Hydrate Equilibrium Data of Multicomponent Systems in the Presence of Structure-II and Structure-H Heavy Hydrate Formers

Kasper Korsholm Ostergaard, Bahman Tohidi, Rod W. Burgass, Ali Danesh, Adrian C. Todd

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

The effect of six newly discovered heavy hydrate-forming compounds on the hydrate phase boundary of a gas mixture, a natural gas, and a model oil has been measured. The study, which is a continuation of a previous work,1 investigates the effect of cyclopentane, cyclohexane, neopentane, isopentane, methylcyclopentane, and methylcyclohexane at various concentrations. The first three compounds form structure-II hydrates, while the last three compounds are known to promote structure-H hydrates. The experimental hydrate dissociation data have been successfully predicted by the use of a thermodynamic model. The results show that structure-II is the stable hydrate structure for the systems investigated at various heavy hydrate former concentrations (from 0.27 mol % to 59.66 mol %). Also, the structure-II heavy hydrate formers promoted structure-II hydrate formation whereas the structure-H heavy hydrate formers (at the concentrations used) did not change the stable hydrate structure to structure-H and hence inhibited hydrate formation in the above fluid systems. On the basis of the above study, it was concluded that the inclusion of structure-II heavy hydrate formers in the thermodynamic modeling would improve the reliability of hydrate-free zone predictions in real reservoir fluids.

Original languageEnglish
Pages (from-to)703-708
Number of pages6
JournalJournal of Chemical and Engineering Data
Volume46
Issue number3
DOIs
Publication statusPublished - 1 May 2001

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