Assessing the performance of foams stabilized by anionic/nonionic surfactant mixture under high temperature and pressure conditions

Abstract

Foam flooding is an effective tertiary recovery method for oil and gas reservoirs. However, foam performance is very sensitive to the reservoir temperature and pressure. In this study, the formation and collapse of a water-based foam stabilized by a mixed ionic and nonionic surfactant system under typical reservoir conditions (up to 150 °C and 50 MPa) were investigated. A multifunctional foam analyzer, an interfacial rheometer, and a coiled tube are used to assess foam microstructure, surface tension and bulk viscosity under 25 – 80 °C and 0.1 – 10 MPa. Results show that the foam comprehensive value is highest under low temperature and high pressure. With increasing temperature, the gas bubbles become larger, fewer in number, and more irregular in shape coupled with a thinner liquid film. Increased pressure, on the other hand, decreases the bubble size, increases the number of bubbles and contributes to a more uniform and dense foam. At constant temperature, the surface tension decreases as the pressure increases, while at constant pressure, a minimum surface tension is observed with increasing temperature, which in turn increased with increasing pressure. Foam viscosity displayed an opposite trend to that of the surface tension. Understanding the variation of foam properties with temperature and pressure is key toward successful application of foam flooding.