MEMS Gyroscope Range Extension via Eccentric Accelerometer Fusion
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Solution Overview
Problem
Existing gyroscope systems used to measure the rotation rate of drill strings in petroleum exploration are unreliable at high rotation rates, leading to errors in tool face angle calculations and subsequent formation parameter measurements, especially during stick-slip conditions.
Innovation Solution
A method and apparatus that combine a gyroscope with accelerometers to measure the rotation rate of a drill string, using a processor to select between gyroscope and accelerometer measurements based on reliability thresholds, and employing a Kalman filter for time-series analysis to determine a final computed rotation rate, thereby extending the measurement range and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gyroscope is used to measure rotation rate, then measurement precision is improved within a certain range, but reliability deteriorates when rotation rate exceeds the gyroscope's reliable range
Solution Approach 1:
The patent combines a gyroscope with accelerometers to create a hybrid measurement system. The gyroscope provides precise measurements within its reliable range, while accelerometers supplement measurements when rotation rates exceed the gyroscope's reliable range. The processor selectively combines data from both sensors based on current operating conditions, resolving the contradiction between precision and reliability across the full rotation rate spectrum.
2Reliability
If accelerometers are used to measure rotation rate, then reliability is improved at high rotation rates, but measurement precision deteriorates compared to gyroscope measurements
Solution Approach 1:
The system dynamically switches between gyroscope and accelerometer measurements based on the current rotation rate. The processor monitors the operation mode and selectively uses gyroscope data when rotation rates are within the reliable range, and accelerometer data when rotation rates exceed this range. This dynamic adaptation optimizes both precision and reliability across varying operating conditions.
3Reliability
If a hybrid system with processor selection is used, then reliability across all rotation rates is improved, but device complexity increases
Solution Approach 1:
The patent creates a multi-functional sensor system where the gyroscope handles precise measurements within its reliable range, and accelerometers handle measurements at high rotation rates. The processor provides intelligent selection between sensors based on current operating conditions. This universal approach allows a single system to reliably perform measurement functions across the entire rotation rate spectrum, from low to high speeds.
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 provides a reliable measurement of rotation rate across a wider range, reducing errors in tool face angle calculations and enhancing the precision of formation parameter measurements, even during high-variation drill string rotation rates, thus improving drilling operations and geo-steering.
Implementation Method 1
The instantaneous rotation rate is often measured using a gyroscope oriented such that its sensitive axis measures rotation around an axis parallel to the drill string
Implementation Method 2
employing a Kalman filter for time-series analysis to determine a final computed rotation rate
Data Source
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AI summary
A tool for use in a borehole penetrating a formation method and a method for using the tool is disclosed. The tool includes a gyroscope for obtaining a first measurement of a rotation rate of the apparatus and at least one accelerometer for obtaining a second measurement of the rotation rate of the apparatus. A processor generates an estimate of the rotation rate using at least one of the first measurement of rotation rate and the second measurement of rotation rate. The estimate of the rotation rate is sued to determine a rotational position of a formation parameter measurement obtained during rotation of the apparatus in the borehole.