Shear Blade With Segmented Edge For Wellbore Equipment
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Solution Overview
Problem
Conventional blowout preventers struggle to effectively cut or shear various types of objects in a wellbore during emergency situations due to limitations in their cutting/shearing blades.
Innovation Solution
The design of a shear blade with a central sharp edge and outer blunt edges, along with an intermediate edge, which allows for efficient cutting of solid and tubular objects by applying varying stress profiles, and a recess or slot to accommodate and guide objects for reliable closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single-edge cutting blade is used, then the blade structure is simple, but it cannot effectively cut through different types of wellbore equipment (solid objects like wirelines and tubular objects)
Solution Approach 1:
The cutting edge is divided into distinct zones with different geometric properties: a central sharp edge region with a smaller radius of curvature for cutting solid objects, and outer blunt edge regions with a larger radius of curvature for cutting tubular objects. This local differentiation in edge geometry allows the single blade to adapt to different object types without increasing overall structural complexity.
Solution Approach 2:
The cutting edge is segmented into multiple functional zones (central sharp edge and outer blunt edges) along its length. Each segment serves a specific cutting function based on the object type it encounters, enabling versatile cutting capability while maintaining a unified blade structure.
2Productivity
If a sharp cutting edge is used, then cutting efficiency is high, but the blade cannot effectively separate cut tubular pieces due to lack of spring effect
Solution Approach 1:
The cutting edge transitions from a sharp central region to blunted outer regions, creating different stress application characteristics. The blunt outer edges apply distributed stress that generates a spring effect in tubular materials, ensuring reliable separation of cut pieces while the sharp central edge maintains high cutting efficiency for solid objects.
Solution Approach 2:
The radius of curvature of the cutting edge is varied along its length, with the central region having a smaller radius (sharper) and outer regions having a larger radius (blunter). This parameter change enables the blade to switch between high-efficiency cutting and reliable separation functions depending on the location of contact with the object.
3Strength
If the cutting edge applies high stress to cut through tough objects, then cutting capability is improved, but the blade may fold or deform during the cutting process
Solution Approach 1:
The blade body is designed with varying thickness and reinforcement at different locations. The central region near the sharp edge is reinforced to handle high cutting forces on solid objects, while the overall blade geometry maintains flexibility to prevent folding during the cutting process.
Data Source
Figure 1~2A
Figure 3~4
Figure 5~6
AI summary
A shear blade (10) for a downhole apparatus (50) defining a throughbore having a main axis. The shear blade comprises a body portion (12) defining a shear face (30). The shear blade also includes a first cutting edge (21) provided at a cutting end of the shear blade. The shear blade comprises a recess or slot (40a) extending within a portion of the shear face in a plane substantially parallel to the main axis of the throughbore and/or in a plane substantially perpendicular to the first cutting edge.