Expandable Casing Recesses for Collapse Resistance
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Solution Overview
Problem
Current expandable casings in subterranean wells face issues with low collapse resistance due to thin wall thickness and radial springback, leading to gaps between inner and outer casings that hinder sealing.
Innovation Solution
The introduction of internal or external grooves on the casing to enhance collapse resistance and reduce gaps between casings, achieved by forming multiple recesses in the tubulars that allow for greater radial retraction at recesses than between them, ensuring contact and improved sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the casing wall thickness is reduced to enable expansion, then the expandability and installation flexibility are improved, but the collapse resistance deteriorates
Solution Approach 1:
The casing wall is segmented into multiple struts separated by circumferential grooves. This segmentation allows each strut to independently resist collapse while maintaining overall structural integrity, enabling thin-walled expandable casing to achieve high collapse resistance through the distributed strut architecture
Solution Approach 2:
The casing employs curved or angled struts with specific geometric configurations rather than straight radial segments. These curved struts provide superior mechanical strength and collapse resistance compared to straight segments, while still allowing the casing to expand from a smaller initial diameter
2Reliability
If the inner casing is expanded with higher strain to fit within the outer casing, then the sealing capability is improved, but the radial springback increases creating gaps between casings
Solution Approach 1:
The outer casing features localized circumferential grooves at specific positions where the inner casing will contact it. These grooves create localized compression zones that allow the inner casing to spring back against the outer casing at precise locations, ensuring contact and sealing while accommodating overall radial springback
Solution Approach 2:
The circumferential grooves in the outer casing are pre-positioned to anticipate and counteract the radial springback of the inner casing. By providing predetermined contact zones at the grooves, the design pre-compensates for the springback effect, ensuring that the inner casing maintains contact with the outer casing after expansion
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 solution provides enhanced collapse resistance and sealing capabilities by maintaining contact between casings at recesses, reducing clearance and improving the overall performance of expandable tubulars in subterranean wells.
Implementation Method 1
the wall of the tubular is allowed to retract radially inward more at each of the recesses than between the recesses
Data Source
AI summary
An expandable casing with enhanced collapse resistance and sealing capability. An expandable tubular for use in a subterranean well includes multiple recesses extending into a wall of the tubular, with the recesses being longitudinally spaced apart along the wall. A method of expanding tubulars in a subterranean well includes the steps of: expanding a tubular in the well, the tubular including multiple recesses extending into a wall of the tubular; and after the expanding step, allowing the wall of the tubular to retract radially inward more at each of the recesses than between the recesses.