Mixed Dipole–Quadrupole Transducers for Reflected Shear-Wave Imaging
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Solution Overview
Problem
Traditional methods for reflection sonic imaging of formation structural changes away from the borehole suffer from strong borehole modes that bury or 'wash out' desired reflected signals due to using the same type of transmitter and receiver for reflected horizontal shear wave imaging.
Innovation Solution
Implementing a hybrid transmitter and receiver combination, such as a dipole transmitter and quadrupole receiver, to suppress borehole guided waves and enhance the detection of reflected signals by utilizing different types of transmitters and receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the same type of transmitter and receiver are used for reflected horizontal shear wave imaging, then the imaging method is simple and easy to implement, but the strong borehole modes bury and wash out the desired reflected signals
Solution Approach 1:
The patent applies asymmetry by using different types of transmitters and receivers (e.g., dipole transmitter with quadrupole receiver, or quadrupole transmitter with dipole receiver) instead of identical pairs. This asymmetric configuration creates different radiation and reception patterns that are specifically optimized to suppress borehole modes while enhancing reflected signal detection, thereby resolving the contradiction between operational simplicity and measurement precision.
2Device complexity
If strong borehole modes are present in the signal, then the transmitter-receiver configuration is straightforward, but the desired reflected signals are buried and washed out
Solution Approach 1:
The patent applies local quality by optimizing the radiation and reception patterns of specific transmitter and receiver types at different locations. The dipole or quadrupole configuration creates localized directional sensitivity that enhances reflected signals from specific formation directions while suppressing borehole modes, thus preventing information loss without overly complicating the overall device configuration.
3Measurement precision
If mixed types of transmitters and receivers are used, then borehole guided waves are suppressed and reflected signals are enhanced, but the system complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing the different physical parameters (radiation patterns, reception patterns, polarization characteristics) of dipole and quadrupole transmitters and receivers. By selecting specific combinations of these parameters, the system achieves suppression of borehole modes and enhancement of reflected signals while managing system complexity through purposeful parameter selection rather than arbitrary complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the influence of borehole guided waves, improving the resolution and accuracy of formation imaging by enhancing the detection of reflected signals, particularly for horizontally-polarized shear formation body waves.
Implementation Method 1
transmit a sonic waveform into a formation... record a reflected wave as waveform data
Implementation Method 2
horizontally-polarized shear formation body waves
Data Source
AI summary
A borehole sonic logging tool and method for imaging. The borehole sonic logging tool may comprise a transmitter configured to transmit a sonic waveform into a formation, wherein the transmitter is a dipole, and a receiver configured to record a reflected wave as waveform data, wherein the receiver is a quadrupole. A method may comprise disposing a downhole tool into a borehole, selecting a frequency range for the transmitter to a horizontally-polarized shear formation body wave, broadcasting the sonic waveform as the horizontally-polarized shear formation body wave into the formation penetrated by the borehole with the transmitter, recording a reflected wave on the receiver as waveform data, wherein the reflected wave is the horizontally-polarized shear formation body wave reflected from a reflector, and processing the waveform data with an information handling system.