Self-anchoring Grip Assembly with Force Amplification
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Solution Overview
Problem
Downhole tractor tools face inefficiencies due to active grips that consume power for radial force generation, reducing overall efficiency and increasing complexity, and passive grip mechanisms can damage soft formations with high contact stresses.
Innovation Solution
A passive grip assembly that uses a force applied in one direction to generate a larger force in another direction for anchoring, utilizing a mechanical or hydraulic force amplifier with a large contact area to minimize formation damage and reduce power consumption, allowing bi-directional anchoring and traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If active grips are used to generate radial forces, then anchoring capability is improved, but power consumption increases and device complexity increases
Solution Approach 1:
The grip assembly uses the axial force applied to move the tool string as self-energy to automatically generate the required radial gripping force through the cam mechanism, eliminating the need for separate power sources or actuators to generate radial force
2Force
If passive grip mechanisms with small contact area are used, then anchoring capability is improved, but formation damage increases due to high contact stress
Solution Approach 1:
The cam surface is designed with a large contact area that distributes the radial gripping force over a broader region of the wellbore wall, transitioning from point or line contact to surface contact, thereby reducing contact stress and preventing formation damage
3Reliability
If active grips are used for anchoring, then anchoring reliability is improved, but device complexity increases
Solution Approach 1:
The solution extracts and eliminates the complex power generation and control systems from the grip assembly, retaining only the passive cam mechanism that naturally converts axial motion to radial gripping force through geometric constraints
Solution Approach 2:
The cam mechanism automatically adjusts the radial gripping force in response to axial loading, providing self-regulating anchoring that adapts to varying downhole conditions without external control
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 solution enhances efficiency by reducing power consumption and minimizing formation damage, enabling reliable anchoring and traction in both uphole and downhole directions while maintaining a low contact stress on the wellbore, suitable for various downhole operations.
Implementation Method 1
a cam (420) converts an axial force applied to the grip assembly into a radial force that anchors the assembly to the wellbore
Implementation Method 2
the friction between the grip assembly and wellbore wall provides the traction necessary for moving the tool string along the well
Data Source
AI summary
A downhole tool is provided that includes a grip assembly for contacting a well formation. The grip assembly includes a gripper body; and a centralizer that is attached to and radially expandable with respect to the gripper body and that has a geometry which is lockable by a locking device. The grip assembly also includes a force amplifier in force transmitting relation with the centralizer, wherein the force amplifier transfers a force in a first direction to a much larger force in a second direction when the centralizer is locked by the locking device.