Foam-oil interaction

Mannhardt, K. Novosad, J. Schramm, L.L. Foam/Oil Interactions at Reservoir Conditions in Proceedings, SPE/DOE Improved Oil Recovery Symposium, Society of Petroleum... 

More detailed aspects of these processes are discussed in Chapter 4 of this book, in the context of foam-oil interactions in porous media. Because the interfacial tensions mentioned can change with time after an initial spreading of defoamer, it follows that the parameters E and S are also time-dependent and that some defoamers are effective only for a limited amount of time. 

The theories of foam—oil interactions will also be discussed in Chapter 4. 

The effect of oil on aqueous foam stability is controlled by the behavior of the pseudoemulsion films. In the previous sections, two extreme cases of the foam-oil interactions were shown foam stabilizing when the pseudoemulsion films are stable and antifoaming that is, fast foam rupture, when these films are very unstable. 

Figure 45 summarizes our current understanding of the possible foam—oil interactions and highlights the role of single-foam lamellae, pseudoemulsion, and emulsion films in foam stability in aqueous foam systems containing solubilized or emulsified oils. Further research is warranted to... 

Experimental Studies of Foam—Oil Interaction in Porous Media... 

A single model of foam-oil interaction cannot account for all situations. Certain foam—oil sensitivity models can be reconciled with both microvisual studies and core-flood foam effectiveness measurements, all for a wide variety of foams, oils, porous media, and other experimental conditions. However, exceptions are readily found. In an earlier section, the models of emulsification—imbibition, pseudoemulsion film thinning, entering, and spreading were introduced. Cases in favor of, and exceptions to, the applicability of each of these can be found in the literature. Although this situation prompts some inclination to search for additional mechanisms, the truth may be that all the models presented have some validity and that one or another valid mechanism is most significant in a given situation. 

Semenova, M.G., Antipova, A.S., Belyakova, L.E., Dickinson, E., Brown, R., Pelan, E., Norton, I. (1999). Effect of pectinate on properties of oil-in-water emulsions stabilized by asi-casein and P-casein. In Dickinson, E., Rodriguez Patino, J.M. (Eds). FoodEmul-sions and Foams Interfaces, Interactions and Stability, Cambridge, UK Royal Society of Chemistry, pp. 163-175. 

Good tolerance of the foam to interaction with crude oil in porous media... 

During the process of three phase foam thinning, three distinct films may occur foam films (water film between air bubbles), emulsion films (water between oil droplets) and pseudoemulsion films (water film between air and oil droplets) (Figure 1). To study the behavior of these films and particularly the oil droplet-droplet, oil droplet-air bubble and oil droplet-foam frame interactions it is necessary to utilize numerous microscopic techniques, including transmitted light, microinterferometric, differential interferometric and cinemicrographic microscopy. 

Oil Droplet-Foam Film Interaction. The commonly known mechanism in the literature by which oil droplets affect foam stability is, as previously mentioned, the mechanism of oil droplet spreading ( ). It is suggested that during the process of foam lamella thinning, the oil droplets are squeezed between the film surface and spread on one of the film surfaces (in the form of lenses) eventually then spreading also on the second film surface. Finally, it is assumed that an "island of oil is formed which breaks the lamella (thick film) ... 

Tertiary oil was increased up to 41% over conventional CO2 recovery by means of mobility control where a carefully selected surfactant structure was used to form an in situ foam. Linear flow oil displacement tests were performed for both miscible and immiscible floods. Mobility control was achieved without detracting from the C02-oil interaction that enhances recovery. Surfactant selection is critical in maximizing performance. Several tests were combined for surfactant screening, included were foam tests, dynamic flow tests through a porous bed pack and oil displacement tests. Ethoxylated aliphatic alcohols, their sulfate derivatives and ethylene oxide - propylene oxide copolymers were the best performers in oil reservoir brines. One sulfonate surfactant also proved to be effective especially in low salinity injection fluid. 

Aqueous foams containing emulsified oils have a wide variety of practical applications. The effect of oil on foam stability is of primary importance because the oil can stabilize or destabilize the aqueous foam. Emulsification of some crude oils can lead to a decrease in foam stability, thus the application of foams for mobility control in enhanced oil recovery (EOR) is strongly affected by the foam—crude oil interactions in the porous medium. 

Manlowe and Radke (77) studied foam—crude oil interactions in a microvisual glass cell, and they also found that the lifetime of the pseudoemulsion film controls the foam stability in foam-flooding systems. 

A major difficulty is the proper selection of foam-forming surfactants for the challenging environments involved in petroleum reservoir applications, since many characteristics are thought to be necessary for performance, including good tolerance of the foam to interaction with crude oil in porous media [66, 102]. Here, the physical situation is even more complex than for bulk foams due to influences of pore structure, wettability and oil saturation. For both bulk foams and foams in porous media, oil-sensitive foams are usually less stable as increasing amounts of emulsified oil are contacted (bulk tests) or in the presence... 

Based on these coefficients, one can predict that three types of oil-foam interactions could take place. 

Results are presented of studies of the oxidation of cable insulation consisting of a solid PE skin and PE foam in contact with a copper conductor. Measurements were made of the stability of PE containing stabilisers and metal deactivators in the presence of blowing agents and hydrocarbon oils, and interactions between stabilisers and blowing agents were analysed. 

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