Self-Locking Centralizer with Internal Spring for Tubular
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Solution Overview
Problem
Existing centralizers in oilfield applications face challenges in securely locking onto tubulars without using stop rings, special torqueing tools, or small fasteners, while also preventing axial and rotational movement, which is crucial for reducing drag and facilitating installation in horizontal sections.
Innovation Solution
A centralizer design featuring an internal spring that induces hoop stress and utilizes ramps and apertures with expandable spring members and retaining pins to self-lock onto the tubular, resisting rotation and axial movement without requiring external fasteners or tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stop rings or set screws are used to anchor the centralizer, then the centralizer can be securely locked onto the tubular, but the installation becomes more complex and requires special tools or multiple components
Solution Approach 1:
The centralizer employs self-locking features where the body geometry and internal spring mechanism automatically secure the centralizer to the tubular without requiring external stop rings, set screws, or special torqueing tools. The ramps and apertures with retainers create a self-contained locking system that eliminates the need for separate fastening components.
Solution Approach 2:
The locking function is merged into the centralizer body itself through integrated ramps, apertures, and retainers. The internal spring mechanism is combined with the body structure to provide both positioning and locking functions in a single unified component, eliminating the need for separate stop rings or fasteners.
2Reliability
If the centralizer is designed to prevent axial and rotational movement, then the centralizer securely locks onto the tubular, but the device complexity increases
Solution Approach 1:
The centralizer body incorporates asymmetric ramp structures that engage with the tubular geometry to prevent both axial movement and rotation. The non-symmetric arrangement of ramps and retainers creates directional locking that simultaneously restricts multiple degrees of freedom through a single structural feature rather than multiple separate constraints.
Solution Approach 2:
The locking function is segmented into distinct geometric features (ramps, apertures, retainers) that work together to prevent different types of movement. The internal spring is segmented into sections that can independently engage with different features on the tubular, allowing complex movement prevention through modular geometric interactions.
3Strength
If the centralizer uses an internal spring to induce hoop stress, then the centralizer resists rotation and axial movement, but the manufacturing precision requirements increase
Solution Approach 1:
The internal spring is pre-loaded during manufacturing to induce hoop stress in the tubular before the centralizer is installed in the well. This preliminary action of pre-compressing the spring ensures that when the centralizer is later installed, the spring immediately engages the locking features without requiring precise alignment or adjustment during installation.
Solution Approach 2:
The spring is designed with specific material properties and geometric parameters that allow it to generate adequate hoop stress within standard manufacturing tolerances. By optimizing the spring wire diameter, coil density, and material selection, the system achieves reliable locking without requiring ultra-precise installation dimensions.
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 centralizer effectively secures itself to the tubular, reducing drag and enabling easier installation by preventing axial and rotational movement, thus addressing safety and installation efficiency concerns in horizontal well sections.
Implementation Method 1
an internal spring is provided to induce a hoop stress into the tubular on which the centralizer resides
Implementation Method 2
installing set screws, hammering in wires or nails into a sleeve to produce friction between the mating parts
Data Source
AI summary
A centralizer capable of self-locking onto a tubular. The centralizer being of the type used in production strings of tubulars in the oilfield. The centralizer relates to mechanisms such as stop rings for centralizers commonly used in downhole applications to prevent axial and rotational movement of centralizers mounted on the tubing or casing outer surface.