Downhole Azimuthal Imaging Cross-Correlation for Depth Detection
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Solution Overview
Problem
The lack of accurate, real-time downhole depth information in boreholes limits advanced drilling and wireline operations due to distorted depth calculations from noise in accelerometer data and significant drifting, making it difficult to determine the precise location of well tools within the borehole.
Innovation Solution
Utilizing a downhole azimuthal imaging tool with sensors to perform image cross-correlation on high-resolution azimuthal borehole images, calculating time delay, and integrating instantaneous velocity to determine downhole measured depth, combining with accelerometer data for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measured depth is calculated at the ground surface based on rotation measurements, then depth information is available, but the depth information is distorted and inaccurate due to noise in accelerometer data and significant drifting
Solution Approach 1:
The patent replaces the mechanical/accelerometer-based depth calculation system with an optical imaging system. By capturing azimuthal borehole images and using image cross-correlation to track feature movements, the system eliminates reliance on noisy accelerometer data and achieves accurate, real-time downhole depth measurement without the distortion and drifting problems of conventional methods
Solution Approach 2:
The patent introduces borehole images as an intermediary medium to determine depth. Instead of directly measuring depth through accelerometers, the system uses images of borehole features as a reference framework. By tracking the movement of these visual features between consecutive images, the system derives accurate depth information indirectly, avoiding the harmful effects of direct accelerometer measurements
2Productivity
If downhole measured depth is estimated from double integral of accelerometer data, then depth can be calculated, but accuracy is low due to noise and significant drifting
Solution Approach 1:
The patent substitutes the double integral acceleration method with an image-based tracking method. By capturing sequential azimuthal images and calculating cross-correlation to determine feature displacement, the system achieves real-time depth calculation with high accuracy, eliminating the noise and drifting errors inherent in accelerometer-based integration
Solution Approach 2:
The patent creates a visual copy or representation of the borehole environment through azimuthal images. These images serve as a reference framework that can be processed to determine depth. By working with image data rather than raw accelerometer signals, the system achieves both real-time calculation capability and high measurement precision
3Measurement precision
If image cross-correlation is performed on high-resolution azimuthal borehole images, then precise time delay can be determined, but computational complexity increases
Solution Approach 1:
The patent segments the borehole image into distinct features or landmarks that can be individually tracked. By identifying and monitoring specific borehole features rather than processing the entire image at once, the system reduces computational complexity while maintaining precise time delay measurement. The cross-correlation is performed on segmented feature data rather than full-resolution images
Data Source
AI summary
Systems, methods, and apparatus, including computer programs encoded on computer-readable media, for detecting downhole measured depth of a borehole are disclosed. A downhole imaging tool of a drilling system may obtain azimuthal borehole images from at least a first sensor and a second sensor of the downhole imaging tool. Image cross-correlation is performed on the azimuthal borehole images. A time delay is determined based on the image cross-correlation on the azimuthal borehole images. A velocity of the downhole imaging tool is determined based on the time delay. A downhole measured depth of the downhole imaging tool within the borehole is determined based on the velocity. The downhole measured depth may be determined dynamically downhole by the downhole imaging tool without communications with surface equipment of the drilling system.