New X-Ray Microtomography Setups and Optimal Scan Conditions to Investigate Methane Hydrate-Bearing Sand Microstructure

Le, Thi Xiu; Aimedieu, Patrick; Bornert, Michel; Chabot, Baptiste; King, Andrew; Tang, Anh Minh

doi:10.1520/gtj20190355

Cited by 2 publications

(2 citation statements)

References 28 publications

(42 reference statements)

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“…The voxel size is 0.9 lm and the scan time is 12-15 min. More details can be found in Le et al (2021b). Optical microscope: Wet sand grains are introduced into a quartz capillary tube closed at one end.…”

Section: Experimental Methodsmentioning

confidence: 99%

Mechanical behaviour and microstructure of methane hydrate-bearing sandy sediment observed at various spatial scales

Le,

Bornert,

Aimedieu

et al. 2024

STET

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Methane hydrates (MHs) are considered as an alternative energy resource but also a potential source of geo-hazards and climate change. The physical/mechanical properties of gas hydrate-bearing sandy sediments are strongly dependent on the distribution of hydrates within the pore space. The purpose of this study is to investigate morphologies and pore-habits of MHs formed in sandy sediments by means of experiments that probe a wide range of scales, from the pore scale – using synchrotron X-ray computed tomography (SXRCT) and optical microscopy – to the core scale, through mechanical property measurements. The same synthetic sands are used, in which MHs are generated successively under excess-gas and excess-water conditions. At macroscopic (core) scale, MH pore habits are inferred by comparing the measured sonic wave velocities to velocities calculated from rock physics models and further assessed via triaxial compression tests. Furthermore, Magnetic Resonance Imaging is used to investigate the kinetics of MH formation and distribution along the core height. The pore habits and MH morphologies are directly visualized at the pore (grain) scale by SXRCT and, with still better spatial and temporal resolution, by transmission optical microscopy, revealing some more complex morphologies than in the hydrate pore habits commonly admitted.

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Section: Experimental Methodsmentioning

confidence: 99%

Mechanical behaviour and microstructure of methane hydrate-bearing sandy sediment observed at various spatial scales

Le,

Bornert,

Aimedieu

et al. 2024

STET

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“…The excess gas method mostly yields hydrate at sediment surfaces and grain contacts [22][23][24], while Priest et al [25] obtained load-bearing hydrate by using the excess water method. XRCT and synchrotron XRCT are being widely used to investigate the microstructure of gas hydrate-bearing sediments [16][17][18][19][20][21][26][27][28][29][30]. Poor contrast between water and the hydrate, and limited temporal resolution, hamper identification of gas hydrate morphologies and growth modes within pores.…”

Section: Introductionmentioning

confidence: 99%

Combining Optical Microscopy and X-ray Computed Tomography Reveals Novel Morphologies and Growth Processes of Methane Hydrate in Sand Pores

Bornert

Brown

et al. 2021

Energies

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Understanding the mechanisms involved in the formation and growth of methane hydrate in marine sandy sediments is crucial for investigating the thermo-hydro-mechanical behavior of gas hydrate marine sediments. In this study, high-resolution optical microscopy and synchrotron X-ray computed tomography were used together to observe methane hydrate growing under excess gas conditions in a coarse sandy sediment. The high spatial and complementary temporal resolutions of these techniques allow growth processes and accompanying redistribution of water or brine to be observed over spatial scales down to the micrometre—i.e., well below pore size—and temporal scales below 1 s. Gas hydrate morphological and growth features that cannot be identified by X-ray computed tomography alone, such as hollow filaments, were revealed. These filaments sprouted from hydrate crusts at water–gas interfaces as water was being transported from their interior to their tips in the gas (methane), which extend in the µm/s range. Haines jumps are visualized when the growing hydrate crust hits a water pool, such as capillary bridges between grains or liquid droplets sitting on the substrate—a capillary-driven mechanism that has some analogy with cryogenic suction in water-bearing freezing soils. These features cannot be accounted for by the hydrate pore habit models proposed about two decades ago, which, in the absence of any observation at pore scale, were indeed useful for constructing mechanical and petrophysical models of gas hydrate-bearing sediments.

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New X-Ray Microtomography Setups and Optimal Scan Conditions to Investigate Methane Hydrate-Bearing Sand Microstructure

Cited by 2 publications

References 28 publications

Mechanical behaviour and microstructure of methane hydrate-bearing sandy sediment observed at various spatial scales

Mechanical behaviour and microstructure of methane hydrate-bearing sandy sediment observed at various spatial scales

Combining Optical Microscopy and X-ray Computed Tomography Reveals Novel Morphologies and Growth Processes of Methane Hydrate in Sand Pores

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