Investigation of synergistic inhibition effect of MEG and salt solution on gas hydrate formation

Abstract

This study examined the under-inhibition concept of MEG considering the influx of pro-duced water, which includes many salts from subsea natural gas production. In particular, the study investigated the hydrate phase equilibrium of solutions containing both MEG and NaCl and proposes a modified model based on SRK EoS. The proposed model reflects the change of vapor pressure in aqueous MEG and NaCl mixed solution. Synergistic kinetic inhibition performance was investigated in the presence of MEG and NaCl. Experimental results show that the hydrate formation condition was shifted toward lower temperature and higher pres-sure in accordance with the increased NaCl concentration. The proposed model produced a better match with experimental data than the Multiflash and CSMGem programs. MEG and NaCl mixed solution induced synergistic kinetic inhibition of hydrate by delaying the hydrate initial growth rate as well as preventing the agglomeration and deposition of hydrate particles. Moreover, when 10 wt% NaCl was added to the 20 wt% MEG solution, no hydrate formation was observed for at least 10 h. The study proved that the amount of MEG could be de-creased, considering the concentration of the produced water.