干热岩开发及发电技术应用概述

Application of HDR Development and Power Generation Technology

干热岩地热资源通过增强型地热系统(EGS)技术体系实现发电,并可能成为未来战略性替代资源之一。通过分析美、日、法4个EGS项目,总结其科研经验及教训,可以取得以下认识:目标热储基底大多为花岗岩,且分布在火山、高原等地貌附近,复杂的地质构造使得原始地应力和天然裂隙难以预测;干热岩水力压裂的主要机制是岩体剪切破坏;单井钻进和激发后配合井下监测手段定向钻入裂隙系统的效果更好,且长时间的低压循环激发比短时高压激发更有效。干热岩商业化开发中还有一些关键技术有待突破,如资源靶区定位技术、储层改造技术及监测技术等。双工质地热发电技术是目前唯一经济可行的EGS发电方案,可避免因地热流体品质引起的设备安全隐患,但只有国外厂商具备成套设计和制造能力。中国开展干热岩研究不足30年,2012年启动的'干热岩热能开发与综合利用关键技术研究'项目在资源靶区定位、大型水力压裂模拟、压裂液和化学激发剂的研发、热储改造评价体系以及地下热—水—化—力三维模拟系统等方面已取得了实质成果。我国目前尚未完全掌握高温钻井、储层激发和流体循环测试等关键技术,需通过政府支持和统一规划,加强科研经费的稳定投入,加大相关领域人才培养力度。

Hot Dry Rock(HDR)resources,which realize power generation through Enhanced Geothermal System(EGS)technology,may become one of the strategic alternative resources in the future.This paper analyzes the data of 4 EGS projects of the United States,Japan and France,and sums up the experiences and lessons of the scientific research.It is concluded that most of the target thermal reservoir basement is granite and distributed near volcanoes and plateau,and the complex geological structure makes it difficult to predict the original ground stress and natural fractures.The mechanism of hydraulic fracturing of HDR is mainly shear failure.The effect of directional drilling into fracture system by single well drilling and excitation combined with underground monitoring means is verified,and long-time low-pressure cycle excitation is more effective than short-time high-pressure excitation.There are still many bottlenecks,which limit the commercial promotion of HDR,to be broken through,such as resource target location technology,reservoir reconstruction technology and monitoring technology.In terms of EGS power generation,binary geothermal power generation technology is the only economically feasible option,and the potential safety hazard caused by the quality of geothermal fluid can be avoided,but only foreign manufacturers have complete design and manufacturing capability.China has studied on DHR for less than 30 years.The Research on Key Technologies for Develop-ment and Comprehensive Utilization of HDR Thermal Energy initiated in 2012 achieved substantial results in terms of resource target location,large-scale hydraulic fracturing simulation,research and development of fracturing fluid and chemical activator,evaluation system of thermal reservoir reconstruction and underground ther-mal-hydraulic-chemical-mechanical(THCM)three-dimensional simulation system.At present,China has not fully mastered the core technologies such as high temperature drilling,reservoir stimulation and fluid cycle testing,and the stable scientific research funds and the personnel training in relevant fields should be strengthened through governmental support and unified planning.