Simultaneous production and injection of two water-bearing layers in the same well

Abstract

Technical and basic economical analyses regarding simultaneous production and injection of two water-bearing layers by one well are presented in this paper. Calculations were done based on geological, hydro-geological and economical data from the southern part of Poland. To estimate reservoir working parameters, i.e. temperature and pressure distribution, the numerical simulator TOUGH2 was used. To estimate temperature drop because of heat losses to surrounding rocks and because of heat exchange processes connected with system characteristics, a semi-empirical solution was used. The results of the calculations confirm the possibility of utilising the system over a long period of time. The design of a geothermal heating station based on compression heat pumps has been proposed. After heat demand specification for a certain location, two types of geothermal heating stations were considered, with, and without additional heat sources operating during the lowest temperature period of the year. Energy production and consumption based on calculated load factor for those installations were estimated. Then economical analyses were carried out taking into account running and investment costs. Based on the analyses, the prices of the energy produced with different financing scenarios were calculated and compared with other popular energy sources. Even when investment costs increased because of additional heat sources, the real costs of energy production were lower than for the case with heat pumps only. The paper discusses positive environmental effects of geothermal utilisation connected with a reduction of emission impurities to the atmosphere. Taxes connected with emission impurities were taken into account.