Structural controls on geothermal systems in the Northern Volcanic Zone, Iceland

世界必然朝着寻找更清洁、更可持续的能源的方向发展，以确保减少碳排放，同时满足世界的能源需求。作为全球可用的清洁能源形式，地热将在这一进程中发挥越来越重要的作用，冰岛等火山活跃地区地热系统的高能量输出将发挥关键作用。因此，至关重要的是要确保未来的地热勘探既能最大限度地发挥地热潜力，又能确保底层地热系统的可持续性。地下结构，从大规模边界断层到分布式裂缝网络，可以作为火山驱动地热系统内热量和流体分布的边界和限制（例如，Eugenio等人，2020年）。裂缝网络，作为流体流动的管道或屏障，是为流体提取和补给提供可持续路线的关键（例如，Perez-Flore等人，2016）。对这些限制的理解不足可能导致过度开采和地热系统寿命的缩短，并影响周围环境（例如，Bromley等人，2013年）。因此，了解这些结构的机制以及它们如何限制或充当流体流动的管道，对于确定地热系统的可用范围以及评估流体提取和未来应力环境变化对结构和地下地热环境的长期可持续性和可用性的可能影响都是关键的。该项目主要关注Theistareykir地热系统，将利用Landsvirkjun在Krafla和Theistareykir地热能生产期间获得的大量数据，比较和对比这两个火山驱动地热系统的结构控制。该项目将建立在大量研究的基础上，这些研究利用了来自两个地点的更多范围的地质和地球物理数据和方法，例如，地表断层测绘、地球化学分析、微地震测绘、断裂网络模型、地震剖面（例如Hjartardottir等人，2014年，Khodayar等人，2018年，Scott等人，2019年，Millet等人，2020年）和地热系统的概念模型（见图2）（例如，Mortensen等人，2009年，Saby等人，2020年）。该项目将着眼于了解结构，从较大的边界断层到分布式裂缝网络，如何控制地热系统中的流体和热流。它将研究断层结构如何作为地热系统的边界的力学，调查这些可能会如何改变断层复活以及这些变化对地热系统的边界条件和约束的影响。此外，该项目可能有机会纳入Theistareykir地热田南部新钻地热威尔斯井的数据，目前计划在项目期间开始

The world moves necessarily towards finding cleaner, more sustainable energy sources to ensure reductions in carbon emissions whilst looking to provide for the world's energy needs. As a globally available form of clean energy, geothermal will have an ever more important part in this process, with the high-energy outputs of geothermal systems in volcanically active areas such as Iceland playing a key role. As such, it is crucial to ensure that future geothermal site exploration both maximises geothermal potential and ensures sustainability of the underlying geothermal system. Subsurface structures, from large-scale bounding faults through to distributed networks of fractures, can act as boundaries and limits to the distribution of heat and fluids within volcanically driven geothermal systems (e.g., Eugenio et al., 2020). Fracture networks, acting as either conduits or barriers to fluid flow, are key for providing sustainable routes for fluid extraction and recharge (e.g., Perez-Flore et al., 2016). Poor understanding of the constraints these provide can lead to over-exploitation and a reduction in the longevity of the geothermal system and impact the surrounding environment (e.g., Bromley et al., 2013). As such, understanding the mechanisms of these structures and how they limit or act as conduits to fluid flow is key for both determining the useable extent of the geothermal system and for assessing the likely impact of fluid extraction and future changes to stress environments on both the structures and the long-term sustainability and usability of the subsurface geothermal environment. With primary focus on the Theistareykir geothermal system, this project will use the wealth of data acquired by Landsvirkjun during geothermal energy production at both Krafla and Theistareykir sites, to compare and contrast structural controls of these two volcanically driven geothermal systems. The project will build upon the numerous studies that make use of an additional range of geological and geophysical data and methods from across the two sites, for example, surface fault mapping, geochemical analysis, micro-seismic mapping, fracture network models, seismic profiling (e.g. Hjartardottir et al., 2014, Khodayar et al., 2018, Scott et al., 2019, Millet et al., 2020) and conceptual models of the geothermal systems (see figure 2) (e.g., Mortensen et al., 2009, Saby et al., 2020). This project will look to understand how structures, from larger bounding faults through to distributed fracture networks, work as controls on fluid and heat flow in the geothermal system. It will look to examine the mechanics of how fault structures act as boundaries for a geothermal system, investigating how these might change following fault reactivation and the impact of these changes to the boundary conditions and constraints of the geothermal system. Additionally, the project may have the opportunity to incorporate data from newly drilled geothermal wells in the south of the Theistareykir geothermal fields, currently planned to start within the duration of the project