热储上下岩层热补偿作用对CO_2羽流地热系统性能的影响

Influence of thermal compensation of geothermal reservoir rock formation on CO_2 plume geothermal system performance

二氧化碳羽流地热系统(CPGS)能够在直接开采地热的同时实现CO_2的地质封存,热储上侧和下侧岩层的热补偿作用是影响CPGS性能的重要因素。建立了三维盖岩-热储-基岩整体模型,研究了热补偿作用对CPGS采热性能及热储内岩石和流体温度演化过程的影响,为优化CPGS设计、提升CPGS的系统经济性和工程应用提供了理论参考。研究结果表明:热补偿作用减小了生产流体在竖直方向上的温度差异及系统运行后期生产流体温度下降的速率,有效延长系统运行寿命,使系统获得更好的采热性能和更稳定的产能输出;考虑热补偿时系统总热开采量明显提高;与盖岩相比,基岩的热补偿作用更强。

Carbon dioxide plume geothermal system（CPGS） can be used to exploit geothermal energy and realize carbon dioxide geological sequestration simultaneously. The thermal compensation from the rock formation around the geothermal reservoir is one of the important factors that affect the performance of CPGS. Based on a three dimensional base and cap rocks enclosed heat reservoir model, the influences of the thermal compensation on the temperature evolutionary process of the rock and fluid in the geothermal reservoir and the heat collection performance of CPGS were studied. The distribution of geothermal reservoir temperature and the temperature of production fluid were compared with that without consideration of the thermal compensation. The results show that the thermal compensation reduces both the production fluid temperature variation along the vertical direction and its temperature decreasing rate in the later period of system operation, therefore extends the lifetime of CPGS and gains better heat collection performance. With consideration of the thermal compensation, the heat production is improved significantly. The results also show that the thermal compensation of the base rocks is stronger than that of the cap rocks.