Seal Section Layout Using High-Density Oil to Block Lubricant Contamination
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Solution Overview
Problem
Conventional seal sections in submersible pumping systems are insufficient in preventing the contamination of motor lubricants in harsh downhole environments, particularly due to the ingress of wellbore fluids.
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 utilizes density differences and gravity traps to prevent contamination by wellbore fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seal bag assemblies are used, then the structure is simple and easy to manufacture, but they are insufficient in preventing contamination of motor lubricants by wellbore fluids
Solution Approach 1:
The seal section is divided into multiple functional chambers: a lower chamber containing the seal bag assembly with motor oil, an upper chamber with high density oil, and an intermediate guide section with a gravity trap. This segmentation creates distinct functional zones that work together to prevent contamination while managing fluid dynamics and thermal expansion.
Solution Approach 2:
The high density oil serves as an intermediary barrier between the motor oil in the seal bag and potential contaminants from wellbore fluids. The gravity trap acts as an intermediary mechanism that uses density differences to separate and trap contaminants, preventing them from reaching the motor lubricant.
2Reliability
If seal bags are used to accommodate volumetric changes, then thermal expansion and contraction is managed, but positive barrier protection against contaminated wellbore fluid is insufficient
Solution Approach 1:
Different chambers are assigned different fluid densities and functions: the lower chamber contains motor oil for lubrication, the upper chamber contains high density oil for barrier protection, and the intermediate section contains a gravity trap for contamination separation. Each zone has specialized properties tailored to its specific function.
Solution Approach 2:
The invention utilizes density as a key parameter to create functional differentiation. High density oil is introduced into the upper chamber and gravity trap to create a positive barrier that leverages density differences to prevent contaminant migration into the motor lubricant, transforming a passive seal into an active protective system.
3Reliability
If the seal section protects against axial thrust and restricts fluid flow, then motor protection is provided, but contamination prevention in critical applications is still insufficient
Solution Approach 1:
The gravity trap is positioned in the intermediate guide section to preliminarily capture and separate contaminants before they can reach the motor oil. The high density oil is pre-positioned in the upper chamber to create a ready barrier, preventing contamination proactively rather than reactively.
Solution Approach 2:
The invention converts the harmful density difference between wellbore fluids and motor oil into a beneficial separation mechanism. By introducing high density oil into the gravity trap and upper chamber, the system uses gravity and density stratification to automatically separate and trap contaminants, turning the physical property that could cause mixing into a protective separation mechanism.
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 contamination of motor lubricants by wellbore fluids through the use of high density oils and gravity traps, maintaining the integrity of the lubrication system in submersible pumping systems.
Implementation Method 1
high density oil that is denser than the motor oil
Implementation Method 2
gravity trap connected to the exterior space through an intermediate passage
Data Source
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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.