Abstract

Natural gas hydrates form under high pressure and low-temperature environments common in deepwater off-shore petroleum production operations. Once hydrates form, they can agglomerate and deposit resulting in solid plugs within the piping system, which could require extensive downtime for remediation and recommission of the systems. Hydrate plug formation is difficult to characterize because of the challenging environments in which they form, the lack of instrumentation for such environments, and the fast reaction time compared to other blocking mechanisms. This study explores the use of X-ray flow visualization, including X-ray radiography and X-ray computed tomography, to help characterize hydrate formation in a laboratory setting. A structure II hydrate was formed in a concentric cylinder mixing tank where a mixture of distilled water and cyclopentane was stirred in the inner tank while the outer tank was cooled. As the tank cooled, the distilled water-cyclopentane mixture converted to hydrate, which was captured with X-ray radiographic videos. Once formed, X-ray computed tomography images were acquired to gather 3D reconstructed images of the hydrate with and without liquid present in the mixing tank. It was shown that X-ray imaging could provide a qualitative assessment of hydrate formation. Quantitative measures were challenging because of the limited contrast between the hydrate and liquid region.

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