Conceptual Overview Hydrate Plug Formation in Oil-Dominated Systems

4 Conceptual Overview Hydrate Plug Formation in Oil-Dominated Systems 

The water phase is emulsified within the oil phase. Usually the oil phase fraction is much greater than the water phase fraction, so the large majority of oil production involves a water within oil (W/O) emulsion. The water droplet size is typically tens of microns (p,m). 

A thin (perhaps smaller than 6 p,m thick) hydrate shell grows around the water droplets, from small gas molecules dissolved in the oil phase. Initially this hydrate shell is extremely malleable, so much so the hydrate-encrusted droplet will extrude through screens, for example. 

While they are malleable, these hydrate shells form a diffusional barrier between the hydrocarbon and water phases. The shells do not usually become very thick, except at long times—periods of days. 

Capillary forces of attraction cause the hydrate-encrusted droplets to agglomerate. These capillary forces are a strong function of temperature at low temperatures the forces decrease between the particles, as measured by Taylor (2006). 

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