Swaged Mandrel End Locking for Bumper Spring Reliability
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Solution Overview
Problem
Conventional bumper spring assemblies in oil and gas wells are prone to damage and loosening due to high-velocity plungers, leading to reduced production and potential well shutdowns, as they are not robust enough to withstand repeated recoil events and can impede fluid flow.
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 a hollow cage with flow ports to enhance durability and fluid flow, reducing the risk of components becoming loose and improving production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bumper spring assemblies use pinned components to secure end pieces, then the assembly can be easily assembled and disassembled, but the pins are frequently sheared under high-velocity plunger impact, causing components to loosen and requiring well shutdowns
Solution Approach 1:
The patent merges the mandrel and end piece into a single integrated component, eliminating the need for separate pins, set screws, or threading mechanisms. This integration ensures that the end piece cannot loosen or become detached under high-velocity plunger impact, directly resolving the reliability issue while simplifying the overall assembly structure.
Solution Approach 2:
The bumper spring assembly is segmented into distinct functional zones: the integrated mandrel-end piece unit, the bumper spring, and the cage. This segmentation allows each component to be optimized for its specific function while maintaining overall simplicity, preventing the complexity that would arise from multiple fastening mechanisms.
2Reliability
If bumper spring assemblies use traditional threaded connections with pins or set screws, then assembly is straightforward, but the components are prone to loosening under repeated recoil events from high-velocity plungers
Solution Approach 1:
The mandrel and end piece are combined into a single machined component, eliminating threaded connections and fasteners. This integration provides inherent connection stability under repeated recoil events while actually simplifying the manufacturing process by reducing the number of parts and assembly steps required.
3Reliability
If conventional bumper spring assemblies use solid construction, then they are durable, but they impede fluid flow and reduce production efficiency
Solution Approach 1:
The cage is designed with localized open spaces or flow ports in specific areas where fluid flow is critical, while maintaining structural integrity in load-bearing regions. This allows the assembly to remain durable under plunger impact while permitting adequate fluid flow through the assembly, thereby maintaining production efficiency.
4Productivity
If plungers are designed to fall at high velocities (up to 2000 feet/minute) to maintain production, then production efficiency is maintained, but the momentum places much greater stress on bumper spring components, causing pins to shear and components to loosen
Solution Approach 1:
The integrated mandrel-end piece construction eliminates weak points where pins or fasteners could fail under high-velocity impact. The unified structure distributes stress more evenly throughout the component, maintaining integrity during high-speed plunger operations that enable continuous production.
Solution Approach 2:
The bumper spring and cage are pre-configured in a tensioned state, ready to immediately absorb and dissipate the kinetic energy of incoming high-velocity plungers. This preliminary positioning ensures that the system is prepared for high-speed impacts before they occur, preventing component failure and maintaining production continuity.
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 enhances the durability and longevity of the bumper spring assembly, reducing the risk of damage and improving fluid flow by up to 20%, thereby maintaining production levels and minimizing well downtime.
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
Implementation Method 2
a bumper spring configured as a coil spring disposed concentrically on the mandrel, a first end thereof adjacent the head end
Data Source
AI summary
A bumper spring assembly having a one piece mandrel including an integral head piece is further configured with a cage assembly retained on the mandrel with a cage nut locked to the mandrel to obviate the need for pins, set screws, and the like, to provide a more robust assembly. In two embodiments the cage nut is locked to the mandrel in a swaging operation. Improved flow of fluids through and around the bumper spring assembly are also provided.