In-Drilling Alignment Using Pneumatic Motion Control
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Solution Overview
Problem
Current inertial navigation systems in horizontal directional drilling face challenges due to magnetic interference and biases, leading to inaccuracies in directional drilling, which are not significantly improved by existing magnetometer/accelerometer-based methods or tactical-grade inertial measurement sensors.
Innovation Solution
An apparatus and method involving controlled motion patterns, such as linear and rotational motions induced by a pneumatic system, to correct alignment errors in inertial measurement units, utilizing a piston within a cylinder and a magnetostrictive sensor to measure position and acceleration, enabling more accurate alignment and error compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetometer and accelerometer triad are used for directional drilling navigation, then position computation is achieved, but accuracy deteriorates due to magnetic interference from surrounding environment and drilling tools
Solution Approach 1:
The patent extracts the harmful magnetic sensing function from the navigation system by removing magnetometers from the downhole assembly. Instead, it uses only inertial sensors (accelerometers and gyroscopes) that are immune to magnetic interference, thereby eliminating the vulnerability to magnetic disturbances while maintaining navigation capability through inertial measurement and periodic surface reference updates.
Solution Approach 2:
The patent introduces an intermediary computational process that uses inertial measurement unit data combined with surface-based reference measurements (from GPS or other non-magnetic references) to compute position. This intermediary approach avoids direct magnetic field sensing downhole while still achieving accurate position computation through coordinated measurement and calculation.
2Object-affected harmful factors
If sensor triads are positioned 50 feet away from drill bit and non-magnetic drill collars are used, then self-magnetic interference is reduced, but cost increases and ability to accurately measure drill bit motion is reduced
Solution Approach 1:
The patent removes the need for non-magnetic drill collars and extended positioning by extracting the magnetic sensing function entirely from the downhole assembly. The inertial measurement unit can be positioned close to the drill bit (within a few feet) because it relies on inertial rather than magnetic fields, simplifying the mechanical configuration and reducing costs while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical solution of using non-magnetic materials and extended positioning with a sensor substitution approach—using inertial sensors that are inherently immune to magnetic interference. This allows standard magnetic materials to be used in drill collars and positions sensors optimally close to the bit for accurate motion measurement.
3Reliability
If tactical-grade inertial measurement sensors are used, then gyro drift and accelerometer bias are reduced, but accuracy is not significantly better than magnetometer-based techniques
Solution Approach 1:
The patent applies preliminary alignment procedures that use initial reference measurements (from magnetic or GPS references at the surface) to establish accurate initial conditions for the inertial navigation system. This preliminary action corrects systematic errors before dynamic navigation begins, allowing tactical-grade sensors to achieve survey-grade accuracy over the drilling interval.
Solution Approach 2:
The patent implements feedback through periodic updates from surface-based reference systems (GPS, magnetic references at surface) that correct accumulated inertial navigation errors. This feedback loop maintains accuracy over time despite sensor drift, achieving precision significantly better than conventional downhole magnetic methods.
4Reliability
If in-flight alignment process is applied to moving platforms, then error handling is improved, but alignment accuracy is still less than stationary alignment
Solution Approach 1:
The patent applies preliminary alignment procedures during drilling operations that use initial reference measurements (from magnetic or GPS references at the surface) to establish accurate initial conditions for the inertial navigation system. This preliminary action corrects systematic errors before dynamic navigation begins, allowing tactical-grade sensors to achieve survey-grade accuracy.
Solution Approach 2:
The patent implements periodic realignment procedures during drilling operations where the system pauses to take reference measurements from surface-based systems. These periodic actions reset and correct accumulated errors, maintaining alignment accuracy comparable to stationary alignment while enabling continuous operation.
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 enhances the observability of inertial navigation system states, reducing alignment errors and improving the accuracy of directional drilling by using controlled accelerations to align the inertial measurement unit, thereby improving the precision of azimuth angle estimation.
Implementation Method 1
utilizing a piston within a cylinder and a magnetostrictive sensor to measure position and acceleration
Data Source
AI summary
To limit the growth of errors of an inertial navigation system for measurement-while-drilling, in-drilling alignment methods can be used. A pneumatics-based design of an apparatus for an in-drilling alignment method and its implementation downhole are described.