Composite-End Bismuth Plug Assembly for Wellbore Sealing Pressure
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Solution Overview
Problem
Existing methods for plugging and abandoning oil and gas wells using low-melting-point alloys face challenges in achieving effective sealing and structural integrity due to the lack of reinforcement at the ends of the plug, which affects the radial force and sealing ability.
Innovation Solution
A plug assembly with composite reinforced ends and a mostly-bismuth-alloy middle section, where the ends consist of composite materials with densities differing from the alloy, ensuring they remain solid and provide structural support while the alloy expands upon solidification, forming a strong seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-melting-point alloy is used for plug formation, then the plug can expand upon solidification to create a seal, but the ends lack structural reinforcement reducing sealing effectiveness
Solution Approach 1:
The plug assembly uses a composite structure combining low-melting-point alloy with high-strength reinforcement materials (such as steel or tungsten) at the ends. The reinforcement materials provide structural integrity and constraint to the expanding alloy, preventing deformation while maintaining the sealing capability. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The reinforcement materials are strategically positioned only at the ends of the plug assembly rather than throughout the entire structure. This localized reinforcement provides structural support where needed (at the ends) while allowing the middle section to maintain its expansion capability for sealing. The local application of reinforcement resolves the contradiction by providing strength only where structural integrity is required.
2Force
If the alloy expands upon solidification to create radial force for sealing, then sealing is achieved, but without end reinforcement the expansion creates insufficient radial force
Solution Approach 1:
The reinforcement materials are positioned at the ends to constrain the alloy expansion locally in the radial direction. This localized constraint ensures that the expansion force is directed appropriately to create effective radial sealing pressure against the wellbore wall, rather than allowing uncontrolled expansion. The end reinforcement transforms the expansion into effective sealing force.
Solution Approach 2:
The composite structure combines the expanding low-melting-point alloy with rigid reinforcement materials that convert the expansion force into effective radial sealing pressure. The reinforcement materials act as constraint elements that focus the expansion force onto the wellbore wall, enhancing the sealing ability through the synergistic interaction of the two material types.
3Strength
If composite reinforcement materials are added to the alloy, then structural integrity is improved, but the device complexity increases
Solution Approach 1:
By applying reinforcement materials only at the ends rather than throughout the entire plug assembly, the structural complexity is minimized while still achieving the required structural integrity. The reinforcement is localized to specific regions where it is most needed, avoiding the complexity of reinforcing the entire structure uniformly.
Solution Approach 2:
The plug assembly is segmented into distinct functional zones: reinforcement material zones at the ends and pure alloy zone in the middle. This segmentation allows each region to perform its specific function optimally while simplifying the overall design and manufacturing process compared to a fully composite structure throughout.
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 composite ends constrain the alloy's expansion, providing enhanced sealing pressure and structural integrity, ensuring effective plugging and abandonment of wells by maintaining a robust seal against the wellbore.
Implementation Method 1
the alloy then resolidifies in the wellbore. Due to its high bismuth content, the expands upon solidification, this expansion creating sufficient radial force between the alloy and the wellbore to create a seal
Implementation Method 2
Plugs are created by melting the alloy in the wellbore, either with electric heater or chemical heat means
Data Source
Figure 1A
Figure 1B
Figure 2~3
AI summary
A plug with composite reinforced end(s) and a mostly-bismuth-alloy middle section. At least one end comprises a composite material. One end is a composite, with a bismuth alloy and a particulate material of greater strength than the bismuth material. A plug having both ends of the composite material.