Modelling underwater dispersion of gas released from seabed soil considering current and wave

Subsea gas release incidents may result in catastrophic consequences, e.g., overturning of offshore floating structures, fire, and explosion. This paper developed a model to investigate the dispersion behavior of underwater gas released from the seafloor soil under combined action of current and wave. Eulerian-Eulerian model is used to track underwater gas dispersion trajectory. Porous model is utilized to describe the seafloor soil and simulate the penetration of gas released from seafloor soil. The numerical model is validated by comparing with small-scale experiments. The effect of release rate, current velocity and soil porosity is investigated. The parameters, e.g., rising time, horizontal dispersion distance and surfacing area are estimated. The uniqueness of this study is that underwater gas plumes are simulated considering the seafloor soil and the combined action of current and wave. The results indicate that the presence of seafloor soil has a significant effect on the migration shape and trajectory of underwater gas plume. The combined action of current and wave increases the dispersion distance of gas plume. This study can support risk assessment and emergency planning of subsea gas release accidents.