Evaluation of fault leakage rates in the context of subsurface hydrogen and carbon storage

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Temporary storage of hydrogen or permanent storage of carbon dioxide in the subsurface requires a profound understanding of associated risks for leakage, bearing environmental, political, and economic risks that are still to be quantified. Faults can pose a potential risk of leakage; they might already be hydrodynamically conductive, or conductivity might be triggered by an increase in fluid pressures due to CO2 or H2 injection. Fluid pressure increase, and thus effective stress decrease, depends on the vicinity of the faults to the injection well. Drilling an injection well near a known fault is rather discouraged, while it remains unknown if faults can act as leakage pathways over engineered time scales on the order of < 105 years.

This study will build on data (laboratory, field) and upscaled modelling concepts available in our two groups to simulate a wide range of combinations for fault fracture networks and laboratory derived fracture permeability data. This will be done under realistic storage conditions with fluid pressure changes characteristic for a near wellbore and a far field example. Outputs of modelling scenarios will then be evaluated statistically to determine the risk of fault leakage within engineering time scales and considering saline aquifers with corresponding caprock thicknesses, stresses, pressures and temperatures that are realistic for potential storage scenarios in the North Sea.

In this context, we will investigate the impact of multiphase flow effects on fault leakage from geological reservoirs used for fluid storage, focusing specifically on CCS and hydrogen. This research will ground on recent data that has been obtained from multiscale 4D X-ray imaging at the Swiss Light Source. It will provide new and detailed insights into the multiphase fluid dynamics in rough fractures. Using novel data from synchrotron experiments will support more accurate predictions of the potential fluid leak rates from subsurface reservoirs. These are urgently needed to improve our confidence in subsurface fluid storage over long periods of time. This research can be divided into the following objectives:

  1. Develop a robust understanding of multiphase flow in rough fractures, based on 4D flow data. The data will be analysed towards displacement to obtain relative permeability and capillary pressure curves at a given effective stress but with varying surface roughness, aperture heterogeneity, and flow rates (capillary numbers).
  2. Represent fracture flow phenomena at the Darcy scale in physical models for fractures and fracture networks. This will support caprock leakage risk assessments by improving our confidence in the determination of leak rates by bringing together fracture network data (from previous research by the PI/co-Is) and upscaled fluid displacement models from this research.

This is a full scholarship which will cover tuition fees and provide an annual stipend in line with EPSRC recommended levels (currently £17,668) for the 42 months duration of the project. In addition, the project is generously supported by Shell Global Solutions to support research and travel expenses.

This scholarship is available to UK and overseas students.

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/physics/applied geoscience/civil engineering/reservoir engineering related qualification and an interest in computational, petrophysical, geomechanical or X-ray physical 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 to apply

How to Apply 

To apply you must complete 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 (1-5 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 (a.busch@hw.ac.uk) or Prof. Florian Doster (f.doster@hw.ac.uk) for informal information.

The closing date for applications is 29th January 2023 and applicants must be available to start in May 2023.