Nanoparticles for Inhibition of Asphaltenes Deposition during CO2 Flooding

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• 作者：Teng Lu ; Zhaomin Li ; Weiyu Fan ; Xinglu Zhang ; Qichao Lv
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2016
• 出版时间：June 15, 2016
• 年：2016
• 卷：55
• 期：23
• 页码：6723-6733
• 全文大小：620K
• 年卷期：0
• ISSN：1520-5045

文摘

The deposition of asphaltenes in porous media is one of the most difficult problems during CO₂ flooding. In this paper, the adsorption of asphaltenes onto Al₂O₃ nanoparticles was studied through two methods: (i) by adding a certain mass of nanoparticles in a fixed volume of solution with different initial concentrations of asphaltenes and (ii) by exposing a certain amount of asphaltenes in a fixed volume of solution to different nanoparticles additions. Then, the impact of Al₂O₃ nanoparticles on the asphaltene precipitation was investigated using the IFT behavior of the oil–CO₂ system. Coreflood tests were conducted to study the potential of nanoparticles for inhibition of asphaltenes damage during CO₂ flooding, and the effect of injection parameters of nanofluid. It is found that the solid–liquid equilibrium (SLE) can well describe the isotherms of asphaltene adsorption. The trend of the IFT–pressure curve is affected by asphaltene accumulation at the oil–CO₂ interface. The slopes in the high pressure region can be used to examine the intensity of asphaltene precipitation. As the addition of nanoparticles increases, the IFT slope in the high pressure range decreases. This is because the asphaltenes are absorbed at the surface of nanoparticles. As a result, the nanoparticles prevent asphaltene precipitation from accumulating at the CO₂–oil interface, hence causing asphaltene to remain within the bulk of oil. The higher the mass fraction of Al₂O₃ nanoparticles is, the lower the intensity of the asphaltene precipitation would be. The coreflood results show that the injection of Al₂O₃ nanofluid can lessen the oil permeability reduction because the nanoparticles can inhibit the deposition of asphaltenes onto the sand surfaces in the porous media. The 0.5 wt % nanoparticles and the 0.1 nanofluid/CO₂ slug volume ratio are considered as the optimum for inhibiting asphaltenes damage during CO₂ flooding. Continuous CO₂ and nanofluid injection could be more effective compared with the cyclic injection pattern.