NI: DEEPHEAT: Digging deep Earth for heat to promote environmental sustainability

NI：DEEPHEAT：挖掘地球深处的热量以促进环境可持续发展

• 批准号: NE/W004127/1
• 负责人: Junlong Shang
• 金额: $ 9.1万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW004127%2F1
• 关键词: NI; DEEPHEAT; Digging; deep; Earth

Geothermal energy provides an important alternative to fossil fuels, both for heating and for electricity generation. EGS (enhanced geothermal systems) enables the targeting of deep rock formations, at ~2 to 5 km depth for heat extraction. However, few attempts at EGS development have reached the commercial stage. A recent review identifies ~30 EGS sites in granites or other crystalline rocks worldwide, a large proportion of which have failed. One main reason is difficulty in developing EGS without generating unwanted seismicity. In the UK, the unsuccessful Rosemanowes project, in the Carnmenellis granite pluton in west Cornwall, was shut down in the early 1990s, after years of hydraulic fracturing failed to establish any significant inter-well hydraulic connection. This failure killed UK EGS R&D for a generation. Most recently, starting with drilling in 2019, a second project - at the United Downs site - has proceeded in the Carnmenellis granite. However, although the developer has not yet made any official announcement, for months the UK geothermal community 'grapevine' has discussed reasons why this project is in trouble, involving both seismicity and the lack of hydraulic connection between wells. This latest failure, involving the loss of a ~£20 million investment, highlights the need for greater expertise in EGS. Despite the body of research on reservoir stimulation, the general processes that govern the evolution of in-situ stress during reservoir stimulation, and the associated anthropogenic seismicity, still remain poorly understood. For example, how does chemical stimulation change the mechanical state of a fault surface? Will chemical reactions, creating new secondary minerals, alter the frictional properties of a fault in a manner that favours instability? How does the traction on a fault evolve as material is removed by dissolution? How do we manage fluid injection rates and pressures to avoid anthropogenic seismicity? This project aims to create a new multidisciplinary environment and identify key scientific questions that need to be addressed to mitigate risks of failure for future EGS projects. We have assembled a team of enthusiastic early-career and more senior researchers with high international standing and expertise in geoscience, geomechanics, and geophysics, from University of Glasgow (UG) in the UK, University of Wisconsin-Madison (UW) and Lawrence Berkeley National Laboratory (LBNL) in the USA, and Sinopec Research Institute of Petroleum Engineering (SRIPE) in China. Only by working together, can we use our complementary expertise, advanced laboratory facilities, unique field resources and site data to cover multiple scales and aspects that cannot be achieved by individual institutions. We will apply integrated laboratory, modelling and field approaches to develop new scientific understanding of how anthropogenic seismicity caused by geothermal reservoir stimulation can be controlled and eliminated. UW and LBNL will lead the experimental study using their laboratory facilities. The laboratory study will provide data for coupled modeling, which will be led by UG. SRIPE will lead field study and bring in unique resources and data from their Gonghe EGS site (the first and the most important EGS site in China). The field study at the unique Gonghe EGS site will provide vast future collaboration opportunities. We have also designed outreach and partnership activities to facilitate interaction and collaboration between researchers, and to develop long-term sustainable collaborations. These activities include two site visits (to Gonghe EGS site), annual 2-day workshops (in 2022 at UW and in 2023 at UG), 6 online smaller group meetings, and a project website. We expect this project will have significant impact on public and governmental attitudes to EGS in the UK and worldwide by contributing to evidence-based seismicity control and thus to breaking the existing pattern of EGS project failure.

地热能是化石燃料的重要替代品，既可用于取暖，也可用于发电。EGS（增强型地热系统）能够针对深度约2至5公里的深层岩层进行热量提取。然而，很少有开发环境商品和服务的尝试达到商业阶段。最近的一项审查确定了全世界花岗岩或其他结晶岩中的约30个EGS位点，其中大部分已经失败。一个主要原因是很难在不产生不必要的地震活动的情况下开发EGS。在英国，位于康沃尔郡西部Carnmenellis花岗岩岩体的Rosemanowes项目在20世纪90年代初被关闭，此前多年的水力压裂未能建立任何重要的井间水力连接。这次失败使英国EGS的研发工作中断了一代人的时间。最近，从2019年的钻探开始，第二个项目-在联合唐斯现场-在Carnmenellis花岗岩中进行。然而，尽管开发商尚未发表任何官方声明，但几个月来，英国地热社区的“葡萄藤”一直在讨论这个项目陷入困境的原因，包括地震活动和威尔斯之间缺乏水力连接。这一最新的失败，涉及约2000万英镑的投资损失，突出了在环境商品和服务方面需要更多的专业知识。尽管对储层刺激进行了大量研究，但对储层刺激期间控制原地应力演变的一般过程以及相关的人为地震活动仍然知之甚少。例如，化学刺激如何改变断层表面的力学状态？产生新的次生矿物的化学反应会不会改变断层的摩擦特性，使其变得不稳定？断层上的牵引力是如何随着物质被溶解作用移走而演化的？我们如何管理流体注入速率和压力以避免人为地震活动？该项目旨在创建一个新的多学科环境，并确定需要解决的关键科学问题，以减轻未来环境商品和服务项目失败的风险。我们组建了一个由来自英国格拉斯哥大学（UG）、美国威斯康星大学麦迪逊分校（UW）和劳伦斯伯克利国家实验室（LBNL）以及中国石化石油工程研究院（SRIPE）的具有较高国际地位和地球科学、地质力学和地球物理专业知识的年轻和更资深的研究人员组成的团队。只有通过共同努力，我们才能利用互补的专业知识，先进的实验室设施，独特的现场资源和现场数据，覆盖单个机构无法实现的多个规模和方面。我们将应用综合实验室、建模和现场方法，对如何控制和消除地热储层刺激引起的人为地震活动建立新的科学认识。UW和LBNL将使用他们的实验室设施领导实验研究。实验室研究将为耦合建模提供数据，这将由UG领导。SRIPE将领导实地研究，并从他们的共和EGS网站（中国第一个也是最重要的EGS网站）带来独特的资源和数据。在独特的共和EGS现场进行的实地考察将为未来的合作提供广阔的机会。我们还设计了外展和伙伴关系活动，以促进研究人员之间的互动和合作，并发展长期可持续的合作。这些活动包括两次实地考察（共和EGS现场），每年为期2天的研讨会（2022年在UW和2023年在UG），6次在线小组会议和一个项目网站。我们预计，该项目将有显着的影响，公众和政府的EGS在英国和世界各地的态度，有助于以证据为基础的地震活动性控制，从而打破现有的模式EGS项目失败。

项目成果

Stress path constraints on veined rock deformation

脉状岩石变形的应力路径约束

• DOI: 10.1016/j.rockmb.2022.100001
• 发表时间: 2022
• 期刊: Rock Mechanics Bulletin
• 作者: Shang J