Beam-angled Transducer Array for Formation Acoustic Measurement
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Solution Overview
Problem
Conventional borehole logging methods face limitations in measurement resolution, sensitivity, and energy efficiency, particularly in detecting formation properties like compressional and shear velocities, due to low-frequency sonic logging tools and high-frequency ultrasonic pulse-echo methods, which struggle with signal attenuation and reflection sensitivity.
Innovation Solution
The method involves exciting ultrasonic critical refraction waves at different critical incident angles to measure formation compressional and shear velocities, using a transmitter array to focus and steer beams at fluid-formation interfaces, and a receiver array to detect these waves, enhancing energy conversion and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If low-frequency sonic logging tools are used, then measurement depth is improved, but measurement resolution and sensitivity deteriorate
Solution Approach 1:
The patent segments the acoustic measurement process by using multiple transducer arrays (transmitters and receivers) positioned at different locations along the borehole. This segmentation allows low-frequency waves to propagate deep while maintaining measurement resolution through distributed sensing across multiple elements, resolving the contradiction between measurement depth and resolution.
Solution Approach 2:
The patent transitions from traditional single-point measurements to distributed measurements along the borehole axis by positioning multiple transducers at different depths. This dimensional extension allows simultaneous achievement of deep measurement capability and high resolution through spatial distribution of measurement points.
2Measurement precision
If high-frequency ultrasonic pulse-echo methods are used, then measurement resolution is improved, but signal attenuation and reflection sensitivity worsen
Solution Approach 1:
The patent introduces borehole fluid as an intermediary medium that couples the ultrasonic energy from transmitters to the formation. This fluid coupling mechanism efficiently transfers high-frequency energy while minimizing attenuation, allowing high-resolution measurements without excessive energy loss. The fluid acts as an acoustic waveguide that preserves signal integrity.
Solution Approach 2:
The patent optimizes the frequency parameter of the ultrasonic signals to balance resolution and attenuation. By selecting specific frequency ranges and adjusting signal parameters, the system achieves high measurement resolution while controlling energy loss through parameter optimization rather than simply using the highest possible frequencies.
3Device complexity
If conventional acoustic sources are used, then device simplicity is improved, but energy efficiency and sensitivity deteriorate
Solution Approach 1:
The patent employs dynamic beam steering and focusing capabilities in the transducer arrays, allowing the acoustic energy to be dynamically directed toward specific formation zones. This dynamic control optimizes energy efficiency by concentrating acoustic power where needed rather than radiating uniformly, improving sensitivity without requiring proportionally higher energy input.
Solution Approach 2:
The transducer arrays serve multiple functions: they act as both transmitters and receivers, can perform both conventional logging and imaging operations, and enable various measurement modes (reflection, refraction, transmission). This multi-functionality improves energy efficiency by using the same hardware for multiple purposes rather than requiring separate dedicated systems for each function.
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 provides finer measurement resolution, higher sensitivity, and better energy efficiency, enabling more accurate determination of formation properties such as compressional and shear velocities, porosity, and fracture detection.
Implementation Method 1
exciting at a first borehole depth at least one critical refraction wave by steering an acoustic beam transmitted by at least one ultrasonic transmitter to an interface in the formation to intercept the interface at a critical angle
Implementation Method 2
The at least one critical refraction wave excited by the acoustic beam comprises at least one of: i) a compressional head wave; ii) a shear head wave
Data Source
AI summary
Methods and apparatus for performing formation evaluation in a borehole intersecting an earth formation. Methods may include exciting at a first borehole depth at least one critical refraction wave by steering an acoustic beam transmitted by at least one ultrasonic transmitter to an interface in the formation to intercept the interface at a critical angle; receiving an acoustic signal comprising critical refraction wave data at a logging tool in the borehole; and obtaining a wave property measurement from the critical refraction wave data. The interface may be the borehole wall in an open-hole well or behind casing. Methods include using ultrasonic transmitter(s) to generate the plurality of acoustic beams, identifying critical refraction wave data within the response signal corresponding to the at least one critical refraction wave, and obtaining the wave property measurement from the critical refraction wave data.