Characteristics of Hydrate Nucleation, Formation and Plugging in Gas-Liquid Two-phase Flow with High Water-cut

A high water-cut gas-liquid two-phase flow pattern is easy to appear in the drainage pipeline of the hydrate exploitation system and the wellbore of deep-water oil and gas drilling. In low-temperature and high-pressure environments, hydrates formed in the pipeline will accumulate and deposit, which will plug the pipeline in serious cases and result in flow assurance risk. The experiment of hydrate formation and plugging under the condition of high water-cut was carried out by using a high-pressure flow loop, and the stage characteristics of hydrate nucleation, fast formation, and plugging evolution were investigated. Regularities of macro induction time, hydrate concentration, and plugging time were analyzed under different initial environmental conditions. A prediction model of hydrate concentration was established for the completely plugged flow system. The results show that within the initial velocity range of 0.46 -1.12 m/s, both macroscopic induction time and hydrate concentration during blockage increase and then decrease with the rise of initial velocity and decrease with the rise of cooling rate. The time of hydrate blockage is positively correlated with the initial velocity and negatively correlated with the cooling rate. The characteristic velocity is 0.86 ± 0.14 m/s, which determines whether the mass transfer or heat transfer is a domination factor in the stage of nucleation and formation of hydrates. The error of the hydrate concentration prediction model is less than 15%. © 2024 Editorial office of Ship Building of China. All rights reserved.