Sliding Support Centralizer for Deviated Wellbore Drag Reduction
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Solution Overview
Problem
Existing devices for centering sensor equipment in deviated wells face challenges due to increased friction and drag forces, which can prevent the tool string from descending to the desired depth, especially at well deviations greater than 60 degrees.
Innovation Solution
A centralizing device with a sliding support and pivotally connected arm assemblies, featuring an adjustable maximum outer diameter and a mechanical stop, is designed to reduce friction by allowing the arm assemblies to radially extend and contact the wellbore wall, thereby providing a centering force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the tool string is lowered into a deviated wellbore, then the logging operation can be performed in deviated wells, but increased friction and drag forces prevent the tool string from descending to the desired depth
Solution Approach 1:
The patent employs a flexible centralizer assembly with collapsible arms that can be compressed to a small diameter for insertion into the wellbore, then expanded to contact the wellbore wall and provide centering force while reducing friction during descent
Solution Approach 2:
The centralizer assembly is designed with movable, pivotally connected arms that can dynamically adjust their configuration - collapsing during descent to minimize drag, and expanding at the target depth to provide centering force for sensor operation
2Measurement precision
If the arm assemblies are extended radially to contact the wellbore wall for centering, then the tool string can be centered effectively, but the device outer diameter increases
Solution Approach 1:
The centralizer is divided into multiple separate arm assemblies that can be independently collapsed or expanded, allowing the device to be inserted in a compact state and then deployed to the required diameter for centering
Solution Approach 2:
The arm assemblies are nested within each other or against a central mandrel in the collapsed state, minimizing the outer diameter during insertion, and can be deployed outward to the required diameter for centering operations
3Measurement precision
If fixed support structures are used to maintain centering force, then the tool string can be centered, but the device cannot adapt to different wellbore diameters
Solution Approach 1:
The centralizer uses dynamically adjustable arm assemblies with pivot joints that allow the device to adapt to different wellbore diameters while maintaining effective centering force through mechanical engagement with the wellbore wall
Solution Approach 2:
The device can change its outer diameter parameter by extending or retracting the arm assemblies, allowing adaptation to different wellbore sizes while maintaining the necessary centering force through adjusted mechanical engagement
Data Source
AI summary
A device for centering a sensor assembly in a bore comprises a first support and a second support axially spaced apart along a central longitudinal axis of the device, one or both of the first and second supports configured to slide axially along the central longitudinal axis, and a plurality of arm assemblies, each arm assembly pivotally connected to the first and second supports by a respective pivot joint. One or both supports comprise an adjustment mechanism configured to set a maximum outer diameter of the device.