A Study On Characteristics Of Gas-water Sever Slug Flow In Combination Riser

The severe slug flow mainly occurs in the Marine riser,which brings many problems to offshore oil and gas field,such as mechanical damage and corrosion of pipes,overflow and disconnection of downstream separator and so on.In order to ensure optimal design and safe operation of pipeline and downstream processing equipment,it is very important to analyze the characteristics of slug flow.In this paper,taking air and water as the medium,and builting experimental platform relying on the multi-phase flow lab.In the experiment,the downdip tube was 3.65 m long,the vertical pipe was 2.64 m high and the inner diameter of them was 25 mm.The Angle of the downdip tube is 1°,4° and 7°.The main research contents and conclusions are as follows: According to the experimental phenomena and the characteristics of the flow pattern,the flow pattern in this experiment can be divided into severe slugging ?,?,and hydrodynamic severe slugging ?? and ?.The cycle length of severe slug flow is affected by flow velocity and the downdip pipe angle,the period decreases with the increase of gas velocity and liquid velocity,and increases with the increase of the downdip pipe angle.Among the three experimental parameters,the influence of liquid velocity and downdip pipe angle is not significant.The maximum pressure,minimum pressure and pressure fluctuation range of the bottom of riser vary with the fluid flow velocity,the change rule of type ??? and ? is different,and the downdip tube angle has no significant effect on it.In the slug formation stage,the liquid slug velocity is positively correlated with the fluid flow velocity and downdip tube angle.When the fluid velocity is constant,the cycle length and pressure fluctuation range of severe slug flow will still fluctuate,their fluctuation changes with gas and liquid velocity,and in a very small range,it can be considered that under the same gas and liquid velocity,the cycle length of severe slug flow and pressure fluctuations range is stable.Cycle length and pressure fluctuation increases rapidly while hydrodynamic severe slugging occurs,and as gas velocity continues increasing,cycle length and pressure fluctuation amplitude will decrease until severe slug flow phenomenon disappears.