Magnetic Thrust Bearing Control for Downhole Shaft Levitation
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Solution Overview
Problem
Downhole equipment faces challenges in harsh environments due to caustic fluids, high pressures, and temperatures, leading to reliability and robustness issues, with conventional mechanical bearings requiring lubrication that is quickly lost and resulting in bearing failure.
Innovation Solution
The use of magnetic bearing systems, including magnetic thrust and radial bearings, which are lubricant-free and can operate in harsh environments, supported by a high-speed permanent magnet motor and sensor-less long-distance variable frequency drive, allowing for axial levitation and radial support without seals or lubricants, and providing operational data on temperature and fluid properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanical bearings are used in downhole equipment, then the equipment can operate with simple structure, but the bearings require lubrication that is quickly lost in harsh environments leading to bearing failure
Solution Approach 1:
The patent replaces conventional mechanical bearings with magnetic thrust bearings that use magnetic fields instead of mechanical contact and lubrication. The magnetic bearing system includes actuators that generate magnetic fields to levitate and support the shaft, eliminating the need for lubricants that are quickly lost in harsh downhole environments. This substitution directly resolves the contradiction by improving bearing reliability through contactless support while managing the increased system complexity through integrated control systems.
Solution Approach 2:
The patent changes the fundamental operating parameters of the bearing system by transitioning from mechanical friction-based support to magnetic field-based support. This parameter change allows the bearing to operate without lubrication in harsh environments with caustic fluids, high pressures, and temperatures, thereby improving reliability while the control system manages the complexity of maintaining precise magnetic field parameters.
2Reliability
If magnetic thrust bearings are used to provide axial levitation, then bearing reliability is improved by eliminating lubrication, but the device complexity increases due to additional actuators and control systems
Solution Approach 1:
The patent replaces mechanical thrust bearings with magnetic thrust bearings that use electromagnetic actuators to provide axial support. The actuators generate magnetic fields that levitate the shaft, eliminating the need for mechanical contact and lubrication. This substitution improves reliability in harsh downhole environments while the control system manages the complexity of coordinating multiple actuators and sensors to maintain precise axial position control.
3Loss of energy
If magnetic bearing systems are used to reduce drag losses, then energy efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical bearing systems with magnetic bearing systems that eliminate physical contact between moving parts. This substitution dramatically reduces drag losses and energy consumption by eliminating friction, while the manufacturing complexity is managed through modular actuator designs and standardized magnetic component assemblies that can be manufactured using conventional electromagnetic manufacturing processes.
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
Magnetic bearing systems enhance the reliability and robustness of downhole equipment by eliminating the need for lubrication and seals, reducing drag losses, and increasing torque output or reducing motor size and power requirements, while maintaining stable axial position control.
Implementation Method 1
multiple magnetic thrust bearings coupled to the shaft and the controller, in which each magnetic thrust bearing can receive the second signal from the controller and modify a load, corresponding to the second signal, on the shaft to maintain the target axial position of the shaft
Implementation Method 2
Each magnetic thrust bearing can include an actuator surrounding the shaft and a target surrounding the shaft, in which the actuator can generate a magnetic field in response to receiving an electric current
Implementation Method 3
the actuator can generate a magnetic field in response to receiving an electric current, and the target can generate an axial force in response to the generated magnetic field
Data Source
AI summary
During rotation of a shaft of a downhole-type wellbore system, a first signal corresponding to an axial position of the rotating shaft is transmitted by a sensor. The shaft is axially levitated by a plurality of magnetic thrust bearings. A controller determines an amount of axial force to apply to the rotating shaft to maintain axial levitation of the rotating shaft based on the first signal. The controller transmits a second signal corresponding to the determined amount of axial force to the plurality of magnetic thrust bearings. The plurality of magnetic thrust bearings applies the amount of axial force on the rotating shaft to maintain the axial levitation of the rotating shaft based on the second signal.