Pore Structure-Transport Relationships in Bowland Shale

Pitcher, Eleanor G.; Fletcher, Robin S.; Large, David J.; Rigby, Sean P.

Abstract

Shale rocks are highly structurally and chemically heterogeneous, such that the pore structure-transport relationship is complex. Shales typically have porosity over many length-scales from the molecular up to macroscopic fractures. This work utilizes gas overcondensation to probe pore sizes from micropores to very large macropores all in the same experiment without the potential for damage due to high pressures as in mercury porosimetry. Indeed, the Bowland shale samples studied here are generally inaccessible to mercury intrusion. The gas overcondensation method can also be augmented using scanning loops to assess the spatial juxtaposition of very different pore sizes, and this has been used to determine that some large macropores are shielded by pore necks less than 4 nm in size in Bowland shale. In addition, the adsorption calorimetry method has been used to assess the accessibility of the void space. It has been found that mass transport is limited by particular ‘hour-glass’-like pore necks that fill at quite low saturation, and thus present a barrier to molecular migration. The shielding of macroporosity by narrow necks was particularly significant for the above marine band sample, with lower shielding observed in the marine band and below marine band materials.

Citation

Pitcher, E. G., Fletcher, R. S., Large, D. J., & Rigby, S. P. (2023). Pore Structure-Transport Relationships in Bowland Shale. In The Bowland Shale Formation, UK: Processes and Resources. Geological Society. https://doi.org/10.1144/sp534-2021-97

• Acceptance Date: Dec 15, 2021
• Online Publication Date: Nov 4, 2022
• Publication Date: Aug 1, 2023
• Deposit Date: Dec 16, 2021
• Publicly Available Date: Nov 5, 2023
• Publisher: Geological Society
• Series Title: Geological Society, London, Special Publications
• Series Number: Volume 534
• Book Title: The Bowland Shale Formation, UK: Processes and Resources
• DOI: https://doi.org/10.1144/sp534-2021-97
• Keywords: Geology; Ocean Engineering; Water Science and Technology
• Public URL: https://nottingham-repository.worktribe.com/output/7020762
• Publisher URL: https://www.lyellcollection.org/doi/10.1144/SP534-2021-97