Metal Casing Patch Using Low-Temperature Alloy Sealing
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Solution Overview
Problem
Existing technologies in the oil and gas industry struggle to properly anchor and seal downhole assemblies within tubular members, leading to inefficiencies in well maintenance and production.
Innovation Solution
A method and device using a low-temperature alloy, such as bismuth, to bond and seal a thin wall steel tube to the previous casing, forming an all-metal to metal casing patch, with protrusions and shape memory alloy stand-offs for centralization and anchoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anchoring and sealing devices are used in tubular members, then the downhole assembly can be anchored and sealed, but the anchoring and sealing are not proper or reliable
Solution Approach 1:
The invention changes the physical state parameter of the bonding material from solid to liquid during installation, then to solid during sealing. The bonding material is heated to melt and flow into the annular space, then allowed to cool and solidify, creating a reliable metal-to-metal seal without complex mechanical anchoring devices
Solution Approach 2:
The invention replaces complex mechanical anchoring and sealing devices with a thermal bonding process. Instead of using mechanical expandable devices, swage means, or setting tools, the patent uses heated bonding material that melts and flows to fill the annular space, then solidifies to create a permanent seal and anchor
2Reliability
If the casing patch is installed in deviated wells, then the patch can seal the casing, but the patch may not be properly centralized and toolstrings may hang up
Solution Approach 1:
The invention uses the self-weight of the bonding material to automatically centralize the patch and create a ramp structure. As the bonding material cools and solidifies in the annular space, it naturally forms a ramp on the low side that guides toolstrings into the patch ID, eliminating the need for additional centralizing devices
Solution Approach 2:
The invention creates a three-dimensional ramp structure within the annular space that provides a geometric pathway for toolstrings. This dimensional feature allows toolstrings to slide easily into the patch ID on deviated wells by providing a gradual transition rather than a sharp edge
3Ease of repair
If the casing patch needs to be removed, then disassembly is required, but conventional anchors and seals cannot be easily disassembled
Solution Approach 1:
The invention uses reversible phase transitions of the bonding material. The material transitions from solid to liquid when heated, allowing the patch to be disassembled and removed. After removal, the material can be remelted to enable disassembly and removal of the patch, while during normal operation it remains solid to provide permanent anchoring and sealing
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 effectively anchors and seals the downhole assemblies, ensuring a reliable metal-to-metal seal and allowing for easy disassembly, while accommodating varying well inclinations and temperatures.
Implementation Method 1
the bismuth can be remelted to enable disassembly and removal of the patch
Implementation Method 2
a low temperature alloy to bond and seal a thin wall steel tube to the previous casing
Implementation Method 3
the stand-offs could be made from shape memory alloy and when gets above its transition temperature centralises the patch perfectly
Implementation Method 4
the thin wall tube has protrusions plasma sprayed on its OD to provide stand-off
Data Source
AI summary
A method of sealing a casing comprising the steps of deploying a thin wall tube in the region the casing is to be sealed, melting a low temperature alloy and allowing it to flow into the annulus between the thin wall tube and the casing, and allowing the low temperature alloy to solidify. The thin wall tube may include protrusions on its outer surface, of similar height so as to centralise the thin wall tube in the casing.