Pore-scale observations of hydrogen trapping and migration in porous rock: demonstrating the effect of Ostwald ripening

Zhang, Y. , Bijeljic, B., Gao, Y., Goodarzi, S., Forough, S. and Blunt, M. J. (2023) Pore-scale observations of hydrogen trapping and migration in porous rock: demonstrating the effect of Ostwald ripening. Geophysical Research Letters, 50(7), 102383. (doi: 10.1029/2022GL102383)

Abstract

We use high-resolution three-dimensional X-ray imaging to study hydrogen injection and withdrawal in the pore space of Bentheimer sandstone. The results are compared with a replicate experiment using nitrogen. We observe less trapping with hydrogen because the initial saturation after drainage is lower due to channeling. Remarkably we observe that after imbibition, if the sample is imaged again after 12 hr, there is a significant rearrangement of the trapped hydrogen. Many smaller ganglia disappear while the larger ganglia swell, with no detectable change in overall gas volume. For nitrogen, the fluid configuration is largely unchanged. This rearrangement is facilitated by concentration gradients of dissolved gas in the aqueous phase—Ostwald ripening, We estimate the time-scales for this effect to be significant, consistent with the experimental observations. The swelling of larger ganglia potentially increases the gas connectivity, leading to less hysteresis and more efficient withdrawal.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Zhang, Dr Yihuai

Creator Roles

Zhang, Y.: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Resources, Software

• Authors: Zhang, Y., Bijeljic, B., Gao, Y., Goodarzi, S., Forough, S., and Blunt, M. J.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Geophysical Research Letters
• Publisher: Wiley
• ISSN: 0094-8276
• ISSN (Online): 1944-8007
• Published Online: 30 March 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Geophysical Research Letters 50(7):102383
• Publisher Policy: Reproduced under a Creative Commons license