Numerical and orthogonal experimental investigation into geothermal reinjection efficiency and the influencing factors of the Minghuazhen reservoir in Luohe Geothermal Field, North China
摘要
Previous studies on the Luohe Geothermal Field focused on resource exploitation and utilization without integrating systematic exploration and assessment, and the technical factors affecting reinjection efficiency were not thoroughly investigated. In this study, core and reinjection tests as well as numerical simulation were used to assess the geothermal reinjection efficiency and its influencing factors in the Luohe Geothermal Field. The division of reservoir–seal pairs was appropriate, and the reservoir had a higher thermal conductivity (2.546 W/mK), specific heat (1.94 MJ/m3·°C), permeability (20.67 mD), and porosity (23.64%) than the seal strata (1.143 W/mK, 1.67 MJ/m3·°C, 3 mD, and 20%, respectively). The tailwater extracted from the reservoir was more efficient as reinjection water than the Quaternary pore water. The reinjection efficiency in the Luohe Geothermal Field was most sensitive to the well spacing (weight: 0.606), followed by the extraction pressure (0.326), and was least sensitive to the reinjection temperature (0.042) and flow rate (0.026). The most appropriate extraction–reinjection parameters included a reinjection flow rate of 20 m3/h, a reinjection temperature of 20 °C°C, a well spacing of 400 m, and an extraction pressure of 1.013 × 105 Pa. The optimization method is applicable to geothermal fields with geological conditions that are similar to those of the Luohe Geothermal Field in north China.