INVESTIGATION OF THE EFFICIENCY OF COMPOSITE SURFACE-ACTIVE POLYELECTROLYTES IN OIL DISPLACEMENT FROM POROUS MEDIA

Abstract

At the late stages of oilfield development, a significant portion of hydrocarbons remains trapped in the reservoir as residual oil that cannot be efficiently recovered by conventional water flooding. This is mainly caused by reservoir heterogeneity, strong capillary forces, unfavorable mobility ratios, and the limited efficiency of the displacing agent. Therefore, chemical enhanced oil recovery methods based on polymer and surfactant systems have gained increasing attention.

This study investigates the efficiency of oil displacement from porous media using composite surface-active polyelectrolytes under the conditions of the Kumkol oilfield. The Kumkol reservoir is characterized by terrigenous formations, relatively low permeability, moderate oil viscosity, and a high water cut, which complicates the oil displacement process.

High-molecular-weight composite polyelectrolytes based on polyacrylamide modified with fatty acids of gossypol resin were synthesized using glycerol and formaldehyde. The spatial structure of the polymers was formed in the presence of a potassium persulfate–sodium bisulfite initiating system. The resulting polymer systems exhibit pronounced polyelectrolyte and surface-active properties.

The physicochemical properties of the synthesized composites were evaluated through viscosity measurements, electrical conductivity analysis, and surface and interfacial tension determination. The structural characteristics were studied using infrared spectroscopy and scanning electron microscopy. The results revealed the formation of a predominantly amorphous three-dimensional polymer network, providing enhanced rheological behavior and improved interaction with the porous medium.

Oil displacement efficiency was evaluated through laboratory core flooding experiments simulating reservoir flooding processes. The results demonstrated that the injection of composite surface-active polyelectrolytes increases oil displacement efficiency by up to 7% compared to conventional water flooding. This improvement is attributed to reduced oil–water interfacial tension, increased viscosity of the displacing agent, and improved sweep efficiency.

The obtained results confirm the feasibility and перспективность of using composite surface-active polyelectrolytes to enhance oil recovery in the Kumkol oilfield and provide a scientific basis for further development of chemical enhanced oil recovery technologies.