Research progress on the growth and plugging laws of gas hydrates

In order to guarantee the safe and stable flow of medium in multiphase pipelines, research achievements on hydrates were investigated globally and experimental conclusions on hydrate plugging were analyzed. On this basis, the formation, growth and plugging of gas hydrates in multiphase pipelines were summarized systematically. Results show that hydrates do not appear right after the thermodynamic conditions are satisfied. Their formation, growth and development occur at the phase interface instead. Kinetics, mass transfer and heat transfer are the key factors controlling the growth of hydrates. The plugging of hydrates in pipelines is divided into three stages, i.e., formation, accumulation and plugging. The multi-stage characteristic of hydrates crystallizing and growing cannot be described sufficiently only by means of hydrates thermodynamic phase equilibrium. It is necessary to study the forming mechanism of hydrates from the aspects of thermodynamics and kinetics so as to understand further the forming mechanisms and plugging laws of hydrates and predict more accurately.