Downhole Liner Oxidation for Faster, Low-Debris Casing Removal
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Solution Overview
Problem
Existing methods for removing well casing, such as milling and thermite-based methods, are slow, generate debris, and use environmentally unfriendly substances.
Innovation Solution
A method involving an oxidizer holding module and ignition module to ignite and burn the casing material, using oxygen or an oxygen-releasing compound to create a controlled oxidation reaction, which is faster and produces less waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If milling is used to remove casing, then the casing can be removed, but the process is slow and generates swarf debris
Solution Approach 1:
The patent replaces the mechanical milling system with a chemical oxidation system. Instead of using mechanical cutters to grind the casing, the invention uses an oxidizer composition that chemically reacts with and destroys the casing material, converting it into removable ash and gas products. This substitution of mechanical action with chemical action resolves the contradiction by eliminating both the slowness of mechanical milling and the generation of problematic metal swarf debris.
Solution Approach 2:
The patent changes the fundamental parameter of casing removal from mechanical force to chemical reactivity. By selecting oxidizers with appropriate reaction rates and temperatures, the process achieves rapid casing destruction without producing solid debris. The chemical reaction parameters (temperature, pressure, oxidizer concentration) are optimized to maximize removal speed while ensuring complete conversion of casing material into easily removable combustion products.
2Productivity
If thermite is used to melt casing, then the casing can be destroyed, but aluminium oxide is generated which is environmentally unfriendly
Solution Approach 1:
The patent changes the chemical composition parameters of the oxidizer system to eliminate harmful waste products. Instead of using thermite (which produces aluminium oxide), the invention employs oxidizers such as nitrate salts, chlorates, or permanganates that react with the casing to produce environmentally benign products like nitrogen gases, water vapor, and soluble metal salts. This parameter change in chemical composition resolves the contradiction by maintaining rapid destruction speed while eliminating toxic waste.
Solution Approach 2:
The patent converts the potentially harmful rapid exothermic reaction of thermite into a beneficial controlled oxidation process. By using oxidizers that produce non-toxic products and controlling the reaction rate, the harmful aspect (rapid heat generation) is retained for efficient casing destruction while the harmful waste product (aluminium oxide) is replaced with beneficial or neutral products (gases and soluble salts) that can be safely dispersed or treated.
3Ease of operation
If milling is used to remove casing, then the casing can be removed, but the process generates debris that needs to be removed from flowlines
Solution Approach 1:
The patent replaces the mechanical milling system that generates debris with a chemical oxidation system that eliminates debris formation. The oxidizer composition directly reacts with and destroys the casing material, converting it into ash and gases that can be easily removed through existing well flowlines without requiring additional debris handling equipment. This substitution resolves the contradiction by simplifying the overall system while maintaining effective casing removal capability.
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 method achieves faster removal of well casing with reduced energy consumption and generates easier-to-handle waste products, enhancing environmental safety.
Implementation Method 1
providing an oxidiser holding module in the tubing for defining an upper and/or lower boundary of a removal space, the space being delimited by at least the oxidiser holding module(s) and the liner and providing oxygen or an oxygen releasing compound in the space. The method further comprises providing an ignition module for igniting the liner material in the space and activating the ignition for igniting the liner material
Implementation Method 2
A method involving an oxidizer holding module and ignition module to ignite and burn the casing material, using oxygen or an oxygen-releasing compound to create a controlled oxidation reaction
Data Source
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AI summary
An aspect provides a method of removing a liner of a well, the liner comprising a liner material. The method comprises providing a seal in the well for defining an upper and/or lower boundary of a removal space, the space being delimited by at least the seal and the liner and providing oxygen or an oxygen releasing compound in the space. The method further comprises providing an ignition module for igniting the liner material near a lower boundary of the space and activating the ignition for igniting the liner material. This method works faster and requires less energy. An important reason for the latter point is that burning of iron generates a large amount of energy. Furthermore, the burning of steel produces a powder (iron oxide) or small droplets so the waste is easier to handle.