Lock Mandrel Spring-Loaded Collar Prevents Pump Disengagement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Downhole pumps in hydrocarbon wells can become unseated due to high pressure differentials, leading to reduced efficiency and accumulation of liquids in the tubing, which increases back pressure and limits gas recovery, as traditional lock mandrels fail to securely maintain the pump position without requiring reduced-diameter shoulders that can disrupt fluid flow.
Innovation Solution
A lock mandrel with a spring-loaded locking collar that presses radially against the locking keys to prevent disengagement during high pressure differentials and retracts to allow easy removal, featuring equalizing pins and a jarring mechanism to aid in detachment, ensuring secure attachment and easy retrieval without the need for reduced-diameter shoulders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional lock mandrels are used to secure downhole pumps, then the structure is simple and ease of manufacture is improved, but the reliability of maintaining pump position under high pressure differentials deteriorates
Solution Approach 1:
The lock mandrel employs a dynamic spring-loaded locking collar that can automatically adjust its gripping force on the locking keys. The spring mechanism allows the collar to exert continuous radial pressure on the keys, maintaining secure engagement under varying pressure differentials while enabling easy release when needed. This dynamic adaptation resolves the contradiction by providing reliable positioning without requiring overly complex fixed structures.
Solution Approach 2:
The locking mechanism is divided into separate functional components: the locking keys, the spring-loaded collar, and the equalizing pins. This segmentation allows each component to perform its specific function independently - the keys provide the locking interface, the spring collar provides continuous engagement pressure, and the equalizing pins manage pressure differentials. This modular approach improves reliability while keeping the overall structure manufacturable.
2Reliability
If no-go landing nipples with reduced-diameter shoulders are used to prevent pump disengagement, then the reliability of preventing downward movement is improved, but the fluid flow efficiency deteriorates due to pressure drops and gas coming out of solution
Solution Approach 1:
The lock mandrel acts as an intermediary device between the downhole pump and the landing nipple. Instead of modifying the landing nipple structure (which would create flow constrictions), the mandrel provides the necessary mechanical retention through its spring-loaded locking mechanism. This intermediary approach maintains full-diameter flow paths while achieving reliable pump positioning.
Solution Approach 2:
The harmful reduced-diameter shoulder is extracted from the landing nipple design and replaced by a separate locking mechanism on the mandrel. This separation allows the landing nipple to maintain its full-diameter, flow-efficient geometry while the mandrel's locking collar provides the necessary mechanical retention, eliminating the harmful pressure drop effect.
3Ease of operation
If locking keys are held in place using key springs, then the ease of operation is improved, but the reliability under high discharge pressure deteriorates as the springs compress and keys become unseated
Solution Approach 1:
The spring-loaded locking collar acts as a counterbalancing mechanism that opposes the downward force generated by high discharge pressure. The spring in the collar provides an upward reactive force that prevents the locking keys from being pushed out of engagement, effectively counteracting the harmful pressure differential without requiring additional complex components.
Solution Approach 2:
The locking mechanism transitions from static key springs to a dynamic spring-loaded collar that can automatically adjust its gripping force. The collar's spring mechanism provides continuous radial pressure on the locking keys, adapting to varying pressure conditions and maintaining reliable engagement while preserving ease of operation through the inherent spring mechanism.
4Reliability
If the lock mandrel is designed for secure attachment during operation, then the reliability is improved, but the ease of removal for retrieval deteriorates
Solution Approach 1:
The spring-loaded locking collar enables periodic action in the locking mechanism - it maintains continuous engagement pressure during operation for reliable positioning, but can be easily released when needed for removal. The spring mechanism naturally alternates between the engaged state (providing retention) and the released state (allowing removal), resolving the contradiction between secure attachment and easy retrieval.
Solution Approach 2:
The spring-loaded collar provides self-service functionality by automatically maintaining engagement pressure without requiring additional actuation during operation. For removal, the spring's inherent elasticity allows the collar to be easily released by simply overcoming the spring force, eliminating the need for complex release mechanisms and enabling easy tool retrieval.
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 spring-loaded locking collar effectively maintains the downhole pump's position during operation and facilitates easy removal, reducing back pressure and enhancing gas recovery by preventing disengagement due to pressure differentials and simplifying the detachment process, thus improving the overall efficiency of hydrocarbon well operations.
Implementation Method 1
a compression spring configured to prevent the spring-loaded locking collar from retracting to the unseated position in response to an increase in a pressure differential within the lock mandrel
Implementation Method 2
a spring-loaded locking collar configured to prevent the locking keys from disengaging from the landing nipple by pressing radially against the locking keys from the inside
Data Source
AI summary
A lock mandrel is described herein. The lock mandrel includes an upper connector and a lower connector. The upper connector includes locking keys configured to attach the lock mandrel to a landing nipple on a tubing within a hydrocarbon well. The upper connector also includes a spring-loaded locking collar configured to prevent the locking keys from disengaging from the landing nipple by pressing radially against the locking keys from the inside when in a seated position, and allow the locking keys to disengage from the landing nipple by retracting away from the locking keys when in an unseated position. The lower connector includes a tool adaptor configured to attach a downhole tool to the lock mandrel.