Asymmetric Sensor Tool for Compensated Formation Parameter Measurement
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Solution Overview
Problem
Zero-dimensional (0D) inversion methods in oil and gas exploration face inaccuracies due to shoulder-bed effects, especially in thin-layered formations, leading to unstable and inaccurate determination of formation anisotropy parameters and relative dip angles.
Innovation Solution
The use of tilted sensors and asymmetric/symmetric sensor tools to generate compensated signals, which are less affected by shoulder-bed effects, allowing for more stable and accurate 0D inversion results, and serving as a reliable initial model for advanced dimensional inversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EM resistivity logging tools are used in thin-layered formations, then formation parameters can be measured, but shoulder-bed effects cause inaccurate and unstable determination of formation anisotropy parameters and relative dip angles
Solution Approach 1:
The patent employs asymmetric sensor tool configurations where sensors are positioned at non-uniform intervals along the tool body. Specifically, the distances between adjacent sensors are deliberately made different to create asymmetric measurement patterns that are less susceptible to shoulder-bed effects, thereby improving both measurement accuracy and reliability in thin-layered formations
Solution Approach 2:
The patent transitions from conventional coplanar sensor arrangements to three-dimensional spatial configurations. Sensors are positioned at different radial distances and angular positions around the tool axis, creating a 3D measurement geometry that provides additional independent measurements and reduces the impact of shoulder-bed effects on formation parameter determination
2Productivity
If 0D inversion is performed using conventional coupling components, then computation is fast and simple, but results are unstable and inaccurate in thin-layered formations with high contrast
Solution Approach 1:
The patent performs preliminary signal compensation by processing raw EM measurements to generate compensated coupling components before inversion. This preliminary processing step removes shoulder-bed effects from the data, ensuring that subsequent 0D inversion operates on corrected measurements, thereby maintaining computational efficiency while improving inversion accuracy
Solution Approach 2:
The patent introduces compensated coupling components as an intermediary between raw measurements and inversion results. These compensated components serve as a bridge that eliminates the harmful influence of shoulder-bed effects while preserving the essential formation response information needed for accurate 0D inversion
3Reliability
If symmetric sensor tools are used, then compensated signals can be generated to reduce shoulder-bed effects, but device complexity increases
Solution Approach 1:
The patent designs sensor tools where the same asymmetric sensor configuration serves multiple functions: it provides both the asymmetric geometry needed for shoulder-bed compensation and the three-dimensional spatial distribution required for complete coupling matrix determination. This multi-functionality reduces the need for additional specialized components
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
Compensated signals provide more stable and accurate formation parameter measurements, reducing the impact of shoulder-bed effects and improving the reliability of anisotropy and dip angle determinations, even in high-contrast formations, and can be used as a basis for higher-dimensional inversion processes.
Implementation Method 1
The reading of these tools is based on the induction principle in which the transmitter produces a magnetic flux, which is picked up by the receiver
Implementation Method 2
Multi-coupling-component signals of electromagnetic (EM) resistivity logging tools are widely used to explore formation parameters
Data Source
AI summary
Various embodiments include apparatus and methods to operate a measurement process in a borehole that uses a symmetric sensor structure or a sensor structure operable to mimic a symmetric sensor structure to provide structural compensation. Apparatus and methods can include a data processing unit to generate compensated signals based on the measurement signals and to determine formation parameters using the compensated signals. Additional apparatus, systems, and methods are disclosed.