Modular Labyrinth Seal for Electric Submersible Pumps
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Solution Overview
Problem
Submersible pumps face pressure differential issues when inserted into wells, risking well fluid leakage into the motor, which can cause electrical short circuits and mechanical damage due to conductive and particulate-rich fluids.
Innovation Solution
A labyrinth seal section with a tortuous fluid path and isolation valves is used to maintain dielectric fluid pressure, preventing well fluid entry into the motor while allowing pressure equalization, featuring labyrinth tube sections and integrally formed tubes with end plates to manage fluid flow and cooling within the sealed annular space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal system is used to prevent well fluid entry into the motor, then motor protection is improved, but pressure differential across the seal increases causing faster seal degradation
Solution Approach 1:
The seal system is divided into multiple labyrinth tube sections arranged in series, creating multiple barriers to well fluid. Each section provides a separate sealing path, and the segmentation allows pressure to be managed in stages, reducing the pressure differential across each individual sealing interface while maintaining overall motor protection.
Solution Approach 2:
Dielectric fluid is introduced as an intermediary substance filling the sealed annular space between the outer housing and inner tube. This fluid acts as a pressure transmission medium that equalizes pressure between the well environment and the motor housing, reducing the pressure differential across seals while preventing well fluid from reaching the motor through the labyrinth tube barriers.
2Reliability
If a tortuous fluid path is created to slow well fluid migration, then motor protection is improved, but fluid flow resistance increases
Solution Approach 1:
The labyrinth tubes are configured with bends and directional changes that force well fluid to travel through a three-dimensional tortuous path rather than a straight line. This multi-directional routing increases the effective path length and complexity of fluid migration without significantly increasing linear dimensions, thereby slowing fluid migration while managing flow resistance through spatial arrangement.
3Stress or pressure
If dielectric fluid is maintained at well ambient pressure, then pressure equalization is improved, but well fluid exclusion becomes more difficult
Solution Approach 1:
The labyrinth tubes are configured with curved and bent geometries rather than straight linear paths. These curved configurations increase the path length and complexity that well fluid must navigate, creating additional flow resistance and slowing migration. The curved geometry works in conjunction with dielectric fluid pressure to enhance the difficulty of well fluid penetration while maintaining pressure equalization benefits.
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 solution effectively reduces the risk of electrical short circuits and mechanical damage by maintaining dielectric fluid pressure and slowing down well fluid migration, thereby prolonging seal life and ensuring safe operation of submersible pumps.
Implementation Method 1
A protector also has a tortuous fluid path that slows down the migration of well fluid through the protector to reduce the chance of well fluid entering the upper drivetrain through any leak in the pressure compensating device or mechanical seal
Implementation Method 2
Pressure within the electrical submersible pump (ESP) is at atmospheric pressure prior to the ESP being inserted into a wellbore. Since well pressure often significantly exceeds atmospheric pressure, the pressure within the ESP should be equalized to well pressure, thereby reducing pressure differential across the ESP housing and seals
Implementation Method 3
An isolation valve at each longitudinal end of the outer housing and in fluid communication with a labyrinth tube at each longitudinal end of the labyrinth tube sections, the isolation valves opened to fill the section with dielectric fluid in the annular space and in the labyrinth tubes
Data Source
AI summary
A labyrinth section for a submersible pump includes an outer housing having a coupling sealingly engaged at each longitudinal end of the outer housing. An inner tube is sealingly engaged at each end to one of the couplings to define a sealed annular space. A plurality of labyrinth tube sections are disposed in the annular space, each comprising labyrinth tubes engaged with end plates. A plurality of the labyrinth tube sections enable movement of fluid through the labyrinth tubes, spaces external to the labyrinth tubes and between the end plates to fill the annular space. One of the labyrinth tube sections constrains fluid to move only within the labyrinth tubes and wherein the inner tube between the end plates of the one of the labyrinth tubes comprises a fluid port into an interior of the inner tube.