Probing the effect of various water fractions on methane (CH4) hydrate phase equilibria and hydrate inhibition performance of amino acid L-proline

Abstract

To develop an effective hydrate risk mitigation strategy for offshore flow assurance its essential to understand the effect of different water fractions on the rate of hydrate formation and study the effect of various water fractions on inhibition effectiveness of eco-friendly gas hydrate inhibitors like amino acids [AA]. This work examines the effect of different water fractions on methane [CH4] hydrate phase equilibria and the effect of various water fractions on the hydrate inhibition strength of AA L-proline at wide operating conditions [40–120 bars]. The experimental results indicate that different water fractions do not have a significant effect on the CH4 hydrate vapor-liquid equilibrium [HLVE] data or hydrate phase equilibria. The 5 wt% L-proline at water fraction 50 vol% shifted the CH4 HLVE by 0.9 ± 0.05 °C (40 bars) and at water fraction 75 vol% it shifted the CH4 HLVE by 1.3 ± 0.05 °C (40 bars). Furthermore, at the same dosage (5 wt%), the THI effect of proline was compared with other amino acids glycine, alanine, and choline based ionic liquids reported in the literature previously. The results indicate that at low dosage [5 wt%], the amino acids glycine and L-alanine tend to slightly more effective thermodynamic hydrate inhibitors compared to the selected choline based ionic liquids. The computer-generated molecular models were used to probe the likely hydrate inhibition mechanism in the presence of amino acids and ionic liquids.