A short review on natural gas hydrate, kinetic hydrate inhibitors and inhibitor synergists

Gas hydrate-caused pipeline plugging is an industrial nuisance for petroleum flow assurance that calls for technological innovations. Traditional thermodynamic inhibitors such as glycols and inorganic salts suffer from high dosing, environmental unfriendliness, corrosiveness, and economical burden. The development and use of kinetic hydrate inhibitors (KHIs), mostly polymeric compounds, with their inhibiting effects on hydrate nucleation and growth are considered an effective and economically viable chemical treatment for hydrate prevention. However, the actual performance of a KHI candidate is dependent on various factors including its chemical structure, molecular weight, spatial configuration, effective concentration, pressure and temperature, evaluation methods, use of other additives, etc. This review provides a short but systematic overview of the fundamentals of natural gas hydrates, the prevailing categories of polymeric kinetic hydrate inhibitors with proposed inhibition mechanisms, and the various synergists studied for boosting the KHI performance. Further research endeavors are in need to unveil the KHI working modes under different conditions. The conjunctive use of KHIs and synergists may facilitate the commercial application of effective KHIs to tackle the hydrate plugging problem in the oil and gas flow assurance practices. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.