(60b) Prevention of Gas Hydrates in Offshore Subsea Lines Using Pyrrolidinium Based Ionic Liquids

Gas hydrates are identified as ice-liked solid, crystalline compounds having polyhedral water cavities, where gas molecule trapped during operation under high pressure and low temperature condition. These hydrates have a tendency to completely block the pipelines and can cause major operations shutdown, leading to large economic losses and high safety risk in transmission pipelines. In order to avoid or delay in hydrate formation, chemical inhibitors like Methanol and Methylene ethylene glycol (MEG) using in transportation networks. However, these inhibitors are not suitable for current environmental scenario. Therefore, there is demand of environmentally beneficial and recycled process to decrease the overall energy cost, major safety and disposal issue. Ionic liquids (ILs) are salt like compounds received great attention in green energy researches due to environmentally friendly, recyclable and non-flammable in nature. These ILs are having potential to prevent hydrate formation. Pyrrolidinium based ILs have been tested as gas hydrate inhibitors and synergistic compounds (Syn) are added with ILs to improve the effectiveness. For the first time kinetic and thermodynamic studied have done using a mixture of high dosage of ILs + Syn on methane rich gas mixture to check their effectiveness in preventing hydrates formation. All the experiments are performed using a high pressure rocking cell assembly supplied by PSL Systemtechnikk GmBH, at different pressures ranging from (40 to 120) bars. According to the tests results, we have evaluated that the mixtures were able to prevent hydrates formation by providing a temperature shift of up to 2.2 °C at low pressures and by delaying hydrates formation time by (6 to 14) hours.

These results confirm the dual inhibition behaviour of these mixtures, as they were able to shift hydrates formation temperature and delay hydrates formation time simultaneously. The results were also compared with widely known industrial inhibitor methanol and only a difference of 0.5 °C was observed. Thus, this research provides an innovative approach towards development of environmentally friendly inhibitors and to reduce energy cost in the oil and gas industry.

Acknowledgement

This work was made possible by NPRP grant # 6-330-2-140 and 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.