Modeling of hydrate layer growth in horizontal gas-dominated pipelines with free water

Flow is obstructed as hydrate layer grows on the wall of pipelines. In gas-dominated pipelines with free water, the gas-liquid-solid (hydrate) flow, gas-solid (hydrate) flow, and water-saturated gas flow may coexist at different locations of the pipeline. Current studies on hydrate layer growth largely focus on a single-flow pattern in gas-dominated pipelines. No studies have been conducted considering different flow patterns in pipelines simultaneously. Considering the flow pattern transition due to the variation in the contents of free water and hydrates in the gas phase, an integrated model is developed to quantitatively predict the hydrate layer growth in horizontal gas-dominated pipelines with free water. Based on the proposed model, the hydrate layer thickness distribution in horizontal gas-dominated pipelines is simulated and the sensitivity analysis of different factors is performed. The results show that the distribution of the hydrate layer thickness on the pipe wall along the pipeline is non-uniform. There exists a point in the flow that is most vulnerable to hydrate layer growth at a given point in time in the gas-liquid-solid flow. This study provides a theoretical basis for preventing hydrate blockage in submarine natural gas pipelines.