Submersible Pump Motor Pressure Compensator for Lubricant Seal Stability
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Solution Overview
Problem
Existing electrical submersible pump systems face challenges in maintaining optimal pressure differentials across the motor lubricant seal, leading to potential well fluid leakage or lubricant depletion due to varying hydrostatic pressures and thermal expansion, which affects the performance and reliability of the pump motor.
Innovation Solution
A pressure compensating chamber with a movable element, controlled by an electrical drive mechanism and a controller, adjusts the volume of the chamber to maintain a desired pressure differential, using sensors to monitor both well fluid and motor lubricant pressures, and optionally assisted by a bias mechanism like a coil spring or bellows, to stabilize the lubricant pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible barrier (bag or bellows) is used in the pressure equalizer to respond to pressure differential, then the pressure equalizer can automatically adjust to pressure changes, but the system cannot actively control or maintain a desired pressure differential, leading to well fluid leakage or lubricant depletion
Solution Approach 1:
The pressure equalizer uses a flexible barrier (bag or bellows) that automatically responds to pressure differentials between well fluid and motor lubricant, causing the barrier to expand or contract and actively adjust the lubricant pressure without external control systems
Solution Approach 2:
The patent replaces traditional mechanical pressure control mechanisms with an electrical drive mechanism (such as a motor-driven pump or compressor) that can be controlled by electronic sensors and controllers to actively maintain the desired pressure differential
2Device complexity
If the pressure equalizer is located between the motor and pump or mounted below the motor, then the structure is simplified, but the flexible barrier movement is limited to direct response from pressure forces, preventing active pressure maintenance
Solution Approach 1:
The patent introduces an electrical drive mechanism that can dynamically adjust the pressure differential in real-time based on operating conditions, transforming the static passive pressure equalizer into an active dynamic control system
Solution Approach 2:
The system incorporates pressure sensors that continuously monitor the pressure differential and provide feedback to a controller, which then adjusts the electrical drive mechanism to maintain the desired pressure differential, creating a closed-loop control system
3Device complexity
If the motor lubricant pressure responds only to thermal expansion and hydrostatic pressure, then the system is passive and simple, but the lubricant pressure cannot be maintained at optimal levels, causing seal failure or lubricant loss
Solution Approach 1:
The electrical drive mechanism actively adjusts the lubricant pressure parameter to maintain the optimal pressure differential, compensating for thermal expansion and hydrostatic pressure variations to prevent seal failure and lubricant loss
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
The system effectively controls lubricant pressure, preventing well fluid ingress and lubricant loss, ensuring consistent lubrication and enhancing the reliability and efficiency of the pump motor operation.
Implementation Method 1
A pressure compensating chamber containing a dielectric lubricant is in fluid communication with an interior of the motor. A movable pressure compensating element has a first side in contact with the lubricant in the chamber. Movement of the element relative to the chamber causes a change in volume of the chamber.
Implementation Method 2
A pressure equalizer or seal section connects to the motor to reduce a pressure differential between lubricant in the motor and the hydrostatic pressure of the well fluid.
Implementation Method 3
A bias mechanism, such as a coil spring, may be included to apply a force to the pressure compensating element.
Implementation Method 4
The drive mechanism comprises a servo motor shaft. A servo motor rotates the shaft.
Implementation Method 5
A rotary to linear translator translates rotation of the servo motor shaft to linear movement.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electrical submersible well pump assembly (11) includes an electrical motor (21) for driving a pump (17). A pressure compensating chamber (38) contains a dielectric lubricant (37) in fluid communication with an interior of the motor. A movable pressure compensating element (47) has a first side in contact with the lubricant in the chamber. Movement of the element relative to the chamber causes a change in volume of the chamber. An electrical drive mechanism (59, 61) is connected with and moves the element. A controller (55) senses a pressure difference between the lubricant pressure and the well fluid pressure and operates the drive mechanism in response. The element may be a piston (47), a bellows (71) or telescoping tubes (91, 93).