Analysis of infrasound measurement of liquid levels during drilling: a numerical study

While drilling, in order to realize the early monitoring of overflow,it is necessary to measure the liquid level depth in the wellbore in real time. At present, echo ranging is the most commonly used liquid level monitoring method. Based on COMSOL software, this paper simulates the echo monitoring process of drilling fluid level. This model couples 1D pipeline acoustics with 3D pressure acoustics, and used parametric modeling. Using the control variable method, the effects of acoustic wave frequency, excitation pressure, pipeline pressure, liquid surface depth, and other factors on the echo signal were compared and analyzed. The results show that the sound wave frequency has an optimum value in a specific pipeline system, and after this value, the higher the frequency, the faster the signal attenuation; The higher the excitation pressure, the stronger the echo signal can be obtained, which can significantly improve the ranging range; If the liquid surface depth is too shallow, the excitation wave and the echo overlap, which will lead to difficulty in later identification; If the liquid level is too deep, the echo is weak, which is lower than the sensitivity of the equipment. It provides a new method and idea for the analysis of the infrasound propagation mechanism of drilling fluid level monitoring.