Elastomer Spring for Wellhead Lubricator Impact
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Solution Overview
Problem
Conventional well head lubricator assemblies in gas producing wells often experience premature failure of coil springs under high impact forces, leading to damage and operational halts due to insufficient bias, which necessitates frequent repairs and replacements.
Innovation Solution
A well head lubricator assembly utilizing an axially elongated one-piece thermoplastic ether ester elastomer spring with flange sections and energy absorbing sections, designed to absorb and dissipate energy, is introduced. The spring is made from a durable elastomer with specific Shore D hardness and molecular structure, allowing for controlled compression and repeated use without tearing or crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional steel coil spring is used in the lubricator assembly, then the spring can provide initial bias force to the plunger, but the spring fails prematurely under high impact forces and collapses
Solution Approach 1:
The patent changes the material parameters from conventional steel to thermoplastic elastomer, fundamentally altering the spring's mechanical properties. The elastomer material provides both the necessary bias force and resistance to high impact forces, eliminating premature failure while maintaining functional performance.
Solution Approach 2:
The patent employs a composite structure combining thermoplastic and elastomer properties in a single integrated spring component. This composite material approach creates a spring that exhibits both elastic recovery for bias force and energy absorption for impact resistance, resolving the reliability issue.
2Strength
If the spring is made from conventional steel, then it can provide structural strength, but it tears or propagates cracks under repeated high impact loading
Solution Approach 1:
The patent changes the material composition from metallic steel to thermoplastic elastomer, fundamentally altering the failure mode. The elastomer material exhibits elongation and energy absorption characteristics that prevent crack propagation, extending service life under repeated impact loading while maintaining sufficient structural strength.
3Stress or pressure
If a rigid tubular body is used for the lubricator assembly, then it can withstand high pressure, but the assembly requires frequent shutdowns for spring replacement
Solution Approach 1:
The patent changes the spring material parameters to eliminate premature failure, thereby extending operational duration between maintenance intervals. The thermoplastic elastomer spring maintains pressure resistance functionality while preventing the operational disruptions caused by spring collapse.
4Loss of energy
If the spring allows free radial expansion, then it can absorb more energy, but it may become unstable or misaligned within the tubular body
Solution Approach 1:
The patent employs the elastomer spring as a flexible structural element that can deform radially to absorb energy while maintaining positional stability through its elastic recovery properties. The flexible nature of the elastomer allows energy absorption, while the material's memory effect maintains alignment within the tubular body.
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 thermoplastic ether ester elastomer spring effectively absorbs and dissipates energy, reducing the risk of premature failure and damage to the lubricator assembly, ensuring prolonged operation and reduced maintenance needs by maintaining a consistent spring rate and preventing blockages.
Implementation Method 1
Any two flange sections on the spring are axially separated by an energy absorbing section for allowing the spring to react to energy imparted to the plunger
Implementation Method 2
An axially elongated one-piece thermoplastic ether ester elastomer spring is also provided. The spring has a plurality of axially spaced flange sections along a length thereof
Data Source
AI summary
A well head lubricator assembly including an elongated rigid tubular body defining an interior chamber open at a lower end to receive a plunger at a well head. The plunger is slidably positioned within the chamber in response to forces or loads acting thereon and has a seat arranged toward an upper end thereof. An upper end of the tubular body is closed. An axially elongated one-piece thermoplastic ether ester elastomer spring is slidingly positioned within the interior chamber of the tubular body. One end of the spring is seated on the seat of the plunger. The spring defines an elongated bore opening to opposed ends thereof. Moreover, the spring is provided with a plurality of axially spaced flange sections along a length thereof for guiding the spring for endwise sliding movement on an inside diameter of the tubular body. Any two flange sections on the spring are axially separated by an energy absorbing section for allowing the spring to react to energy imparted to the plunger. Each energy absorbing section on the spring defines a wall having a lateral thickness ranging between about 20% to about 30% of an axial length of the energy absorbing section extending axially between any two adjacent flange sections and such that radial expansion of the energy absorbing sections is limited to about an outermost edge of the flange sections.