(152d) Prospects of Amino Acids and Ionic Liquids As a Potential Gas Hydrate Inhibitors for Offshore Flow Assurance

The gas hydrates are crystalline ice-like compounds that are formed under high pressure and low-temperature conditions in the offshore subsea lines. The formation of gas hydrates in the subsea lines is likely to cause unexpected operations shut-down, maintenance issues, safety issues and pipeline rapture in the worst case scenario. Therefore, the formation of hydrates is considered a major flow assurance issue in the oil and gas industry.

Annually, it is reported that the oil and gas industry spends over 200 million US $ on the purchase of chemical inhibitors like methanol and mono-ethylene glycol, to prevent the risk of hydrate formation by shifting the hydrate vapor liquid equilibrium (HVLE) curve to lower temperatures. However, these thermodynamic inhibitors are required in high dosage (> 30 wt%), they are toxic, flammable and there are environmental constraints associated with the disposal of these inhibitors. Therefore, the industry is in the quest of finding hydrate inhibitors that are environmentally benign, economical, required in low dosage and easily disposable.

Amino acids are biological compounds that naturally exist in nature and are considered as building blocks of life. The amino acids due to their inherited eco-friendliness and enhanced biodegradability do have a potential to act as the hydrate inhibitors. Ionic liquids are organic salts that have a low melting point and negligible vapor pressure. Ionic liquids are widely being used in green chemical processes, as many classes of ionic liquids are considered to be environmentally benign. Therefore, in this work, the prospect of amino acids and ionic liquids as future potential hydrate inhibitors have been experimentally tested at different pressures and concentrations.

All the experimental work has been conducted using pure methane gas and rocking cell assembly (RC-5) under diverse operating conditions (40-120 bars). The group has tested five commercially available amino acids and four specially synthesize ammonium based ionic liquids as hydrate inhibitors on pure methane gas. The dual functional behavior of ionic liquids and amino acids has also been investigated and the results obtained have been compared with the conventional hydrate inhibitors like methanol and mono-ethylene glycol. Accordingly, the synergistic effect of a water soluble polymer on the hydrate inhibition effectiveness of amino acids and ionic liquids has also been tested. This work provides valuable insight for the industry flow assurance experts and academic researchers.

Acknowledgement

This work was made possible by GSRA # 2-1-0603-14012 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.