增强型地热系统研究开发：以美国新墨西哥州芬登山为例

Research and development of enhanced geothermal system: a case of Fenton hill in New Mexico(USA)

增强型(或工程)地热系统是指从地壳深部低孔渗的干热岩体中,采用人工工程方法形成储层,经济地采出具有相当数量的热能.这种早期被称之为干热岩的技术首次在美国新墨西哥州芬登山得到示范.本文以芬登山增强型地热系统为例,通过综述其发展历程,论述了增强型地热系统钻井与储层激发、工质流动与储层测试、储层性能评价等关键问题,总结了从芬登山增强型地热系统研究中获得的认识和启示.芬登山地热项目发展的经验表明,增强型地热储层是通过重新打开本来存在、但被密封的、多重连通的节理组,或通过水力压裂创造新的流动通道和换热面,利用复杂裂隙网络中的流循环,从储层系统中开采热能.芬登山实践表明,在稳态条件下增强型地热系统的持续运行是可能的,芬登山地热项目对世界和我国深层地热发展具有重要指导意义.

Enhanced（or engineered） Geothermal Systems（EGS） is engineered reservoirs that created to extract economical amounts of heat from hot dry rock of low permeability and/or porosity.The hot dry rock（HDR） technology was first demonstrated at Fenton Hill,New Mexico（USA）.This paper reviews the history of the project,discusses key issues of drilling and reservoir stimulation,work fluid flow and reservoir test,and reservoir capability,and then some significant understanding and enlightenment are gained from the EGS project.Experience clearly showed that enhanced geothermal reservoirs can be formed by opening pre-existing,but sealed,multiply-connected joint sets,or creating new fluid pathway and heat exchanging surface by hydraulic fracture,that heat resource is recovered from deeper hot rock though circulating fluids in complex fracture network.The practice at Fenton Hill indicates that sustained operation of HDR systems under steady-state conditions is possible,and that development of EGS is of great economic potential,and Fenton Hill geothermal project has great significance on development of deeper geothermal researches in the world.