(425d) Biocompatible Ionic Liquid As Inhibitor for Qatari Natural Gas Hydrates

The formation of stable gas hydrates in the production and transmission pipelines in oil and gas industries can cause operational and safety hazards, as well as production and massive economical loss. Due to the vast development in deep water activities carried out in many locations all over the world including Qatar, flow assurance has become one of the major and critically important challenges in overcoming hydrates problem [1]. Thereby, search for new class of chemicals know as gas hydrate inhibitors which are economic and used in low dosages are the centre of attraction to avoid hydrate formation [2]. 

In this work, hydrate equilibrium curves have been obtained for a Qatari natural gas type mixture (QNG) using a bench top reactor and gas hydrate autoclave. The hydrate inhibition effect of a biocompatible ionic liquid, choline chloride (ChCl) has also been tested at lower concentrations (1 and 5 wt%) and found little compared to conventional thermodynamic inhibitors. Moreover purging of nitrogen into the system to make the QNG mixture N₂ rich up to approximately (0.5 QNG+0.5 N₂) has also been studied in presence of 1 and 5 wt% of ChCl. It has been found that the presence of N₂ and ChCl together enhance the performance of thermodynamic inhibition. The obtained results suggest that the synergistic inhibition effect of (N₂+ChCl) could be an alternative economic strategy for the inhibition of natural gas hydrates.

Further, the obtained experimental for QNG were compared to each other and to the predicted curves using commercial software (HydraFLASH) and Katz gas gravity method. The possible reasons of the discrepancies between the experimental and predicted values were discussed in terms of the mixture composition uncertainty and the limitation of software prediction power for complex mixtures like QNG.

[1] M. Tariq, D. Rooney, E. Othman, S. Aparicio, M. Atilhan, M. Khraisheh, Gas hydrate inhibition: a review of the role of ionic liquids, Ind. Eng. Chem. Res. 53 (2014) 17855 – 17868.

[2] M. A. Kelland, History of the development of low dosage hydrate inhibitors, Energy Fuels 20 (2006) 825 – 847.