The effect of gas-wetting nano-particle on the fluid flowing behavior in porous media. (15th May 2017)

• Record Type: Journal Article
• Authors: Jin, Jiafeng; Wang, Yanling; Nguyen, Tuan A.H.; Nguyen, Anh V.; Wei, Mingzhen; Bai, Baojun
• Is Part Of: Fuel. Volume 196(2017)
• Page Start: 431
• Page End: 441
• Publication Date: 2017-05-15
• Subjects: Nano-silica -- Functional modification -- Super gas-wetting -- Grape-like particle; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2017.01.083
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: The influence of gas-wetting alteration on the flow and distribution of fluids in porous media was studied with visualization flooding on a transparent glass micromodel whose original wettability is liquid-wetting. The glass model was first saturated with brine before gas-flooding to simulate the liquid-blocking effect near the wellbore region, as can be seen from Fig. 1a. As a result, severe liquid-blocking regions within the core did not allow gas passing through the outlet end of the micromodel (Fig. 1b). Fig. 1c shows how the liquid trapped in the outlet end of the micromodel is mostly removed after a certain amount of FG40-NP solution was injected. The red arrows in Fig. 1b show flow paths formed by the displaced. The liquid saturation in visualized flooding was calculated using MATLAB, which shows a sharp decline in liquid saturation after gas-wetting alteration, as shown in Fig. 1(g)–(i). If the initial liquid saturation in the micromodel is considered as 100%, the liquid saturation after gas-flooding is 33.23%. A liquid-blocking region can be observed in the top right corner of Fig. 1(h). Fig. 1(i) shows the liquid in the liquid-blocking region scattering as discontinuous phase after gas-wetting alteration, the liquid saturation declines to 20.77% in this stage. Hence, the flow path for fluids in porous media can be seen clearly. The amount of trapping liquid in micromodel decreased sharply after gas-wetting alteration. Therefore, the novel gas-wetting alteration agent can be applied to solve the liquid-blocking effect near wellbore region on the gas-condensate reservoir. Highlights: Nano-silica particle is functionally modified by fluorosurfactant. The wettability is dominated by the morphology of adsorption layer on core. Wettability alteration can facilitate enhanced oil recovery. The mobility of fluids trapped in porous media can be improved. Abstract: The effect of gas-wetting on the liquid-blocking effect near a wellbore region is significant. Here, we functionally modified nano-silica particles with a size of approximately 40 nm each by using a fluorosurfactant and obtained a super gas-wetting nano-silica particles, which could improve the contact angles of brine and hexadecane from 23° and 0° to 152° and 140°, respectively, and decrease the surface free energy of rock surface from 72 to 1.6 mN/m. The decrease in the gas displacement was approximately 30%. FT-IR, SEM and EDS were employed to determine the morphological change in the rock surface before and after gas-wetting alteration. Results indicate that when the fluorosurfactant molecules are joined to the nano-silica surface, and CF bond is recognized. The grape-like particles forming a multi-adsorption on the rock surface, which play an important role in super gas-wetting by decreasing surface free energy and increasing roughness on the rock surface. The data of EDS was consistent with the results of FT-IR and SEM. To further understand the influence of gas-wetting alteration on the flow and distribution of fluids in porous media, visualization flooding was conducted. The results show that the initial liquid saturation in the micromodel decreased sharply from 33.23% to 20.77% after the gas-wetting treatment, and the contact angle of isolated brine droplet on the treated pore-wall was approximately 125°, which also verifies that pore wettability can be altered to gas-wetting. The analytical data of the oil displacement experiment demonstrates that the substantial decrease in oil saturation may contributes to enhancing oil recovery. Furthermore, the mobility of oil trapped in micro channels can also be enhanced significantly after gas-wetting alteration due to the presence of methane.