Field, laboratory and modelling constraints on fluid transport in fractured mudrocks with a focus on chemical self-healing

One of the requirements for a Geological Disposal Facility (GDF) for higher-activity radioactive waste is that it needs to contain radionuclides away from the surface environment whilst they are still harmful, which for some radionuclides can be up to tens of thousands of years. The containment function provided by the geology is affected by the presence of fault-fracture systems, which can create pathways for the migration of radionuclides carried by gas and water. The Mercia Mudrock Group (MMG) is currently being considered as a potential host rock, and fault-fracture systems therein are potential conduits for fluid flow. Prediction of radionuclide migration in such geologies is challenged by the complex architecture of fault-fracture systems and mechanical stratigraphy of the interbedded mudrock and evaporites of the MMG, together with the inherent challenges of modelling complex multi-scalar transport phenomena in geological media. Demonstrating an understanding of the fracture hosted (single and two phase) fluid flow and solute transport process will be integral to such assessments. To deliver confidence to stakeholders in a safety case, prior rehearsal and understanding of tools, processes and validation approaches involved with numerical representation of fault-fracture systems in the MMG, including the forward prediction of radionuclide mobility therein is required. This PhD project will help to reduce uncertainty in the characterisation of fault-fracture systems and fluid flow in the MMG.

This broad scope of this research involves the observational description of MMG fault-fracture systems from outcrops and cores including assessing the mechanical-stratigraphic controls on fracture network geometries, the measurement of single (and multi-phase) flow in fractures as a function of rock-fracture properties, effective stress, and fracture / stress field orientations as well as the measurement of adsorbing solute and fluid specific transport processes.

All this information needs to be integrated in model frameworks focusing on flow and transport in fractures or the exchange between fractures and matrix. Given the need for models to describe flow at various length-scales, including regional scales, detailed numerical upscaling workflows are required to derive constitutive relationships and effective properties for radionuclide and gas transport at decametre scales. This specifically requires a strong interplay between observations done in outcrops (fracture network and statistics thereof, understanding of fracture mineralisation versus stress directions etc) and the development of coupled hydro-chemical-mechanical models. This interplay, supported by laboratory data, will be a key output of this project to advance the understanding of fluid flow along fractures and to highlight the potential of multi-scale, multi-method approaches to evaluate the safety case for radioactive waste storage in the MMG.

Industrial Placement

We aim for a placement of at least 3 months at a European Geological Survey (e.g. British Geological Survey) or with energy companies having similar interest in multi-phase fracture flow.

Partners 

The project is in close collaboration with Nuclear Waste Services in the UK, which is part of the Nuclear Decommissioning Authority.

Eligibility

This scholarship is available to UK students only who are eligible for Home fee status.

To be eligible, applicants should have a BSc/MSci 2:1 and/or Masters (MSc) at Merit/Distinction level (>60%) and/or evidence of significant relevant professional experience equivalent to Masters level. Applicants with a geomaterials/geochemistry/chemistry/physics/applied geoscience/reservoir engineering related qualification and an interest in field work, geochemical, computational, petrophysical, or geomechanical methods are particularly encouraged. Applicants should further have a strong motivation to succeed in scientific research, excellent presentation, and scientific writing skills as well as very good to excellent English language skills (verbally and written). Scholarships will be awarded by competitive merit, taking into account the academic ability of the applicant. We particularly encourage female candidates as well as candidates from ethnic minorities to apply! The successful candidate will be joining a cohort of about 40-50 PGRs who are roughly 50/50 male/female. Flexibility can be offered if someone has any caring responsibilities

How to apply

To apply you must complete our online application form our online application form

Please select PhD GeoEnergy Engineering as the programme and include the full project title, reference number and supervisor name on your application form. You will also need to provide a CV, a supporting statement (1-2 A4 pages) outlining your suitability and how you would approach the project, a copy of your degree certificate and relevant transcripts and an academic reference.

Please contact Prof. Andreas Busch ([Email Address Removed]), Dr. Niko Kampman ([Email Address Removed]), Prof. Florian Doster ([Email Address Removed]) or Dr. Nathaniel Forbes Inskip ([Email Address Removed]) for informal information.

Timeline

The closing date for applications has been extended to 14 March 2023 and applicants must be available to start in September 2023.