Evaluating the impact of sodium chloride and iron carbonate ions on gas hydrate formation in Monoethylene Glycol‐enhanced aqueous solutions

Abstract

The management and prevention of hydrates are crucial for the gas industry. This study delves into the intricate challenges associated with gas hydrate formation, with a specific focus on investigating the impact of corrosion by‐products on prevention strategies. Employing a distinctive methodology, the sapphire pressure–volume temperature (PVT) cell was utilized. Experimental tests were conducted using sodium chloride (NaCl) concentrations of 1% and 3% to simulate brine solution levels at the wellhead, incorporating 3% filtrate and unfiltered iron carbonate (FeCO3) as corrosion products associated with the production process. The 1% and 3% salt concentrations were chosen to encompass a broad range of temperature depressions, reflecting common industry standards for simulating realistic environmental conditions. PVT cell test conditions ranged from 80 to 200 bar, with increments of 40 bar. The experiments investigate the effects of common pipeline salts on a monoethylene glycol (MEG)/water mixture in the presence of methane gas at typical industry high‐pressure conditions. The investigation uncovers that the introduction of salts to water, methane, and MEG solutions serves as a hydrate inhibitor, with inhibitory effects directly correlated to salt concentration. While generally hydrate growth inhibition is beneficial in natural gas pipelines, the findings indicate that elevated salt concentrations and lower pressure conditions contribute to the formation of larger hydrates, heightening the risk of surface adhesion and potentially introducing complications in piping equipment, despite the decreased temperature at which these hydrates form due to the inhibitory effects of the salts. In particular, the mixed condition of 3% NaCl and 3% FeCO3 (filtered) has the strongest effect. Examination of hydrate formation temperature and macroscopic observations suggests that the existence of substantial precipitates, as evidenced in the unfiltered FeCO3 sapphire cell experiment, may have the potential to enhance hydrate growth.