A Study On The Acoustic Measurement And Assessment Of Fluid Property In Pipes

With the rapid development of national economy,the demand for energy resources is increasing dramatically,and the exploitation of marine oil and gas resources has become a significant way to solve the current problem of energy resources.Because of the particularity of the ocean drilling,the existence of marine shallow gas may cause a serious blowout,which has been a technical problem in current ocean drilling.Based on the well control of the ocean drilling,this study adopts one annular acoustic emission transducer and multiple annular receiving transducers,with which the Lamb wave is generated and received on the outside of solid pipes.The response characteristics of the amplitude and attenuation of Lamb wave are the main problems to be analyzed while the gas content changes.Regarding to the numerical algorithm,FDTD is used to realize the numerical simulation of Lamb wave propagation in pipes.The Fortran is adopted to realize the program,in which the velocity-stress staggered finite difference grid is applied.Besides,the Convolutional Perfectly Matched Layer(CPML)is adopted to deal with the problem of boundary,which can obviously absorb the wave,and at the same time save memory with its simple format.For the purpose of avoiding the distortion of acoustic wave signal,the simulation utilizes a hard source to generate the sound wave,which is more similar to the real source,and more easy to realize as well.The conclusions are drawn as follows: if the solid pipe is filled with liquid alone,S0 mode of Lamb wave and its reflection waveform can be received,and A0 mode of Lamb wave is not able to be observed apparently.When gas flows in the pipe,for both modes of Lamb wave,a drastic change can be detected in amplitude and attenuation.While the gas content continues to improve,the amplitude of S0 mode of Lamb wave drops almost linearly.This study can provide a reference value for the application of Lamb wave in well control of ocean drilling.