Simulation on Sound Field of Leakage Below Fluid Level in Annulus of Gas Well
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 characteris-tics 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.
gas welltubing leakbelow fluid levelleak sound wavegas-liquid two-phase flowsound fieldflow field
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