Polyamine Surfactant for CO2 EOR Emulsion Stability

The patent introduces surfactant compounds as intermediary substances that mediate between carbon dioxide and the reservoir environment. These surfactants form stable emulsions with carbon dioxide and water, creating a foam-like mixture that increases apparent viscosity and density, thereby preventing viscous fingering and gravity override while maintaining the pressure maintenance and viscosity reduction benefits of carbon dioxide injection

The patent applies parameter changes by modifying the physical properties of carbon dioxide through surfactant addition. The surfactant compounds change the apparent viscosity and density parameters of the carbon dioxide phase, transforming it from a low-viscosity gas that causes fingering into a higher-viscosity emulsion that maintains stable displacement fronts and prevents gravity override

The patent applies local quality by designing surfactant molecules with specific local functional groups that provide different properties at different molecular locations. The surfactant structure includes a hydrophilic head group containing nitrogen atoms with lone pairs that interact with carbon dioxide, and a hydrophobic tail that interacts with oil and water phases. This localized functional design provides simultaneous solubility in carbon dioxide, stability against adsorption on minerals, and resistance to thermal and chemical degradation

The patent employs composite material principles by creating surfactant compounds that combine multiple functional groups within a single molecular structure. These composite surfactant molecules integrate carbon dioxide-interacting groups (nitrogen-containing groups with lone pairs), oil-soluble groups (hydrophobic chains), and water-soluble groups (polar regions), resulting in a multifunctional material that simultaneously addresses solubility, stability, and emulsion formation requirements

The patent applies parameter changes by modifying the molecular structure parameters of conventional ethoxylated amines. The invention introduces nitrogen atoms with lone pairs that can form coordinate covalent bonds with carbon dioxide, and adjusts the hydrophobic chain length and branching to optimize interfacial tension reduction. These parameter changes result in surfactants that provide both effective mobility control and high oil recovery efficiency

The patent employs composite material principles by creating enhanced surfactant compounds that combine the mobility control properties of ethoxylated amines with additional functional groups that increase carbon dioxide solubility and interaction. The composite surfactant structure integrates the ethoxylated amine backbone with nitrogen-containing groups that specifically interact with carbon dioxide, resulting in a material that outperforms conventional surfactants in both mobility control and oil recovery efficiency