Hydrate Plug Dissociation via Nitrogen Purge: Experiments and Modeling

We present a novel and promising method for the remediation of gas hydrate blockages in oil and gas pipelines, involving purging the gas hydrate plug with nitrogen gas. The resulting lower chemical potential of the hydrate former in the gas phase promotes hydrate dissociation, even though the pressure and temperature remain unchanged. Laboratory measurements on hydrate dissociation enabled the development of a model that estimates the dissociation time for gas hydrate plugs using nitrogen. The hydrate plug dissociation mechanism using a nitrogen purge was shown to involve growing channels and was significantly different from the radial dissociation mechanism observed for the conventional plug depressurization method. The nitrogen purge plug dissociation method provides an important new technology for hydrate plug remediation, in which the hydrate is permeable to gas.