Study of mechanisms responsible for foaming-agent loss in porous media at high-temperature conditions

Abstract

Steam-foam processes require the correct selection of a surfactant agent resistant to high temperatures, stable over time, and capable of producing mobility reduction of the steam. A state-of-the-art revision allows identifying the main phenomena that could cause surfactant loss in porous medium. These phenomena are phase partitioning, adsorption, and thermal degradation, where phase partitioning could cause higher loss. Additionally, adsorption and phase partitioning have a direct relationship with the surfactant concentration below its critical micellar concentration. Reservoir conditions such as temperature, salinity and presence of clay are parameters that influence surfactant solution behavior. High temperatures in porous medium could reduce tensoactive loss by adsorption due to exothermic reactions. However, the foaming agent could be partitioned into oleic phase owing to viscosity reduction and molecules motion improvement towards crude oil. High concentrations of salt could increase adsorption measurements, produce surfactant preference to oil or even precipitation. Surfactant solution should be formed by a mixture of components that provides stability during the steam injection process. Generally, the solution is composed mainly of an anionic surfactant. Some widely used surfactants are alkyl aryl sulfonates and alpha olefin sulfonates, suitable for steam procedures up to 300°C. Despite, non-ionic surfactants, and pH adjustment substance could be added to give foaming agent an improved performance.