Ultrasonic Borehole Imaging for Azimuthal Formation Classification
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Solution Overview
Problem
Conventional acoustic logging measurements lack azimuthal sensitivity, particularly in monopole measurements, and existing ultrasonic logging techniques provide limited azimuthal sensitivity and do not enable effective azimuthal imaging of subterranean formations.
Innovation Solution
The use of ultrasonic logging tools with pulse-echo and pitch-catch sensors to measure azimuthal shear and compressional slowness images, allowing classification of formations as homogeneous or heterogeneous, and distinguishing between stress-induced and intrinsic anisotropy, while drilling, using ultrasonic transducers and receivers deployed on a logging tool body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional monopole acoustic logging measurements are used, then the logging tool structure is simple and easy to operate, but the azimuthal sensitivity is insufficient and cannot provide accurate formation classification
Solution Approach 1:
The ultrasonic logging tool is segmented into multiple functional components: a monopole source for general acoustic measurements, and multiple dipole sources arranged in different azimuthal orientations for directional sensitivity. This segmentation allows the system to achieve both simple monopole operations and complex azimuthal imaging capabilities simultaneously
Solution Approach 2:
The logging tool is designed with multi-functionality to perform both conventional monopole acoustic logging and advanced dipole azimuthal imaging using the same tool body. The tool can operate in different modes (monopole-only, dipole-only, or combined) depending on the measurement requirements, making it universally applicable to various logging scenarios
2Measurement precision
If dipole and quadrupole waveforms are used for azimuthally sensitive measurements, then some azimuthal sensitivity is achieved, but the capability for comprehensive azimuthal imaging is limited
Solution Approach 1:
The invention transitions from conventional single-plane dipole measurements to three-dimensional azimuthal imaging by incorporating dipole sources in multiple azimuthal orientations (e.g., 0°, 45°, 90°, 135°). This dimensional expansion enables comprehensive characterization of formation properties in all azimuthal directions, providing true 3D imaging capability
Solution Approach 2:
The logging tool uses a composite measurement approach combining monopole and multiple dipole waveforms to create a composite data set. This composite approach leverages the strengths of each waveform type: monopole for general formation properties and dipoles for directional information, achieving comprehensive azimuthal imaging that neither waveform could provide alone
3Measurement precision
If conventional acoustic logging is used, then the logging process is fast and efficient, but the formation classification accuracy is insufficient for complex formation types
Solution Approach 1:
The logging tool performs preliminary classification of formation types using快速 monopole measurements first, then selectively applies more time-consuming dipole azimuthal imaging only in intervals where complex formations are detected or where high accuracy is required. This preliminary action approach optimizes the balance between speed and accuracy
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
Enables accurate classification of subterranean formations during drilling, providing valuable information for borehole stability analysis and subsequent fracturing operations, and enhances the precision of ultrasonic measurements in identifying and characterizing the formation of the formation.
Implementation Method 1
An ultrasonic transducer and an array of spaced apart ultrasonic receivers
Implementation Method 2
an array of spaced apart ultrasonic receivers deployed on a logging tool body
Data Source
AI summary
A method for classifying a subterranean formation includes rotating an ultrasonic logging tool in a borehole penetrating a formation. The ultrasonic logging tool includes an ultrasonic transducer and an array of spaced apart ultrasonic receivers deployed on a logging tool body. The ultrasonic logging tool measures an azimuthal shear slowness image and an azimuthal compressional slowness image while rotating in the borehole. The images are evaluated to classify the homogeneity/heterogeneity and isotropy/anisotropy of the formation.