Transient two-phase flow behavior in wellbores and well control analysis for sour gas kick with high H₂S content

Complex two-phase flow phenomena in wellbores after sour gas kick may lead to severe well control incidents. By bridging the solubility, H2S phase transition and equations, a model is established under conditions of transient non-isothermal states wellbores, which validated against experimental data. The following conclusions are drawn article: (1) higher dissolved quantity larger density invaded containing CH4 drilling fluids makes detection influx with high content more difficult at an early stage; (2) when mixed move up wellhead, release gas, sharp decline reduce annulus pressure induce complicated risks; (3) during influx, there five major parameters that impact bottom-hole pressure, evaluated for analysis. proposed shows strong capacity exhibit proper wellhead back can help prevent risks control.