Static adsorption of anionic surfactant on asphaltene partially hydrophobized natural sandstone core samples

Ördög, Tibor István and Imre-Deák, Ágota and Balassa, Lilla and Ágoston, Áron and Puskás, Sándor and Janovák, László and Dékány, Imre (2025) Static adsorption of anionic surfactant on asphaltene partially hydrophobized natural sandstone core samples. JOURNAL OF MOLECULAR LIQUIDS, 425. No.-127207. ISSN 0167-7322

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Abstract

Surfactant (or surfactant / polymer) flooding is a well-established process of chemical EOR because it increases oil recovery through a combination of interfacial tension (IFT) reduction, wettability alteration and emulsification. However, surfactants used in chemical EOR formulations tend to adsorb on the reservoir rock, which can result in uneconomical quantities of products required. Furthermore, while the crude oil contains naturally surface-active agents like asphaltenes, it necessary to study the presence of asphaltene on the adsorption properties of anionic surfactant. In this paper the static adsorption properties of SDBS anionic surfactant on asphaltene partially hydrophobized natural sandstone core samples were investigated. The results indicated that the layered silicate components increase the specific surface area of ​​the samples and consequently the adsorption capacity of anionic surfactants. Furthermore, the specific adsorbed amounts (mg/g) of SDBS surfactant in same rock system depends on the asphaltene coverage. We also clarified the effect of the surfactant adsorption on the surface zeta-potential of the reservoir rock and interpreted the influence of the surface modification of asphaltene on the adsorption of anionic surfactants. The evoluation of the zeta potential values represented that the SDBS molecules adsorbed onto the rock surface with the apolaric hydrocarbon chain part and thus the negatively charged sulphate groups are the main reason for the very low zeta potential. The zeta potential value decrease driven by the formation of hemimicelles from surfactant molecules via increased concentration of SDBS in below CMC level SDBS concentration range. In both cases, a quantitative description of the sorption processes is necessary, which means that adsorption isotherms were determined for both the asphaltenes, and the anionic surfactants used. Based on the experimental results, we have proposed an adsorption mechanism model of anionic surfactant on the modified crude oil reservoir rock surface. These physicochemical data provide information for the use of surfactants in reservoir layers during the planning of EOR/IOR technologies.

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