Phased Array Transducer Module for Mud Velocity Measurement
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Solution Overview
Problem
Current ultrasonic downhole imaging tools face inaccuracies in determining the mud propagation velocity (V mud) due to unknown or varying outer diameter and wall thickness of the casing, leading to inaccuracies in acoustic impedance measurements, especially in cased boreholes where assumptions introduce errors.
Innovation Solution
A phased array transducer module that emits a circular wavefront and measures the propagation time between transducers to directly determine V mud, using geometric parameters and arrival times of acoustic signals to calculate the velocity independently of casing dimensions, and subsequently determines guided wave velocities in the casing to infer bulk material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic imaging tools use conventional methods to determine mud propagation velocity, then the measurement process is simplified, but measurement precision deteriorates due to unknown or varying casing dimensions
Solution Approach 1:
The patent introduces an intermediary approach by using the casing itself as a reference medium. Instead of directly measuring mud velocity through the complex path involving unknown casing dimensions, the system measures guided wave velocities in the casing (which can be determined more reliably) and uses these as intermediaries to infer bulk material properties and correct the mud velocity measurements, thereby resolving the measurement precision issue without requiring precise knowledge of casing geometry
Solution Approach 2:
The system implements feedback by using the measured guided wave velocities in the casing to continuously refine and correct the mud propagation velocity measurements. The guided wave measurements provide feedback information about the actual casing properties, which is then used to adjust and improve the accuracy of the mud velocity determination, creating a self-correcting measurement system that overcomes the initial precision problems
2Measurement precision
If ultrasonic imaging tools assume fixed casing dimensions, then device complexity is reduced, but measurement precision deteriorates due to varying actual dimensions
Solution Approach 1:
The system applies self-service by using the casing structure itself to provide the measurement references needed. The guided wave propagation in the casing automatically provides information about the actual casing dimensions and properties, eliminating the need for external dimensional measurement devices. The casing serves its own structural function while simultaneously providing the reference data needed for accurate acoustic impedance measurements
Solution Approach 2:
The patent changes the measurement parameters from direct geometric dimension measurements to acoustic property measurements. Instead of measuring outer diameter and wall thickness directly (which requires complex dimensional measurement systems), the system measures acoustic velocities and uses these parameter changes to calculate acoustic impedance, thereby achieving high measurement precision without complex dimensional measurement equipment
3Measurement precision
If the tool measures multiple acoustic parameters, then measurement precision improves, but loss of time increases due to multiple measurement steps
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated acoustic measurement process. By simultaneously measuring both the mud propagation velocity and the guided wave velocities in the casing during the same ultrasonic imaging operation, the system obtains multiple acoustic parameters without requiring separate measurement steps, thereby improving measurement precision for bulk material properties while minimizing time loss through combined measurements
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 method provides accurate and independent measurements of V mud and guided wave velocities, enhancing the accuracy of acoustic impedance calculations and reducing errors associated with casing dimensions, allowing for precise characterization of borehole environments.
Implementation Method 1
emit an acoustic signal into a fluid surrounding a tool and record arrival times of the acoustic signal at multiple transducers
Implementation Method 2
measures the propagation time between transducers to directly determine Vmud
Implementation Method 3
determining a velocity of the guided wave in the casing
Implementation Method 4
enhancing the accuracy of acoustic impedance calculations
Data Source
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AI summary
Methods and apparatus for automatic recognition of environmental parameters with azimuthally distributed transducers. For example, a toolstring is disposed in a cased portion of a borehole penetrating a subsurface formation. The toolstring comprises a module comprising azimuthally distributed acoustic transducers each operable to emit and receive acoustic signals. The module is operated to emit an acoustic signal into fluid surrounding the module in the casing and record data indicative of receipt, by a plurality of the transducers, of acoustic waveforms resulting from interaction of the emitted acoustic signal with the casing, including at least a non-specular diffraction head wave excited by a guided wave that is excited by diffraction of the acoustic signal propagating in the casing metal. Acoustic velocity of the guided wave in the casing metal is determined utilizing the recorded data and geometric parameters of the module.