Broadband Electrical Impedance Matching of Transmitter Transducer for Acoustic Logging While Drilling Tool

To obtain qualified logging while drilling (LWD) data, a new acoustic LWD tool was designed. Its overall design is introduced here, including the physical construction, electronic structure, and operation flowchart. Thereafter, core technologies adopted in this tool are presented, such as dominant exciting wave bands of dipole source, a sine wave pulse excitation circuit, broadband impedance matching, and an intellectualized active reception transducer. Lastly, we tested this tool in the azimuthal anisotropy module well, calibration well, and normal well, working in the model of the cable, sliding eye, and logging while drilling. Experiments showed that the core technologies achieved ideal results and that the LWD tool obtained qualified data.

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Investigation of the high-frequency wavefield of an off-center monopole acoustic logging-while-drilling tool

Geophysics ◽

10.1190/geo2014-0426.1 ◽

2015 ◽

Vol 80 (4) ◽

pp. D329-D341 ◽

Cited By ~ 23

Author(s):

Hua Wang ◽

Guo Tao ◽

Michael C. Fehler

Keyword(s):

High Frequency ◽

Drilling Tool ◽

Acoustic Logging ◽

Logging While Drilling

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Initial Results from an Acoustic Logging-While-Drilling Tool

10.2118/36543-ms ◽

1996 ◽

Author(s):

John W. Minear ◽

Dale R. Heysse ◽

Paul M. Boonen

Keyword(s):

Drilling Tool ◽

Acoustic Logging ◽

Logging While Drilling ◽

Initial Results

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Investigation of collar properties on data-acquisition scheme for acoustic logging-while-drilling

Geophysics ◽

10.1190/geo2016-0016.1 ◽

2016 ◽

Vol 81 (6) ◽

pp. D611-D624 ◽

Cited By ~ 9

Author(s):

Hua Wang ◽

Mike Fehler ◽

Guo Tao ◽

Zhoutuo Wei

Keyword(s):

Low Frequency ◽

Shear Velocity ◽

P Wave ◽

Flexural Wave ◽

Drilling Tool ◽

P Waves ◽

Acoustic Logging ◽

Advanced Composite ◽

Acquisition Scheme ◽

Logging While Drilling

We have used the wavenumber integration, velocity-time semblance, and dispersion methods to investigate the influence of collar properties including velocities, density, and attenuation on acoustic logging-while-drilling wavefields. We have found that when the velocities of the collar wave and the P-wave of the formation are similar, they interfere. However, the interference disappears when the velocity difference increases. Having a collar with large velocities (especial large shear velocity) and density makes the direct P-velocity determination possible in a fast formation even without isolators. For a slow formation, the interference of the collar flexural wave with the formation flexural and leaky P-waves is slight for a dipole tool when collar velocities are large. For this case, the S velocity can be determined by the flexural formation wave at low frequency (approximately 2 kHz). Based on these observations, we propose that the measurement of the P- and S-velocities can be easier if the collar is made of an advanced composite material that has high compressional and shear velocities as well as density. This is a direct and easy change to implement and a new idea for an acoustic logging-while-drilling tool design.

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Detection of formation S-wave in a slow formation using a monopole acoustic logging-while-drilling tool

Geophysics ◽

10.1190/geo2017-0300.1 ◽

2018 ◽

Vol 83 (1) ◽

pp. D9-D16 ◽

Cited By ~ 3

Author(s):

Xinding Fang ◽

Arthur Cheng

Keyword(s):

Low Frequency ◽

Stoneley Wave ◽

Secondary Source ◽

S Wave ◽

Drilling Tool ◽

Acoustic Logging ◽

Modeling Analysis ◽

Logging While Drilling ◽

Refracted Waves ◽

Drill Collar

Acoustic logging-while-drilling (LWD) is a technology that is used to measure formation elastic properties during drilling. When the formation shear slowness is smaller than the borehole fluid slowness (i.e., fast formation), monopole logging can be used to obtain formation compressional and shear slownesses by measuring the corresponding refracted waves. In a slow formation in which the shear slowness is larger than the borehole fluid slowness, other logging methods, such as quadrupole LWD, are used instead for shear slowness measurement due to the lack of a fully refracted S-wave. Through modeling analysis, we find that the transmitted S-wave generated by a monopole LWD tool in a slow formation can be detected and used to measure the formation shear slowness. This phenomenon can be explained by Huygens’ principle, which states that every point on a wavefront can be considered as a secondary source that induces particle motion. It is hard to discern the transmitted S-wave in monopole wireline data because it strongly interferes with the Stoneley mode in wireline logging. However, the transmitted S-wave decouples from the Stoneley in the LWD environment because the drill collar slows down the low-frequency part of the Stoneley mode. The nondispersive nature of the transmitted S-wave makes it suitable for shear slowness extraction using time semblance analysis, but sophisticated signal preprocessing might be needed because this wave is generally weak compared with the Stoneley wave. Moreover, our study helps us better understand how the Stoneley mode behaves and interferes with other modes in a slow formation under LWD conditions.

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