Project description: The use of CO2 to displace methane from unconventional reservoirs, like gas shales, offers the potential for simultaneous improved methane recovery and CO2 storage. A clear understanding of the mass transport mechanisms is essential for predicting the gas recovery efficiency due to its impact on how far the CO2 will permeate throughout the reservoir. Unconventional reservoir rocks like shales have complex void spaces, with various surface chemistries and pore types, corresponding to various phases such as organic carbon and inorganic minerals. Due to the high prevalence of microporosity and surface adsorption in shales, the surface diffusion flux constitutes the largest component of the mass transport. This work will aim at predicting the surface diffusion rates, and thence mass transport fluxes, from the surface properties of typical reservoir rocks. These can then be used to predict large-scale gas recovery and storage.
This work will develop a model for surface diffusion on heterogeneous surfaces using fractal-based models. Many previous studies have shown that the internal surface of shales is fractally rough. The model will use fractal physics to predict the Arrhenius parameters for surface hopping motion using transition state theory. These parameters will then be incorporated into a model for larger length-scale transport, using percolation theory and critical path analysis to determine the particular rock surface and pore types that control the overall surface diffusion flux within a heterogeneous system. The model will be tested against experimental gas mass transport data for rock core samples.
The impact of the predicted differences in surface diffusion rates in different rock types will be assessed by up-scaling to field scale simulations of the displacement of methane by CO2 in typical reservoirs.
The student will develop expertise in rock core characterisation and permeation/uptake measurements, and reservoir simulation using commercial software.
The PhD position is available from 1st October 2020. This project will include the payment of tuition fees as well as a stipend equivalent to RCUK rates (currently at £15,285 p.a. 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 of the application. This will help in ensuring your application is sent directly to the academic advertising the studentship.