Hydrate equilibrium model for gas mixtures containing methane, nitrogen and carbon dioxide
Proceedings of the Annual Offshore Technology Conference
The Society of Petroleum Engineers (SPE)
School of Engineering
© 2020, Offshore Technology Conference. Gas hydrate formation is considered one of the major problems facing the oil and gas industry as it posesa significant threat to the production, transportation and processing of natural gas. These solid structurescan nucleate and agglomerate gradually so that a large cluster of hydrate is formed, which can clog flowlines, chokes, valves, and other production facilities. Thus, an accurate predictive model is necessary fordesigning natural gas production systems at safe operating conditions and mitigating the issues induced bythe formation of hydrates. In this context, a thermodynamic model for gas hydrate equilibrium conditionsand cage occupancies of N2 + CH4 and N2 + CO4 gas mixtures at different compositions is proposed.The van der Waals-Platteeuw thermodynamic theory coupled with the Peng-Robinson equation of stateand Langmuir adsorption model are employed in the proposed model. The experimental measurementsgenerated using a cryogenic sapphire cell for the pressure and temperature ranges of (5-25) MPa and(275.5-292.95) K, respectively, were used to evaluate the accuracy of this model. The resulting data showthat increasing nitrogen mole percentage in the gas mixtures results in decreasing of equilibrium hydratetemperatures. The deviations between the experimental and predictions are discussed. Furthermore, the cageoccupancies for the gas mixtures in hydrate have been evaluated. The results demonstrate an increase in thecage occupancy for both the small and large cavities with pressure.