A comparative performance evaluation of cubic equations of state for predicting the compositional distribution of hydrate inhibitors in reservoir fluid systems

Abstract

This study presents a comparative computational examination of different cubic equations of state (EoS) on hydrate inhibition fluid systems involving real reservoir fluids. Two gas hydrate inhibitors (Monoethylene glycol – MEG and methanol) were considered alongside 4 cubic EoS namely; Cubic-Plus-Association (CPA) EoS coupled with Infochem mixing rules, Soave-Redlich-Kwong (SRK) EoS coupled with the Huron-Vidal (HV) mixing rule, Peng Robinson EoS coupled with the HV mixing rule and the Predictive-Soave-Redlich-Kwong EoS with the PSRK-type mixing rule. Pressure-Temperature (PT) – flash calculations were carried out using MultiflashTM software (version 6.1) and the obtained results were compared with experimental data from various literature. The tested Cubic EoS successfully modelled the distribution of water, a hydrate inhibitor and hydrocarbons in the complex mixtures at different conditions with the CPA EoS performing best. The PSRK EoS produced results farthest from experimental data.