Rotating Antenna Coupling Matrix Measurement Tool
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Solution Overview
Problem
Electromagnetic resistivity logging tools face challenges in accurately measuring formation resistivity, anisotropy, dip, and strike angles due to complex interactions and the need for multiple antenna orientations, which can increase costs and reduce measurement reliability.
Innovation Solution
The use of an azimuthally sensitive antenna configuration that rotates to obtain a complete antenna coupling matrix with fewer antenna orientations, allowing for the measurement of formation resistivity, anisotropy, dip, and strike angles, and enabling geosteering by combining coupling matrix values with orientation information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple antenna orientations are used to measure formation resistivity, anisotropy, dip, and strike angles, then measurement completeness is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs a rotating antenna assembly that dynamically changes its orientation during logging operations. The antenna configuration rotates through multiple angular positions (e.g., 0°, 45°, 90°, 135°) to collect coupling matrix data from different orientations, eliminating the need for multiple fixed antenna arrays. This dynamic approach achieves complete formation parameter measurements while reducing device complexity.
Solution Approach 2:
The antenna assembly performs periodic rotation through discrete angular positions to systematically collect electromagnetic coupling data. By rotating through specific angles and measuring at each position, the system accumulates sufficient data to calculate all formation parameters (resistivity, anisotropy, dip, strike) using periodic sampling, thereby reducing the number of antennas required compared to continuous multi-orientation systems.
2Reliability
If multiple antenna orientations are used to measure formation parameters, then measurement reliability is improved, but the number of antennas and costs increase
Solution Approach 1:
Instead of deploying multiple static antenna orientations simultaneously, the patent uses a single antenna assembly that rotates to assume different orientations sequentially. This dynamic repositioning allows one antenna to perform the measurement functions that would otherwise require multiple fixed antennas, reducing the total number of antennas while maintaining measurement reliability through multi-orientation data collection.
Solution Approach 2:
The rotating antenna assembly serves multiple measurement functions across different orientations, making a single antenna system universal. The same physical antenna structure performs the role of multiple oriented antennas by rotating through different angular positions, thereby achieving reliable formation parameter measurements with fewer physical components.
3Measurement precision
If a complete antenna coupling matrix is obtained through rotation, then formation parameter accuracy is improved, but measurement time and complexity increase
Solution Approach 1:
The antenna rotation system performs measurements at discrete periodic angular intervals (e.g., every 45 degrees) rather than continuously. This periodic sampling approach captures sufficient information to reconstruct the complete coupling matrix while minimizing rotation time and measurement duration, balancing accuracy with efficiency.
Solution Approach 2:
The system pre-determines the optimal set of rotation angles and measurement sequences before actual logging. By planning the measurement protocol in advance with predetermined angular positions and timing, the system eliminates unnecessary rotations and measurements, thereby reducing total measurement time while ensuring all necessary data for accurate formation parameter calculation is collected.
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 enables accurate and reliable resistivity measurements with reduced costs and complexity, improving geosteering capabilities by determining formation parameters with a reduced number of antennas.
Implementation Method 1
a transmitter transmits an electromagnetic signal that passes through formation materials around the borehole and induces a signal in ore or more receivers
Implementation Method 2
obtain a complete antenna coupling matrix
Data Source
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AI summary
Disclosed herein are electromagnetic resistivity logging systems and methods that employ an antenna configuration having at most two transmitter or receiver antenna orientations that rotate relative to the borehole. The measurements made by this reduced-complexity antenna configuration enable the determination of at least seven components of a coupling matrix, which may be determined using a linear system of equations that express the azimuthal dependence of the measurements. For increased reliability, measurement averaging may be performed in azimuthally spaced bins. The coupling matrix components can then be used as the basis for determining logs of various formation parameters, including vertical resistivity and anisotropy.