An experimental investigation on methane hydrate morphologies and pore habits in sandy sediment using synchrotron X-ray computed tomography

• Published in: Marine and Petroleum Geology
• Main Authors: Le, Thi Xiu, Bornert, Michel, Aimedieu, Patrick, Chabot, Baptiste, King, Andrew, Tang, Anh Minh, A.M.
• Other Authors: École des Ponts ParisTech (ENPC), Laboratoire Navier (NAVIER UMR 8205), École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), ANR-15-CE06-0008,HYDRE,Comportement mécanique des sédiments contenant des hydrates de gaz(2015)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: methane hydrate; sandy sediments; morphology; pore habits; synchrotron X-ray computed tomography; [SPI.GCIV.GEOTECH]Engineering Sciences [physics]/Civil Engineering/Géotechnique; Methane hydrate
• Online Access: https://enpc.hal.science/hal-03053577; https://enpc.hal.science/hal-03053577/document; https://enpc.hal.science/hal-03053577/file/Le%20et%20al%202020_JMPG-D-20-00412_HAL.pdf; https://doi.org/10.1016/j.marpetgeo.2020.104646

International audience As pore-scale morphologies and spatial distribution (pore habits) of natural gas hydrates in marine sediments considerably affect their physical/mechanical properties, they have extensively been investigated by X-ray computed tomography (XRCT) and especially synchrotron X-Ray computed tomography (SXRCT). While both image spatial and scan temporal resolutions are being improved over time, it is still challenging to distinguish water from methane hydrate in an image due to their low absorption contrast. In this study, methane hydrate formation and growth in wet sand were observed at submicron/micron scale using SXRCT. Saline water (Potassium iodide-KI) was used in order to improve the image contrast. Evolutions of methane hydrate morphologies and distribution at both the pore and sample scales were observed. Results are discussed based on various mechanisms related to material behaviors and experimental conditions, e.g. suction variation during methane hydrate formation, local temperature gradient in the sample, and particularly the interaction of X-rays with the sample. Methane hydrate formation is interpreted as a dynamic process, favoring the Ostwald ripening. Furthermore, morphologies and pore habits of methane hydrates under excess-gas and excess-water conditions are discussed. Some recommendations are finally given for further studies on methane hydrates-bearing sediments via XRCT or SXRCT.