Vibration and horizontal directivity analysis of transmitting transducer for acoustic logging while drilling. (2nd July 2021)

• Record Type: Journal Article
• Authors: Gou, Yang; Fu, Xin
• Is Part Of: Journal of geophysics and engineering. Volume 18:Number 3(2021)
• Page Start: 379
• Page End: 391
• Publication Date: 2021-07-02
• Subjects: acoustic LWD piezoelectric transducer -- coupled vibration resonance frequency equation -- acoustic logging while drilling -- numerical simulation; Geophysics -- Periodicals; Prospecting -- Geophysical methods -- Periodicals; Engineering -- Periodicals; 622.1505
• DOI: 10.1093/jge/gxab021
• Languages: English
• ISSNs: 1742-2132

Abstract

Abstract: Radially polarized open-cylindrical piezoelectric transducers are widely used in the field of acoustic logging while drilling (LWD). Unlike the wireline logging transducer, the structure of the acoustic LWD transducer is an open structure; in this case, its radial vibration is accompanied by apparent circumferential vibration. In this paper, based on the two-dimensional wave equations and electrostatic charge equation, according to the free boundary conditions of the transducer, the resonance frequency equation of radial-circumferential coupled vibration for the acoustic LWD transducer is obtained. The vibration modal and resonance frequency for transducers of several typical sizes are simulated using COMSOL software. The results show that when the geometrical size of the transducer satisfies certain conditions, the theoretical calculation and the numerical analysis are in good agreement and the relative error is controlled below 3%. Meanwhile, the horizontal directivity of the LWD transducer after actual installation is discussed, and it is found that adding appropriate coupling materials can improve the monopole sound field radiation. So, it is expected that this work can serve as a reference for the acoustic LWD transducer design and install.