Downhole Stroking Tool Axial Force Generation
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Solution Overview
Problem
Current downhole tools lack the necessary power to effectively pull plugs, especially those stuck due to precipitated scale, as they are not designed to generate high enough axial force.
Innovation Solution
A downhole stroking tool with a housing, a first chamber, and a pump unit providing pressurized fluid, where the shaft is fixed and the housing is slidable, allowing for higher axial force transfer without bending, and optionally incorporating a pressure intensifier for increased pressure and a second chamber for enhanced operational capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the shaft is made to transfer force in prior art tools, then the tool structure is simpler, but the axial force capacity is limited due to bending
Solution Approach 1:
The patent inverts the traditional force transfer mechanism by making the shaft stationary and non-force-transferring, while the housing becomes the moving force-transferring component. This inversion allows the housing to bear the full axial load without bending, as it slides along the stationary shaft rather than the shaft bending to transfer force.
Solution Approach 2:
The stationary shaft acts as an intermediary element that provides structural support and guidance for the moving housing without itself transferring the axial force. This mediator approach allows the force to be transferred through the housing which has higher bending stiffness, while the shaft simply provides the sliding surface and structural framework.
2Force
If a pressure intensifier is added to increase fluid pressure, then the axial force capability is enhanced, but the device complexity increases
Solution Approach 1:
The patent employs hydraulic principles through the pressure intensifier which uses fluid pressure multiplication to generate the extremely high axial forces required. The intensifier converts the relatively low-pressure output from the pump unit into the ultra-high pressures needed to achieve 100,000 pounds of axial force, leveraging hydraulic force multiplication.
3Strength
If the housing overlaps the first tool part, then the bending stiffness is increased, but the device complexity increases
Solution Approach 1:
The tool is segmented into distinct functional parts: the first tool part containing the pump unit, the stationary shaft, and the movable housing. The housing overlaps the first tool part to create a structurally reinforced configuration where the housing acts as both a protective casing and a force-transferring member, distributing loads more effectively throughout the structure.
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 tool can generate significantly higher axial forces, up to 100,000 pounds, reducing the risk of bending and enabling the effective removal of stuck plugs, while maintaining structural integrity and allowing for wireless operation.
Implementation Method 1
a pump unit providing pressurised fluid to the chamber... generating a pressure on the piston
Implementation Method 2
a pressure intensifier arranged downstream of the pump unit to increase the pressure of a fluid before the fluid is fed to the chamber
Data Source
AI summary
A downhole stroking tool (1) comprising a housing (2), a first chamber (3), a first tool part (4) comprising a pump unit (5) providing pressurized fluid to the chamber, a shaft (6) penetrating the chamber, and a first piston (7) dividing the first chamber into a first chamber section (8, 8a) and a second chamber section (9, 9b). The piston is connected to or forms part of the housing which forms part of a second tool part (10) and is slidable in relation to the shaft so that the housing moves in relation to the shaft, the shaft being stationary in relation to the pump unit during pressurization of the first or the second chamber section, thereby generating a pressure on the piston, wherein the shaft is fixedly connected with the first tool part, and wherein the housing is slidable in relation to the first tool part and overlaps the first tool part.