Nonionic Surfactant Stable Foam for Enhanced Oil Recovery
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Solution Overview
Problem
Current gas flooding methods for enhanced oil recovery face issues such as poor sweep efficiency due to unstable foams and surfactant adsorption onto reservoir rock, leading to early breakthrough and reduced oil recovery.
Innovation Solution
The use of a nonionic, non-emulsifying surfactant that forms a stable foam with carbon dioxide and water, reducing viscosity and promoting efficient oil recovery by inhibiting gas flow through previously depleted areas, while minimizing surfactant adsorption and emulsion formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional surfactants are used to generate foam in gas flooding, then oil recovery efficiency is improved, but the foam stability deteriorates leading to early breakthrough
Solution Approach 1:
The patent changes the chemical parameters of the surfactant by selecting a nonionic surfactant with specific molecular structure (containing hydrophobic alkyl group and hydrophilic polyethylene oxide group) and controlling its molecular weight and composition ratio. This parameter optimization enables the surfactant to form stable foam structures that resist breaking while maintaining oil recovery effectiveness
Solution Approach 2:
The patent uses a composite surfactant system combining nonionic surfactant with specific molecular architecture that integrates both hydrophobic and hydrophilic segments. This composite molecular structure creates foam with enhanced stability compared to traditional single-component surfactants, preventing early gas breakthrough while maintaining productivity
2Productivity
If anionic surfactants with high affinity to formation rock are selected, then foam generation capability is improved, but surfactant loss increases due to adsorption
Solution Approach 1:
The patent inverts the conventional approach by selecting a nonionic surfactant instead of the traditional anionic surfactant. This inversion of charge property eliminates the electrostatic attraction between surfactant and negatively charged rock surfaces, preventing adsorption losses while maintaining foam generation capability through the surfactant's amphiphilic molecular structure
Solution Approach 2:
By using nonionic surfactant that does not adsorb onto rock, the patent effectively creates a reusable surfactant system rather than a consumable one. The surfactant remains in the fluid phase throughout the flooding process, maintaining its foam-generating function over extended periods without being depleted by rock adsorption
3Ease of operation
If gas flooding is performed without foam, then injection simplicity is maintained, but sweep efficiency deteriorates due to poor gas distribution
Solution Approach 1:
The patent introduces foam as an intermediary substance between the injected gas and the reservoir formation. The foam acts as a mediator that modifies gas flow behavior, forcing it to follow more uniform pathways through the formation and improving contact with oil-bearing zones, thereby enhancing sweep efficiency while maintaining the simplicity of gas injection methodology
4Productivity
If foam is generated to improve sweep efficiency, then gas flow control is improved, but emulsion formation increases leading to separation difficulties
Solution Approach 1:
The patent inverts the conventional surfactant choice from anionic to nonionic, which fundamentally changes the foam's interaction with oil and water phases. The nonionic surfactant creates foam that does not strongly emulsify oil and water, eliminating the production separation problems associated with traditional surfactant-based foam while maintaining sweep efficiency improvements
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 nonionic surfactant enhances oil recovery by creating a stable foam that increases apparent viscosity, improving sweep efficiency and reducing production costs by preventing surfactant loss and emulsion formation, thereby increasing oil extraction rates.
Implementation Method 1
the nonionic, non-emulsifying surfactant promotes a formation of a stable foam formed of carbon dioxide and water
Implementation Method 2
allowing the carbon dioxide in the stable foam to dissolve into the oil in the reservoir formation to provide a lowered viscosity of the oil
Implementation Method 3
A foam can generate an apparent viscosity of about 100 to about 1,000 times that of the injected gas, therefore, the foam can inhibit the flow of the gas
Data Source
Figure 1
AI summary
Embodiments of the present disclosure include compositions for use in enhanced oil recovery, and methods of using the compositions for recovering oil. Compositions of the present disclosure include a nonionic, non-emulsifying surfactant having a CO2-philicity in a range of about 1.5 to about 5.0, carbon dioxide in a liquid phase or supercritical phase, and water, where the nonionic, non-emulsifying surfactant promotes a formation of a stable foam formed of carbon dioxide and water.