Study of the hydrate formation in a pipeline with insulation coating during gas transfer from the “dome-separator”

The paper proposes a mathematical model describing the process of the hydrate formation in a vertical pipeline through which the gas is transported from the dome-separator designed to eliminate a technogenic spill of oil from the well at the seabed. If the dome is located in the zone of stable hydrate existence, then hydrate deposits can form within and in the pipeline, which can lead to the pipeline clogging.
The influence of the presence of a pipeline insulation coating, which consists of the layers of polyurethane and polyurethane foam, and its thickness on the hydrate formation process in a steel pipeline is studied on the basis of numerical modeling. It is shown that if the gas is derived from the dome located at a depth of 1500 m, the zone of hydrate deposits is formed at the inlet of the pipeline without insulation (in the dome-separator vicinity). When the thermal insulation of the pipeline is used, it leads to an upward shift of the hydrate formation conditions. As a result, depending on the thickness of the insulation coating, the zone of hydrate deposits is formed near the outlet of the pipeline (in the ocean surface vicinity) or no hydrates are formed in the pipe.
It is also shown that the motion of the seawater around the pipeline has almost no effect on the process of hydrate formation within the pipe.