Numerical Study on CO₂-Brine-Rock Interaction of Enhanced Geothermal Systems with CO₂ as Heat Transmission Fluid

Key Laboratory of Groundwater Resources and Environment/ Inisitute of Water Resources and Environment, Jilin University, Changchun, Jilin 130026, China

^a wanyuyu@jlu.edu.cn
^b tuianfu_xu@jlu.edu.cn
^c 1525758864@qq.com

Abstract

Enhanced Geothermal Systems (EGS) with CO₂ instead of water as heat transmission fluid is an attractive concept for both geothermal resources development and CO₂ geological sequestration. Previous studies show that CO₂ has lots of favorable properties as heat transmission fluid and also can offer geologic storage of CO₂ as an ancillary benefit. However, after CO₂ injection into geological formations, chemical reaction between brine and rock can change chemical characteristics of saline and properties of rock such as porosity and permeability. Is this advantage or disadvantage for EGS operating? To answer this question, we have performed chemically reactive transport modeling to investigate fluid-rock interactions and CO₂ mineral carbonation of Enhanced Geothermal Systems (EGS) site at Desert Peak (Nevada) operated with CO₂. The simulation results show that (1) injection CO₂ can create a core zone fulfilled with CO₂ as main working domain for EGS, and (2) CO₂ storage can induced self-enhancing alteration of EGS.