Evaluation of NaCl and MgCl2 heat exchange fluids in a deep binary geothermal system in a sedimentary halite formation

Abstract Halite formations are attractive geothermal reservoirs due to their high heat conductivity, resulting in higher temperatures than other at similar depths. However, halite highly reactive with undersaturated water. An understanding of the geochemical reactions that occur within halite-saturated formation waters can inform decision making regarding well construction, prevention clogging, dissolution, and thermal short-circuiting. Batch reaction numerical 3-D flow equilibrium transport modeling were used characterize produced NaCl-brine a targeting formation. The potential for inhibition precipitation dissolution using an MgCl 2 -brine NaCl + also investigated. Within injection well, heating from 70 120 °C caused solubility decrease, 0.479 mol kg −1 Conversely, cooling 100 production resulted 0.196 halite. Concurrent anhydrite is expected. Introduction into exchange brine, which has common Cl − ion, decreased by 0.290 formation, as compared NaCl-brine. was altered changes pressure up 0.045 . This indicates designing monitoring composition fluids saline environments important component project design.