Acoustic Dipole Waveform Generator for Borehole Logging
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Solution Overview
Problem
Existing dipole acoustic logging tools face challenges in generating sufficient output pressure for effective acoustic logging in large diameter boreholes and formations with low velocities, leading to high acoustic noise levels and limited signal-to-noise ratios.
Innovation Solution
An acoustic dipole waveform generator with a hollow housing and length-changeable actuator elements, such as piezoelectric or magnetostrictive actuators, that amplify the motion of piston members to increase surface velocity and output pressure, allowing for improved signal-to-noise ratios and deeper penetration of acoustic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional dipole acoustic logging tools are used, then the device complexity is kept simple, but the output pressure is insufficient for effective acoustic logging in large diameter boreholes and low velocity formations
Solution Approach 1:
The waveform generator is divided into multiple independent actuator elements (first and second actuator elements) that can be independently controlled. Each actuator element generates pressure waves that combine to create the dipole waveform pattern, allowing complex pressure profiles to be achieved through coordinated operation of simpler individual components.
Solution Approach 2:
The patent employs dynamically adjustable actuator elements that can change their operational characteristics in real-time. The actuator elements are controlled to produce different pressure amplitudes and timing patterns, enabling the system to adapt to varying borehole conditions and optimize output pressure for different geological formations.
2Measurement precision
If conventional acoustic logging methods are used, then the device operation is straightforward, but the signal-to-noise ratio is limited in large diameter boreholes and low velocity formations
Solution Approach 1:
The actuator elements operate in periodic cycles with controlled timing intervals. The first and second actuator elements are activated in sequence or simultaneously depending on the desired waveform pattern, creating periodic pressure waves that enhance signal detection. This periodic operation allows for optimized signal generation while maintaining manageable system control.
Solution Approach 2:
The system dynamically adjusts operational parameters including actuator activation timing, pressure amplitude, and waveform frequency to optimize the signal-to-noise ratio. By changing these parameters based on detected formation characteristics and borehole conditions, the system achieves improved measurement precision while maintaining ease of operation through automated parameter optimization.
3Length of stationary object
If conventional acoustic wave generation is used, then the device structure is simple, but the depth of investigation is limited due to insufficient output pressure
Solution Approach 1:
The dipole waveform generation employs asymmetric pressure distribution through the first and second actuator elements positioned at different locations and activated with different timing. This asymmetric operation creates directional pressure waves that penetrate deeper into the formation, extending the depth of investigation while the underlying symmetric housing and modular actuator design keep the overall device structure relatively simple.
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
The solution enhances the signal-to-noise ratio and increases the depth of investigation in acoustic logging, providing clearer geological data even in challenging formations and borehole conditions.
Implementation Method 1
length-changeable actuator elements, such as piezoelectric or magnetostrictive actuators
Implementation Method 2
length-changeable actuator elements, such as piezoelectric or magnetostrictive actuators
Implementation Method 3
each generate a respective pressure wave and the hollow housing permitting transmission of each said pressure wave externally of the acoustic waveform generator
Data Source
AI summary
An acoustic dipole waveform generator has a hollow housing defining an elongate axis and having secured therein at least a force reaction member defining at least a force reaction surface and having hingingly secured thereto an actuator element. The piezoelectric actuator elements define mutually non-aligned length change axes and extend from the reaction member towards at least one moveable piston member hingingly secured to at least one of the actuator elements inside the housing. The piston member is constrained to move in a direction extending perpendicular to the axis, the piston member defining respectively at mutually spaced locations in the housing a pair of heads that, on movement of the piston member, each generate a respective pressure wave and the housing permitting transmission of the wave externally thereby permitting generation of a dipole pressure waveform externally of the housing on changing of the lengths of the actuator elements.