Annular Barrier Axial Force Mechanism
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Solution Overview
Problem
Existing annular barriers in wellbores face issues with inexpedient thinning of expandable sleeves during expansion, leading to potential rupture and reduced strength, which impairs the ability to achieve the desired expanded size without excessive pressure exposure.
Innovation Solution
The annular barrier employs an actuation mechanism with a connection unit that simultaneously injects hydraulic fluid into the expandable sleeve and displaces one end towards the other, using a pressure chamber and fluid bypass passages to control pressure and prevent thinning, while a pressure-regulated valve maintains pressure within safe limits to prevent rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the thickness of the expandable sleeve is decreased to reduce expansion pressure, then the expansion pressure is reduced, but the strength of the expandable sleeve is impaired and it may collapse or rupture before reaching the desired expanded size
Solution Approach 1:
The connection part is displaced in the longitudinal direction before and during the expansion process to pre-compress the expandable sleeve. This preliminary action distributes the stress more evenly throughout the sleeve material, preventing localized thinning and rupture while reducing the peak expansion pressure required to achieve the desired expanded size.
Solution Approach 2:
The system transitions from a static expansion process to a dynamic one where the connection part moves longitudinally during expansion. This dynamic approach allows the sleeve to be compressed and expanded in a controlled sequence, maintaining material integrity while achieving the desired expansion with lower pressure.
2Volume of moving object
If hydraulic fluid is injected to expand the expandable sleeve, then the sleeve expands to engage with the outer tubular structure or borehole wall, but inexpedient thinning of the sleeve material occurs causing potential rupture
Solution Approach 1:
The connection part is displaced longitudinally to pre-compress the expandable sleeve before full expansion pressure is applied. This preliminary compression ensures uniform stress distribution throughout the sleeve material, preventing localized thinning and rupture during the expansion process while achieving the desired expanded size.
Solution Approach 2:
The invention replaces pure radial expansion with a combined longitudinal compression and radial expansion mechanism. By using the actuation mechanism to displace the connection part longitudinally, the system creates a more favorable stress state in the sleeve material that prevents thinning and rupture.
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 approach effectively prevents inexpedient thinning and rupture of the expandable sleeve, allowing for controlled expansion with reduced pressure requirements, enhancing the barrier's strength and reliability in zone isolation between well tubular structures and borehole walls.
Implementation Method 1
an actuation mechanism adapted to induce an axial force on the first end of the expandable sleeve, whereby the connection part is displaced in the longitudinal direction towards a second end of the expandable sleeve connected with the tubular part
Implementation Method 2
a first fluid passage for letting fluid into the space to expand the sleeve
Data Source
AI summary
The present invention relates to an annular barrier to be expanded in an annulus between a well tubular structure and an inside wall of a borehole downhole for providing zone isolation between a first zone and a second zone of the borehole. The annular barrier comprises a tubular part extending in a longitudinal direction for mounting as part of the well tubular structure; an expandable sleeve surrounding the tubular part and defining a space being in fluid communication with an inside of the tubular part; a first fluid passage for letting fluid into the space to expand the sleeve; and a connection unit comprising a connection part slidably connected with the tubular part, a first end of the expandable sleeve being connected with the connection part, wherein the connection unit further comprises a stationary part fixedly connected with the tubular part and an actuation mechanism adapted to induce an axial force on the first end of the expandable sleeve.