中深层井下换热器联合热泵供暖系统性能提高技术途径分析

Performance Analysis, Countermeasures and Suggestions of Integrated Heating System Combined Medium-deep Borehole Heat Exchanger with Heat Pump

目前,我国地热资源出水量少、干孔以及回灌难,市场上缺乏有效的利用手段,深井换热器(DBHE)是利用该种资源的有效方式之一。针对出水量少、干孔以及回灌难的地热资源,为全面了解DBHE,本文通过试验和数学模拟的手段研究其性能,计算了其20年的运行情况,结果表明DBHE的取热性能年均衰减率低于0.5%。分析了岩石的温度分布和热阻,指出了岩石导热系数小是限制DBHE性能提高的主要因素。针对固井水泥、保温管、井身结构和系统运行,给出了优化设计方案和运行建议。同时,在开源方面,提出了采用填充高导热材料进入漏失构造的方案来提高地层的导热系数和输出热功率;在节流方面,充分利用废弃油气井改造为DBHE进行地热开发。

For geothermal resources with less water amount,dry hole and difficult recharge,so far there is no satisfactory method to apply them.Deep borehole heat exchanger(DBHE)is an effective method to utilize this kind of geothermal resources..To get a comprehensive understanding of DBHE,its performance is studied with experiments and mathematical simulating methods,and the simulation results with twenty years’operation show that the annual attenuation rate of heat output is less than 0.5%.The temperature distribution and thermal resistance of surrounding rocks are analyzed,indicating that the main obstacle to performance improvement of DBHE is the poor thermal conductivity of rocks.Some suggestions are given for the optimum design and operation for casing-cement sheath,insulation pipe,well structure and system operation.Furthermore,in the respect of opening up the source,a scheme of filling high conductivity material into leakage formation is proposed in order to improve the thermal conductivity of rocks and heat output of DBHE;in the respect of regulating the flow,the abandoned oil and gas wells should be fully utilized as a kind of geothermal resource developed by DBHE technology.