Risk Research Of Gas Leakage On Subsea Production Systems

There are protective devices outside the subsea production systems.Due to the particularity of its structure and function,the jumper is difficult to protect and is easily damaged by third-party activities.The research object of this thesis is the jumper,and analyzes the gas leakage of the subsea production systems in three stages: underwater diffusion,sea surface diffusion and sea surface fire.The results provide a reference for relevant enterprises to make emergency decisions in practical projects.The main research contents and conclusions are as follows:(1)In the underwater diffusion stage,the three leakage holes of the jumper are coupled with the four water velocities,and the underwater gas diffusion is simulated by the FLUENT,obtaining the change law of the shape of the bubble plume in the water and the water-air interaction surface.The research results show that the bottom angle of the bubble plume formed by the leakage of the 6-inch jumper is between 25° and 35°,and the radius of the methane pool formed in the 94 m deep water is about 25 m.(2)In the sea surface diffusion stage,based on the simulation results of the underwater diffusion stage,the FLUENT was used to simulate the methane diffusion under 6 levels of wind force and 3 methane pool flow rates,obtaining the methane diffusion law when the volume fraction was 5%.The research results show that: 1-5 winds are favorable for methane gas diffusion;6-level winds are favorable for methane gas dilution;the change of methane pool flow has a significant effect on the extension of methane gas under 6-level winds.(3)In the sea surface fire stage,use KFX to simulate the flame bending and smoke diffusion of the sea surface combustion methane pool under 2 main wind directions and6 levels of wind,and obtain the distribution law of flame heat radiation in the methane pool and safety distance for ships at sea.The research results show that the wind speed of level 3 and above accelerates the heat dissipation of the sea surface,and equivalent heat flux area is smaller than that of the wind force of level 1 and 2;the methane pool fire caused by the leakage of the 6-inch jumper requires the ship to reach a distance of at least259 m to ensure ships safety.