Investigation of CO2-foam stability with anionic and nonionic surfctants at different salinities

Abstract

Gas flooding is one of the most widely applied EOR methods in field applications, but viscous fingering and gravity segregation are the main issues in gas displacing. To mitigate these problems, water alternating gas injection (WAG) has been used. Another useful proposal is applying foams to improve sweep efficiency because of their high viscosity and mobility. Surfactants have historically been used in field applications to reinforce foam. One of the most important tasks in petroleum engineering is the characterization of the properties of the reservoirs for the application of the method that will lead to a greater oil recovery factor. Among the different tertiary recovery methods with great potential for improving the oil recovery factor, foam injection can be mentioned. In this study, comprehensive laboratory research explored the performance of CO2 foam with anionic and nonionic surfactants. The objectives were to determine the critical micellar concentration (CMC) of SDS and TX100 surfactants and to investigate the effect of varying surfactants salinities and ratios on CO2-FOAM stability. The concentrations of SDS and TX100 were considered in a range of (0.01-0.4wt%). Furthermore, the salinities of SDS and TX100 were fixed at (25000, 30000, 35000, 40000, and 45000 ppm) during the stability tests. This study's methodology included several laboratory tests divided into two sections. In the first section, the surface tension of (SDS) and (TX-100) surfactants was measured to estimate CMC. The second section was to consider the behavior of foam stability in various salinity and ratios of surfactant solutions. The results showed that the CMC for SDS and TX100 surfactants was equal to 0.05 and 0.02 wt%, respectively. Moreover, CO2 foam stability can be improved by increasing the salinity of surfactants solution. SDS at 35000 ppm salinity was the best for CO2 foam stability, which was stable for 8 minutes.