How Is a Hydrate Plug Dissociated

This section provides a qualitative understanding of CSMPlug, the plug dissociation program which accompanies this book and is illustrated in Appendix B. Sometimes a hydrate plug does form, with the consequences of blocking fluid flow. When a flowline plugs, the usual responses are 

Carefully evaluate the safety concerns of plug removal (please read the following section to determine the major safety implications imposed by hydrate plugs) 

Evaluate the methods of plug removal, of which there are four types  

The below concepts are an extension of those in Chapter 3 of Hydrate Engineering (Sloan, 2000). Details of the model can be found in the work by Davies et al. (2006). Here, only the first, most-common method of depressurization is treated conceptually. 

From both a safety and technical standpoint, the preferred method to dissociate hydrate plugs is to depressurize from both sides. Depressurization is particularly difficult when the liquid head on the hydrate plug is greater than the dissociation pressure, as in mountainous terrain or in very deepwater, in which case electrical heating may be used (Davies et al., 2006), a method not considered here. 

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