关键词: 深海, 油气集输, S形立管, 周期性, 持液率

Abstract: S-sharped riser, one of the main structures in deep-water gathering system, runs frequently into typical severe slug flow at small liquid and gas rates, which show a great destroy on downstream devices.In this work, the classification and flow characteristic of severe slug flow are studied.The result shows that:①Like in the L-shaped riser, the severe slug flow in S-shaped riser displays strict periodicity, and the formation process covers five stages, namely, liquid slug formation in down limb, liquid slug formation in up limb, liquid production, gas blowout stage and liquid fallback.②The cycle and liquid slug length of typical severe slug flow decrease with the increased gas and liquid rates.③The composition of fluid mixture doesn't make much difference on the performance of severe slug flow.④The hazard of severe slug flow goes up with the diameter or/and height of the riser; Once the severe slug flow occurs to the deep-water oil & gas large diameter gathering system, the overwhelming damage could take place.⑤The cycle of severe slug flow rise with the operating pressure of separator, which could cause a more serious consequences.

Key words: deep-water, gathering system, S-shaped riser, periodicity, liquid holdup