Wireline Centralizer Reducing Eccentricity in Small Casing
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Solution Overview
Problem
Conventional wireline roller centralizers experience significant eccentricity and non-linear centralizing force issues when used in smaller casing diameters, leading to inaccurate log data and wear problems due to excessive radial arm play and spring loading.
Innovation Solution
The design replaces the conventional centralizer with a dual centralizer assembly featuring slider blocks with different biasing elements and arm configurations, reducing radial arm play and optimizing centralizing force through a two-stage biasing mechanism, ensuring proper tool alignment and force distribution across varying casing sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If long arms are used in the roller centralizer to accommodate large range of casing sizes, then the centralizer can be used in a large range of casing sizes (4.5-in to 18-in), but the arms have considerable effective radial play (linkage slop) when run in smaller casing sizes, resulting in high levels of eccentricity
Solution Approach 1:
The single long arm is segmented into multiple shorter arms connected by pins. This segmentation reduces the effective length of each arm segment, thereby reducing radial play and linkage slop while maintaining the overall reach and adaptability to different casing sizes through the articulated configuration
Solution Approach 2:
The arm structure is made dynamic through the use of pinned connections that allow relative movement between arm segments. This dynamic configuration enables the arm assembly to adapt to different casing diameters while maintaining shorter effective arm lengths that reduce eccentricity in smaller casings
2Force
If spring loading is used to provide centralizing force, then the centralizer can maintain contact with the casing wall, but the spring loading creates non-linear centralizing force and excessive wear on the radial supports
Solution Approach 1:
The patent replaces the spring loading mechanism with a simpler, wear-resistant structure. The radial supports are designed as robust, replaceable components that can withstand repeated use without the non-linear force characteristics and wear problems associated with spring mechanisms
Solution Approach 2:
The spring loading mechanism is extracted from the design and replaced with an alternative force application method. The radial supports are directly engaged with the casing wall through the arm structure, eliminating the intermediate spring mechanism that causes non-linear force and excessive wear
3Ease of operation
If the proximal slider block is allowed to travel freely to accommodate maximum operating range, then the centralizer can prevent getting stuck, but the long arms still have considerable radial play that allows the mandrel to be supported off center
Solution Approach 1:
The slider block travel mechanism is combined with segmented arms. The segmentation of the arms reduces radial play independently of the slider block travel, allowing the slider to maintain its full travel allowance for preventing getting stuck while the segmented arm structure simultaneously reduces eccentricity and improves tool alignment
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 solution significantly reduces eccentricity and improves centralizing force consistency, maintaining tool alignment and reducing wear, with a compact form factor that maintains effective centralization across a wide range of casing diameters.
Implementation Method 1
first and second biasing elements disposed on the common pin between the first and second slider blocks. The first biasing element pushes the first and second slider blocks apart an initial extent, and the second biasing element pushes the first and second slider blocks apart a subsequent extent
Data Source
AI summary
A centralizer assembly replaces an existing centralizer of a wireline tool so the tool can be used with smaller casing, such as casing smaller than 6-in. The assembly includes first and second centralizer units that replace the existing centralizer on a mandrel. Each unit has a sleeve that fits in a recess of the mandrel, and each unit has slider blocks disposed together in the recess on opposing sides of a divider on the sleeve. Arms hingedly connected to the blocks on each unit connect together at a joint having a roller for engaging in the casing. On each unit, a common pin is disposed through the slider blocks, and biasing elements on the common pin bias the blocks toward one another with different amounts of bias.