The Effect of Acidic Gases and Thermodynamic Inhibitors on the Hydrates Phase Boundary of Synthetic Malaysia Natural Gas

Abstract

In this work, PVTSim was used to predict the hydrate phase equilibrium boundaries of a Malaysia synthetic natural gas (SNG) composition with increasing CO2 and H2S compositions in the presence of commonly used hydrate thermodynamic inhibitors such as methanol (MeOH), ethanol (EtOH), mono-ethylene glycol (MEG), diethylene glycol (DEG), tri-ethylene glycol (TEG). The increasing CO2 and H2S concentrations studied ranged from 5 – 50 mol%, while the inhibitors were tested at 10 wt%. To validate the accuracy of PVTSim, a validation test was conducted by predicting the phase behavior of a natural gas in the open literature. The predicted results were in good agreement with the literature data with a percentage deviation of 0.08% from the experimental data. From the predicted hydrate phase equilibrium for pure SNG field, it was found that, when the SNG composition was modified, the hydrate formation region shrank at increasing CO2 composition, reducing the hydrate formation risk whereas the hydrate formation region expanded at increasing H2S composition, increasing the hydrate formation threat. TEG was found to best inhibit hydrate formation in the studied gas compositions.