Galvanic Corrosion Wellbore Isolation Device Removal

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Solution Overview

Problem

Traditional methods for removing retrievable isolation devices in oil and gas well operations are often time-consuming and costly, and can result in premature dissolution when using acidic fluids, making it difficult to control the dissolution process effectively.

Innovation Solution

A metal alloy with magnesium at a concentration of at least 50% by volume, in a solid solution, is used that can dissolve via galvanic corrosion in the presence of an electrolyte, allowing for controlled dissolution without the need for a distinct cathode, enabling efficient removal of the isolation device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional retrieval tools or milling methods are used to remove isolation devices, then the device can be removed, but the process becomes time-consuming and costly

Engineering Contradiction:

Improveremoval efficiencyVSAvoidremoval time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent replaces mechanical removal methods (retrieval tools, milling) with a chemical dissolution system. The isolation device is constructed from a metal alloy that dissolves through galvanic corrosion when exposed to an electrolyte, eliminating the need for mechanical intervention and significantly reducing removal time and cost

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the material parameters of the isolation device by using a specifically formulated metal alloy with controlled composition (e.g., magnesium 50-90%, aluminum 5-30%, zinc 5-20%). These parameter changes enable the device to dissolve at controlled rates through galvanic corrosion, allowing for efficient removal without mechanical methods

Inventive Principle:

Principle #35Parameter changes

2Productivity

If acidic fluids are used to dissolve the isolation device, then removal can be achieved, but premature dissolution occurs making the process difficult to control

Engineering Contradiction:

Improvedissolution rate controlVSAvoidcontrolled dissolution

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical parameters by replacing acidic fluids with a neutral or near-neutral electrolyte solution (pH 6-8). The metal alloy composition is specifically designed to undergo controlled galvanic corrosion in this electrolyte environment, providing reliable and predictable dissolution rates without premature degradation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The isolation device contains embedded sacrificial anodes made of highly active metals (e.g., magnesium, zinc, aluminum) that automatically initiate and sustain galvanic corrosion when exposed to the electrolyte. This self-service mechanism eliminates the need for external acid injection and provides inherent control over the dissolution process

Inventive Principle:

Principle #25Self-service

3Reliability

If a distinct cathode is used in the galvanic corrosion system, then corrosion can occur, but the system complexity increases

Engineering Contradiction:

Improvegalvanic corrosion functionVSAvoidcathode requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the cathode function into the structural body of the isolation device. The metal alloy composition is designed so that the main structural material (e.g., magnesium-aluminum-zinc alloy) serves as the cathode, while embedded sacrificial anodes provide the anodic function. This integration eliminates the need for separate cathode components, simplifying the device design while maintaining reliable galvanic corrosion functionality

Inventive Principle:

Principle #5Merging (Combining)

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 allows for a controlled and efficient dissolution of the isolation device, reducing the complexity of the removal process and avoiding the limitations of traditional methods, such as the use of retrieval tools or milling, while ensuring the device is removed when desired.

Implementation Method 1

A metal alloy with magnesium at a concentration of at least 50% by volume, in a solid solution, is used that can dissolve via galvanic corrosion in the presence of an electrolyte

Methodology Applied

Scientific EffectGalvanic corrosion: Crevice Corrosion

Data Source

PatentUS9759035B2Methods of removing a wellbore isolation device using galvanic corrosion of a metal alloy in solid solution

Publication Date: 2017.09.12 HALLIBURTON ENERGY SERVICES INC

AI summary

At least a portion of a wellbore isolation device consists essentially of: a metal alloy, wherein the metal alloy: (A) comprises magnesium at a concentration of at least 50% by volume of the metal alloy; and (B) at least partially dissolves in the presence of an electrolyte. A method of removing the wellbore isolation device comprises: contacting or allowing the wellbore isolation device to come in contact with an electrolyte; and allowing at least a portion of the metal alloy to dissolve.