Downhole Tool Anti-Extrusion Finger Segmentation
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Solution Overview
Problem
Downhole tools in the oilfield industry face issues with sealing element extrusion due to the use of soft materials for back-up rings, which can lead to failure and compromise the seal between the tool and the casing string, resulting in reduced isolation efficiency.
Innovation Solution
The design incorporates a mandrel with a sealing element that expands radially, cones, fingers that break away at a weak point, and a ring to prevent extrusion, along with a slip that slides along a tapered surface to secure the tool in place, ensuring effective sealing and isolation by transmitting reactionary forces through compressive loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If back-up rings are made from soft materials (e.g., composites) to facilitate drilling through the tools, then the ease of operation during drilling is improved, but the reliability of preventing sealing element extrusion deteriorates
Solution Approach 1:
The anti-extrusion device is divided into multiple fingers that are segmented and positioned around the mandrel. Each finger can independently contact the sealing element, providing distributed support that prevents extrusion while maintaining drilling capability through the weak points in the fingers
Solution Approach 2:
The device uses fingers made from materials that combine the properties needed for both drilling operation and extrusion prevention. The fingers incorporate weak points that allow them to break away during drilling (facilitating ease of operation) while their overall structure maintains sufficient strength to prevent sealing element extrusion
2Reliability
If the sealing element is expanded radially outward to form a seal with the casing string, then the sealing efficiency is improved, but the tendency for axial extrusion along the mandrel increases
Solution Approach 1:
The fingers are positioned in advance around the mandrel to contact and support the sealing element before extrusion can occur. This preliminary positioning creates a mechanical barrier that counteracts the axial extrusion force generated during radial expansion, preventing the harmful effect before it can compromise the seal
Solution Approach 2:
The fingers act as an intermediary mechanical structure between the sealing element and the mandrel. They transfer and distribute the compressive forces, mediating the interaction between the expanding sealing element and the mandrel surface, thereby preventing direct contact that would cause extrusion while maintaining effective sealing
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 configuration enhances the sealing efficiency by preventing extrusion of the sealing element and maintaining a secure position within the wellbore, thereby improving the tool's ability to isolate sections effectively and withstand drilling operations.
Implementation Method 1
The sealing element is configured to expand radially-outward from a contracted state to an expanded state
Implementation Method 2
The slip includes a tapered inner surface configured to slide along a tapered outer surface of the cone
Data Source
AI summary
A downhole tool including a mandrel, a sealing element, a cone, a plurality of fingers, and a slip. The sealing element may be positioned around the mandrel. The sealing element is configured to expand radially-outward from a contracted state to an expanded state. The cone may be positioned around the mandrel and proximate to the sealing element. The plurality of fingers may be positioned at least partially around the mandrel. The fingers may be axially-aligned with at least a portion of the sealing element. The fingers are coupled to a base and configured to break away from the base at a weak point when the sealing element expands into the expanded state. The slip may be positioned around the mandrel and proximate to the cone. The slip may include a tapered inner surface configured to slide along a tapered outer surface of the cone.