Experimental study on ultrasonic wave propagation characteristics of gas-liquid two-phase flow in riser annulus

Abstract

Deepwater drilling projects face challenges such as delays in gas kick monitoring and a high risk of well control failure. How to monitor gas kicks as early and accurately as possible is one of the keys to preventing significant accidents such as well blowouts. Monitoring gas kicks at risers is a promising method for early monitoring of gas kicks in deepwater drilling. In this paper, by constructing an experimental device for ultrasonic gas kicks monitoring of the riser, the response law of the ultrasonic signal to the gas-liquid two-phase flow was tested under different air intake, drill pipe rotation speeds, and liquid flow rates. This was done by constructing an experimental riser ultrasonic gas kick monitoring device. The signal-to-noise ratio and the root-mean-square error are used as measurement standards, and the wavelet threshold noise reduction method is used to reduce noise-containing signals. The ultrasonic sensitivity characteristics of the gas-liquid two-phase flow are demonstrated by analyzing the signal in the time domain and frequency domain: peak amplitude, attenuation coefficient, wave velocity, and fundamental frequency. A non-linear relationship exists between peak amplitude, fundamental frequency, and air intake, whereas an approximately linear relationship is evident between the attenuation coefficient and wave velocity with air intake. A quantitative characterization relationship between ultrasonic characteristic parameters and air intake was obtained by conducting a multiple regression analysis using the least-squares method on the attenuation coefficient, wave velocity, fundamental frequency, and air intake. Experiments demonstrate that the relative error between the actual air intake of 86.4 % of the test data group and the theoretical air intake determined based on the quantitative characterization relationship is less than 10 %.