CO2 sequestration and storage offers the potential to manage the transition to fully non-carbon energy by allowing the continued use of fossil fuels while new technologies are developed, but with heavily reduced or net zero atmospheric emissions. CO2 is generally stored underground in suitable spent reservoirs, such as the old gas fields in the southern North Sea. Successful storage requires that the reservoir caprock maintain its integrity and sealing efficiency for long periods. However, during CO2 injection, the plume will migrate through the reservoir, and begin to permeate any shale inter-layers, and even the cap-rock. This will begin geochemical reactions that can alter the rock pore structure leading to increased porosity and permeability. These changes could lead to a failure of the caprock, and the leakage of CO2.
This project will combine experimental modelling studies of the impact of CO2 on the void space of different sorts of common caprocks, and reactive transport computer modelling of the field-scale implications of these changes. The experimental work will involve laboratory experiments to simulate the long-term impact of exposure of caprock materials to supercritical (sc) CO2 with and without simultaneous presence of water. The treated rock will be examined to assess changes in mineralogy and pore structure. In particular, the pore structure analysis will involve use of novel methods such as serial rate of gas adsorption and mercury porosimetry experiments on the same sample. This involves measuring the rate of gas uptake before and after the new porosity has been blocked with entrapped mercury. These experiments will be used to assess the particular importance to mass transport of the newly created porosity. Further sophisticated techniques such as NMR cryodiffusometry, computerised X-ray tomography (CXT) and hyperpolarised gas-phase MRI experiments will be used to understand how the pore structure changes will affect mass transport, and thus sealing efficiency. The resulting data will allow the development of understanding of how the pore structure of the caprock will evolve with increased exposure time to scCO2 under different conditions.
The findings from the experimental studies will be up-scaled and incorporated into field-scale simulations of the impact of shale inter-layer and caprock changes on plume migration and sealing efficiency.
The student will develop expertise in geochemical reactions, rock core characterisation methods, and reservoir simulations.
The PhD position is available from 1st October 2020 and will include the payment of tuition fees as well as a stipend equivalent to RCUK rates (£15,285 tax free for 2020/21) awarded to the suitable candidate.
When applying for this studentship, please include the reference number (beginning ENG) within the personal statement section. This will help insuring your application is sent directly to the academic advertising the studentship.