Improvement of the Technique for Predicting the Temperature Modes of Low-Potential Geothermal Wells

Saint Petersburg Mining University, Saint Petersburg, Russia

^* Corresponding author: yakovlev_pv@pers.spmi.ru

Abstract

The experience of operating geothermal thermal power plants shows that during the first 5 years, their economic performance deteriorates, because there is a change in the temperature field of the soil. It is also important to consider: seasonal cyclical changes in the heat load and possible reversal of the heat flow when switching from heating to air conditioning and vice versa. An option is considered, which, when the coolant fills the well, directly contacting the surface of the casing. During well operation, seasonal or technological changes in well load are taken into account. The well is operating in reverse mode. The conditions for calculation are determined by the alternation of the periods of turning on the heat pump with the cyclical periods of stopping, determined by the season. Research have shown that as a result of longterm operation of a geothermal well in a cyclic mode of thermal loading, there are changes of a temperature field of the rock surrounding a well, with effect of interference of thermal waves, leading to accumulation of heat. Based on the processing of the results obtained criterion equations for calculating the dimensionless temperature of the well at the time of completion of the cycle of heat supply or removal, as the corresponding largest temperature difference heat pump. The received equations allow to specify calculation of technical and economic indicators taking into account duration of geothermal well operation and its mode.