New X-ray microtomography setups and optimal scan conditions to investigate methane hydrate-bearing sand microstructure

Methane hydrates, which are naturally formed at high pressures and low temperatures in marine and permafrost sediments, represent a great potential energy resource but also a considerable geo-hazard and climate change source. Investigating the grain-scale morphology of methane hydrate-bearing sandy sediments is crucial for the interpretation of geophysical data and reservoir-scale simulations in the scope of methane gas production as methane hydrate morphologies and distribution within the porous space significantly impact their macroscopic physical/mechanical properties. X-ray computed tomography (XRCT) and synchrotron X-ray computed tomography (SXRCT) are commonly used to analyze the microstructure of geo-materials. However, methane hydrates exist only at high pressures (up to several megapascals) and low temperatures (a few degrees Celsius). This article describes the development of three experimental setups, which aim at creating methane hydrates in sandy sediment, adapted to XRCT and SXRCT observations. The advantages and drawbacks of each setup are discussed. The discussions focus on the effects of the choice of the system to control temperature and pressure on the quality of images. The obtained results would be useful for future works involving temperature control systems or pressure control systems, or both, adapted to XRCT and SXRCT observations of various geo-materials.