Effect of interfacial rheology on model emulsion coalescence

Yarranton, Harvey W.; Sztukowski, Danuta M.; Urrutia, P.

doi:10.1016/j.jcis.2007.01.071

Cited by 164 publications

(226 citation statements)

References 20 publications

(37 reference statements)

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“…It is noteworthy that irreversible adsorption of asphaltenes was observed even for 10 min aging time. Other authors reported a reversible adsorption of 1% asphaltene in a 25% toluene/75% heptane solvent (Yarranton et al, 2007b), probably due to a lower asphaltene concentration and different solvent. Figure 13: Effect of aging on compressibility film formation for diluted oil (50% diluent B).…”

Section: Compressibility and Crumpling Ratiomentioning

confidence: 94%

Effect of Diluents on Interfacial Properties and SAGD Emulsion Stability: I. Interfacial Rheology

2013

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In SAGD (Steam Assisted Gravity Drainage) operations the produced fluids are a complex water-in-oil-in-water (W/O/W) emulsion. A diluent, which is a major operational cost item, is often added to the produced fluid to reduce the density and viscosity of the heavy crude, thereby facilitating oil and water separation. The variable quality of the diluent and various types of diluent can increase the emulsion stability and cause the dehydration of the oil to be more difficult as there are more surface-active agents added to the oil from the diluent stream. In this work, the effect of various diluents on interfacial films was studied by measuring interfacial elasticity and "dynamic" surface pressure isotherms and then correlated with emulsion stability and oil dehydration. Compressibility, crumpling film ratio (ratio of the compressed surface area to the original area at which the interface starts to collapse), and surface pressure were determined from the surface pressure isotherms.When interfacial rheological measurements were conducted on fluids treated with the diluent, the system behaved as if a bidimensional gel near its gelation point had organized at the interface. In other words, adsorbed amphiphilic materials such as asphaltenes and resins had self-aggregated at the interface and formed a network, which presents all the rheological characteristics of a gel, acting as a stabilizing mechanism for produced emulsions. When the interface was aged for 20 hrs, its gel strength was nearly 70% higher than the fresh interface, suggesting an explanation why aged emulsions are more difficult to treat. As the surface area of an oil droplet submersed in water is reduced, asphaltene molecules adsorbed onto the interface are drawn closer together and resist compression. This gives information about how rigid the drop surface becomes. The software of interfacial rheological measurements can be set up to capture drop images during compression measurements, allowing us to observe the formation of rigid interfacial skins at the oil-water interface. The amount of skin formed at a droplet surface increased with increasing asphaltene concentration and varied in different diluents. Unlike elasticity and interfacial tension measurements, this method can predict emulsion stability in different diluents and at various asphaltene concentrations. A correlation exists between the interfacial compressibility, crumpling film ratio, and emulsion stability: the higher the crumpling film ratio and the lower the compressibility, the more stable the emulsion. This new test method gives more insights into mechanisms of emulsion stabilization caused by the diluent and asphaltene and potentially can be employed to study the structure and demulsifying performance relationships of EBs (emulsion breakers) and REBs (reverse emulsion breakers).

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Section: Compressibility and Crumpling Ratiomentioning

confidence: 94%

Effect of Diluents on Interfacial Properties and SAGD Emulsion Stability: I. Interfacial Rheology

2013

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“…The presence (formation) of solid-like (elastic dominant) asphaltene films at the oil-water interface has been shown to significantly hinder the coalescence of two contacting water droplets, as such that when two droplets interact and undergo significant compression, they continue to remain stable without coalescence. 48,51 The correlation between interfacial dilatational elasticity and overall emulsion stability has been qualitatively proven by several researchers, 49,50,[52][53][54][55][56] although there is clear disagreement at high asphaltene concentrations where emulsion stability increases and E' decreases. The discrepancy between the interfacial rheology and emulsion stability is believed to be associated with a change in the interfacial layer structure, transitioning from a compact and rigid monolayer, to a collapsed interfacial layer dominated by threedimensional structures.…”

Section: Asphaltene Adsorptionmentioning

confidence: 96%

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

et al. 2017

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SARA fractionation separates the oil into fractions of saturates (S), aromatics (A), resins (R), and asphaltenes (A) based on the differences in their polarizability and polarity.Defined as a solubility class, asphaltenes are normally considered as a menace in the petroleum industry mainly due to their problematic precipitation and adsorption at oil water and oil-solid interfaces. As a broad range of molecules fall within the group of asphaltenes with distinct sizes and structures, considering the asphaltenes as a whole was noted to limit the deep understanding of governing mechanisms in asphaltene-induced problems.Extended-SARA (E-SARA) is being proposed as a concept of asphaltene fractionation according to their interfacial activities and adsorption characteristics, providing critical information to correlate specific functional groups with certain characteristics of asphaltene aggregation, precipitation and adsorption. Such knowledge obtained is essential to addressing asphaltene-related problems by targeting specific subfractions of asphaltenes for selective removal.2

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“…The stabilization mechanisms involve the presence of asphaltenes as lipophilic surfactants adsorbed at interface as well as their contribution to the formation of a viscous or rigid film around the water drops that slows down the interdrop film drainage and retards or inhibits the coalescence [4][5][6][7][8][9] . The role of the demulsifier, which is basically a hydrophilic surfactant according to the physicochemical formulation concept 10 , is to counteract these stabilization mechanisms by attaining the so-called optimum formulation at interface.…”

Section: Introductionmentioning

confidence: 99%

Breaking of Water-in-Crude Oil Emulsions. 6. Estimating the Demulsifier Performance at Optimum Formulation from Both the Required Dose and the Attained Instability

et al. 2016

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Hydrophilic surfactant molecules with the proper formulation are able to break W/O emulsions stabilized by asphaltenes and other lipophilic amphiphiles as found in the effluent of petroleum wells. The demulsifier performance is here tested according to two critera. The first one, as in previous research, is the minimum dose of demulsifier used to attain the minimum stability at the so-called optimum formulation in a simplified bottle test. The second criterion is the value of this minimum stability at optimum formulation that has a direct relation with the separation time. Our findings show that in a family of ethoxylated surfactants, the best demulsifier is a hydrophilic one, though not too much. When the demulsifier is a mixture of two surfactants, it usually exhibits an intermediate behavior between the components. However, the mixture sometimes appears to be better than any of the components alone with some synergistic effect that improves the performance.

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Effect of interfacial rheology on model emulsion coalescence

Cited by 164 publications

References 20 publications

Effect of Diluents on Interfacial Properties and SAGD Emulsion Stability: I. Interfacial Rheology

Effect of Diluents on Interfacial Properties and SAGD Emulsion Stability: I. Interfacial Rheology

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

Breaking of Water-in-Crude Oil Emulsions. 6. Estimating the Demulsifier Performance at Optimum Formulation from Both the Required Dose and the Attained Instability

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