Annular Blowout Preventer Iris Geometry Pipe Stripping
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Solution Overview
Problem
Existing annular blowout preventers lack an effective mechanism for pipe stripping and tool suspension, as they do not provide a leading entry for pipe stripping or a hang-off zone, leading to inefficiencies in flow control and load management.
Innovation Solution
An annular packer with curved blades arranged in an iris-like geometry, transforming the bore from a parallel cylindrical shape to an hourglass shape with a waist or pinch point, providing a funnel shape for pipe stripping and a keystone arrangement for tool suspension, and utilizing resilient elastomer-coated metal elements for efficient actuation and retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat plates are used in the annular packer, then the structure is simple and easy to manufacture, but the bore remains parallel and does not provide a leading entry for pipe stripping or a hang-off zone
Solution Approach 1:
The patent applies curvature to the packer elements by replacing flat plates with curved blades that form an iris-like geometry. This curvature transformation creates the hourglass-shaped bore with a waist section that provides both pipe stripping capability and tool hang-off zone, resolving the contradiction between structural simplicity and functional adaptability.
2Device complexity
If parallel cylindrical bore is maintained, then the structure is simple, but pipe stripping is difficult and no natural lead is provided for pipe entry
Solution Approach 1:
The curved blade design transforms the parallel cylindrical bore into an hourglass shape with a tapered leading section. This curvature provides a natural lead for pipe entry and facilitates pipe stripping operations, improving ease of operation while maintaining reasonable structural complexity through the iris-like arrangement of curved elements.
3Device complexity
If conventional parallel packer elements are used, then the closing action is straightforward, but shear loads are concentrated at the contact edge causing damage to work pieces
Solution Approach 1:
The curved leading edges of the blades distribute the closing force across a broader contact area rather than concentrating it at a sharp edge. This curvature blurs the contact edge, reducing shear load concentration and minimizing damage to pipes and tools during the closing operation.
4Device complexity
If no waist section is provided in the bore, then the structure is simpler, but tool suspension and load management are ineffective
Solution Approach 1:
The hourglass-shaped bore created by curved blades naturally segments the through-bore into an upper section and a lower section separated by a waist. This segmentation provides a distinct hang-off zone for tool suspension and load management, improving reliability without requiring additional structural components.
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 hourglass shape enhances pipe stripping and tool suspension by minimizing shear loads and providing a natural lead for pipe entry, while the elastomer's resilience ensures quick re-opening, improving operational efficiency and reducing waiting time compared to conventional annular packers.
Implementation Method 1
the elements are coated in resilient elastomer such that when pressure on said piston is released when said elements are in second position, the resilience of said elastomer moves said elements back to the first position
Data Source
AI summary
An annular packer (10) for use with an annular blow out preventer (20) formed of a plurality of blades or elements (21,30,72) where each of the blades (21,30,72) is curved and arranged in the annular bore such that the curve of the blade is not parallel with the longitudinal axis of the assembly. This creates an “iris” type of geometry which, as the iris closes, the annular bore (24) transforms from a parallel cylindrical shape to a smaller bore with a shape having at least one waist or pinch point (32,34,73,75) of smaller cross-section.