Controlled Disintegration of Downhole Tools via Cathodic Protection
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Solution Overview
Problem
Self-disintegrating downhole tools face uncontrollable disintegration due to corrosion reactions, which affects their mechanical integrity and service life, leading to inefficient well recovery operations.
Innovation Solution
A downhole assembly comprising a disintegrable article made of metals or alloys, coupled with a current source and controller to delay corrosion through electron supply, allowing controlled disintegration after tool functionality is complete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If self-disintegrating downhole tools are used to enable rapid well recovery, then well recovery time is reduced, but the disintegration process becomes uncontrollable and may compromise tool mechanical integrity during service
Solution Approach 1:
The patent applies parameter changes by using a current source to alter the electrochemical state of the disintegrable tool. By supplying electrical current, the corrosion rate parameter is dynamically controlled, allowing the tool to maintain mechanical integrity during service (low corrosion rate) and then rapidly disintegrate when current is removed (high corrosion rate). This resolves the contradiction by making the disintegration rate controllable rather than fixed.
Solution Approach 2:
The current source acts as an intermediary between the operator and the disintegrable tool. It mediates the corrosion process by controlling electron flow to or from the tool, enabling precise timing of disintegration. This intermediary allows the tool to remain stable during installation and operation, then disintegrate on demand, solving the uncontrollability issue while maintaining reliability.
2Reliability
If disintegrable material with high mechanical strength is used to ensure tool integrity under high pressure, then tool reliability is improved, but the disintegration rate decreases
Solution Approach 1:
The patent uses parameter changes to decouple the relationship between mechanical strength and disintegration rate. By controlling the electrochemical potential through current supply, the material can exhibit high strength properties during service while maintaining a controlled disintegration rate. When current is removed, the disintegration rate parameter increases dramatically without requiring a change in material composition, thus resolving the contradiction.
Solution Approach 2:
The current source performs preliminary action by pre-conditioning the disintegrable tool during its service life. The supplied current creates a protective electrochemical state that prevents premature corrosion while maintaining mechanical strength. This preliminary protective action allows the tool to fulfill its operational requirements before deliberate disintegration is initiated.
3Loss of substance
If conventional milling or drilling operations are used to remove tools, then complete tool removal is achieved, but operation time and cost increase
Solution Approach 1:
The patent replaces the mechanical removal system (milling or drilling tools and equipment) with an electrochemical dissolution system. Instead of mechanically cutting and removing the tool, electricity is used to accelerate the corrosion and dissolution of the disintegrable material. This substitution eliminates complex mechanical operations while achieving complete tool removal, resolving both the time and complexity issues.
Solution Approach 2:
The disintegrable tool performs self-service by dissolving itself through controlled corrosion rather than requiring external mechanical intervention. The tool's own material composition enables it to break down when electrical control is removed, eliminating the need for separate removal operations. This self-service mechanism dramatically reduces operation time and cost while ensuring complete removal.
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
Enables controlled disintegration of downhole tools, maintaining mechanical integrity during service and accelerating disintegration once the tool is no longer needed, thereby optimizing well recovery operations.
Implementation Method 1
a current source configured to supply electrons to the disintegrable article and to delay or reduce the corrosion of the disintegrable article in the downhole fluid
Implementation Method 2
the disintegration process can start as soon as the conditions in the well allow the corrosion reaction of the engineering material to start
Data Source
AI summary
A downhole assembly comprises a disintegrable article comprising a metal, a metal alloy, a metal composite, or a combination comprising at least one of the foregoing; the disintegrable article being corrodible in a downhole fluid; a current source configured to supply electrons to the disintegrable article and to delay or reduce the corrosion of the disintegrable article in the downhole fluid; anda controller configured to control the supply of electrons to the disintegrable article.