Study On Longitudinal Acoustical Properties Of Deepwater Drilling Riser

Drilling riser is an important part of deepwater drilling,it is important to study the acoustic propagation characteristics to explore new method of underwater information transmission and judge the state of the riser.This paper focus on the propagation characteristics of longitudinal wave in the riser,establishes a periodic riser model and analyses different boundary conditions.The main contents are as follows: Firstly,the influence of different sizes of periodic water diversion pipe on the acoustic transmission characteristics is analyzed by using the dispersion analysis method on the basis of the periodic structure model.The results show that the change of the parameters of the single pipe and the joint has a significant effect on the acoustic characteristics and frequency distribution of the riser.The acoustic signal can be transmitted to the receiver at the current drilling depth Secondly,the characteristics of sound waves in different media inside and outside the riser are studied.The results show that the water damping has little effect on the sound wave characteristics of the riser,and the drilling fluid has obvious blocking effect on the acoustic transmission,the influence of water to the medium on the frequency distribution is small,but the drilling fluid has a strong effect on the high frequency signal,and the obstruction effect increases with the increase of the viscosity of the drilling fluid.Thirdly,the influence of the axial force on the acoustic characteristics of the riser under the actual working conditions is analyzed,the results show that the axial force increases the small vibration of the receiving end of the riser,it has a more obvious shock in a pass band spectrum curve,sound transmission performance got worse.Current is the main factor of the bottom support force,greater current velocity is more detrimental to the transmission of acoustic signals...