一注超临界CO2开采高温废弃气藏地热机制与采热能力分析

摘要

The potential for heat mining from depleted high temperature gas reservoirs is very high. In this study, geothermal energy exploitation from depleted gas reservoirs via injection of supercritical CO2 was proposed and investigated using heat transfer and numerical reservoir simulation methods. The heat mining capacity of supercritical CO2 was calculated and its re-lated influence factors were analyzed. The simulation results show that the heat mining capacity of supercritical CO2 can be 50% higher than that of water due to superior mobility of CO2 and good thermophysical properties at high pressure and tem-perature conditions. Geothermal exploitation via CO2 injection can not only produce geothermal energy, but also can achieve the goal of CO2 geological storage. Geothermal development from depleted gas reservoirs can significantly reduce its initial capital investment via using the existing wells and surface facilities, and it can prolong the gas reservoir's economic life.%高温废弃气藏具有巨大的地热开采潜力。在对比分析超临界CO2和常规携热介质水的热物性基础上，提出注超临界CO2开采高温废弃气藏地热的方法。利用数值模拟方法对CO2在高温废弃气藏中的采热能力及影响因素进行评估。结果表明，由于CO2具有很高的可注性和流动性，超临界CO2的采热速率可达到水的1.5倍；利用CO2循环开采高温气藏地热，不仅可以实现高效地热开发，还可以实现CO2地质埋存；对废弃气藏而言，可以充分利用现有井网和地面设施，减少初期资本投入，实现高温废弃气藏地热的有效和经济开发，进一步提高气藏的利用价值，延长其经济寿命。