Labile Vinyl Polymers for Subterranean Viscosity Control
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Solution Overview
Problem
In subterranean applications, synthetic polymers used as viscosifiers are often stable and persist in the environment, leading to formation damage due to adsorption and accumulation on mineral surfaces, requiring costly clean-up operations, and existing breakers like enzymes and oxidants are ineffective at high temperatures and extreme pH levels, resulting in incomplete polymer degradation.
Innovation Solution
Development of water-soluble degradable synthetic vinyl polymers with labile groups in their backbone, produced through redox polymerization, which can be tailored to degrade under specific conditions, such as high temperatures, allowing for complete degradation and reduced formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If synthetic polymers are used as viscosifiers in subterranean applications, then high molecular weight and viscosity are achieved, but the polymers remain stable and persist in the environment causing formation damage
Solution Approach 1:
The polymer backbone is segmented into repeat units containing labile groups (ester, amide, carbonate, orthoester, acetal, etherester, or ether groups) that can be cleaved by hydrolysis, oxidation, reduction, or enzymatic attack. This segmentation allows the polymer to maintain high molecular weight for viscosity during application, then degrade into smaller fragments for removal, resolving the contradiction between needing stable high-viscosity polymer and avoiding persistent formation damage
Solution Approach 2:
The patent changes the chemical parameter of the polymer backbone by incorporating labile functional groups that alter the polymer's stability characteristics. These groups allow the polymer to transition from a stable, persistent state to a degradable state under specific subterranean conditions (hydrolysis, oxidation, reduction, enzymatic attack), enabling controlled degradation after serving its viscosity function
2Reliability
If existing breakers (enzymes or oxidants) are used to degrade polymers, then viscosity reduction is achieved, but they are ineffective at high temperatures and extreme pH levels resulting in incomplete degradation
Solution Approach 1:
Instead of relying on external enzymes or oxidants that have limited effectiveness under subterranean conditions, the patent incorporates labile groups directly into the polymer backbone structure. These built-in labile groups replicate the degradation function that external breakers attempt to provide, but are inherently capable of degrading under the actual subterranean conditions (high temperature, extreme pH) where external enzymes would fail
Solution Approach 2:
The polymer structure itself contains the means for its own degradation through the incorporated labile groups in the backbone. The polymer does not require external enzymes or oxidants to break it down; instead, the labile groups enable the polymer to self-degrade under subterranean conditions through hydrolysis, oxidation, reduction, or enzymatic attack, making the degradation process self-sufficient and effective at high temperatures and extreme pH levels
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 polymers degrade into smaller, soluble pieces that do not accumulate, reducing formation damage and enabling effective viscosity reduction for proppant deposition and fluid recovery, while avoiding the limitations of existing breakers.
Implementation Method 1
The labile group may be an ester group, an amide group, a carbonate group, an orthoester group, an acetal group, an etherester group, or an ether group and the polymer may be degraded by hydrolysis, oxidation, reduction, or enzymatic attack
Implementation Method 2
The labile group may be an ester group, an amide group, a carbonate group, an orthoester group, an acetal group, an etherester group, or an ether group and the polymer may be degraded by hydrolysis, oxidation, reduction, or enzymatic attack
Implementation Method 3
The labile group may be an ester group, an amide group, a carbonate group, an orthoester group, an acetal group, an etherester group, or an ether group and the polymer may be degraded by hydrolysis, oxidation, reduction, or enzymatic attack
Implementation Method 4
water-soluble degradable synthetic vinyl polymers having at least one labile group in the backbone of the polymer
Data Source
AI summary
Of the many embodiments presented herein, one is a subterranean treatment fluid comprising: an aqueous fluid; and a water-soluble degradable synthetic vinyl polymer having a labile link in its backbone. Also provided in one instance is a water-soluble degradable synthetic vinyl polymer with labile group in its backbone made by a redox polymerization, the redox polymerization reaction comprising these reactants: a macroinitiator that comprises a labile link, an oxidizing metal ion, and a vinyl monomer.