Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - ITHERLAB (In-situ thermal rock properties lab)

Teaser

The ITHERLAB project investigates the influence of in-situ (present state in the geological subsurface) pressure and temperature on rock thermal properties (thermal conductivity and thermal diffusivity) as one of the essential thermal properties in the evaluation of the Earth...

Summary

The ITHERLAB project investigates the influence of in-situ (present state in the geological subsurface) pressure and temperature on rock thermal properties (thermal conductivity and thermal diffusivity) as one of the essential thermal properties in the evaluation of the Earth thermal field. The ITHERLAB project will establish mathematic formulations for p/T dependence of both parameters and demonstrate whether micro-structural effects affect these relations for different rock types. For that purpose, an innovative laboratory device will be developed and pilot-tested allowing for dry and saturated rocks measurements of thermal conductivity and thermal diffusivity at pressures and temperatures that are simultaneously raised to values up to 200 MPa and 200°C, respectively. These are the conditions for depths (to approx. 7 km), which are of interest in the use of Earth resources (such as geothermal energy, hydro-carbons, storage of energy or waste). Currently, no laboratory standard procedure exists for this task. Precise knowledge of reliable in-situ thermal rock properties and derived thermal parameters (e.g. heat-flow density) is in-dispensable for understanding the Earth’s subsurface thermal structure and heat budget. Heat mainly drives geody-namic processes (e.g. mantle convection, plate tectonics). Practical implications for the society are arising for exam-ple from the extraction of the Earth’s heat for heating purposes or electricity generation and from the subsurface storage of heat to compensate different seasonal energy demands—techniques that can help to secure and diversify Europe’s energy supply. Moreover, knowledge and methods provided by the ITHERLAB project are paramount for the planning, management and realization of any scientific and industrial subsurface application, which is affected technologically or economically by the subsurface thermal field (temperature and heat budget).

Work performed

A new laboratory prototype apparatus was developed, which included the conceptual development and design of a new autoclave system to measure highly-sensitive thermal rock properties at simultaneously elevated p/T/fluid conditions. This required a detailed planning of hydraulic, pneumatic and electric systems and an extensive investment in associated components (valves, control features, pipes, etc.) The apparatus is capable to provide mantle pressure up to 300 MPa and temperatures up to 300°C, both values 50% higher than initially expected in the project proposal. The autoclave is controlled with a newly coded user interface that is designed for both a manual and an automated operational mode that would allow to control a series of measurement operations fully automatically. A software was developed for the pulse control and the extraction of measured temperature data from the measurement cell.

Rock samples and ceramic reference materials are measured with standard laboratory devices to determine petrophysical, mineralogical, structural and thermal properties. These data are used as validation data for the autoclave measurements at ambient conditions and the post-autoclave analysis of the micro-structural effects. For these initial measurement campaign, typical crustal rocks, as pure quartz sandstone, pure-calcite limestone, basalt and fine-grained granite are sampled and prepared. Beside the rock samples (minimum 5 samples for each rock type), manufactured ceramic standard samples are characterized. Parameters measured are: thermal conductivity and thermal diffusivity (with optical scanning technology and transient divided bar), bulk and matrix density and porosity (Archimedes and He pycnometry), bulk mineralogy (XRD/XRF), and compressional and shear waves (vp, vs) using a mobile ultrasonic sensor. Beside this, thin sections have been prepared and the structure is imaged by µCT (with support by the LIAG institute, Hannover, Germany).
We started to generate new data on rock thermal properties at elevated (in-situ) p/T conditions on the ceramic standards and a variety of different rock types. First measurements of thermal rock properties on ceramic standards and granite has been performed.

Final results

The construction of the innovative lab device was finished and from now on allows to measure thermal rock properties under simultaneously increased pressure, temperature and fluid conditions for crustal depth of 8 to 10 km maximum.

Regarding the enhancement of my career perspectives – i.e. the impact on my scientific career – ITHRLAB brought several opportunities to life. I gave university lectures at the University of Greifswald (winter term 2017/18) and University of Potsdam (since winter term 2018/19), supervised the Master thesis of students from Bologna (Italia), Berlin (TU) and Potsdam (UP) and was the advisor for several undergraduates and student workers.
I am currently writing the final papers for a cumulative habilitation at the University of Potsdam and expect to submit the thesis to the beginning of 2020. I also tightened my research network, including existing collaboration, e.g. with Aarhus University (Denmark), where new projects (GEOTHERM DK) and publications (Fuchs, 2018; Fuchs et al., 2019) has been generated. But this also includes new collaborations, for example, with Uppsala University (C. Juhlin, Sweden), the National Geophysical Research Institute, Hyderabad (L. Ray, India), or Freiberg University (R. Wulf, Germany).
I used the fellowship to professionally extend my presentation and teaching skills attending the one-year Potsdam-Graduate-School-Certificate program: ’Senior Teaching Professionals’ (03.2017-02.2018). This module-based course of 8 days’ duration included didactic training, designing competence-oriented lesson, teaching sessions, subject-specific support and feedback by a mentor; and collegial consultation. I further attended courses of the ‘SQB Certificate program’ (sqb | network for academic quality Brandenburg) but didn’t finished this certificate yet. In terms of leadership skills, I was selected for and attended the Helmholtz Academy program ‘Start leading’; which includes leadership skills, self-management, and the understanding complex organisations (The Helmholtz Management Academy; 10 days, 03.2017-06.2018). I furthermore attended the basic module ‘Management Skills for Research and University’; including proposal Training, financial and legal issues; project management; communication and conflict resolution (Potsdam Graduate School; 9 days).
Visibility through ITHERLAB helped me to get a member of the Geo.X working group Geothermics (since 04.2018), to get a member of the speaker’s committee of the DGG (German Geophysical Society) working group geothermics (since 03.2017) and to become an associated editorial board member for the journal Grundwasser (Springer).

Website & more info

More info: http://www.itherlab.science.