Variable Linkage Gripper for Downhole Wellbore Adaptability
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Solution Overview
Problem
Existing downhole gripper systems face challenges in maintaining effective expansion forces over a wide range of diameters, particularly in harsh environments with high pressures and temperatures, and require designs that can adapt to varying borehole sizes while preventing overstressing of components.
Innovation Solution
The Variable-Linkage Assisted Gripper (VLG) employs a linkage mechanism that forms either a three-bar or four-bar linkage, utilizing a hydraulically-actuated piston and a flexible continuous beam to achieve large expansion ratios, with a ramp surface for initial expansion and buckling of links for further expansion, limiting forces at high diameters to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional gripper system is used, then it can grip the borehole wall, but it cannot maintain effective expansion forces over a wide range of diameters
Solution Approach 1:
The linkage mechanism dynamically transitions between different geometric configurations (three-bar and four-bar linkages) as the gripper expands, allowing the base angle to be controlled at different expansion stages. This dynamic adaptation enables the system to maintain effective expansion forces across a wide diametrical range from small entry wellbores to larger internal diameter wellbores
Solution Approach 2:
The system changes the geometric parameters of the linkage mechanism, specifically controlling the base angle relative to the longitudinal axis. By limiting the rate of change in the base angle during expansion, the system maintains optimal force transmission characteristics throughout the expansion range, preventing both insufficient grip and component overstressing
2Adaptability or versatility
If the gripper is expanded to large diameters, then it can grip larger wellbores, but the components may be overstressed
Solution Approach 1:
The linkage mechanism transitions from a three-bar configuration to a four-bar configuration as expansion progresses. This dynamic reconfiguration limits the rate of change in the base angle, which in turn limits the expansion force at high diameters, preventing component overstressing while maintaining gripping capability
Solution Approach 2:
The variable linkage mechanism proactively limits expansion force before components can be overstressed. By controlling the base angle rate of change throughout the expansion range, the system prevents excessive forces from developing, thereby protecting components from damage before it occurs
3Device complexity
If a single gripper is used, then the structure is simple, but the tractor cannot generate substantial force against the formation
Solution Approach 1:
The variable linkage mechanism provides a more efficient force transmission path compared to traditional gripper designs. By controlling the base angle and transitioning between linkage configurations, the system maximizes the mechanical advantage, enabling a single gripper to generate substantial thrust forces against the formation (up to 30,000 pounds) while maintaining structural simplicity
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 VLG maintains acceptable expansion forces across a wider diametrical range, enabling effective gripping in small entry but larger internal diameter wellbores, with controlled expansion to prevent component overstressing, thus enhancing operational reliability and adaptability.
Implementation Method 1
The VLG employs a linkage mechanism that forms either a three-bar or four-bar linkage, utilizing a hydraulically-actuated piston
Implementation Method 2
achieve large expansion ratios, with a ramp surface for initial expansion and buckling of links for further expansion
Implementation Method 3
a flexible continuous beam to achieve large expansion ratios
Data Source
AI summary
A gripper mechanism for downhole tool is disclosed that includes a linkage mechanism and a flexible toe disposed over the linkage mechanism. In operation, an axial force generated by a power section of the gripper expands the linkage mechanism, which applies a radial expansion force to the flexible toe. For certain expansion diameters, the expansion force can be primarily transmitted to the toe from a roller-ramp interface expanding the linkage. For other expansion diameters, the expansion force can be primarily transmitted to the toe by expansion of the linkage in a three-bar linkage configuration. For other expansion diameters, the expansion force can be primarily transmitted to the toe by expansion of the linkage in a four-bar linkage configuration. Thus, the gripper can provide a desired expansion force over a large range of expansion diameters.