Foam stability in the presence and absence of hydrocarbons: From bubble- to bulk-scale

One of the pioneering applications of foam is in enhanced oil recovery (EOR). A major stumbling-block to the success of foam application in EOR is the adverse influence of oil on foam stability. The objectives of the present work were to evaluate the effects of various surfactants and hydrocarbons with well-defined properties on foam stability. To do so, we have conducted a comprehensive series of experiments at bulk- and bubble-scale to investigate the foam stability of four surfactants in the absence and presence of three isoparaffins distinguished by their carbon chain length, density and viscosity. For the bulk foam stability experiments, foam was generated by sparging pure air into surfactant solution in a vertical cylindrical column. An automated camera was used to record the gradual decay of foam as a function of time. The results showed the significant impact of the type of the surfactant on foam stability. Besides, our results illustrated less stable foam in the presence of oil with less adverse impact on foam stability as oil viscosity and density increased. The limitation of the method used in the present study to quantify foam stability, i.e., measuring the decay of foam height over a certain period of time, which is a commonly used method in literature, is discussed here and an alternative approach is proposed to investigate foam stability at bubble-scale to supplement and improve understanding of the physical phenomena controlling foam stability. (C) 2015 The Authors. Published by Elsevier B.V.