Author Identifier
Date of Award
2026
Keywords
geological formations, micro-CT, pore network model, SNOW algorithm, python modules, residual hydrogen saturation, residual helium gas saturation
Document Type
Thesis - ECU Access Only
Publisher
Edith Cowan University
Degree Name
Doctor of Philosophy
School
School of Engineering
First Supervisor
Stefan Iglauer
Second Supervisor
Alireza Keshavarz
Third Supervisor
Muhammad Ali
Abstract
This thesis studies subsurface gas phenomena utilising an integrated pore-scale modelling approach, emphasising hydrogen (H2) storage, and helium entrapment within geological deposits. This study is motivated by the growing interest in underground energy storage and the imperative to address concerns related to gas migration, retention, and dynamic reactivity. Sandstone reservoirs are emphasised, as pore design and wettability primarily govern multiphase flow and long-term entrapment efficacy.
A comprehensive review of current research delineates the primary mechanisms of gas retention in porous media, including relative permeability hysteresis, capillary trapping, and mineral-fluid dynamics. Utilising developments in digital rock physics (DRP) and micro computed tomography (CT), realistic pore geometries are reconstructed. These reconstructions facilitate the creation of pore network models (PNM) that reflect lithology-dependent heterogeneity and provide an adequate basis for simulating multiphase transport mechanisms under reservoir-relevant contexts.
The methodological framework integrates high-resolution micro-CT imaging with computational modelling tools to generate three-dimensional (3D) PNMs of Berea, Bentheimer, and Heletz samples. Python-based platforms, including OpenPNM and custom numerical routines, are employed to simulate capillary pressure–saturation relationships, relative permeability, and residual hydrogen/helium trapping. Thus, model validation is achieved through consistency with published experimental datasets, ensuring reliability in representing pore-scale displacement dynamics.
H2 storage simulations reveal strongly water-wet conditions, characterised by stable advancing and receding contact angles and pressure-independent wettability behaviour. Capillary controlled displacement leads to significant residual trapping, particularly in tighter pore circumstances. Further, H2 simulations provided water-wet conditions (θadv ~35±5°, θrec ~25±4°), resulting in high capillary migration pressures and residual trapping in Berea (Sgr = 0.43) PNM. These findings confirm that pore-throat distribution and connectivity are critical determinants of H2 immobilisation and recovery.
Helium behaviour is evaluated using the same pore-scale framework, with adjustments to account for its distinct physicochemical properties. The simulations indicate comparatively lower residual trapping due to helium’s low viscosity and high diffusivity, with flow regimes influenced by transitional and Knudsen effects in smaller pores. Variations across sandstone types of formation highlight the combined influence of pore geometry and transport mechanisms, demonstrating reduced storage security relative to H2 under equivalent conditions.
In conclusion, this research establishes a unified DRP for analysing multiphase flow and reactive transport in geological formations. The findings highlight the importance of pore geometry, wettability, and mineralogy in governing gas behaviour, providing quantitative insights for the design and risk assessment of underground storage operations. The approach offers a scalable pathway for advancing predictive models of subsurface energy storage and reactive geochemical/geo-mechanical processes.
Access Note
Access to this thesis is embargoed until 12th August 2027
Recommended Citation
Saraf, S. A. (2026). Pore-scale modelling of multiphase flow in geological energy storage: Insights into hydrogen and helium behaviour. Edith Cowan University. https://doi.org/10.25958/bmw4-dx12