Static and dynamic foam/oil interactions: Potential of CO2-philic surfactants as mobility control agents

摘要

Examination of the nature and extent of CO2 foam/oil interactions is essential for the successful design and application of surfactants in foam assisted water alternating gas (FAWAG) process. A structure-property relationship of surfactants based on theoretical method, static bulk tests, and dynamic displacements in porous media subjected to foam flooding is provided in this study. Surfactants with an increased affinity towards CO2 are intended to improve foam mobility control mechanism in a Malaysian oil reservoir. Two anionic foaming agent surfactants (in-house developed Fomaxll and industry benchmark alpha olefin sulfonate (AOS)), and two CO2-philic surfactants (in-house developed FomaxVII and UTP-Foam) are selected to investigate the effect of surfactant tail groups on the phase interactions in a system of CO2-oil-brine. The effect of surfactant presence on the CO2/water and oil/water interfaces under reservoir conditions is measured by using a high pressure, high temperature tensiometer. Surfactants with higher tolerance against oil are selected based on static stability column tests and the equilibrium spreading coefficients model. The surfactant alternated with gas (SAG) displacements are then conducted by using the selected CO2-philic surfactants dissolved in injection brine to study the interactions of foam and oil in porous media at the reservoir conditions.