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Item type:Publication, Access status: with files , Pressure-driven growth with forward and reverse foam flow: Modelling foam flow in geological formations(2025-06-04); ; The pressure-driven growth model is used to investigate the propagation of a foam front in a porous medium. Initially, the foam front moves forward due to an imposed gas injection pressure. Later, however, the injection pressure is reduced so that part of the front, deeper down in the medium, switches to reverse flow. The foam front is not, however, predicted to retrace its original path. Along most of its length moreover, the reverse flow front is predicted to move surprisingly quickly, which also affects the total area swept out. On the other hand, some parts of the front very close to the bottom move only slowly in reverse flow, such that the front is predicted to develop a kinked shape. Perturbations superposed on the front shape can also cause it to develop sharp concave corners. Overall, the findings enhance the understanding of foam behaviour in porous media, when sudden changes in flow direction occur during the course of the flow.Publicationtype: Journal Article6 16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Foam Generation and Stability: Role of the Surfactant Structure and Asphaltene Aggregates(2022-01-12); ; ; ; Understanding how the surfactant molecular structure affects foam stability is important in various applications, such as soil remediation, the food industry, enhanced oil recovery, and hydraulic fracturing. In this study, we conduct a systematic series of experiments in a Hele-Shaw cell to assess and explain the effect of surfactants on foamability and foam stability in the absence and presence of oil and asphaltene aggregates. Four surfactants with different molecular weights were studied, including three anionic surfactants, sodium 1,5-bis[(1H,1H,2H,2H-perfluorohexyl)oxy]-1,5-dioxopentane-2-sulfonate (FG4), C18H37SO4Na (LSES), and sodium dodecyl sulfate (SDS), and one cationic surfactant (CTAB, (C16H33NMe3)Br). We observed that the higher electrostatic repulsion between the foam film surfaces for the anionic surfactants (FG4 > LSES > SDS) strongly influences the process of foam generation and stability when compared with the cationic surfactant (CTAB). For example, the foam coarsening rate for CTAB was 700% higher than that for FG4 when we performed experiments in an empty Hele-Shaw cell. Furthermore, the foam experiments performed in the presence of oil revealed maximum long-term stability and minimum bubble coarsening for the partially fluorinated FG4 surfactant. The experiments in the presence of asphaltene-oil mixtures revealed that the latter has a detrimental effect on foam stability, except for FG4. The foam experiments clearly show the significance of the subtle interactions between the surfactant headgroup charge, chain length, and branching. The obtained results could be useful in designing appropriate surfactants for foam stabilization in various applications.Publicationtype: Journal Article53 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Combined effects of nanoparticles and surfactants upon foam stability(2021-07-20); ; ; ; We investigate effects of surfactants with different charges (anionic, cationic, and non-ionic) on foam stability in the presence of charge-stabilized silica (SiO ) nanoparticles. Toward this aim, a comprehensive series of experiments on a Hele-Shaw cell and a foam column is conducted at bubble and bulk-scale respectively, that is, investigating the phenomenologies of foam coarsening by gas diffusion and bubble coalescence, and separately by gravitational drainage. Our results show that nanoparticles, despite their ability to position themselves at liquid–gas interfaces and thus limit the resulting surface tension coefficient, do not necessarily have a positive effect on foam stability; the nature and magnitude of this effect depends strongly on the nature of the surfactant, its concentration and the concentration of nanoparticles. In less stable systems, significant coarsening occurs. Both results from bubble-scale and the bulk-scale experiments suggest that compatibility experiments are pre-requisite to foam stability analysis to test the compatibility between surfactants and nanoparticles. 2Publicationtype: Journal Article73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Interaction of Nanoparticles and Surfactant in Controlling Foam StabilityStability of foam in the presence of hydrocarbons is a crucial factor in the success of its use in various applications in porous media, such as soil remediation and enhanced oil recovery. (EOR).In this study, we investigate the effect of surfactants with different charges (anionic, cationic, and non-ionic) on foam stability in the presence of charge-stabilized silica (SiO2) nanoparticles. Toward this aim, a comprehensive series of experiments on a Hele-Shaw cell and a foam column is conducted at bubble and bulk-scale respectively, that is, investigating phenomenologies of foam coarsening separately by gas diffusion and gravitational drainage. Our results show nanoparticles, despite their ability to position themselves at liquid-gas interfaces and thus limit the resulting surface tension coefficient, do not necessarily have a positive effect on foam stability; the nature and magnitude of this effect depends strongly on the nature of the surfactant, its concentration and the concentration of nanoparticles. Both results from bubble-scale and the bulk-scale experiments suggest that compatibility experiments are pre-requisite to foam stability analysis to test the compatibility between surfactants and nanoparticles.Publicationtype: Conference Paper53 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Foam Stability Influenced by Displaced Fluids and by Pore Size of Porous Media(2019-01-16); ; ; ; Stability of foam in the presence of hydrocarbons is a crucial factor in the success of its use in various applications in porous