Hydrate plug dissociation

Abstract

in Wiley InterScience (www.interscience.wiley.com).It was shown that flowline hydrate plugs dissociate radially not horizontally; this has significant implications for the remediation of a hydrate blockage, a major flow assurance problem. Over a decade of measurements has enabled models to estimate the dissociation time for hydrate plugs in flowlines, using radial heat transfer with two moving boundaries. Three different plug dissociation scenarios were modeled: singlesided depressurization, two-sided depressurization, and dissociation by radial electrical heating. The models were able to replicate the experimental observations with no fitted parameters. Structure I hydrate was found to dissociate faster than structure II; this was attributed to the different latent heats between the structures. These results indicate that hydrate dissociation in these systems is

Direct measurements of multi-component hydrates on the seafloor: Pathways to growth

“…Similar to laboratory experiments on hydrate plug dissociation [34] where heat transfer controls the dissociation, radial dissociation was initially dominant over axial dissociation due to the greater surface area with the surroundings. This resulted in a gas-filled gap between the hydrate and the cell walls ( Fig.…”

“…Qualitatively using the relative intensity of the water to hydrate guest Raman peaks, a significant fraction of the sample was measured to be water ice. Although there were no temperature measurements of the hydrate phase during recovery, formation of ice during rapid dissociation of hydrate has been routinely observed in the laboratory [34], and was most likely the cause of ice formation in this case.…”

A natural hydrate dissolution experiment on complex multi-component hydrates on the sea floor

“…However, to date, little work has been done on the rate at which this dissolution occurs. The majority of hydrate dissociation work has focused on heat-transfer controlled systems, more relevant to oil and gas pipeline blockages (Davies et al, 2006). The only field study to report a measured dissolution rate was performed on laboratory-synthesized sI CH 4 and CO 2 hydrates exposed to ambient undersaturated seawater around 1000 m depth in the Monterey Bay (Rehder et al, 2004).…”

Towards a Green Hydrate Inhibitor: Imaging Antifreeze Proteins on Clathrates

“…In the laboratory, gas hydrates are conveniently modeled using tetrahydrofuran (THF) which is enclathrated at atmospheric pressures [3]. THF hydrate forms cubic sII clathrates, similar to the hydrates that form in pipelines during oil and gas production [4].…”