Xue Haitao, Dong Zhentao, Chen Xiaodong, Tian Shansi, Lu Shuangfang, Lu Shudong
Key Laboratory of Deep Oil and Gas (China University of Petroleum (East China)), Qingdao, 266580, P. R. China.
China Petroleum Logging Co., Ltd., Xian, Shanxi, 710000, China.
J Nanosci Nanotechnol. 2021 Jan 1;21(1):225-233. doi: 10.1166/jnn.2021.18727.
Kaolinite is widely distributed in shale formations. Kaolinite has two surface types, Si-O and Al-OH, and the two surfaces have different chemical properties. The surface wettability of kaolinite minerals is closely related to the occurrence of crude oil, the migration process of crude oil, and the filling process of crude oil. In this paper, we focus on the oil-water rock wettability of different alkane hydrocarbons on the different surfaces of kaolinite and construct a model of oil and water with variation of the alkane components on the surface of tetrahedral and octahedral kaolinite. Molecular dynamics methods were used to study the morphological changes in water clusters in different alkanes on different surfaces of kaolinite and to calculate the wetting angles. Studies have shown that the octahedral kaolinite surface is strongly hydrophilic, and the water clusters become monolayers adsorbed on the surface. Water easily displaces the oil on the surface and preferentially drives low carbon number alkanes. The tetrahedral siloxane kaolinite surface is oleophilic, the water molecules in CH-CH are clustered on the surface, and the wetting angle of the water cluster in the alkane increases with increasing carbon number. Water has difficulty displacing oil on this surface.
高岭石广泛分布于页岩地层中。高岭石有两种表面类型，即硅氧（Si-O）和铝羟基（Al-OH），且这两种表面具有不同的化学性质。高岭石矿物的表面润湿性与原油的赋存、原油的运移过程以及原油的充填过程密切相关。在本文中，我们聚焦于不同链烷烃在高岭石不同表面上的油水岩润湿性，并构建了四面体和八面体高岭石表面烷烃成分变化的油水模型。采用分子动力学方法研究了高岭石不同表面上不同链烷烃中水分子簇的形态变化，并计算了润湿性角度。研究表明，八面体高岭石表面具有强亲水性，水分子簇在表面形成单层吸附。水很容易置换表面的油，并优先驱替低碳数链烷烃。四面体硅氧烷高岭石表面亲油，CH-CH中的水分子在表面聚集，链烷烃中水分子簇的润湿性角度随碳数增加而增大。水在该表面难以置换油。
