Challenge: Quantifiying brittle behavior in salt caverns

Change: Monitor integrity via local seismic measurements

Impact: Safe abandonement of salt caverns

Job description
This PhD project is a joint venture between Delft University of Technology and Nobian Industrial Chemicals B.V. Solution mining creates caverns in the subsurface, which may be re-used for pressurized air or H2 storage. The capacity of caverns to provide large-scale storage capacity is foreseen to play a major role in the energy transition.

Caverns should be abandoned such that any long-term effects at the surface are acceptable to all stakeholders. This requires evidence that any effects of mining can be properly monitored. While salt deformation is considered to be mainly governed by plastic deformation processes, (brittle) dilatancy within the rock salt adjacent to the cavern wall may occur under certain circumstances. If this localizes, a leakage path could theoretically emerge: a hydraulic fracture. Microseismic monitoring may be helpful as an early-warning system to avoid hydraulic fracturing. However, this hinges on if we can correlate the microphysical processes with the acoustic signature of salt. It has been shown for other rocks that the seismic signature of acoustic signals can be differentiated into different fracture mechanisms, which hypothetically can be scaled to a field situation. This would allow the comparison of seismic signals from controlled lab conditions with seismic signals from the field. The proposed experiments will enable the following:

• Assess fracturing limits within a known stress field.
• Assess fracture permeability of fractured rock salt and any subsequent healing which may occur.
• Compare between laboratory acoustic emission under a range of conditions and field-measured seismicity.

The results of this PhD will improve our understanding of the risks associated with short and long-term containment of brine and/or gas in salt caverns, during and after the caverns lifetime. You will mainly work in the lab at TU Delft, performing mechanical and flow-through experiments, studying the microstructures and analysing data. Tests will be equipped with an acoustic monitoring system, to listen to the laboratory micro-earthquakes occur during fracture and/or fluid propagation, and you will analyse their seismic signature. Moreover, you will have access to micro-seismic monitoring data from a cavern in Denmark, where a field test on abandonment is planned. You will interpret your data in terms of microphysical processes, and implement and combine with salt cavern assessments to determine whether fracturing is expected to occur. You will have the opportunity to present nationally and internationally to other researchers, industry partners and stakeholders at scientific and industrial meetings. This will culminate in writing open access scientific publications.

You will be part of the Rock Deformation team (@RockDefTUD on X and BlueSky), a dynamic and social core group of ~10 persons. The team has weekly scientific meetings to pick each other’s brains, fuelled by coffee and tea, and several social outings per year. We are part of the Department of Geoscience and Engineering, housed within the Faculty of Civil Engineering and Geosciences (https://www.tudelft.nl/en/ceg/), and there is social and scientific contact with researchers from different disciplines, from Applied Geophysics and Petrophysics to Applied Geology, Geo-Engineering, Resource Engineering and Reservoir Engineering. There is considerable scope for interdisciplinary research, and you will be encouraged to engage with those working on Storage. Several researchers are working on salt cavern mechanics, from an experimental or numerical perspective.

Moreover, this project is embedded within a research project funded by the Solution Mining Research Institute (SMRI), led by Nobian. You will be asked to contribute on reporting of the research effort, including attendance at the SMRI conferences. You will have the opportunity to learn about salt solution mining in the field, and its role in facilitating storage caverns for the energy transition.

Job requirements
You are curious and love expanding your horizon. You have a hands-on attitude with respect to laboratory work, demonstrated by (for example) a love of repairing or building things, enjoyment of practical exercises during studies, etc. Any previous experience with rock deformation work will be a plus. In your contacts with your colleagues and your project partners you put your communication skills to good use. You enjoy mentoring and interacting with students, while growing your own skills and expertise.

You also have:

• An MSc in a relevant subject, preferably Geoscience or Geology, though (Applied) Physics or (Applied) Chemistry with an interest in the more practical Earth Sciences is also possible. Your curriculum should have included Continuum Mechanics and Thermodynamics.
• Good experimental skills. Learning on the job will definitely occur, but a practical mindset to problem-solving is prerequisite.
• Knowledge of Excel, Python and/or Matlab for data analysis.
• Excellent analytical skills.
• A keen interest in interdisciplinary research.
• An excellent command of English, as you’ll be working in an internationally diverse community and with international partners. Knowledge of the Danish language is considered a plus.

TU Delft (Delft University of Technology)
Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context.

At TU Delft we embrace diversity as one of our core values and we actively engage to be a university where you feel at home and can flourish. We value different perspectives and qualities. We believe this makes our work more innovative, the TU Delft community more vibrant and the world more just. Together, we imagine, invent and create solutions using technology to have a positive impact on a global scale. That is why we invite you to apply. Your application will receive fair consideration.

Challenge. Change. Impact!

Faculty of Civil Engineering and Geosciences
The Faculty of Civil Engineering & Geosciences (CEG) is committed to outstanding international research and education in the field of civil engineering, applied earth sciences, traffic and transport, water technology, and delta technology. Our research feeds into our educational programmes and covers societal challenges such as climate change, energy transition, resource availability, urbanisation and clean water. Our research projects are conducted in close cooperation with a wide range of research institutions. CEG is convinced of the importance of open science and supports its scientists in integrating open science in their research practice. The Faculty of CEG comprises 28 research groups in the following seven departments: Materials Mechanics Management & Design, Engineering Structures, Geoscience and Engineering, Geoscience and Remote Sensing, Transport & Planning, Hydraulic Engineering and Water Management.

Click here to go to the website of the Faculty of Civil Engineering & Geosciences.

Conditions of employment
Doctoral candidates will be offered a 4-year period of employment in principle, but in the form of 2 employment contracts. An initial 1,5 year contract with an official go/no go progress assessment within 15 months. Followed by an additional contract for the remaining 2,5 years assuming everything goes well and performance requirements are met.

Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities, increasing from € 2872 per month in the first year to € 3670 in the fourth year. As a PhD candidate you will be enrolled in the TU Delft Graduate School. The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills.

The TU Delft offers a customisable compensation package, discounts on health insurance, and a monthly work costs contribution. Flexible work schedules can be arranged.

For international applicants, TU Delft has the Coming to Delft Service. This service provides information for new international employees to help you prepare the relocation and to settle in the Netherlands. The Coming to Delft Service offers a Dual Career Programme for partners and they organise events to expand your (social) network.

Additional information
For more information about this vacancy, please contact dr. Anne Pluymakers (anne.pluymakers@tudelft.nl) or dr. Auke Barnhoorn (Auke.Barnhoorn@tudelft.nl).

Application procedure
Apply via the application button and upload your the following documents to your application:

1. Motivation letter (1 page).
2. Detailed CV (2 pages).
3. Copies of your BSc and MSc degrees and transcripts.
4. Names and contact information of at least two relevant references.

Please apply no later than 20 January 2025.

After the first selection, video interviews will be held in the period between 27-31 Jan. Ideally, candidates can start in spring 2025.

Doing a PhD at TU Delft requires English proficiency at a certain level to ensure that the candidate is able to communicate and interact well, participate in English-taught Doctoral Education courses, and write scientific articles and a final thesis. For more details please check the Graduate Schools Admission Requirements.

Please note:

• You can apply online. We will not process applications sent by email and/or post.
• A pre-employment screening can be part of the selection procedure.
• For the final candidates, a knowledge security check will be part of the application procedure. For more information on this check, please consult Chapter 8 of the National Knowledge Security Guidelines. We carry out this check on the basis of legitimate interest.
• Please do not contact us for unsolicited services.