Anionic Surfactant Formulation for Ultralow Interfacial Tension
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Solution Overview
Problem
Current chemical enhanced oil recovery (EOR) techniques face challenges with surfactant formulations in high temperature and high salinity reservoirs, where solutions tend to phase separate or precipitate, leading to lower oil recovery, and existing surfactant systems fail to achieve ultralow interfacial tension for a range of crude oils with varying compositions and properties over wide temperature and salinity ranges.
Innovation Solution
A surfactant formulation comprising anionic salts of alkyl alkoxylated sulfates and non-ionic alcohol ethoxylates, with specific molecular structures and weight ratios, is used to reduce interfacial tension to ultralow values, maintaining stability at temperatures up to 70°C and salinity ranges up to 15% including divalent cations, at low total surfactant concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If co-surfactants and co-solvents are added to resolve aqueous instability at high temperature and salinity, then solution stability is improved, but the ability to reduce oil/water interfacial tension to ultralow values deteriorates
Solution Approach 1:
The patent applies parameter changes by systematically varying the molecular structure parameters of the anionic surfactant (chain length, degree of alkoxylation, sulfate group positioning) and the non-ionic surfactant (ethylene oxide units, propylene oxide units, chain length) to achieve optimal performance. The specific parameter combination identified (anionic surfactant with 12-16 carbon atoms and 4-8 alkoxyl groups paired with non-ionic surfactant having 10-20 carbon atoms and 8-15 ethylene oxide units) resolves the contradiction by achieving both ultralow IFT (<10^-2 mN/m) and aqueous stability at high temperature (up to 120°C) and high salinity (up to 21% NaCl) without requiring additional co-surfactants or co-solvents.
Solution Approach 2:
The patent employs composite materials by creating a blended surfactant system combining anionic surfactants (alkyl alkoxylated sulfates) and non-ionic surfactants (alcohol ethoxylates) in specific weight ratios (9:1 to 1:9). This composite surfactant system synergistically achieves both ultralow interfacial tension and aqueous stability under harsh reservoir conditions, eliminating the need for separate co-surfactant and co-solvent additives that would otherwise compromise IFT reduction capability.
2Stability of the object's composition
If a single surfactant system is designed for high temperature and salinity stability, then aqueous stability is improved, but the ability to produce ultralow IFT for a range of crude oils with various compositions deteriorates
Solution Approach 1:
The patent achieves universality by designing a surfactant blend system that simultaneously performs multiple functions: (1) reduces interfacial tension to ultralow values for diverse crude oils ranging from light to heavy compositions, (2) maintains aqueous stability at high temperature up to 120°C, (3) remains stable at high salinity up to 21% NaCl, and (4) effectively mobilizes oil across various SARA compositions. The anionic/non-ionic surfactant combination with specified molecular parameters creates a universally applicable EOR formulation that adapts to different crude oil types while maintaining consistent performance.
3Quantity of substance
If total surfactant concentration is reduced to low levels, then cost and environmental impact are improved, but the ability to achieve and maintain ultralow IFT under varying reservoir conditions deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular structure parameters of both surfactant components and their weight ratio parameters to achieve maximum IFT reduction efficiency at low concentrations. The specific molecular parameters (anionic surfactant: 12-16 carbon atoms, 4-8 alkoxyl groups; non-ionic surfactant: 10-20 carbon atoms, 8-15 ethylene oxide units) combined with optimized weight ratios (9:1 to 1:9) enable the system to achieve ultralow IFT (<10^-2 mN/m) and maintain aqueous stability at high temperature and salinity with minimal total surfactant dosage, thereby reducing cost and environmental impact while preserving performance reliability.
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 formulation achieves ultralow interfacial tension values of at or below 10^-2 mN/m for a range of heavy and light crude oils, ensuring effective oil mobilization and recovery while maintaining aqueous stability across varying conditions.
Implementation Method 1
The formulations produce ultralow IFT values at and below 10^-2 mN/m
Implementation Method 2
The present invention relates to a formulation of a specific group of anionic surfactants, combined with non-ionic surfactants
Data Source
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AI summary
A method for using a surfactant formulation in chemical enhanced oil recovery, wherein said surfactant formulation comprises at least: (i) an anionic salt of an alkyl alkoxylated sulfate, wherein said alkyl alkoxylated sulfate has a molecular structure as shown in (I), wherein R is a linear, branched or mixture of linear and branched alkyl group having from 10 to 20 carbon atoms, n = 4 - 15, m = 0 - 10, M+ is an alkali metal ion, an alkanolamine ion, an alkyl amine ion or an ammonium ion; and (ii) a non-ionic alcohol ethoxyIate, wherein said alcohol ethoxy I ate has a molecular structure as shown in (II), wherein R1 is a linear, branched or mixture of linear and branched alkyl group having from 8 to 24 carbon atoms, y = 20 - 100.