气井环空液面下泄漏声场模拟

Simulation on Sound Field of Leakage Below Fluid Level in Annulus of Gas Well

气井油套管环空液面下泄漏声波的产生及传播机理一直备受关注。为研究液面下泄漏声波声源特性,建立了井下油套管环空泄漏物理模型,联合STAR-CCM+软件对环空液面下气体泄漏状态进行了流场及声场的仿真分析,得到了泄漏流场的压力和相态云图及不同泄漏孔径、泄漏位置和泄漏速度下的声压频率曲线。研究结果表明:随着泄漏速度升高,泄漏气流冲击管壁且液面震荡剧烈,液面下泄漏声源主要以四极子声源为主;液面上泄漏声源主要由液面震荡破裂及液面下四极子声源共同产生,泄漏声波能量的主要频率分布在0~100 Hz区间;在单一变量条件下,泄漏声压级随泄漏孔径、泄漏速度及泄漏位置距底部距离的增大而增大。研究结果可为在井口应用声波法检测液面下泄漏奠定理论基础。

The generation and propagation mechanism of sound waves of leakage below fluid level in tubing-casing annulus of gas wells have always been of great concern.In order to study the sound wave source characteristics of leakage below fluid level,a physical model for downhole tubing-casing annulus leakage was built;then,the STAR-CCM+ software was used to conduct simulation analysis of flow field and sound field on gas leakage state below annular fluid level,and obtain the cloud charts for pressure and phase of leak flow field as well as sound pressure frequency curves under different leak apertures,positions and speeds.The study results show that as the leak speed increases,the leak gas flow impacts the pipe wall and the fluid level oscillates violently;the leak sound source below fluid level is dominated by quadrupole sound source;the leak sound source above fluid level is mainly generated by the oscillation rupture of fluid level and the quadrupole sound source below fluid level,and the main distribution frequency of leak sound wave energy is in the range of 0~100 Hz;under single variable conditions,the leak sound pressure level increases with the increase of leak aperture and speed as well as the distance from leak position to bottom.The study results lay a theoretical foundation for the application of acoustic method to detect leakage below fluid level at the wellhead.