Modeling of Methane Hydrate Inhibition in the Presence of Green Solvent for Offshore Oil and Gas Pipeline

摘要

In offshore gas transmission pipeline systems, typically gas andrnwater are produced under high pressure and low temperaturernconditions causing the formation of gas hydrates blockingrnpipelines. Thermodynamic modeling is necessary to understandrnthe phase stability of hydrate in the presence of green solventsrnnamely, ionic liquids (ILs). In this work, the thermodynamicrnmodels are based on the computation of fugacity of hydrate phasernusing Van der Waals and Platteeuw solid solution theoryrncombined with Peng – Robinson equation of state (PR-EoS) forrnfugacity of hydrate former in the gas phase and the computation ofrnfugacity of aqueous water phase using activity coefficient modelsrnsuch as the non – random two – liquid (NRTL) model and Pitzer –rnMayorga model. The model results are compared with availablernexperimental data from open literature and observed to be in goodrnagreement with the reported literature. Finally, the hydraternsuppression temperature due to ILs on methane hydrate isrncalculated to know the inhibition effectiveness of IL on methanernhydrate formation in offshore pipeline system. The overallrnaccuracy of Pitzer-Mayorga model is found to be 5.8 % whilernNRTL model's accuracy was 6.3 % for various ILs and methanernhydrate system. Model results further indicated that ILs withrnshorter alkyl chain length exhibit better inhibition effect. Thernmodel developed in this work shows potential application in therndetermination of hydrate phase stability using green solvent forrnoffshore oil field applications.