Seal Section Gravity Trap for High-Density Oil Contamination Control
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Solution Overview
Problem
Conventional seal sections in submersible pumping systems are insufficient in preventing the contamination of motor lubricants in critical applications, particularly in harsh downhole environments with varying temperatures and pressures.
Innovation Solution
A seal section design incorporating a lower chamber with a seal bag containing motor oil and an exterior space filled with high density oil, an intermediate guide section with a gravity trap and intermediate passage, and an upper chamber with a volume of high density oil, which uses density differences and gravity traps to prevent contamination by wellbore fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seal bag assembly is used, then the seal section can accommodate thermal expansion and contraction of motor lubricant, but it is insufficient for preventing contamination of motor lubricants in critical applications
Solution Approach 1:
The seal section is divided into multiple chambers (first chamber with seal bag assembly, second chamber with gravity trap) separated by a barrier. This segmentation allows each chamber to perform specific functions: the first chamber handles thermal expansion/contraction while the second chamber provides enhanced contamination prevention through density-based separation, thereby improving reliability without requiring a complete redesign of the entire seal section.
Solution Approach 2:
A barrier (intermediate guide section) is introduced between the first chamber containing the seal bag assembly and the second chamber containing the gravity trap. This intermediary structure allows controlled interaction between the two chambers while maintaining their functional independence, enabling the system to achieve superior contamination protection through the combined action of both chambers.
2Reliability
If high density oil is introduced into the seal section, then wellbore fluids are prevented from contaminating motor lubricant, but the device complexity increases
Solution Approach 1:
The invention utilizes a change in fluid density parameter by introducing high density oil into the second chamber. This high density oil creates a density gradient that prevents lighter wellbore fluids from penetrating into the motor lubricant chamber, providing passive protection against contamination without requiring active control mechanisms or complex valve systems.
Solution Approach 2:
The gravity trap chamber with high density oil provides self-service contamination protection through natural density-based separation. The system automatically prevents wellbore fluid ingress without requiring external control systems, sensors, or active intervention, thereby improving reliability while adding minimal complexity to the seal section configuration.
3Reliability
If multiple chambers and separation mechanisms are added to prevent contamination, then lubricant purity is maintained, but the ease of operation and maintenance decreases
Solution Approach 1:
The seal section is segmented into distinct functional chambers (first chamber with seal bag, second chamber with gravity trap) that are separated by a barrier. This segmentation allows for targeted maintenance approaches where the seal bag assembly can be serviced independently from the gravity trap chamber, reducing the overall complexity of maintenance operations while maintaining lubricant purity through the multi-chamber configuration.
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
Effectively prevents the ingress of wellbore fluids into the motor lubricant, maintaining lubricant purity and protecting the motor from contamination, even under thermal cycling and pressure variations.
Implementation Method 1
an exterior space around the seal bag that contains high density oil that is denser than the motor oil
Implementation Method 2
The upper chamber includes a volume of the high density oil at the bottom of the upper chamber and a gravity trap connected to the exterior space through an intermediate passage
Data Source
AI summary
A seal section for use in a downhole submersible pumping system includes a lower chamber, an upper chamber and an intermediate guide section between the lower chamber and the upper chamber. The lower chamber includes a seal bag assembly that has a seal bag containing motor oil and an exterior space around the seal bag that contains high density oil that is denser than the motor oil. The upper chamber includes a volume of the high density oil at the bottom of the upper chamber and a gravity trap connected to the exterior space through an intermediate passage in the intermediate guide section. The gravity trap includes an opening submerged in the volume of high density oil in the upper chamber.