Experimental Study On Characteristics Of Acoustic Propagation In Gas Content With Different Cross Sections Within Marine Riser

Deepwater oil and gas exploration and development is an important trend in energy development.However,there are many risks and challenges in drilling engineering for deepwater oil and gas development.How to realize early monitoring of deepwater drilling gas intrusion,reduce and avoid gas intrusion and even blowout accidents during drilling.It is the focus and difficulty of deepwater drilling well control.An ultrasonic probe was installed at the bottom of the submarine riser,and the ultrasonic transmission method was used to study the propagation law of sound waves in the air-liquid two-phase flow of the riser ring,and the experimental research method for early monitoring of gas intrusion was realized.Firstly,the experimental device for ultrasonic gas intrusion monitoring of the riser used to simulate the monitoring of gas intrusion in deep water drilling is established and improved.The experimental device can study the gas-liquid two-phase of acoustic signals under different intake air,drill pipe speed and liquid flow rate.The law of propagation in the stream.Then,since the acoustic wave received signal obtained by the experiment contains a lot of noise,it is not conducive to analyzing the law of sound wave propagation,so the noise-reducing signal is effectively denoised.Secondly,the time-frequency analysis of the wanted signal after noise reduction is carried out,and the relationship between the ultrasonic characteristic parameters and the intake air amount is analyzed.At the same time,the influence of drill pipe drilling speed and circulating liquid flow rate on the characteristic parameters of acoustic signals is studied.Finally,a quantitative representation relationship between the characteristic parameters of the ultrasonic signal and the intake air amount is established,and the relationship is tested.Acoustic wave receiving noisy signals under different intake air volume,drill pipe speed and circulating liquid flow rate were obtained by using the ultrasonic gas intrusion monitoring experimental device of the riser.The research results show that the signal-to-noise ratio and root mean square error are used as the measurement standard,and the wavelet threshold denoising method is used to denoise the noisy signal to obtain ideal noise reduction effect.By analyzing the time-frequency analysis of the acoustic signal,it is found that the ultrasonic sensitivity characteristic parameters of the gas-liquid two-phase flow mainly include the peak amplitude of the acoustic wave,the attenuation coefficient,the wave velocity and the main frequency.There is a nonlinear relationship between the amplitude peak and the main frequency and the intake air amount,and there is an approximately linear relationship between the attenuation coefficient and the wave speed and the intake air amount.By using the least squares multiple regression analysis of attenuation coefficient,wave velocity,main frequency and intake air quantity,the quantitative relationship between ultrasonic characteristic parameters and intake air quantity is obtained.The relationship is verified by experiments,which shows that the relative error between the actual air intake of 86.4% in the test data set and the theoretical intake air calculated by the quantitative relationship is less than 10%.