Disruption of Cationic/Anionic Viscoelastic Surfactant Micellar Networks by Hydrocarbon as a Basis of Enhanced Fracturing Fluids Clean-Up

Shibaev, A.V.; Aleshina, A.L.; Arkharova, N.A.; Orekhov, A.S.; Kuklin, A.I.; Philippova, O.E.

Авторы: Shibaev A.V., Aleshina A.L., Arkharova N.A., Orekhov A.S., Kuklin A.I., Philippova O.E.
Журнал: Nanomaterials
Том: 10
Год издания: 2020
Издательство: MDPI
Местоположение издательства: Basel, Switzerland
Номер статьи: 2353
DOI: 10.3390/nano10122353
Аннотация: Studies of the effects produced by the solubilization of hydrophobic substances by micellar aggregates in water medium are quite important for applications of viscoelastic surfactant solutions for enhanced oil recovery (EOR), especially in hydraulic fracturing technology. The present paper aims at the investigation of the structural transformations produced by the absorption of an aliphatic hydrocarbon (n-decane) by mixed wormlike micelles of cationic (n-octyltrimethylammonium bromide, C8TAB) and anionic (potassium oleate) surfactants enriched by C8TAB. As a result of contact with a small amount (0.5 wt%) of oil, a highly viscoelastic fluid is transformed to a water-like liquid. By SANS combined with cryo-TEM it was shown that this is due to the transition of long wormlike micelles with elliptical cross-section to ellipsoidal microemulsion droplets. The non-spherical shape was attributed to partial segregation of longer- and shorter-tail surfactant molecules inside the surfactant monolayer, providing an optimum curvature for both of them. As a result, the long-chain surfactant could preferably be located in the flatter part of the aggregates and the short-chain surfactant - at the ellipsoid edges with higher curvature. It is proven that the transition proceeds via a co-existence of microemulsion droplets and wormlike micelles, and upon the increase of hydrocarbon content, the size and volume fraction of ellipsoidal microemulsion increase. The internal structure of the droplets was revealed by contrast variation SANS, and it was shown that, despite the excess of the cationic surfactant, the radius of surfactant shell is controlled by the anionic surfactant with longer tail. These findings open a way for optimizing the performance of VES fluids by regulating both the mechanical properties of the fluids and their clean-up from the fracture induced by contact with hydrocarbons
Добавил в систему: Шибаев Андрей Владимирович

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Disruption of Cationic/Anionic Viscoelastic Surfactant Micellar Networks by Hydrocarbon as a Basis of Enhanced Fracturing Fluids Clean-Upстатья

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