Adjusted Kalman Filters for Drilling Borehole Projection Accuracy
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Solution Overview
Problem
Existing methods for determining the position and orientation of a borehole during drilling, such as those using Kalman filters, are limited by gaps between downhole sensors and the drill bit, leading to inaccuracies due to physical separation and time delays in data transmission, which affect the reliability of borehole steering.
Innovation Solution
The method involves applying multiple adjusted Kalman filters based on measurements from both surface and downhole sensors, separated by a plurality of segments, to account for gaps in distance and time, allowing for continuous correction and improved accuracy of borehole projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If downhole sensors are placed at a distance from the drill bit to avoid damage and interference, then sensor reliability is improved, but measurement precision deteriorates due to physical separation and time delays
Solution Approach 1:
The patent divides the distance between the drill bit and downhole sensors into multiple discrete segments. By segmenting the separation distance, the system can apply different correction strategies to each segment, improving the overall accuracy of borehole projections while maintaining sensor reliability at a safe distance from the drill bit.
Solution Approach 2:
The patent applies preliminary corrections to sensor measurements before using them for borehole projections. By pre-correcting the measurements to account for the known separation distance and time delays, the system compensates for the precision loss caused by placing sensors away from the drill bit, thus maintaining both reliability and accuracy.
2Productivity
If traditional Kalman filter modifications are used to correct sensor measurements, then computation speed is improved, but manufacturing precision deteriorates due to limited correction capabilities
Solution Approach 1:
The patent segments the correction process into multiple stages corresponding to different segments of the sensor-to-bit distance. Each stage applies a simplified Kalman filter correction, maintaining computational efficiency while collectively achieving high precision through the cumulative effect of multiple segmented corrections.
Solution Approach 2:
The patent implements dynamic correction factors that adapt to the specific segmentation of the distance between sensors and drill bit. The correction methodology changes based on the number and size of segments, allowing the system to optimize between computation speed and precision depending on the operational conditions and sensor placement.
Data Source
AI summary
The method for drilling includes extending a borehole from a surface location to a borehole end with a drill string having a bottom hole assembly with a drill bit. A surface sensor and a downhole sensor take measurements used to project borehole features, like the borehole end. The measurements are used to project the borehole end so that the drill bit can be steered through the rock formation. The downhole sensor is separated from the bit location by a plurality of segments. The method includes corrections when the measurements at the downhole location are not the measurements at the bit location. As the drill bit travels, the types of corrections change, including applying an initial Kalman filter, a first adjusted Kalman filter, a second adjusted Kalman filter, and a third adjusted Kalman filter, according to the plurality of segments between the downhole sensor and the bit location.