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Effects of fracture aperture distribution on the performances of the enhanced geothermal system using supercritical CO2 as working fluid

2023; Elsevier BV; Volume: 284; Linguagem: Inglês

10.1016/j.energy.2023.128655

1873-6785

Dejian Zhou, Alexandru Tatomir, Ingrid Tomac, Martin Sauter,

Concrete and Cement Materials Research

Enhanced Geothermal Systems (EGS) technology has the potential to be a significant source of clean, renewable energy worldwide. A promising alternative to water as the working fluid in EGS is the supercritical carbon dioxide (scCO 2 ), which simultaneously contributes to reducing the atmospheric greenhouse gas emissions . The existing thermal-hydraulic coupled numerical models for non-isothermal two-phase flow in fractured porous media overlook the fracture aperture distributions, which significantly affects EGS performance . This study employs a discrete fracture model with a normal distribution of fracture apertures to investigate the EGS energy performance and carbon sequestration ability. The Monte Carlo method is applied to ensure the simulation results reach a statistical equilibrium from multiple realizations . Results show that the aperture distribution significantly affects EGS performances. The cumulative energy output and total sequestered scCO 2 mass can be roughly divided into three stages based on fracture aperture distributions. On the other hand, the effects of aperture distribution become more important as the increase of mean fracture aperture and the reduction of injection pressures . Furthermore, comparing the performances of the EGS using scCO 2 and H 2 O as working fluid, the study found that scCO 2 -EGS performs better with larger injection pressure, but it is more sensitive to aperture distribution. • A two-phase thermal-hydraulic coupled model with discrete fracture network is established. • Normal distribution is applied to describe fracture apertures within discrete fracture network. • Monte Carlo method is applied to statistically analyze the simulation results. • Reservoir abilities on energy output and carbon storage are investigated. • Aperture distribution leads to significant reductions on 30-year reservoir energy output and sequestered CO 2 mass.