Shape Memory Alloy Springs for Downhole Liner Hanger Actuation
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Solution Overview
Problem
Downhole tools using shape memory materials face safety risks during assembly due to pre-compression of springs, which can become projectiles, and operational issues from temperature-induced phase changes, leading to premature actuation before reaching the desired location.
Innovation Solution
The use of shape memory materials for springs that can be pre-compressed to higher percentages below their transition temperature, reducing assembly risks, and independent actuation to set the tool after crossing the transition temperature, utilizing well fluids or a heater to store potential energy without premature setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard spring materials are used and pre-compressed during assembly, then the tool can be set, but the springs become projectiles posing safety risks to assembly personnel
Solution Approach 1:
The patent changes the material parameter of the springs from standard spring material to shape memory material, which has a temperature-dependent modulus of elasticity. Below the transition temperature, the shape memory material has low modulus allowing easy compression during assembly without high pre-compression forces, eliminating the projectile hazard. Above the transition temperature, the modulus increases to provide the necessary setting force.
Solution Approach 2:
The springs are pre-compressed during assembly at surface conditions (below transition temperature) where the material has low modulus and can be safely compressed. The actual setting action is delayed until the tool reaches the target location and the temperature rises above the transition temperature, at which point the springs automatically energize to set the tool.
2Reliability
If shape memory material is used for springs, then assembly safety is improved and tool length is shortened, but the tool may actuate prematurely when exposed to well fluids above transition temperature
Solution Approach 1:
The patent introduces a thermal barrier or insulation mechanism as an intermediary between the shape memory springs and the well fluids. This prevents direct thermal contact that would cause premature actuation, allowing the springs to remain below their transition temperature even when surrounded by hot well fluids, thus delaying actuation until the tool reaches the desired location.
Solution Approach 2:
The tool is designed to maintain the shape memory springs in their low-temperature state during the run-in phase, even when exposed to well fluids. The springs are prepared in advance (pre-compressed during assembly) but their actuation is delayed until the specific condition of reaching the target location is met, preventing premature activation.
3Measurement precision
If heating elements are added to control phase change, then precise actuation is achieved, but device complexity and safety risks increase
Solution Approach 1:
The patent employs the natural thermal environment of the well (well fluids at various temperatures) to automatically trigger the phase change in the shape memory springs. The system uses the existing temperature gradient in the wellbore as a self-service mechanism, eliminating the need for external heating elements. The springs automatically transition from austenite to martensite phase when the well fluid temperature exceeds their transition temperature, providing precise actuation control without additional complexity.
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 approach reduces assembly hazards and allows controlled, precise setting of downhole tools by leveraging the low modulus of shape memory materials to store energy, ensuring the tool is properly positioned before activation, thereby enhancing safety and operational reliability.
Implementation Method 1
Shape memory materials are materials that revert to an original shape once reaching a transition temperature
Implementation Method 2
the way temperature is used to change phases of shape memory materials
Implementation Method 3
If heat is added artificially, then the tool has to be configured to contain a heating element in close proximity to the shape memory material
Implementation Method 4
utilizing well fluids or a heater to store potential energy
Data Source
AI summary
The invention features the use of a shape memory material in a downhole application to provide an energy source for at least in part setting the tool. In a specific application the springs that set slips for a liner hanger are made from the shape memory material and easily pre-compressed below the transition temperature when the material has low modulus of elasticity. The tool is run into position where a heat source such as well fluids or a heater can bring the springs above the transition temperature to store a force. The tool is then independently released to allow the stored force to set the tool.