美国能源部地热钻井技术研发最新部署及干热岩开发示范创新实践

The latest deployment of the U.S. Department of Energy’s geothermal drilling technology R&D and innovative practices in the demonstration of hot dry rock development

摘要:

与其他主要的可再生能源相比，地热能是唯一能够提供基本负载电力的能源。干热岩是指不含原生水或含少量水的高温深部岩体，可通过水力刺激改造形成增强型地热系统储层，从而提取数量可观的地热能。干热岩型地热资源的开发面临两方面主要技术挑战，一是花岗岩和玄武岩等极坚硬岩石对机械钻速的限制，二是钻井所处地层温度超过随钻测量和旋转导向等工具电子设备的运行温度上限。近年来，美国能源部资助的FORGE计划犹他州项目为测试新的钻头技术和优化钻井作业流程提供了机会，以逐步提升机械钻速并降低钻井成本。本文综述了美国能源部地热技术办公室近年发展规划中对地热钻井技术研发的部署，重点分析了犹他州项目在钻井实践过程中对基于物理限制因素重新设计的工作流程的应用，总结了美国能源部围绕地热钻井技术开展的多次规划编制以及部署实施的相关项目涉及的主要领域，以及犹他州项目在探索和实践钻井作业流程优化方面取得的认识。

Abstract:

Geothermal energy is the only base load power among the major renewable energy sources. Hot dry rock （HDR） is a high temperature rock mass buried in the deep earth without connate water or with a little water， which can form an enhanced geothermal system reservoir through hydraulic stimulation， and a considerable amount of geothermal energy can be extracted. There are two main technological challenges associated with the development of HDR geothermal resource， i.e.， very hard rock， such as granite or basalt limits the rate of penetration （ROP）， and the temperature of the drilling system exceeds the operational limits of electronic tools like measurement while drilling （MWD） and steerable rotary tools. In recent years， the Utah FORGE project funded by the U.S. Department of Energy （DOE） provided an opportunity to test new drill bit technology and optimize drilling procedures to deliver a step change in ROP performance and drilling cost reduction. In this paper， the deployment of geothermal drilling technology R&D in the recent development plan of DOE Geothermal Technology Office is reviewed， the application of the redesign workflows based on physical limits in the drilling practice of the Utah project is selective analyzed， and the main areas covered by the multiple plans and projects funded by DOE in terms of geothermal drilling technology as well as the lessons learned from the Utah project in exploring and practicing drilling operation optimization are summarized.