Supercritical adsorption of CO2 and CH4 on shales and other porous media
File(s)
Author(s)
Ansari, Humera Sultana
Type
Thesis
Abstract
Low natural gas recovery factors from shale reservoirs have stimulated interest in Enhanced Shale Gas Recovery (ESGR) using CO2 injection. This process seeks to exploit the preferential adsorption of CO2 in shale's nanometric pores, so as to enhance desorption of CH4 and to promote geological sequestration of CO2. To facilitate the design of this process, an integrated experimental and modelling workflow was
developed and deployed on shale samples from the Longmaxi (China), Marcellus (USA) and Bowland (UK) formations to achieve the following: (i) high-resolution textural characterisation, (ii) supercritical adsorption measurements with CO2 and CH4, and (iii) their description by a novel mathematical model
that predicts adsorption in chemically and morphologically heterogeneous materials. The results show that CO2 adsorbs more than CH4 at all pressures (2-3 times) and that both adsorption capacities and textural properties are strongly influenced by the shale mineralogy. The model developed in this work is based on the lattice Density Functional Theory and describes adsorption systems featuring both slit and cylindrical pores and accounts for the presence of energetically distinct organic- and clay-rich pore surfaces. The workflow was calibrated on three model adsorbents (mesoporous carbon, microporous activated carbon and micro/mesoporous zeolite) to reveal the distinct pore- filling mechanisms in micro- and meso-pores. The use of these model materials enabled the creation of a predictive modelling
approach for the description of shale adsorption data, which only requires knowledge of the shale's composition. An equilibrium-based ESGR proxy reservoir model was also developed and demonstrated that a cyclic CO2 injection operation, which includes a so-called soaking stage, may be required to achieve sufficient recovery and secure CO2 storage. The practical workflow presented in this thesis can be used to quantify accurately the Gas-in-Place and CO2 storage potential of shale reservoirs at subsurface conditions and design an optimal CO2-ESGR process.
developed and deployed on shale samples from the Longmaxi (China), Marcellus (USA) and Bowland (UK) formations to achieve the following: (i) high-resolution textural characterisation, (ii) supercritical adsorption measurements with CO2 and CH4, and (iii) their description by a novel mathematical model
that predicts adsorption in chemically and morphologically heterogeneous materials. The results show that CO2 adsorbs more than CH4 at all pressures (2-3 times) and that both adsorption capacities and textural properties are strongly influenced by the shale mineralogy. The model developed in this work is based on the lattice Density Functional Theory and describes adsorption systems featuring both slit and cylindrical pores and accounts for the presence of energetically distinct organic- and clay-rich pore surfaces. The workflow was calibrated on three model adsorbents (mesoporous carbon, microporous activated carbon and micro/mesoporous zeolite) to reveal the distinct pore- filling mechanisms in micro- and meso-pores. The use of these model materials enabled the creation of a predictive modelling
approach for the description of shale adsorption data, which only requires knowledge of the shale's composition. An equilibrium-based ESGR proxy reservoir model was also developed and demonstrated that a cyclic CO2 injection operation, which includes a so-called soaking stage, may be required to achieve sufficient recovery and secure CO2 storage. The practical workflow presented in this thesis can be used to quantify accurately the Gas-in-Place and CO2 storage potential of shale reservoirs at subsurface conditions and design an optimal CO2-ESGR process.
Version
Open Access
Date Issued
2021-05
Date Awarded
2021-09
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Maitland, Geoffrey
Sponsor
Commonwealth Scientific and Industrial Research Organization (Australia)
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)