Multiscale characterization of sedimentological heterogeneity in the Bunter Sandstone Formation with application to CO2 storage
File(s)
Author(s)
Hossain, Shakhawat
Type
Thesis
Abstract
This study develops a multiscale reservoir characterization framework for the Bunter Sandstone Formation, a Triassic fluvial succession widely targeted for CO2 storage across northwestern Europe, including at the Endurance CO2 storage site, offshore UK. Facies and facies association analysis of core and outcrop analogues, photomosaic analysis, minipermeameter measurements, thin section petrography, spatial statistical analysis, and numerical modeling have been integrated to characterize heterogeneity at scales ranging from lamina (mm) to channel fill storeys (100s m). Thirteen lithofacies were identified and grouped into three facies associations, and three architectural elements were defined based on the stacking patterns and geometrical configuration of lithofacies. Facies permeability varies over three orders of magnitude (0.18–5400 mD), primarily controlled by grain size, clay content, and cementation. Representative Elementary Volume (REV) analysis showed effective permeability for different lithofacies stabilizes at scales much larger than typical core plugs and is highly anisotropic. Effective permeability correlates linearly with the proportion of high-permeability (clay-poor) lithologies in each facies. The resulting values of effective permeability for different facies were populated in architectural element-scale models. Simplifying these models of architectural elements by grouping lithofacies into two or three permeability-based categories resulted in estimated values of equivalent permeability at this scale that are within 10-20% of those for models containing all the constituent lithofacies. Building on the result that a two-facies representation is sufficient to capture heterogeneity at the architectural-element scale, this approach was extended to the channel-fill storey scale by characterising 100s m scale outcrop faces as sandstone containing thin, discontinuous mudstone bodies. Spatial statistical analysis shows these mudstone lenses are randomly distributed and occur at the scale of 3rd- and 4th-order erosional elements, allowing their influence to be evaluated using a streamline-based statistical method. These mudstone lenses reduce effective vertical permeability to ~3 % of the horizontal value.
Version
Open Access
Date Issued
2025-10-27
Date Awarded
01/01/2026
License URL
(https://creativecommons.org/licenses/by-nc-nd/4.0/
Advisor
Hampson, Gary
Jackson, Matthew
Jacquemyn, Carl
Sponsor
Dhaka University
Publisher Department
Department of Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)