Back Pressure Valve Thread Release for Fouled Wellhead Connections
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Solution Overview
Problem
Existing back pressure valves (BPVs) in wellhead assemblies face issues with thread fouling due to deposits from corrosion and fluid substances, making them difficult to remove from the tubing hanger.
Innovation Solution
A back pressure valve design featuring a sleeve assembly with radially moveable thread segment blocks and a contingency release mechanism, allowing for disengagement of threads by changing the sleeve configuration from armed to activated, facilitated by springs and telescoping sleeves, enabling easy removal even when threads are fouled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the BPV is installed with threaded connection in the tubing hanger, then the valve can be securely mounted and controlled, but the threads become fouled with deposits making removal difficult
Solution Approach 1:
The threaded connection is segmented into two independent parts: inner threads on the BPV and outer threads on the tubing hanger. This segmentation allows the BPV to be securely mounted through threaded engagement while providing a separate contingency release mechanism for easy removal without unscrewing the fouled threads.
Solution Approach 2:
The contingency release mechanism acts as an intermediary that bypasses the fouled threaded connection. When activated, it provides an alternative path for removal that does not require engaging the contaminated threads, thus solving the removal difficulty while maintaining secure mounting during normal operation.
2Ease of operation
If conventional removal methods are used, then the BPV can be removed under normal conditions, but removal fails when threads are fouled with deposits
Solution Approach 1:
The contingency release mechanism is pre-installed and prepared within the BPV structure before deployment. This preliminary action ensures that if thread fouling occurs during operation, the removal mechanism is already in place and can be activated to reliably remove the valve without depending on the condition of the threaded connection.
Solution Approach 2:
The design anticipates potential thread fouling by incorporating a backup removal mechanism that compensates for the harmful effect of deposits. This beforehand cushioning ensures that removal reliability is maintained even when conventional methods fail due to fouled threads.
3Ease of operation
If the BPV structure is simplified for easy removal, then removal becomes easier, but the valve cannot be securely mounted
Solution Approach 1:
The BPV structure merges two functional systems: a threaded connection system for secure mounting and a contingency release system for easy removal. The threaded portions provide strong mechanical engagement for secure installation, while the integrated contingency release mechanism enables simple pull-out removal without compromising the strength of the mounted connection during normal operation.
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
Enables efficient and reliable removal of the BPV from the wellhead assembly without requiring unscrewing, even when conventional methods fail due to thread fouling, ensuring operational flexibility and ease of maintenance.
Implementation Method 1
a spring in biasing contact with the outer surface of the block, in alternatives, a portion of the body forms a skirt that circumscribes a portion of the recess, and where the spring is compressed between the thread segment block and the skirt when the sleeve assembly is in the armed configuration and exerts a biasing force that moves the thread segment block radially inward when the sleeve assembly is in the activated configuration
Data Source
AI summary
A back pressure valve (“BPV”) for use in a wellhead assembly has a contingency release means. The BPV is coupled to the wellhead assembly with a threaded connection, that is formed by engaging threads on the BPV with threads in a tubing hanger inside the wellhead assembly. The contingency release means is activated by applying an overpull to the BPV, which retracts the BPV threads radially inward and away from engagement with tubing hanger threads. Disengaging the threads uncouples the BPV from the tubing hanger allowing BPV removal from the wellhead assembly. The BPV threads are on blocks that are disposed around the BPV circumference. The blocks are biased radially inward with springs. Concentric sleeves inside the blocks resist block inward movement. The overpull telescopes the concentric sleeves allowing the springs to urge blocks radially inward, which moves the BPV threads away from the tubing hanger threads.