A geothermal doublet has been installed in a sedimentary reservoir for direct-use heating on the TU Delft campus, targeted to supply around 25 MW of thermal energy at peak conditions. This contribution presents the implementation and initial data collection from the doublet, including an initial evaluation of the logging and coring campaign. Nearly half of Netherlands natural gas consumption is allocated to heating, and the on-campus CO2 emissions from heating exceed 50%. The doublet has been designed with two primary aims of research and commercial heat supply, with the wells being completed in December 2023. The project will be operated by a commercial entity, and built into a larger thermal energy system including a high temperature underground storage system, with the first energy production planned in 2025. The research questions relate to field-scale geothermal operations, e.g. how reliable is the long-term energy production?, how do materials perform in the long-term? and how can geothermal projects be best monitored? The research programme involves the installation of a wide range of instruments alongside an extensive logging and coring program and monitoring network. The doublet has been cored, with substantial continuous samples from the heterogenous reservoir, alongside a large suite of open hole well logs in the reservoir and through casing logs in overlying geological units. A fiber-optic cable will monitor distributed pressure throughout the producer reservoir section, at approximately 2300m depth, which will be installed during commissioning. A local seismic monitoring network has been installed in the surrounding area with the aim of monitoring very low-magnitude natural or induced seismicity. The project is a key national research infrastructure and is being incorporated into the European EPOS (European Plate Observing System, https://www.epos-eu.org/), such that accessibility and data availability will be as wide as possible. All observations will be included in a digital-twin framework that will allow to make better decisions in future geothermal projects.@en

A geothermal well doublet, designed with two primary aims; one of research and the second of commercial thermal energy supply, is currently being installed on the campus of Delft University of Technology, with the wells being drilled in the second half of 2023. The project includes a comprehensive research program, involving the installation of a wide range of instruments alongside an extensive logging and coring program and monitoring network. The doublet has been cored, with continuous samples from the heterogenous reservoir being complimented with more distributed side-wall cores, alongside a large suite of open-hole well logs in the reservoir section of both wells. Such investigation is rarely undertaken in geothermal projects. A fiber optic cable will monitor the production well, and will be installed all-the-way down to the reservoir section when the well completion is installed, at approximately 2300m depth. The reservoir is the fluvial Lower Cretaceous Delft Sandstone that is used as a geothermal reservoir in a series of existing and planned doublets in the West Netherlands Basin. A local seismic monitoring network has been installed in the surrounding area with the aim of monitoring very low-magnitude natural or induced seismicity. A vertical observation well with electromagnetic sensors will be drilled in a few y ears’ time between the injector and producer to monitor cold-front propagation. The total project is targeted to supply around 25 MW of thermal energy at peak conditions, next to this project a thermal energy storage system is planned to provide a seasonal buffer. The project is a key national research infrastructure and is being incorporated into the European infrastructure EPOS (European Plate Observing System, https://www.epos-eu.org/), such that accessibility and data availability will be as wide as possible. All observations will be included in a digital-twin framework that will allow better decisions to be made in future geothermal projects. This paper presents the implementation and initial data collection from the project, including an initial evaluation of the logging and coring campaigns.@en

The TU Delft campus geothermal project has joint objectives of research and commercial thermal energy production. It has been developed and will be operated by the Geothermie Delft (GTD) consortium, a commercial cooperation between TU Delft, Aardyn, EBN and Shell Geothermal. This report gives an overview of the research activities that have been carried out during the implementation of the doublet drilling the wells DEL-GT-01 and DEL-GT-02, and the sidetracks DEL-GT-02-S1 and DEL-GT-02-S2 in the period June - December 2023. The research programme and related operations during the installation of the campus geothermal wells have been led by the scientific team of TU Delft department of Geoscience and Engineering. The project is part of the national research infrastructure for solid Earth science (https://epos-nl.nl/), and offers the possibility to do state of the art research on an operating geothermal system.
The main research activities that were carried out during the implementation of the geothermal wells included rock sampling in the form of a detailed drill cutting sampling set, full cores and sidewall cores of the caprock and the geothermal reservoir, open-hole logging of the reservoir formations and the installation of a fibre optic cable in the producer (still to be carried out).
Overall, the following samples and data were collected as part of the scientific programme:
- 15m of 4”core from the direct caprock of the producer reservoir section
- 71m of 4”core from the reservoir section of the producer
- 78 sidewall cores from the injector reservoir section
- 2400 cutting samples
- 3000m of open-hole and closed-hole logging data
Details of these activities can be found in the report and the related appendices. All data presented in this report have been published via TU Delft institutional data repository and can be found online as part of the data collection associated with the research programme of the project: Geothermal Project on TU Delft Campus Collection at https://doi.org/10.4121/85b3725b-80fa-4b0b-9db2-475bfd8f0265.@en