media, such as soil remediation and enhanced oil recovery (EOR). It is generally believed that shorter-chain hydrocarbons with lower density and viscosity have more detrimental effect on foam stability than longer-chain hydrocarbons. However, it is still unclear how the pore size of porous media could influence this behavior. The main objective of the present study was to investigate the combined effect of the hydrocarbon chain length and hence the hydrocarbon's viscosity and pore size of porous media on the foam stability and its displacement efficiency. To this end, a systematic series of experiments was conducted using an empty Hele-Shaw cell and glass bead packs with different pore size. The results in the Hele-Shaw cell and with coarse and medium beads revealed that the lighter, less viscous oil (Isopar G) was more destructive to foam. However, the results in the fine glass bead pack experiments did not correlate well with this finding. In the fine bead pack, foam appeared to have higher displacement efficiency in the presence of the lighter, less viscous oil. Generally, our results suggest that the pore size of the porous medium plays a more important role on the foam displacement efficiency, compared to the type of oil.Publicationtype: Journal Article31 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effects of Pore Geometry on Flowing Foam Dynamics in 3D-Printed Porous Media(2018-09-01); ; Foam flow in porous media is important in several environmental and industrial applications including soil remediation and enhanced oil recovery. The behaviour of foam is greatly influenced by transport properties of porous media, properties of foam and the fluid residing in porous media. We conducted a series of experiments to investigate the effects of pore geometry on foam flow in porous media and its implications for hydrocarbon displacement. We fabricated four porous media with well-defined pore throat size distributions, permeability and angularity by means of 3D printing technology. The models were initially saturated with oil. Gas and surfactant solution were subsequently injected into the model simultaneously for in situ generation of foam to displace the oil. Displacement dynamics were recorded using an automated imaging setup. Analysis of the pore-scale images revealed that the injected pore volumes required for the initiation of foam generation decreased as the pore size of porous media increased, presumably due to the lower entry capillary pressure. For the same pore throat size range, changes in the permeability due to increased number of pore throats did not appear to have a significant influence on the overall recovery of oil. Our results illustrate the impact of grain angularity on foam generation owing to its influence on the pore-to-throat aspect ratio and capillary pressure gradient.Publicationtype: Journal Article38 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Foam Flow Investigation in 3D-Printed Porous Media: Fingering and Gravitational Effects(2018-05-30); ; ; Flow in porous media investigations have shown foam injection has a higher sweep efficiency compared to gas injection. However, fingering of highly mobile gas within the foam bank and separation of fluids (gas and surfactant) resulting from gravity segregation can influence the performance of the foam injection project. To the best of our knowledge, this phenomenon has not been investigated experimentally in the literature. In this study, foam injection experiments have been performed in a model oriented in horizontal and perpendicular orientations with respect to gravity using different flow rates. High-resolution imaging tools were utilized to record the displacement process of oil by gas/surfactant/foam. The recorded images enabled us to monitor gas fingering and the foam flow dynamics at the pore scale. The obtained results highlighted the adverse effect of fingering of gas phase into the foam bank and fluid separation by gravity segregation on the performance of the foam projects.Publicationtype: Journal Article27 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effects of gravity segregation on oil displacement by foam in a 3D printed porous medium(2017-09); ; ; Publicationtype: Conference Presentation29 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Investigation of foam flow in a 3D printed porous medium in the presence of oil(2017-03-15); ; Foams demonstrate great potential for displacing fluids in porous media which is applicable to a variety of subsurface operations such as the enhanced oil recovery and soil remediation. The application of foam in these processes is due to its unique ability to reduce gas mobility by increasing its effective viscosity and to divert gas to un-swept low permeability zones in porous media. The presence of oil in porous media is detrimental to the stability of foams which can influence its success as a displacing fluid. In the present work, we have conducted a systematic series of experiments using a well-characterised porous medium manufactured by 3D printing technique to evaluate the influence of oil on the dynamics of foam displacement under different boundary conditions. The effects of the type of oil, foam quality and foam flow rate were investigated. Our results reveal that generation of stable foam is delayed in the presence of light oil in the porous medium compared to heavy oil. Additionally, it was observed that the dynamics of oil entrapment was dictated by the stability of foam in the presence of oil. Furthermore, foams with high gas fraction appeared to be less stable in the presence of oil lowering its recovery efficiency. Pore-scale inspection of foam-oil dynamics during displacement revealed formation of a less stable front as the foam quality increased, leading to less oil recovery. This study extends the physical understanding of oil displacement by foam in porous media and provides new physical insights regarding the parameters influencing this process.Publicationtype: Journal ArticleScopus© Citations 69 21