Complex foam flow in series and parallel through multiscale porous media: Physical model interpretation

•Complex foam flow in series and parallel through multiscale porous media with wide permeability range•Gas saturation curve of foam flows in series distinguished with a sharp rising and a quasi-stable range•Profile control effect of foam flow in parallel proven to be favorable for medium permeability range•Gas and liquid mobilities are simultaneously controlled for foam flows in multiscale porous media. Complex foam flows in series and parallel are investigated by means of a self-designed high-pressure high-temperature laboratory physical model. A total of twenty-two foam flow experiments were conducted in the porous media with a wide permeability range over two orders of magnitude. Specifically, fifteen single and seven dual foam flows in porous media with respective permeability range of 37−9705 mD and 41−7838 mD were performed to determine a series of physiochemical properties in terms of foam rheology, fluid profile and mobility control. For the foam flows in series, the overall gas saturation with process of foam injection is found to quickly increase within initial period but then tend to be stable. At the end of foam injection, the gas saturation curve could be clearly distinguished with permeability variances that a sharp rising range for permeability from 37 to 1233 mD while a quasi-stable range from 1233 to 9705 mD. Mobility reduction factor and apparent viscosity of the single flow cases are found to increase initially but in subsequent a decline with the permeability increase, whose maximum values were equal to 726.34 and 646.44 mPa•s at the permeability of 4386 mD. Moreover, the mobility curve basically performs as a U shape with three distinct periods: a sharp initial decrease period from 37 to 564 mD in subsequent of a second uniform mobility from 564 to 7309 and third increase period from 7309 to 9705 mD. On the other hand, for the foam flow in parallel, the profile control effect is determined to be favorable for a medium permeability ranging from 282 to 3855 mD but unfavorable for either lower- or higher-permeability cases. In the post-foam water injection period, the gas saturation for the single flow case monotonically decreases while for the flow in parallel, the gas and liquid production profiles perform oppositely to the profile control effect with respect to the permeability. Overall, gas and liquid mobilities are proven to be simultaneously controlled for foam flows in series and parallel through multiscale porous media, whereas a