HYDRATE DISSOCIATION RATES IN PIPELINES

Recent laboratory and field data suggest that hydrates form very porou s pipeline plugs which transmit pressure freely, while hydrates act as significant flow obstructions. The blocked flow causes an ocean pipel ine to rapidly equilibrate to the ocean temperature at 4 degrees C, Wh en the hydrate plug is dissociated through total depressurization of t he pipeline, the hydrate plug will be converted to an ice plug which s ignificantly dissociates longer than the hydrate. This work formulates the first dissociation model in rectilinear coordinates. It indicates that there may be an optimum pipeline pressure for the most rapid dis sociation of all solid phases resulting from hydrate pipeline blockage s. Surprisingly, the high ice thermal diffusivity provides the highest heat flux when some ice is present. (C) 1998 Elsevier Science B.V. Al l rights reserved.