Use of a CO2 geological storage system to develop geothermal resources: A case study of a sandstone reservoir in the Songliao basin of northeast China

Abstract

The concept of a carbon dioxide(CO2) plume geothermal (CPG) system, which uses the CO2 geological storage system to develop geothermal resources has been proposed recently. On the basis of the geological structures and geothermal conditions in the Songliao Basin in North East China, a threedimensional model of a sandstone layer with a temperature of 120°C was developed using TOUGHREACT. Numerical simulations for operating both the geothermal system using CO2 only and that using water only were carried out, and the results compared. A number of comprehensive processes including flow (under gravity, buoyancy and injection pressure), and heat transfer have been considered. A cold fluid (20°C) injection well and a hot fluid production well were specified in the geothermal reservoir. The heat extraction rates for CO2 and water as heat transfer medium were analysed and compared. Modeling results indicate that compared to the CPG system, the variation range of temperature of the water system reduces by about 50% during the same simulation period. This phenomenon is caused by the favorable properties of CO2 such as low density and viscosity. The heat extraction rate for CO2 significantly increased by nearly 200% more than water in this sandstone reservoir under the present simulation conditions. Thus, the fundamental understanding and the scientific base for the future CPG development could be provided by this research. © Springer-Verlag Berlin Heidelberg 2013.