Mandrel Head Annular Sleeve Positioning for Wellhead Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wellhead isolation tools face reliability issues due to extreme pressures and flow rates during oilfield operations, leading to potential leaks through packoff assemblies, as existing designs fail to provide adequate support against external forces and sealing integrity.
Innovation Solution
The improved mandrel head incorporates an integral, longitudinally-extending annular sleeve with internal threads that engage the mandrel below the seal pack, ensuring fluid containment and maintaining full-bore access, with O-rings sealingly engaging the mandrel head and mandrel at a location below the seal pack to prevent leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the threaded connection between mandrel and mandrel head is positioned above the seal pack, then the assembly is simpler, but sealing integrity deteriorates under high pressure
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the threaded connection between the mandrel and mandrel head below the seal pack rather than above it. This inversion allows the seal pack to rest directly on the mandrel shoulder, creating a positive mechanical stop that prevents lift-off under high pressure while maintaining sealing integrity through the O-rings at the threaded connection.
2Ease of manufacture
If the mandrel head design does not include integral annular sleeve, then manufacturing is easier, but support against external forces is insufficient
Solution Approach 1:
The patent merges the mandrel head body and the annular sleeve into a single integral component rather than assembling them separately. This integration provides continuous structural support against external forces applied to the mandrel, eliminates potential leak paths at the interface between separate components, and maintains manufacturing feasibility through standard machining or forming processes.
3Device complexity
If O-rings are positioned above the seal pack, then assembly is simpler, but fluid containment deteriorates under high pressure
Solution Approach 1:
The patent positions the O-rings at the threaded connection below the seal pack to preemptively prevent fluid leakage before pressure can cause lift-off. This preliminary sealing arrangement ensures that even if the seal pack experiences high pressure, the O-rings maintain fluid containment at the threaded connection point, preventing leaks into the wellhead equipment.
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
This design enhances the sealing integrity and support against external forces, preventing fluid leaks and ensuring reliable operation under high-pressure conditions by extending the threaded connection below the seal pack, thereby maintaining the integrity of the wellhead isolation tool.
Implementation Method 1
The threaded connection between the mandrel and mandrel head will also typically include sealing elements, such as o-rings, intended to prevent the passage of fluid from the interior of the mandrel through the threaded connection.
Data Source
AI summary
An improved mandrel head for use with a wellhead isolation tool for protecting a wellhead. In an exemplary embodiment, the wellhead isolation tool includes a lock assembly with a mandrel head with a longitudinally extending annular sleeve. The inner surface of the mandrel head is connected to the mandrel and adapted to sealingly engage the mandrel. The outer surface of the mandrel head also sealingly engages with a seal pack within the wellhead isolation tool, and the mandrel head is configured such that the point of the connection between the mandrel and mandrel head is axially located below the engagement with the seal pack.