On Study of Mineral Scaling of Brine Reinjection Using Thermo-hydro-chemical Coupled Simulation

Abstract

Geothermal energy shows great potential in reducing the environmental impact of power generation and greenhouse gas emissions. However, changes in temperature and pressure during geothermal fluid production can lead to oversaturation of dissolved minerals, leading to mineral precipitation. The Soultz (France) geothermal site is located in the central area of the upper Rhine River, where the salinity of water could be up to 100 g/L. The reinjection of cold water with high salinity could cause minerals precipitation and scale in wellbore and fractures around injection well. Consequently, a significant decline of permeability and injection capacity could occur.Scaling phenomenon is a key problem, which restricts sustainable utilization of geothermal development. It is necessary to evaluate the influence of cold water reinjection from the aspects of water-rock interaction, mineral scaling, pipeline corrosion. In this paper, thermal-hydraulic–chemical coupled fracture-medium simulations were carried out by the non-isothermal multi-phase reactive geochemical transport code TOUGHREACT. According to the simulation scheme and results, reasonable measures are proposed to avoid mineral scaling and improve the heat extracting performance of the reservoir.