Investigating the Effect of Sub-Cooling Temperature on Methanol Requirements for Hydrate Formation Prevention

Abstract The primary factor driving hydrate formation is the degree of subcooling, which is highly temperature-dependent. It is well-established that greater subcooling increases the driving force for hydrate formation. However, the relationship between subcooling and the amount of methanol required as an inhibitor for hydrate suppression has not been thoroughly explored. This study aims to investigate how varying subcooling temperature affect the kinetic inhibition efficiency of methanol in preventing methane hydrate formation. To conduct this analysis, the OLGA hydrate module, which utilizes the Colorado School of Mines Hydrate Kinetic model (CSMHyK), was employed to simulate hydrate formation across different sections of the system. Additionally, Multiflash, a software tool for phase behavior and fluid properties, was used to generate the necessary input files for the OLGA model. A baseline model with a standard subcooling temperature of 6.5°F was created, and the hydrate formation tendencies at various methanol concentrations were evaluated. Sensitivity analysis was performed at subcooling temperatures of 3.5°F and 5°F to assess their impact on methanol requirements. The results indicated that an increase in subcooling temperature leads to a proportional increase in the quantity of methanol needed to prevent hydrate formation. Furthermore, it was found that higher subcooling temperatures enhanced the driving force for hydrate formation. Specifically, methanol concentrations of 40 mol%, 50 mol%, and 60 mol% were identified as optimal for complete inhibition of hydrate formation at subcooling temperatures of 3.5°F, 5°F, and 6.5°F, respectively. The findings of this research suggest that hydrate formation prevention modeling should consider a range of subcooling temperature rather than relying solely on the default subcooling temperature assumed in most commercial simulators.