Retractable-Strut Centraliser for Wellbore Restriction Passage
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Solution Overview
Problem
Conventional centralisers fail to adapt to wellbore restrictions and deform under the weight of casing strings in horizontal wellbores, leading to uneven cementing and potential operational risks.
Innovation Solution
A centraliser with retractable strut members and angled wing portions that allow for flexible deployment and reconfiguration, reducing deformation and maintaining tubing centralisation while passing through bore restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid body centralisers with fixed radial blades are used, then the casing string can be maintained in a central position, but the centraliser cannot adapt to wellbore restrictions and washouts, inhibiting the ability to reach desired total depth
Solution Approach 1:
The patent applies the dynamics principle by replacing fixed rigid blades with movable flexible elements. The centraliser uses a flexible body with movable radial blades that can dynamically adjust their position and flexibility based on encounters with wellbore restrictions, washouts, or deviations. This allows the centraliser to maintain centralisation reliability while adapting to varying wellbore conditions, enabling the casing string to reach desired total depth without being blocked by rigid structures.
2Adaptability or versatility
If bow spring centralisers are used, then the spring elements can deflect radially inwards to permit passage through wellbore restrictions, but in horizontal wellbores the weight of the casing string deforms the spring elements beyond capacity, causing the casing to lie towards the low side and risking uneven cementing
Solution Approach 1:
The patent applies local quality by differentiating the mechanical properties at different locations of the centraliser body. The flexible body is constructed with varying stiffness characteristics - the radial blades are made flexible to deflect through restrictions, while the overall structure maintains sufficient rigidity in horizontal wellbores to counteract casing weight and prevent low-side positioning. This localized variation in mechanical properties allows the centraliser to simultaneously achieve adaptability to restrictions and reliability for maintaining centralisation in horizontal sections.
Solution Approach 2:
The patent employs composite materials by combining flexible and rigid properties in a single centraliser structure. The flexible body material provides the necessary compliance to pass through wellbore restrictions, while integrated rigid elements or structural configurations maintain the centralisation capability in horizontal wellbores. This composite approach resolves the contradiction between needing flexibility for restriction passage and rigidity for maintaining central position against casing weight.
3Ease of operation
If the centraliser is made more flexible to pass through bore restrictions, then it can navigate restrictions more easily, but it may deform excessively under the weight of the tubing in horizontal wellbores
Solution Approach 1:
The patent applies segmentation by dividing the centraliser into distinct functional segments with different mechanical characteristics. The flexible body is segmented into radial blades that can deflect independently to pass through restrictions, while the overall centraliser structure maintains a core rigidity to resist excessive deformation under tubing weight. This segmentation allows each portion to optimize its behavior - the blades provide flexibility for restriction passage, while the overall structure provides stability to prevent excessive deformation in horizontal wellbores.
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
Enhances cementing operations by maintaining tubing centralisation, reducing deformation risks, and facilitating deeper well penetration with reduced friction and obstruction, thus improving operational safety and efficiency.
Implementation Method 1
a resilient device extending between the first and second collars, the resilient device being resiliently biased in a radial direction away from the locking ring
Implementation Method 2
at least one fixing between the at least one catch device and the locking ring and made from a sacrificial material adapted to degrade in wellbore conditions
Data Source
Figure 1~2
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Figure 5~6
AI summary
A centraliser (10) for use in centralising tubing (12) in a bore (W) comprises a first end collar (14), a second end collar (16) and a number of elongate strut members (18). The strut members (18) are interposed between the first end collar (14) and the second end collar (16) and are circumferentially arranged and spaced around the first end collar (14) and second end collar (16). The strut members (18) have angled wing portions (32). The centraliser (10) comprises a retaining arrangement (20) for holding the strut members (18), which comprises a retainer member (22) extending circumferentially between and disposed through the strut members (18). The centraliser (10) comprises a release arrangement (24) configured to release the retaining arrangement (20) and permit the strut members (18) to move between radially retracted and radially extended positions.