Response Process and Mechanism of Sandstone Geothermal Reservoir Temperature to Reinjection Parameters
The evolution of geo-temperature within the geothermal reservoir induced by reinjection of geothermal cooled water is of great importance for the sustainable utilization of geothermal resources. This study focuses on examining the quantitative relationship between reinjection parameters and the thermal breakthrough time of production wells. A simulation test using a large sand tank combined with numerical simulation methods was conducted. Permeation tests,tracer tests,and reinjection tests were performed in the simulation test model. Additionally,sensitivity analysis and nonlinear fitting were carried out to discuss the impact of fluid viscosity and density on reinjection results,as well as the degree of influence of reinjection parameters on the thermal breakthrough time of production wells and its underlying mechanisms and principles. The results show that the migration speed of reinjection water is different in sand reservoirs with different permeability,and the thermal breakthrough time t is linearly correlated with Q-0.85,ΔT-0.21,and R1.4. The correlation equation and analysis show that when the temperature difference between production and reinjection ΔT is more than 30 ℃,the influence of ΔT on the thermal breakthrough time of production well becomes weak,because ΔT exerts an effect on the thermal breakthrough time of production well t by influencing the relative position of the 18.5 ℃ isotherm in the temperature transition region,and the error for reinjection from high temperature fluid to low temperature fluid can be corrected by introducing the viscosity correction coefficient αμ.
reinjection parameterssimulation testnumerical simulationgeo-temperaturemechanism of evolutiongeothermal energygeothermal wells
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