Quantifying leakage and dispersion behaviors for sub-sea natural gas pipelines

Accidental leakages in underwater natural gas pipelines pose significant risks for the environment. Therefore, it is essential to estimate the leakage rate and monitor the methane diffusion range outside the pipeline, which is challengeable due to the presence of water. The main contribution of this work is to establish the leakage rate calculation and gas dispersion models using the experimental and numerical methods. Firstly, the influences of the pressure, leakage orifice diameter and water depth on the leakage rate and gas dispersion process were revealed through experiments. Further, according to the established experimental facilities, the numerical models including the integral mathematical model and computational fluid dynamic model were established. According to the axial velocity, radius and spring height, the two model were compared and validated. In addition, a field simulation using computational fluid dynamic model was conducted to quantify the gas leakage rate and dispersion prediction, predicting the rising time and diffusion range. The results indicate that the quantifying estimation correlation can predict the leakage rate in the sea with errors less than 16.47%, and the computational fluid dynamic model could predict the dispersion process more accurately while the integral mathematical model could predict the dispersion process more quickly. •A leakage rate model for underwater NG pipelines was established with errors less than 16.47%.•The integral mathematical model could predict the gas dispersion process more quickly.•The CFD model predicts the dispersion process accurately with spring height relative error of 8.9%.