RAPID: Distributed Temperature Instrumentation for Performance Assessment and Long-Term Implications of an Unconventionally Deep Geothermal Exchange Well

该项目的目标是安装一套全面的光纤（FO）分布式温度传感（ESTA）仪器，以获得短期和长期的测量温度和热流分布在一个非常规的深（~300米）地热地源热泵（GSHP）系统目前正在建设中的威斯康星州。 单个但非常深的交换井的构造提供了优于构造多个但相对浅的常规实践（例如，~50-75 m）热交换威尔斯井，用于住宅/商业加热和冷却应用。 然而，有一些不为人知的问题具有重要的实际和科学影响。 首次对深层地源热泵系统的整个换热路径（600 m）进行了沿着的短期和长期的换热流体温度和热通量测量。 当系统用于满足单户住宅的季节性加热/冷却需求时，将获得热通量分布的长期测量。 短期测量将从一系列“刺激”测试中获得，这些测试旨在研究施加给系统操作变量的扰动（例如，交换流体流速或输入温度）。 这些数据将用于将热通量剖面与地质学和水文地质学中的地下不均匀性联系起来（例如，地下水流动）和天然地热梯度。 结果还将用于地面实况和校准基于有限元的数值模型，以进行长期（例如，20年）的地源热泵效率模拟、生命周期评估，并将项目结果扩展到更一般的地下地质、钻孔几何形状和季节性供暖和制冷应用。 项目成果将具有重要的实际和科学价值。从仪器和建模工作的信息可以用来设计更好的地面回路系统，非常规的深（以及浅）地热热交换系统，量化短期和长期的地源热泵性能，并评估季节性负载不平衡对系统效率的影响。 这些信息还可用于解决有关将地球用作热源/热汇的潜在地球化学影响的基本科学问题，并更有效地校准从深层地下温度测量中收集的气候变化自然记录。 虽然这项研究预计将对地热行业产生广泛的影响，但预计对威斯康星州的地热行业的影响将特别重大。 威斯康星州93%以上的电力燃料是从其他州进口的，地热能源越来越被认为是一种必不可少的能源。 项目活动将通过旨在影响K-12学生，本科生，研究生和执业专业人员的推广和教学活动，在多个教育环境中发挥作用。 活动将与以下方面结合起来：（1）威斯康星大学麦迪逊分校（UW）目前正在进行的能源岩土工程本科生（REU）研究经验计划，（2）通过UW工程专业发展（EPD）计划向实践工程和科学界提供的扩展课程，包括岩土工程系统设计的短期课程，（3）与威斯康星州地热协会的平台会议，（4）在威斯康星大学的大型新生课程讲座，（5）在期刊和会议出版物中传播，以及（6）为威斯康星大学环保署的獾营（TM）的地热会议和实地考察，为对STEM领域感兴趣的中学生举办的知名住校夏令营。

The objective of this project is to install a comprehensive suite of fiber optic (FO) distributed temperature sensing (DTS) instrumentation to obtain short- and long-term measurements of temperature and heat flux profiles in an unconventionally deep (~300 m) geothermal ground source heat pump (GSHP) system currently being constructed in Wisconsin. Construction of a single, but very deep, exchange well offers potential advantages over conventional practice of constructing multiple, but relatively shallow (e.g., ~50-75 m) heat exchange wells for residential/commercial heating and cooling applications. There are, however, a number of poorly understood issues having both important practical and scientific implications. Short- and long-term measurements of exchange fluid temperature and heat flux will be made along the entire (600 m) heat exchange path of a deep GSHP system for the first time. Long-term measurements of the heat flux profile will be obtained while the system is in use to meet seasonal heating/cooling demand of a single-family residence. Short-term measurements will obtained from a series of "stimulation" tests designed to investigate perturbations imposed to the system operating variables (e.g., exchange fluid flow rate or input temperature). These data will be used to link the heat flux profile to subsurface heterogeneities in geology and hydrogeology (e.g., groundwater flow), and the natural geothermal gradient. Results will also be used to ground-truth and calibrate a finite-element based numerical model to conduct long-term (e.g., 20-year) simulations of GSHP efficiency, life-cycle assessment, and to extend the project results for application to more general subsurface geologies, borehole geometries, and seasonal heating and cooling applications. Project results will have significant practical and scientific merit. Information from the instrumentation and modeling effort can be used to design better ground loop systems for unconventionally deep (as well as shallow) geothermal heat exchange systems, to quantify short- and long-term GSHP performance, and to assess the implications of seasonal load imbalance on system efficiency. Information can also be used to address basic scientific questions regarding the potential geochemical ramifications of using the earth as a heat source/sink and to more effectively calibrate natural records of climate change gleaned from deep subsurface temperature measurements. While the study is expected to impact the geothermal industry on a broad scale, the impact to the industry in Wisconsin in particular is expected to be significant. Over 93% of Wisconsin's electrical fuel is imported from other states and geothermal energy is increasingly being considered an essential energy source. Project activities will be leveraged across multiple educational environments through outreach and teaching activities designed to impact K-12 students, undergraduate students, graduate students, and practicing professionals. Activities will be integrated with: (1) a Research Experience for Undergraduates (REU) program on Energy Geotechnics currently ongoing at the University of Wisconsin-Madison (UW), (2) extension courses offered to the practicing engineering and science community through the UW Engineering Professional Development (EPD) program, including a short course on Design of Geothermal Systems, (3) a platform session with the Wisconsin Geothermal Association, (4) lectures in large freshmen-level courses at UW, (5) dissemination in journal and conference publications, and (6) a geothermal session and field tour for UW-EPD's Badger Camp(TM), a renowned in-residence summer camp for middle school students interested in the STEM fields.