Turned-Down Centralizer Assembly for Wellbore Restriction Clearance
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Solution Overview
Problem
Bow-spring centralizers face damage and reduced effectiveness when passing through wellbore restrictions due to limited clearance, and the tolerance in oilfield tubulars' outer diameters complicates precise clearance determination.
Innovation Solution
A centralizer assembly with a mandrel featuring a turned-down region and stop segments to limit the centralizer's range of motion, allowing it to maintain annular clearance and withstand restrictions while preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bow-spring centralizers are used to maintain annular clearance in restrictions, then the centralizer can pass through reduced clearance areas, but the centralizer may be damaged when clearance is too small
Solution Approach 1:
The centralizer assembly incorporates a collapsible bow-spring centralizer that can dynamically change its configuration. The bow-springs are designed to collapse radially inward when encountering restrictions, allowing the centralizer to pass through reduced clearance areas, and then expand back to their original configuration to maintain annular clearance after passing the restriction, thus adapting to different clearance conditions without damage
Solution Approach 2:
The centralizer assembly changes its geometric parameters (radial dimension) in response to clearance conditions. The mandrel diameter is reduced in the turned-down region to accommodate the collapsed centralizer configuration, while the stop segments control the expansion parameter to ensure the centralizer maintains proper annular clearance after passing through restrictions, preventing damage through parameter control
2Manufacturing precision
If the mandrel diameter is reduced to accommodate the centralizer in the turned-down region, then the centralizer can be positioned correctly, but the range of motion of the centralizer must be limited to prevent damage
Solution Approach 1:
Stop segments are introduced as intermediary elements between the mandrel and the centralizer. These stop segments are positioned on the mandrel in the turned-down region and engage with the centralizer to limit its axial range of motion, preventing the centralizer from moving too far axially while still allowing it to be properly positioned and collapsed radially, thus mediating between positioning requirements and motion constraints
Solution Approach 2:
The mandrel is segmented into different diameter regions (raised region and turned-down region), and the stop segments are separately positioned on the mandrel. This segmentation allows the centralizer to be positioned accurately in the turned-down region while the stop segments provide discrete constraint points that limit the range of motion without requiring a completely constrained design
Data Source
AI summary
A method for manufacturing a centralizer assembly includes reducing a diameter of a mandrel such that a turned-down region is formed in the mandrel, positioning a first stop segment in the turned-down region, and positioning a centralizer at least partially in the turned-down region, wherein the first stop segment is positioned intermediate of axial extents of the centralizer, such that the first stop segment at least partially limits a range of motion of the centralizer relative to the mandrel.