Film formation kinetics of Methane-propane hydrate on gas bubble in MEG and luvicap EG solutions

Abstract

Hydrate plugging in deep sea oil & gas transportation is the final result of morphological evolution of hydrate growth. However, effect of hydrate morphological evolution in the presence of hydrate inhibitors with respect to flow assurance is rarely studied. In this work, methane-propane hydrate forming system by suspending gas bubbles in pressurized aqueous phase was studied to evaluate the hydrate film growth kinetics in the presence of thermal and kinetic inhibitors (MEG, LuviCap EG) at subcooling levels of 10–15 K. Along with morphological observations with optical microscope, the results suggested that: (1) KHI showed better inhibition performance on hydrate growth with hydrate film as a barrier for mass transfer; (2) 4000 ppm performed as a threshold concentration of hydrate film formation on bubble; (3) crater structures, as potential mass transfer channels, are the morphological characteristics of KHIs adsorbing to the hydrate film. In addition, the effects of environmental factors on the growth kinetics of hydrate on bubble showed that the subcooling determined the lateral growth rate of hydrate film, the inhibitor concentration determined whether a film was formed, and the craters structure on the hydrate film determined the mass transfer in the initial thickening stage of hydrate film growth. The research could shed new light on fine-tuning of the inhibitor concentration and level of subcooling to effectively inhibit the growth of hydrate in gas pipelines and assure the multiphase flow in deep sea oil & gas transportation.