The obtained phosphors can be used for the manufacture of intensifying screens applied in industrial X-ray flaw detection.

Currently, the problem of depletion of easily recoverable oil reserves is urgent. Such a problem can be solved by involving in the development of fields with hard-to-recover reserves, which include high-viscosity oils. For the development of such deposits, thermal enhanced oil recovery methods are used to reduce the viscosity of oil, increase the inflow into producers. Among such methods, the cyclic steam stimulation is fully used the injected heat into the reservoir. One of the main problems of this method is the need to supply steam to the bottom of the well. This problem is relevant, since production with high water cut is formed in a number of fields as a result of cyclic steam stimulation, which indicates steam condensation even in the borehole. The article describes the construction of a physical and mathematical model of the injection of a heat carrier (steam — water) into the reservoir, considering the movement of it along the wellbore, heat loss through the walls of the well and flow modes for the first time. The aim of the work is to determine the influence of technological parameters on the characteristics of the heat carrier in the well, considering the flow modes. The mathematical model developed in the article is based on the laws of conservation of mass, momentum and energy, the friction pressure losses are calculated using empirical formulas for various flow regimes. The distribution of steam quality over the depth of the well, the influence of technological parameters on the wellhead (steam quality, pressure, heat carrier flow rate at the wellhead and thermal conductivity of thermal insulation) on the parameters of the coolant at the bottom of the well (steam condensation depth and heat carrier flow rate at the bottom) are obtained and analyzed. It is shown that with an increase in the thermal conductivity coefficient of thermal insulation, steam condenses higher along the borehole. It is determined that the higher the flow rate of the heat coolant at the wellhead, the deeper the steam penetrates through the well.

Currently, the problem of depletion of easily recoverable oil reserves is urgent. Such a problem can be solved by involving in the development of fields with hard-to-recover reserves, which include high-viscosity oils. For the development of such deposits, thermal enhanced oil recovery methods are used to reduce the viscosity of oil, increase the inflow into producers. Among such methods, the cyclic steam stimulation is fully used the injected heat into the reservoir. One of the main problems of this method is the need to supply steam to the bottom of the well. This problem is relevant, since production with high water cut is formed in a number of fields as a result of cyclic steam stimulation, which indicates steam condensation even in the borehole. The article describes the construction of a physical and mathematical model of the injection of a heat carrier (steam — water) into the reservoir, considering the movement of it along the wellbore, heat loss through the walls of the well and flow modes for the first time. The aim of the work is to determine the influence of technological parameters on the characteristics of the heat carrier in the well, considering the flow modes. The mathematical model developed in the article is based on the laws of conservation of mass, momentum and energy, the friction pressure losses are calculated using empirical formulas for various flow regimes. The distribution of steam quality over the depth of the well, the influence of technological parameters on the wellhead (steam quality, pressure, heat carrier flow rate at the wellhead and thermal conductivity of thermal insulation) on the parameters of the coolant at the bottom of the well (steam condensation depth and heat carrier flow rate at the bottom) are obtained and analyzed. It is shown that with an increase in the thermal conductivity coefficient of thermal insulation, steam condenses higher along the borehole. It is determined that the higher the flow rate of the heat coolant at the wellhead, the deeper the steam penetrates through the well.