Stability Analysis of Anionic-CO₂-Soluble Surfactant Di-(2-ethylhexyl) Sodium Sulfosuccinate-Assisted Oily Foam Based on Statistical Analysis of Bubble Dynamic Characteristics

Abstract

Currently, oily foam stability in CO 2 injection for heavy oil recovery exhibits inadequacies that considerably constrain its extensive application. Some scholars have conducted research demonstrating that CO 2 -soluble surfactants can assist in inducing heavy oil to form oil-based foams (oily foam). In this study, stability tests for the oily foam were conducted at different surfactant concentrations using a visualized PVT cell. Oily foam stability was assessed by calculating the comprehensive foam index (S) and analyzing the bubble images. The research indicates that AOT can effectively reduce the interfacial tension between oil and gas. At a concentration of 0.1 wt % AOT, the interfacial tension can be effectively reduced from 1.75 to 1.14 mN/m. The concentration of 0.3 wt % AOT represents a turning point, with an S of 16 101.7 mL•min. Beyond this concentration, the increase in S becomes less pronounced. As the concentration of CO 2soluble surfactant is increased from 0.1 to 0.5 wt %, the average bubble radius decreases from 2.74 to 0.43 mm, while the number of bubbles per unit area increases from 5.56 to 81.1 per cm 2 . With an increasing concentration of the CO 2 -soluble surfactant, the system generates more and smaller gas bubbles within the oily foam, resulting in a slower bubble coalescence. The findings of this study are poised to play a pivotal role in enhancing heavy oil recovery efficiency.

Investigation of the Stability Mechanism of Stimulus-Responsive Wormlike Micelle-CO2 Foams in the Oil Phase

“…The use of foam as an enhanced oil recovery method has received considerable attention since it was first proposed by Fried in 1956 and has been subjected to a succession of experiments. − CO 2 foam results from the dual selection of green chemical development strategies and field application. CO 2 not only can diffuse into crude oil to reduce its viscosity but also can make an outstanding contribution to the CCUS. − However, the use of foam flooding is mainly limited by the physical shear action of the formation pore throat and its oil-resistant stability. In recent years, researchers have selectively focused their efforts on strengthening the shear resistance of foams and prolonging the survival time of foams in the oil phase.…”