Analysis of Gas Hydrate Formation in Subsea External Sleeve Choke

Gas hydrates are well-known challenge for subsea gas production and transportation, since the hydrates can plug subsea production equipments with potential risks for safety, environment and economic. In the present paper, combining CFD technology with temperature-pressure curve of natural gas hydrate forming, the hydrate formation in subsea external sleeve choke is studied. The difference between real pressure in the choke and critical pressure of gas hydrate formation is defined as equivalent pressure, based on which a new approach to predict gas hydrate formation called Maximum Equivalent Pressure Method is proposed, and the influence of inlet temperature, outlet pressure and relative opening to the maximum equivalent pressure are investigated. The critical relative opening ranges of gas hydrate formation under conditions of certain inlet temperature and outlet pressure are obtained. In case that the relative opening is within the critical range, there would be no hydrate formation in the choke, otherwise it would generate hydrate.