Example Problem for One-Sided Dissociation

A 30 ft hydrate blockage occurs in a 12 in. diameter un-insulated pipeline. The upstream and downstream pressures are 780 and 180 psia, respectively. The Structure II equilibrium pressure is 200 psia (from CSMGem at the ambient temperature). 

The temperature of the seabed is known to be 42°F, but the downstream end of the pipeline will be colder than this (38°F) due to Joule-Thompson cooling when it is vented. A porosity of 0.5 and a permeability of 0.01 mD are default values. An annulus spacing of 0.1 is required for pressure flow communication. 

Using this information, what is the dissociation time until flow and pressure communication can be re-established  

FIGURE B.1 Layout of the 1SD tab in CSMPlug with default values. 

Inputting these values and then clicking the Calculate button gives these results in the output boxes flow restart time and phases present during dissociation. Simulation runtime increases substantially for large values of  

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