Rotary Steerable Control with Hybrid Toolface Sensing
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Solution Overview
Problem
Existing rotary steerable tools for directional drilling face inaccuracies due to dynamic downhole conditions, particularly stick-slip and high-frequency torsional oscillations, leading to difficulties in maintaining precise control over borehole trajectory.
Innovation Solution
A control system that adjusts angular rate readings based on angular position corrections, using magnetic toolface and highside toolface measurements, and performs self-calibration to account for sensor biases and scale factors, enabling high-resolution angular position measurements and actuator control to steer the drill bit accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rotary steerable tools are used for directional drilling, then the ability to steer the drill bit in any chosen direction is improved, but measurement accuracy deteriorates due to stick-slip and high-frequency torsional oscillations
Solution Approach 1:
The system continuously monitors angular position using multiple sensors (magnetometers, accelerometers, gyroscopes) and feeds this information back to a controller that calculates corrections for stick-slip and torsional oscillations. This closed-loop feedback mechanism compensates for measurement errors in real-time, maintaining accuracy despite the dynamic drilling conditions
Solution Approach 2:
The patent introduces intermediary computational algorithms that process raw sensor data and separate the desired angular position information from the unwanted stick-slip and torsional oscillation components. These algorithms act as intermediaries between the physical sensors and the steering control system, filtering out harmful vibrations while preserving accurate positional data
2Measurement precision
If high-resolution sensing capabilities are implemented to compensate for downhole dynamics, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The system divides the sensing function into multiple specialized sensors, each optimized for detecting specific parameters (magnetometers for magnetic field orientation, accelerometers for gravitational reference, gyroscopes for rotational rate). This segmentation allows each sensor to be simpler and more reliable, while their combined data processed through algorithms achieves high overall measurement accuracy
Solution Approach 2:
The patent replaces complex mechanical sensing mechanisms with electronic and optical sensors coupled with computational processing. Instead of using complex mechanical linkages and physical measurement devices, the system uses electronic sensors and algorithms to achieve high-resolution angular position measurement, reducing mechanical complexity while improving precision
Data Source
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AI summary
Angular position readings are obtained during rotation of an apparatus in a borehole, and angular rate readings are obtained over time of the rotation. The angular rate readings are adjusted based at least on the angular position readings. The angular position measurement does not require calibrated magnetometers or accelerometers to function. Additionally, a dynamic scale factor calculation for an angular rate gyroscope (ARG) allows the ARG to be used over a much wider operating range than without such a calculation. Finally, an integrated angular rate from the ARG calibrated for bias and scale factor fills in positional information between the magnetometers' zero crossings to deliver a high resolution hybrid angular position system capable of measuring precise angular position at high and irregular downhole rotation rates.