Composite Surfactant System for High Salinity EOR
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Solution Overview
Problem
Conventional chemical solutions for enhanced oil recovery (EOR) face challenges in maintaining compatibility and stability at room temperature and high-salinity, high-temperature reservoir conditions, leading to increased interfacial tension and reduced oil recovery.
Innovation Solution
A surfactant mixture solution comprising an anionic surfactant, a cationic surfactant, a nonionic surfactant, a brine solution, and a co-solvent is introduced to hydrocarbon-bearing reservoirs, reducing interfacial tension and improving stability at extreme conditions, allowing for increased oil production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemical solutions are introduced to reservoirs, then interfacial tension decreases initially, but the solution becomes insoluble under high-salinity and high-temperature conditions, causing IFT to increase again
Solution Approach 1:
The patent uses a composite surfactant system comprising multiple surfactants with different charge types (anionic, cationic, and/or zwitterionic) combined in specific ratios. This composite approach creates a synergistic effect where the mixed surfactant system maintains solubility and IFT reduction capability under high-salinity and high-temperature conditions that would cause individual surfactants to fail and precipitate.
Solution Approach 2:
The patent optimizes specific parameters including the charge ratio of surfactants (e.g., anionic to cationic ratio), concentration ranges, and molecular structure characteristics to ensure the chemical solution remains soluble and effective across the full range of reservoir conditions (salinity up to 300,000 mg/L and temperature up to 200°C).
2Reliability
If chemical mixtures with different charges are used, then IFT reduction capability is improved, but mixing requires high dissolution temperature and is time-consuming
Solution Approach 1:
The patent formulates the mixed-charge surfactant system in advance with pre-determined optimal ratios and compositions. This preliminary preparation ensures that when the solution is deployed to the reservoir, the surfactants are already properly combined and dissolved, eliminating the need for time-consuming on-site mixing and high-temperature dissolution procedures.
Solution Approach 2:
The patent adjusts formulation parameters such as surfactant concentration, charge ratio, and the addition of co-solvents or auxiliary chemicals to enable complete dissolution and effective mixing at lower temperatures and shorter times, making the process more efficient for field application.
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 surfactant mixture solution effectively reduces interfacial tension by two to three orders of magnitude, enhancing oil production during chemical EOR processes and maintaining stability at high temperatures and salinity levels.
Implementation Method 1
surfactant molecules adsorb droplets of hydrocarbon fluid at the liquid-liquid interface by inserting the hydrophobic group into the hydrocarbon fluid and placing the hydrophilic group in the water phase
Implementation Method 2
inserting the hydrophobic group into the hydrocarbon fluid
Implementation Method 3
placing the hydrophilic group in the water phase
Implementation Method 4
Surfactant mixture comprising an anionic surfactant, a cationic surfactant, and a nonionic surfactant may reduce the IFT by two to three orders of magnitude
Implementation Method 5
Co-solvent may reduce a dissolution temperature of surfactant mixture solutions and forms a stable concentrated formulation at room temperature
Implementation Method 6
The hydrocarbon fluid disperses in the water and forms a stable emulsion
Data Source
AI summary
A process for reducing the interfacial tension between a hydrocarbon fluid and a surfactant mixture during chemical enhanced oil recovery includes introducing a surfactant mixture solution comprising an anionic surfactant, a cationic surfactant, a nonionic surfactant, a brine solution, and a co-solvent to a hydrocarbon-bearing reservoir under conditions of a salinity of greater than or equal to 50,000 mg/L, a hardness of greater than or equal to 2,500 mg/L, and a temperature of greater than or equal to 90° C., thereby reducing the interfacial tension at a liquid-liquid interface of the hydrocarbon fluid and the surfactant mixture solution. The anionic surfactant comprises organo sulfate. The cationic surfactant comprises quaternary ammonium, brominated trimethylammonium, chloride trimethylammonium, or combinations thereof. The nonionic surfactant comprises polyoxyethylene fatty acid ester, phenylated ethoxylate, or combinations thereof.