The effects of fluid flow on the transport properties of faults in Enhanced Geothermal Systems

增强型地热系统（EGSs）的成功运行要求地热流体易于流动。预先存在的断层通常为流体流动提供低渗透率通道。然而，这些断层可能会在地热作业期间重新激活，潜在地导致诱发地震活动。断层运动是否导致诱发地震活动取决于断层的摩擦特性，而摩擦特性受包括断层岩石组成在内的一系列因素的影响。渗透率和摩擦性能都可能受到地热作业中欠饱和溶液流动的影响，这可能导致矿物溶解和沉淀，从而改变（连接的）孔隙度和断层岩石组成。该项目旨在量化不饱和溶液的流动如何影响EGSs典型断层材料的组成和输运特性，以及对摩擦特性的影响，从而诱发地震活动性。采用的方法包括实验工作、微观结构调查和微物理建模。此外，学生可能能够与工业反应传输建模代码的工作。该项目有助于更好地了解EGSs中的活动过程，包括断层摩擦特性和诱发地震活动性。预计将产生关于地热流体在一系列条件下流过时断层岩石组成和渗透率演变的实验数据和模型预测，并确定和量化趋势。这些结果可用于研究EGCs中典型断层岩输运性质的演化以及此类系统中诱发地震活动的风险。该项目与成功的NERC重点主题“英国花岗岩地热发电（GWatt）”项目直接相关，该项目的主要主管是HWU的PI。博士生将学习：设计一个实验方案；进行岩石变形实验；分析数据;进行显微结构分析，使用光学和电子显微镜；制定微观物理模型和可能的数值模型；写科学论文。最后，你可能会有机会在工业合作伙伴那里实习。

Successful operation of Enhanced Geothermal Systems (EGSs) requires easy flow of geothermal fluids. Pre-existing faults often provide low permeability pathways for fluid flow. However, such faults may be reactivated during geothermal operations, potentially leading to induced seismicity. Whether or not fault movement leads to induced seismicity depends on the fault frictional properties, which is affected by a range of factors, including the fault rock composition. Both permeability and frictional properties can be affected by the flow-through of the undersaturated solutions involved in geothermal operations, which can lead to mineral dissolution and precipitation, as such changing the (connected) porosity and the fault rock composition. This project aims to quantify how flow-through of undersaturated solutions affects the composition and transport properties of fault materials typical for EGSs, and what the implications are for the frictional properties and thus induced seismicity. The approach adopted involves experimental work, microstructural investigations and microphysical modelling. In addition, the student may be able to work with an industry reactive transport modelling code.The project contributes to a better understanding of the processes active in EGSs, including fault frictional properties and induced seismicity. It is anticipated to result in experimental data on and model predictions of the evolution of fault rock composition and permeability during flow-through of geothermal fluids under a range of conditions with trends identified and quantified. These results can be used as input for studies addressing the evolution of the transport properties of typical fault rocks found in EGCs and the risk of induced seismicity in such systems. This project is directly linked to the successful NERC highlight Topics "Geothermal Power Generated from UK Granites (GWatt)" project, on which the primary supervisor is PI for HWU. The PhD student will learn to: design an experimental program; perform rock deformation experiments; analyse data; perform microstructural analysis, use optical and electron microscopes; formulate microphysical and potentially numerical models; and write scientific papers. Finally, there may be the possibility for an internship with an industrial partner.