Shear-Stable Aqueous Injection Fluids for High Salinity Oil Recovery
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Solution Overview
Problem
Conventional aqueous injection fluids for oil recovery face challenges such as shear degradation and reduced viscosity in high salinity conditions, leading to inefficient oil extraction and increased costs due to the use of high molecular weight polymers and multiple injection fluids.
Innovation Solution
Development of shear-stable aqueous injection fluids comprising polymers with hydrophilic moieties and hydrophobic groups, combined with an aqueous crude oil emulsion and a basic compound or amphiphilic diblock copolymer, which enhances viscosity and stability under high salinity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high molecular weight polymers are used to increase injection fluid viscosity, then sweep efficiency improves, but shear degradation increases during pumping
Solution Approach 1:
The patent changes the molecular weight parameter of the polymer from high (conventional) to low (innovative), specifically using polymers with molecular weights of 10,000-500,000 g/mol. This parameter change allows the polymer to maintain sufficient viscosity enhancement capability while significantly reducing shear degradation during pumping operations, as lower molecular weight polymers have smaller coil sizes that are less susceptible to mechanical breakdown
Solution Approach 2:
The patent creates a composite injection fluid system by combining low molecular weight polymer with surfactant and brine. The polymer provides viscosity enhancement while the surfactant system (including crude oil emulsion and amphiphilic diblock copolymer) provides stability under high salinity conditions. This composite approach allows each component to contribute its strengths without the weaknesses of conventional single-component systems
2Productivity
If polymer concentration is increased to compensate for shear degradation, then desired viscosity is achieved, but cost increases
Solution Approach 1:
By changing the molecular weight parameter to lower values, the patent achieves a polymer system that is much more resistant to shear degradation. This eliminates the need to add excess polymer to compensate for breakdown, thereby reducing polymer consumption and cost while maintaining the required viscosity level in the reservoir
3Ease of operation
If conventional polymers are used in high salinity reservoirs, then injection is possible, but viscosification is lost due to charge screening
Solution Approach 1:
The patent changes the chemical nature of the polymer from charged (conventional) to uncharged (innovative). Conventional polymers like HPAM rely on electrostatic charges along the backbone to maintain hydrodynamic size and viscosity, but these charges are screened in high salinity. The uncharged polymer avoids this screening effect entirely, maintaining viscosity enhancement capability in high salinity reservoirs
Solution Approach 2:
The patent develops a composite system combining uncharged polymer with a surfactant system including crude oil emulsion and amphiphilic diblock copolymer. This composite provides both viscosity enhancement and stability under high salinity conditions, overcoming the limitation of conventional charged polymers that lose viscosification when salt concentrations are high
4Productivity
If multiple injection fluids are used following polymer injection, then recovery is improved, but process complexity increases
Solution Approach 1:
The patent creates a universal single-injection-fluid system that performs multiple functions simultaneously: viscosity enhancement, shear stability, high salinity tolerance, and improved sweep efficiency. This eliminates the need for multiple sequential injection fluids (such as brine flush or polymer post-flush), simplifying the injection process while maintaining or improving recovery performance
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 proposed solution achieves improved sweep efficiency and oil recovery with reduced shear degradation and viscosity maintenance, allowing for single injection fluid use and cost savings by stabilizing the injection fluid across varying shear rates and salinity levels.
Implementation Method 1
an aqueous crude oil emulsion, wherein the crude oil has a total acid number (TAN) greater than about 0.4
Implementation Method 2
a polymer comprising hydrophilic moieties and a plurality of hydrophobic groups
Data Source
AI summary
Viscous aqueous injections fluids including polymers having hydrophilic moieties and hydrophobic groups and at least one of crude oil emulsions and amphiphilic diblock copolymers are provided herein. Methods of making the aqueous injection fluids, and methods of using the aqueous injection fluids for oil recovery are also provided.