Borehole Transducer Orientation for P-Wave Anisotropy
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Solution Overview
Problem
Current methods for determining anisotropic seismic velocities in earth formations face challenges due to poor data quality and low frequencies in surface seismic data, making it difficult to accurately account for directional changes in compressional wave velocity, especially in complex subsurface structures like those with shale or sandstone layers.
Innovation Solution
A method and apparatus using a logging tool with a transducer that measures impedance changes at various orientations within a borehole, allowing for the estimation of absolute compressional wave velocities and anisotropic elastic properties, enabling the determination of seismic velocities as a function of propagation angle through calibration measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If surface seismic data is used for determining anisotropic velocities, then data coverage is improved, but measurement precision deteriorates due to poor data quality and low frequencies
Solution Approach 1:
The patent uses borehole measurements as an intermediary to obtain high-precision anisotropic velocity data, which then serves to improve and calibrate the lower-quality surface seismic data. The borehole measurements act as a mediator that bridges the gap between low-precision surface data and the need for accurate velocity modeling.
Solution Approach 2:
The patent changes the measurement parameters by transitioning from surface-level seismic data to borehole-based acoustic measurements. This parameter change involves moving from low-frequency, low-precision surface data to high-frequency, high-precision borehole data, enabling accurate determination of P-wave velocities at different angles.
2Measurement precision
If conventional wireline logging is used for velocity measurement, then measurement precision is improved, but device complexity increases due to multiple borehole requirements
Solution Approach 1:
The patent makes a single logging tool multi-functional by equipping it with transducers that can measure acoustic properties in multiple orientations. The tool can determine both vertical and horizontal P-wave velocity components, as well as anisotropic parameters, through a single deployment, eliminating the need for multiple specialized tools or boreholes.
Solution Approach 2:
The logging tool incorporates dynamically adjustable transducer orientations that can be rotated or repositioned during measurement. This dynamic capability allows the same tool to measure velocities at different angles (0°, 45°, 90°) without requiring multiple static tool configurations or separate measurement campaigns.
3Ease of operation
If traditional acoustic logging is used in vertical boreholes, then measurement simplicity is maintained, but measurement precision deteriorates for anisotropic formations
Solution Approach 1:
The patent transforms the static vertical borehole measurement into a dynamic multi-orientation measurement system. The logging tool can rotate or reposition transducers to measure acoustic properties at multiple angles relative to the borehole axis, enabling precise characterization of anisotropic formations while maintaining the simplicity of single-borehole operation.
Solution Approach 2:
The patent adds an angular dimension to the traditional vertical borehole measurement. Instead of only measuring along the vertical axis, the system incorporates angular measurements at different orientations (0°, 45°, 90°) within the borehole, transforming a one-dimensional measurement into a multi-dimensional characterization of formation properties.
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 high-quality data for anisotropic velocity modeling, improving the accuracy of depth imaging by accounting for directional variations in seismic velocities, enhancing the quality of subsurface structure imaging.
Implementation Method 1
Relative changes in impedance of the formation with orientation are estimated from the measurements
Data Source
AI summary
Measurements of impedance are made using a piezoelectric transducer oriented at different angles to a formation bedding plane. The impedance measurements are then used to estimate the anisotropic velocity of the formation.