Asymmetric Spring Bow Centralizer for Wellbore Torque Reduction
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Solution Overview
Problem
Centralizers in oil and gas wells face challenges in maintaining consistent radial spacing between the tubular string and the well bore, leading to uneven cement layers and increased torque and wear during tubular rotation, which complicates the completion operations and reduces the efficiency of fluid recovery.
Innovation Solution
A centralizer design featuring resilient devices with convex and concave arcs that deform radially upon insertion, allowing for reduced axial force during tubular placement and enhanced freedom of rotation, while maintaining radial spacing and minimizing wear on both the tubular and centralizer components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid centralizer is used to maintain radial spacing, then the radial spacing is maintained consistently, but the axial force required for tubular insertion increases and torque during rotation increases
Solution Approach 1:
The centralizer employs resilient bows that can dynamically adjust their radial position. The bows are compressed during insertion to reduce radial extent, lowering insertion force, then expand to maintain radial spacing during cementing operations. This dynamic adjustment resolves the contradiction between maintaining precise radial spacing and reducing insertion force.
Solution Approach 2:
The centralizer changes the parameter of radial spacing dynamically. During insertion, the radial spacing is reduced by compressing the bows, requiring less axial force. During operation, the radial spacing is maintained at the designed dimension as the bows expand. This parameter change resolves the contradiction between insertion force and radial spacing consistency.
2Manufacturing precision
If a rigid centralizer is used to maintain radial spacing, then the radial spacing is maintained consistently, but wear on tubular and centralizer components increases
Solution Approach 1:
The resilient bows provide dynamic adjustment capability, allowing the centralizer to adapt to variations in bore geometry and tubular position. This reduces concentrated stresses and wear at fixed points, while still maintaining consistent radial spacing for cementing. The elasticity of the bows absorbs impact loads that would otherwise cause wear and damage.
3Ease of operation
If axial force is reduced during insertion, then ease of operation improves, but the ability to maintain radial spacing may be compromised
Solution Approach 1:
The resilient bows are designed to compress under axial load during insertion, reducing resistance and easing operation. Once the centralizer is in position, the bows expand back to their designed radial extent, maintaining the required radial spacing. This dynamic behavior resolves the contradiction between ease of insertion and radial spacing maintenance.
4Ease of operation
If the centralizer allows free rotation of the tubular, then torque is reduced, but control over tubular position may be lost
Solution Approach 1:
The resilient bows allow the tubular to rotate freely by accommodating radial movements, reducing torque during rotation operations. At the same time, the bows maintain constant radial spacing, ensuring the tubular remains properly positioned for cementing. The dynamic resilience of the bows decouples rotation freedom from positioning control.
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
The design reduces the axial force required for tubular insertion, lowers torque, and minimizes wear by maintaining radial spacing and allowing free rotation of the tubular within the centralizer, while reducing the risk of damage to the tubular and centralizer components.
Implementation Method 1
the resilient device is deformable radially inwardly upon axial compression
Implementation Method 2
allowing for reduced axial force during tubular placement and enhanced freedom of rotation, while maintaining radial spacing and minimizing wear
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A centraliser comprises two collars that are connected by asymmetric spring bows. The spring bows each comprise two arcs, where the curvature of one arc is inverted with respect to the curvature of the other arc, one being concave and the other convex. The spring bows are in sets that are equidistantly spaced around the circumference of the collars, each set having the same configuration, and the opposite configuration to the spring bows in the other set. Upon insertion into a wellbore, one set of spring bows is therefore compressed before the other set. Upon compression, the deformation of the concave arc leads to mutual deformation of the convex arc, and the spring bows adopt a flatter configuration, enhancing the rotational freedom of the tubular.