Downhole Extendable Elements With Curved Tracks for Stress Relief
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Solution Overview
Problem
Existing drill strings face challenges in efficiently managing high stress and torque loads during wellbore drilling and cementing, particularly when using liner drilling techniques, leading to reduced reliability and component lifespan.
Innovation Solution
The implementation of extendable elements with optimized stress profiles and stop blocks in downhole tools, featuring curvilinear track profiles and torque transmission mechanisms, to distribute forces more evenly and reduce stress amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional extendable elements with fixed geometries are used in downhole tools, then the tool structure is simple and easy to manufacture, but high stress amplitudes occur and component life is reduced due to inefficient force distribution
Solution Approach 1:
The patent applies curvilinear geometries including three-center curve profiles and arc lengths of circles or multi-center curves to the track profiles of extendable elements. These curved geometries distribute forces and torques more evenly across the extendable element during operation, reducing stress amplitudes and preventing premature failure, thereby improving component life and reliability.
Solution Approach 2:
The patent optimizes geometric parameters such as the radii of curvature, center coordinates, and arc lengths of the track profiles to achieve optimal force distribution. By carefully selecting and varying these parameters, the design reduces stress concentrations while maintaining manufacturability, resolving the contradiction between reliability improvement and geometric complexity.
2Stress or pressure
If extendable elements with optimized curvilinear track profiles are implemented, then force distribution is improved and stress amplitudes are reduced, but manufacturing complexity and precision requirements increase
Solution Approach 1:
The use of curvilinear geometries with defined radii of curvature and arc lengths provides a systematic approach to reducing stress amplitudes. These geometric forms are well-established in manufacturing and can be produced using conventional CNC machining or milling operations, balancing stress reduction with manufacturing feasibility.
Solution Approach 2:
The track profile is divided into multiple arc segments, each defined by specific radii and center points. This segmentation allows for manageable manufacturing complexity while achieving superior force distribution. Each arc segment can be independently manufactured and assembled, reducing the overall precision requirements compared to a single complex curved surface.
3Power
If screw-on nuts are used for weight transmission in extendable elements, then torque distribution is improved, but device assembly complexity increases
Solution Approach 1:
The weight transmission function is divided into multiple screw-on nuts distributed around the extendable element, each handling a portion of the total torque load. This segmentation allows for improved torque distribution while keeping individual components simple and the assembly process straightforward, as each nut can be independently installed and adjusted.
Solution Approach 2:
Multiple screw-on nuts are used to transmit weight and distribute torque, with each nut providing partial load-bearing capacity. This partial action approach ensures that no single component is overloaded, improving overall system reliability while maintaining simple individual component designs that are easy to manufacture and assemble.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Extendable elements (602) of downhole tools (600) are provided having an extension direction component (Ex) perpendicular to a tool axis (Z), wherein a force is applied to the extendable element when in operation. The extendable elements comprise a first cross-section that includes the extension direction component, a first surface (650) configured to receive a first force component (Fi) of the force, the first force component substantially perpendicular to the first surface and a second surface (652) configured to transfer at least a portion of the first force component of the force to a body of the downhole tool. The second surface and the extension direction component perpendicular to the tool axis draw a first angle (A1) that is between 0° and 90°.