Speaker
Description
Gas hydrates are solid compounds formed by crystallization of water and gas upon cooling and/or pressurization. Hydrates form naturally in marine sediments and permafrost (mostly CH4), whereas CO2 hydrates form during carbon subsurface storage due to rapid gas expansion, which can inhibit further injection. Changes in porosity affect further fluid transport, mechanical stability, and gas-water mixing hence further hydrate formation, making prediction of porosity evolution key in hydrate-bearing sediments. Still, our understanding is limited by lack of data, in particular time-resolved measurements of porosity evolution during hydrate formation.
We quantify this experimentally using time-resolved Magnetic Resonance Imaging (MRI), which distinguishes between mobile (liquid) and immobile (solid-like) hydrogen, here used to distinguish between water/THF and hydrates. We continuously inject tetrahydrofuran (THF) into glass bead packs saturated with deionized water, within the equilibrium conditions for THF hydrate. THF is stable at much lower pressures than CH4 or CO2, making it a useful proxy.
We show that fluid-filled porosity decreases during THF injection, a reduction is strongly time-dependent: (i) initial rapid decrease shortly after the onset of hydrate formation, indicating efficient conversion of water and THF into hydrate; (ii) at later times, slower porosity reduction, suggesting that hydrate growth becomes increasingly constrained by pore connectivity and limited transport of reactants through partially blocked flow pathways. Our experimental quantification of the coupling between hydrate formation and fluid transport offer invaluable constraints for models of hydrate-bearing media, required for planning and monitoring subsurface geonergy.
| References | Mahabadi, N., Dai, S., Seol, Y., Jang, J., 2018, Impact of hydrate saturation on water permeability in hydrate-bearing sediments, Journal of Natural Gas Science and Engineering, 58, 244–250. Taylor, C. J., Miller, K. T., Koh, C. A., Sloan, E. D. Jr., 2007, Macroscopic investigation of hydrate film growth at the hydrocarbon/water interface, Chemical Engineering Science, 62, (23), 6524–6533. Xue, K., Zhao, J., Song, Y., Liu, W., Lam, W., Zhu, Y., Liu, Y., Cheng, C., Liu, D., 2012, Direct observation of THF hydrate formation in porous microstructure using magnetic resonance imaging, Entropy, 14, (4), 698–707. Zhao, Y., Lei, X., Zheng, J., Li, M., Johns, M. L., Huang, M., Song, Y., 2021, High-resolution MRI studies of CO₂ hydrate formation and dissociation near the gas–water interface, Journal of Natural Gas Science and Engineering, 91, 103950. |
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| Country | United Kingdom |
| Green Housing & Porous Media Focused Abstracts | This abstract is related to Green Housing |
| Student Awards | I would like to submit this presentation into the Earth Energy Science (EES) and Capillarity Student Poster Awards. |
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