Extendable Rigid Member Centralizes Downhole Tool
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Solution Overview
Problem
Inability to centralize downhole tools in wellbores results in incomplete seals between packers and the sidewall, leading to leakage and inaccurate measurements during subterranean formation analysis and sampling.
Innovation Solution
Employing a rigid member spanning first and second setting pistons to centralize the downhole tool, ensuring packers form a complete seal with the wellbore sidewall, utilizing a telescopic piston mechanism to maintain alignment and contact with the sidewall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a downhole tool is deployed in a wellbore without a centralizing mechanism, then the tool can be easily conveyed and installed, but the tool cannot maintain a central position, resulting in incomplete seals between packers and the sidewall
Solution Approach 1:
The centralizing mechanism is divided into multiple setting pistons (first setting piston, second setting piston) that can be independently extended to push the rigid member against the wellbore sidewall. This segmentation allows for more reliable centralization by distributing the centralizing force across multiple contact points, ensuring complete seals between packers and the sidewall while maintaining a manageable structural complexity
Solution Approach 2:
A rigid member is introduced as an intermediary element between the setting pistons and the wellbore sidewall. This rigid member translates the axial movement of the setting pistons into radial positioning forces, effectively mediating between the downhole tool and the wellbore wall to achieve centralization and complete sealing without requiring direct complex mechanical connections
2Reliability
If the downhole tool is centralized using a rigid member with setting pistons, then complete seals are achieved between packers and the sidewall, but the device structure becomes more complex
Solution Approach 1:
The rigid member serves multiple functions: it acts as a centralizing element, a structural support for the setting pistons, and a positioning reference for the packers. By making the rigid member multi-functional, the patent achieves complete sealing without proportionally increasing structural complexity, as the same component performs several critical roles in the centralizing mechanism
Solution Approach 2:
The setting pistons are pre-configured to extend before the packing operation, and the rigid member is pre-positioned to engage the wellbore sidewall. This preliminary action ensures that the tool is centralized and the packers are properly positioned before sealing is attempted, achieving complete seals while keeping the mechanical structure efficient by avoiding repositioning operations
3Measurement precision
If setting pistons are extended to push the rigid member against the sidewall, then the downhole tool is centralized, but the mechanism requires additional components and operational complexity
Solution Approach 1:
The setting pistons are designed to be extendable and retractable, allowing the rigid member to dynamically adjust its position against the wellbore sidewall. This dynamic mechanism enables precise positioning of the downhole tool by controlling the extension distance of the pistons, achieving high positioning accuracy while managing operational complexity through a well-defined actuation sequence
Solution Approach 2:
The rigid member provides mechanical feedback by engaging the wellbore sidewall, which stops the extension of the setting pistons when the correct centralizing position is achieved. This feedback mechanism ensures precise positioning without requiring complex sensors or control systems, as the mechanical contact itself signals when centralization is complete
Data Source
AI summary
An apparatus including a downhole tool for conveyance in a wellbore extending into a subterranean formation. The downhole tool includes a feature to physically interface a sidewall of the wellbore, and first and second setting pistons each extendable from the downhole tool opposite the feature. The downhole tool also includes a rigid member spanning and extendable with the first and second setting pistons, wherein a length of the rigid member is variable.