Hydrophobically-Modified Polyelectrolytes for High Salinity Viscosity
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Solution Overview
Problem
Current viscosifiers and friction reducers used in the oil and petroleum industry, such as xanthan gum and guar powder, break down at high temperatures and are prone to biological degradation, and synthetic hydrophobically modified polyelectrolytes are ineffective in high salinity and high pH environments, especially when exposed to oil-based components, leading to viscosity loss and slow dissolution in brines.
Innovation Solution
A copolymer comprising units derived from a nonionic monomer, an ionic monomer, and a surface-active monomer, which is water-soluble and can rapidly increase viscosity when mixed with hydrocarbon oil, maintaining stability at high temperatures and pH levels, and does not require additional surfactants for dissolution, thus suitable for high salinity fluids and applications like well stimulation and drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydrophobically modified polyelectrolytes are used to increase viscosity in high salinity fluids, then viscosity is significantly enhanced, but dissolution becomes extremely slow requiring hours or days of agitation
Solution Approach 1:
The copolymer is segmented into distinct functional blocks: hydrophilic segments (acrylamide/ATBS) for water solubility and ionic segments (lauryl acrylate) for hydrophobic association. This segmentation allows the polymer to dissolve rapidly while still forming the dynamic networks needed for viscosity enhancement in high salinity conditions.
Solution Approach 2:
The patent modifies the chemical parameters of the polymer by incorporating ionizable groups (ATBS) that change the polymer's interaction with water and salts. This parameter change enables fast dissolution in brines while maintaining the hydrophobic associations necessary for viscosity at high salinity (>100k TDS).
2Productivity
If natural polymers like xanthan gum or guar powder are used for viscosity control, then fast viscosity development and ideal rheology are achieved, but they break down at high temperatures (200°F) and are prone to biological degradation
Solution Approach 1:
The patent creates a composite polymer structure combining synthetic components (acrylamide, ATBS, lauryl acrylate) that collectively provide both fast viscosity development and high thermal/biological stability. This composite approach achieves the performance of natural polymers without their degradation issues at high temperatures and in biological environments.
3Strength
If synthetic polymers are modified with hydrophobic groups to function in high salinity, then viscosity is significantly higher in high salinity fluids, but oil-based lubricants interfere with hydrophobic associations causing viscosity loss
Solution Approach 1:
The patent applies local quality by placing hydrophobic groups (lauryl acrylate) at specific locations along the polymer chain rather than uniformly distributing them. This localized placement creates distinct hydrophobic domains that can associate without being completely disrupted by oil, maintaining viscosity in the presence of oil-based lubricants while still functioning in high salinity conditions.
Solution Approach 2:
The patent converts the potential harm of oil presence into a benefit by designing hydrophobic associations that are dynamic and reversible. The oil can temporarily interact with these associations but the polymer network rapidly re-forms, actually utilizing the oil-polymer interactions to maintain stability in complex oil-brine environments.
4Reliability
If high molecular weight acrylamide/acrylate copolymers are used for thermal resistance, then superior thermal and biological resistance is achieved, but they require modification with hydrophobic groups which slows dissolution and requires additional surfactants
Solution Approach 1:
The copolymer achieves multi-functionality by incorporating three types of monomers that collectively provide: water solubility (acrylamide), thermal/biological stability (ATBS), and hydrophobic association for viscosity (lauryl acrylate). This universal design eliminates the need for separate surfactant additives and complex formulation steps, as the polymer itself provides all necessary functions.
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 copolymer provides rapid viscosity increase and friction reduction in high salinity brines, maintaining stability and effectiveness in the presence of oils and high pH, making it suitable for a wide range of oil field applications, including well stimulation and drilling, with improved thermal and pH stability compared to traditional polymers.
Implementation Method 1
The hydrophobic chains in HM polyelectrolytes form dynamic polymer networks via hydrophobic associations, leading to significantly higher viscosity compared to non-HM polyelectrolytes, particularly in high salinity fluids.
Implementation Method 2
Fast dissolving, water soluble, hydrophobically-modified polyelectrolytes
Data Source
AI summary
Copolymers and compositions containing copolymers having advantageous viscosity, friction reduction, dissolution, pH-stability, and temperature-stability are provided. These copolymers can be used as rheology modifiers for oil field applications.