Swaged Mandrel End Nut for Bumper Spring Durability

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Solution Overview

Problem

Conventional bumper spring assemblies in oil and gas wells are prone to damage from high-velocity plungers, leading to loosening of components and obstruction of fluid flow, resulting in reduced production and potential well shutdowns.

Innovation Solution

A robust bumper spring assembly design featuring a one-piece mandrel with a swaged end nut for secure locking without pins or set screws, combined with a solid headpiece and hollow cage with flow ports to enhance durability and fluid flow, reducing the risk of component disassembly and turbulence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional bumper spring assemblies use pinned components to secure end pieces to the mandrel, then the assembly can be disassembled for maintenance, but the pins are frequently sheared by high-velocity plungers causing component loosening and well shutdowns

Engineering Contradiction:

Improvedisassembly for maintenanceVSAvoidcomponent security

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The end piece is divided into a modular assembly that can be independently removed from the mandrel using the slot and tool interface, allowing maintenance without affecting other components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pinned mechanical connection system is replaced with a slot-based interface that accepts a removal tool, eliminating pins and set screws that are susceptible to shearing from plunger impacts

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If conventional bumper spring assemblies use pins or set screws to secure end pieces, then the structure can be simple, but the components loosen and become unscrewed under high-velocity plunger stress

Engineering Contradiction:

Improvesecuring mechanismVSAvoidcomponent retention

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The vulnerable securing elements (pins, set screws, and especially the third set screw) are completely removed from the design. The end piece is instead retained through the slot interface that requires a specific tool for removal, eliminating the loosening problem entirely

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The slot is pre-formed in the end piece during manufacturing, creating a built-in retention mechanism that prevents loosening under stress while allowing controlled removal when needed

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If the bumper spring assembly uses traditional threaded connections for the cage nut, then assembly is straightforward, but the connections fail under repeated high-velocity plunger impacts

Engineering Contradiction:

Improveassembly processVSAvoidconnection strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

Traditional threaded connections using multiple set screws are replaced with a slot-based retention system. The slot interface provides superior strength against plunger impacts while maintaining ease of assembly through the cage nut threading mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Strength

If conventional bumper spring assemblies use solid structures without flow ports, then component strength is maintained, but fluid flow is obstructed causing production loss

Engineering Contradiction:

Improvestructural integrityVSAvoidfluid flow

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The cage structure transitions from a solid form to a lattice structure with strategically placed openings. This local modification allows fluid to pass through the cage while the remaining material maintains structural integrity and bumper spring functionality

Inventive Principle:

Principle #3Local quality

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 design significantly increases the durability of the bumper spring assembly and improves fluid flow by eliminating the risk of component loosening and reducing drag, thereby enhancing production efficiency and longevity.

Implementation Method 1

a distal portion of the tail end of the mandrel is expanded outward in a cold forming process against the threads in the cage nut next to the outward chamfer to lock the threads of the cage nut to the tail end of the mandrel

Methodology Applied

Scientific EffectCold forming: Cold-forming

Implementation Method 2

A bumper spring assembly is a tool that is typically placed in a seating nipple at the lower end of the tubing in the well to absorb the momentum of the bypass or lift plunger as it reaches the seating nipple

Methodology Applied

Scientific EffectMomentum: Conservation of Momentum

Implementation Method 3

a bumper spring configured as a coil spring disposed concentrically on the mandrel

Methodology Applied

Scientific EffectSpring: Spring

Data Source

PatentUS10677027B2Apparatus and method for securing end pieces to a mandrel

Publication Date: 2020.06.09 FLOWCO PRODUCTION SOLUTIONS LLC

AI summary

A method for locking an internally threaded end piece such as a head piece, a tail piece, an end or sealing nut to a mandrel for a down hole tool to obviate the need for pins, set screws, and the like, to provide a more robust assembly. In two embodiments the threaded end piece is locked to the mandrel in a swaging operation.