Acoustic Logging Tool Eccentricity Compensation
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Solution Overview
Problem
Acoustic logging tools face challenges in maintaining data quality due to tool eccentricity within boreholes, particularly in varying diameters and irregular cross-sections, leading to waveform smearing and distortion, which existing methods like multiple receiver arrays or ultrasonic pingers are costly and unreliable.
Innovation Solution
An acoustic logging tool with a single receiver array at each axial spacing, using independent measurements to determine azimuthal orientation and firing the transmitter at 180-degree angles to average or sum responses, effectively compensating for tool eccentricity by mimicking centralized tool positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single receiver array is used in LWD tools, then device complexity is reduced, but measurement precision deteriorates due to tool eccentricity effects
Solution Approach 1:
The transmitter is fired periodically at two different azimuthal orientations (separated by 180 degrees) as the tool rotates in the borehole. By acquiring measurements at these periodic intervals and combining them, the system compensates for eccentricity effects while using a single receiver array, thus maintaining measurement precision without increasing device complexity
Solution Approach 2:
The system performs preliminary measurements at two different azimuthal orientations before combining the results. This preliminary action of acquiring data from multiple orientations allows the subsequent combination process to eliminate eccentricity effects, achieving high measurement precision with a simple single-array configuration
2Measurement precision
If multiple receiver arrays are used to compensate for tool eccentricity, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of using multiple simultaneous receiver arrays, the system uses a single array and fires the transmitter periodically at different azimuthal orientations. The measurements taken at these different orientations are then combined to achieve the same eccentricity compensation that multiple arrays would provide, but with reduced device complexity
Solution Approach 2:
The system effectively creates a virtual copy of the measurement process by firing the transmitter at two different azimuthal orientations and combining the results. This copying approach simulates the effect of having multiple receiver arrays without actually duplicating the hardware, thus reducing device complexity while maintaining measurement precision
3Measurement precision
If ultrasonic pingers are used to measure tool standoff, then measurement precision is improved, but device complexity and operational reliability worsen
Solution Approach 1:
The system extracts the eccentricity compensation capability from the acoustic measurement process itself by using azimuthally spaced transmitter firings. This eliminates the need for separate ultrasonic pinger systems, reducing device complexity while maintaining measurement precision through the inherent geometry of the acoustic measurements
Solution Approach 2:
The acoustic transmitter and receiver system performs multiple functions: it measures formation acoustic properties and simultaneously determines tool eccentricity through azimuthal orientation measurements. This multi-functionality eliminates the need for separate ultrasonic pinger systems, improving operational reliability while maintaining measurement precision
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 reduces tool eccentricity effects, maintaining data coherence and quality without the need for multiple receiver arrays or ultrasonic pingers, enhancing operational reliability and reducing costs.
Implementation Method 1
A portion of the energy emitted by the one or more transmitters propagates through formation material surrounding the borehole, and is subsequently detected by the one or more receivers
Implementation Method 2
Another system embodied to reducing tool eccentricity effects comprises a plurality of single acoustic receiver arrays combined with an ultrasonic transducer or 'pinger'
Data Source
AI summary
A system for measuring an acoustic property of material penetrated by a well borehole. The system uses a borehole logging tool comprising preferably one acoustic transmitter and preferably a plurality of acoustic receivers. An independent measurement is used to determine azimuthal orientation of the tool within the borehole. Firings of the transmitter are based upon azimuthal orientation of the tool. Receiver responses resulting from preferably a plurality of transmitter firings per tool revolution are combined to form at least one composite transmitter response. The composite receiver response is compensated for adverse effects of the tool operating eccentered within the borehole.