scholarly journals Vibration and horizontal directivity analysis of transmitting transducer for acoustic logging while drilling

2021 ◽  
Vol 18 (3) ◽  
pp. 379-391
Author(s):  
Yang Gou ◽  
Xin Fu
Keyword(s):  
Resonance Frequency ◽  
Wave Equations ◽  
Sound Field ◽  
Frequency Equation ◽  
Acoustic Logging ◽  
Field Radiation ◽  
Transducer Design ◽  
Logging While Drilling ◽  
Vibration Modal ◽  
Radially Polarized

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.

scholarly journals Metal rings and discs Matlab/Simulink 3D model for ultrasonic sandwich transducer design

2012 ◽  
Vol 44 (3) ◽  
pp. 287-298 ◽  
Author(s):  
I. Jovanovic ◽  
D. Mancic ◽  
V. Paunovic ◽  
M. Radmanovic ◽  
V.V. Mitic
Keyword(s):  
Resonance Frequency ◽  
3D Model ◽  
Mechanical Impedance ◽  
Analytical Models ◽  
Resonant Frequencies ◽  
Matlab Simulink ◽  
Simulink Model ◽  
Metal Rings ◽  
Resonant Modes ◽  
Transducer Design

Metal-endings are integral part of different ultrasonic sandwich transducers. In this paper a new Matlab/Simulink 3D model of the finite metal rings and discs of various dimensions is realized. With this model, which describes both the thickness and the radial resonant modes, and the coupling between them, mechanical impedance of the sample can be easily computed. Resonance frequency-length curves for rings and disks with various materials and for different selected dimensions are given. Also, comparisons of the different approaches in determining of their resonant frequencies are shown. The proposed Matlab/Simulink model requires simpler implementation than other analytical models. That enabled modifying of 1D theory and simplified modelling and projecting of the ultrasonic sandwich transducers with short-endings. Finally, the computed and experimental results are compared.

Numerical Study on the Characteristics of Multipole Acoustic Logging While Drilling in Cracked Porous Medium

2014 ◽  
Vol 57 (4) ◽  
pp. 591-606 ◽  
Author(s):  
XU Song ◽  
SU Yuan-Da ◽  
CHEN Xue-Lian ◽  
TANG Xiao-Ming
Keyword(s):  
Porous Medium ◽  
Numerical Study ◽  
Acoustic Logging ◽  
Logging While Drilling

The design of a vibration transducer to monitor the integrity of dental implants

1998 ◽  
Vol 212 (4) ◽  
pp. 265-272 ◽  
Author(s):  
P Cawley ◽  
B Pavlakovic ◽  
D N Alleyne ◽  
R George ◽  
T Back ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Bone Loss ◽  
Bone Formation ◽  
Resonance Frequency ◽  
Beam Element ◽  
Titanium Implants ◽  
Missing Teeth ◽  
Transducer Design ◽  
Tissue Interface ◽  
Partially Dentate

Bone-anchored titanium implants are being used increasingly to provide support for prostheses replacing missing teeth in edentulous and partially dentate patients. A technique is required to monitor bone formation at the implant-tissue interface during healing, and also to check whether there has been bone loss from around the top of the implant. One possible method is to screw a beam into the implanted fixture and to measure the first flexural resonance frequency of the resulting system. This resonance frequency is affected by both the exposed length of fixture and the stiffness of the interface between the implant and the bone. This paper describes the design of a beam-like transducer for clinical trials of the technique. The sensitivity of the transducer resonance frequency to the changes of interest is dependent on the thickness and length of the beam element. However, the choice of these dimensions is constrained by the need to avoid closely spaced resonances. The performance of different transducer shapes and the influence of the thickness and length of the beam element in the transducer has been studied. The results have been used to finalize a transducer design for the clinical trials.

Measurement of the shear slowness of slow formations from monopole logging-while-drilling sonic logs

Geophysics ◽  
2019 ◽  
Vol 85 (1) ◽  
pp. D45-D52
Author(s):  
Yuanda Su ◽  
Xinding Fang ◽  
Xiaoming Tang
Keyword(s):  
Numerical Modeling ◽  
Wave Velocity ◽  
Fluid Velocity ◽  
S Wave ◽  
Data Set ◽  
Acoustic Logging ◽  
Wave Velocities ◽  
Logging While Drilling ◽  
Sonic Logs ◽  
Refracted Waves

Acoustic logging-while-drilling (LWD) is used to measure formation velocity/slowness during drilling. In a fast formation, in which the S-wave velocity is higher than the borehole-fluid velocity, monopole logging can be used to obtain P- and S-wave velocities by measuring the corresponding refracted waves. In a slow formation, in which the S-wave velocity is less than the borehole-fluid velocity, because the fully refracted S-wave is missing, quadrupole logging has been developed and used for S-wave slowness measurement. A recent study based on numerical modeling implies that monopole LWD can generate a detectable transmitted S-wave in a slow formation. This nondispersive transmitted S-wave propagates at the formation S-wave velocity and thus can be used for measuring the S-wave slowness of a slow formation. We evaluate a field example to demonstrate the applicability of monopole LWD in determining the S-wave slowness of slow formations. We compare the S-wave slowness extracted from a monopole LWD data set acquired in a slow formation and the result derived from the quadrupole data recorded in the same logging run. The results indicated that the S-wave slowness can be reliably determined from monopole LWD sonic data in fairly slow formations. However, we found that the monopole approach is not applicable to very slow formations because the transmitted S-wave becomes too weak to detect when the formation S-wave slowness is much higher than the borehole-fluid slowness.

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