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Micelles [mi-sel] (singular "[[Glossary:Micelle|micelle]]"), or micellae (singular "micella"), are spherical clusters of hydrocarbon molecules that act as emulsifying agents. A typical micelle in aqueous solution forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre. This type of micelle is known as a normal-phase micelle (oil-in-water micelle). An Inverse micelle has a hyprophobic and hydrophilic side, with the hyrodphilic side at the center and the hydrophobic side facing the solvent. Micelles are approximately spherical in shape. Other phases, including shapes such as ellipsoids, cylinders, and bilayers, are also possible. The shape and size of a micelle are a function of the molecular geometry of its surfactant molecules and solution conditions such as surfactant concentration, temperature, pH, and ionic strength. The process of forming micelles is known as micellisation and forms part of the phase behaviour of many lipids according to their polymorphism.<ref name="r1">Micelle. 2015. In Wikipedia, The Free Encyclopedia.</ref>
[[File:Micelle.png|thumb|Micelle - Villarreal, Mariana Ruiz 2007]]
== Formation ==
where [[File:Vo.png|top|Vo.png]]&nbsp;<span style="line-height: 1.6;">is the surfactant tail volume, [[File:Lo.png|top|Lo.png]]&nbsp;is the tail length, and [[File:Ae.png|top|Ae.png]]&nbsp;is the equilibrium area per molecule at the aggregate surface.</span>
[[File:Vol1 Page 544 Image 0002.png|thumb|Schematic of a surfactant molecule and formation of micelles]] 
Gale (1987) reported the combined solvent power of supercritical fluids with the solvent power of micellar solutions which appears promising in connection with enhanced oil recovery. Likewise, recognition of the possible formation and destruction of reversed micelles by naturally-occurring amphiphilic substances, such as those associated with asphaltenes, may explain problems experienced in some EOR projects. Lipophilic supercritical components of reservoir fluids (e.g. light hydrocarbons and CO2) interact, in a controllable manner, with hydrophilic micellar complexes to achieve selective extraction of desirable components of crude oil. Fundamentals of supercritical fluids and of micellar systems are reviewed in terms of their mutual interaction and their potential applicability in EOR processes.<ref name="r4">Carnahan, N. F., & Quintero, L. (1992, January 1). On Reversed Micelles, Supercritical Solutions, EOR and Petroleum Reservoirs. Society of Petroleum Engineers.</ref>
When surfactants are present above the critical micelle concentration , they can act as emulsifiers that will allow a compound that is normally insoluble (in the solvent being used) to dissolve. This occurs because the insoluble species can be incorporated into the micelle core, which is itself solubilized in the bulk solvent by virtue of the head groups' favorable interactions with solvent species. The most common example of this phenomenon is detergents, which clean poorly soluble lipophilic material (such as oils and waxes) that cannot be removed by water alone. Detergents clean also by lowering the surface tension of water, making it easier to remove material from a surface. The emulsifying property of surfactants is also the basis for emulsion polymerization.<ref name="r1">Micelle. 2015. In Wikipedia, The Free Encyclopedia.</ref> [[File:Vol1 Page 544 Image 0001.png|thumb|Asphaltene-resin micelle]]
== Detection ==
== Category ==
[[Category:Category:1.11.2 Drilling fluid selection and formulation]] [[Category:5.4 Improved and enhanced recovery]] [[Category:5.10.1 Co2 capture and sequestration]] [[Category:DW All Pages]] [[Category:POST]] [[Category:SBNew pages]] [[Category:New pagesDW]]
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