Increasing the efficiency of geothermal energy utilization in oil wells

Based on the application of heat balance equations for flow in the hydraulic channels of the riser pipes and the annulus, the coolant temperature was determined for different ratios of working medium flow rates, oil well depths, and standard tubing string sizes. The extreme nature of the dependence of coolant temperature on its flow rate was established. The coolant temperature increases with increasing well depth according to a nonlinear dependence. The use of a riser string with a larger diameter reduces the coolant temperature at the well outlet. The efficiency of heat extraction increases when well backwashing is implemented. Taking into account the results of the conducted research, a pump-circulation system scheme for extracting thermal energy from an oil well is proposed. The pump-circulation system includes a jet pump with hydraulically separated lines for supplying the injected and mixed flows. The additional circulation circuit created by the jet pump increases the flow rate of the working medium during the lifting of the heated coolant. The procedure for determining the operating mode of the jet pump is implemented using an automated algorithm developed in the Python programming language. The speed of lifting the heated coolant increases with an increase in the injection coefficient of the jet pump while maintaining the same speed and flow rate of the working flow entering the well. Concurrently, the duration of heated coolant transportation decreases, as does the amount of heat loss, while the temperature of the coolant exiting the oil well increases. The operating characteristics of a downhole jet pump are limited by its ability to generate the required pressure. The minimum required flow rate of the working flow, the maximum permissible diameter of the working nozzle, and the depth of placement in the well determine the application range of the jet pump.