Encapsulated Filter Cake Breakers with pH-Triggered Release
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Solution Overview
Problem
Existing methods for removing filter cakes in subterranean wells face issues with premature release of peroxides, which degrade the filter cake and reduce the effectiveness of polysaccharide polymers, and require operator intervention, leading to additional costs and potential harm to formations.
Innovation Solution
An encapsulated internal filter cake breaker comprising magnesium peroxide, an anti-caking agent, and a zinc-crosslinked acrylic polymer film, which is insoluble in wellbore fluids with a pH between 7.5 and 10.5 and has a glass transition temperature greater than 45°C, is used to control the release of peroxide and enhance filter cake removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peroxide sources are used to remove filter cakes, then filter cake removal effectiveness is improved, but premature release of peroxide occurs causing filter cake degradation and polymer ineffectiveness
Solution Approach 1:
The peroxide source is encapsulated within a filter cake matrix before deployment, allowing it to be positioned and activated only when needed. This preliminary positioning ensures the peroxide remains contained during filtration operations and is only released when the filter cake needs removal, preventing premature degradation while ensuring effectiveness when required.
Solution Approach 2:
An encapsulation structure is employed to contain the peroxide source, creating a protective shell that prevents premature release. This encapsulation allows the peroxide to remain stable during filter cake formation and only releases when triggered by specific conditions such as pH change or chemical activation, thereby maintaining filter cake integrity during operation while enabling effective removal when needed.
2Reliability
If acid wash is used to dissolve filter cakes, then filter cake removal is achieved, but harmful effects on subterranean formation occur
Solution Approach 1:
The invention employs pH-triggered release mechanisms where the encapsulated peroxide remains stable at neutral or basic pH levels during normal operations but activates when exposed to acidic conditions. This allows selective activation only in the immediate vicinity of the filter cake where acid is introduced, rather than exposing the entire formation to damaging acid concentrations, thereby achieving effective filter cake removal while minimizing formation damage.
Solution Approach 2:
The harmful acid treatment is replaced by extracting the filter cake removal function into a localized peroxide release system. Instead of applying acid throughout the formation, the peroxide is encapsulated and activated only where needed, concentrating the removal action at the filter cake interface while leaving the surrounding formation unaffected by harsh chemical treatments.
3Reliability
If operator intervention is required to remove filter cakes, then controlled removal can be achieved, but additional costs and operational delays occur
Solution Approach 1:
The filter cake removal system is designed to activate automatically in response to specific triggers such as pH changes, chemical reactions, or environmental conditions. Once activated, the encapsulated peroxide self-digests the filter cake matrix without requiring continuous operator intervention or complex control systems, enabling autonomous removal operations that reduce both labor costs and operational delays while maintaining controlled release through the encapsulation mechanism.
Solution Approach 2:
The system employs periodic or triggered activation rather than continuous operation. The encapsulated peroxide remains dormant during normal operations and activates only when specific conditions are met, such as periodic acid injection or reaching a threshold pH level. This periodic action pattern enables automated, on-demand filter cake removal that eliminates continuous monitoring requirements and reduces operational delays while maintaining precise control over the removal process.
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 provides improved temperature stability and reduced premature release of the filter cake breaker, allowing for more effective and controlled removal of filter cakes with less permeability and swelling in basic solutions, reducing operational costs and minimizing formation damage.
Implementation Method 1
a film comprising a zinc-crosslinked acrylic... which is insoluble in wellbore fluids having a pH value between 7.5 and 10.5
Implementation Method 2
The peroxide source and the filter cake breaker are in intimate contact such that upon activation of the peroxide source, degradation of the polysaccharide polymer occurs
Implementation Method 3
Encapsulation of the peroxide breakers... was introduced to provide improve performance regarding delayed release of the peroxide breaker payload
Data Source
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AI summary
A wellbore fluid including a peroxide degradable polymer and an encapsulated peroxide source. The peroxide degradable polymer may be a polysaccharide. The peroxide source may include an inorganic peroxide, including zinc and alkaline earth metal peroxides, such as magnesium peroxide. The encapsulating material may be a polymer, including a metal crosslinked acrylic polymer. The release of peroxide, from peroxide sources generally, can be controlled by means of pH such that peroxide source can be activated, and peroxide released, by a change in pH. In a wellbore, this pH change can be effected by using produced fluids to lower the pH of a more basic wellbore fluid.