Issue 7, 2025, Issue in Progress

Wettability modification of a nano-silica/fluoro surfactant composite system for reducing the damage of water blocking in tight sandstone reservoirs

Abstract

In the process of drilling and development of tight sandstone reservoirs, a large number of external fluids can invade the pore structure of the reservoir due to its strong hydrophilicity, resulting in blockage of the pore structure and a decrease in oil and gas production capacity. To reduce the aqueous phase trapping damage of tight sandstone reservoirs, the SiO2@KH550/FC-A nano-composite system was prepared to construct hydrophobic surfaces in core samples. First, the surface of nano-SiO2 was modified by KH550 to prepare nanoparticles with good dispersion. FTIR, XRD, SEM, and TG were used to characterize the nanoparticles before and after modification. The fluorosurfactant FC-A was prepared in the laboratory and combined with SiO2@KH550 to produce the SiO2@KH550/FC-A composite system. The system increases the contact angle of the hydrophilic surface from approximately 20° to 130°, achieving wetting modification. Excellent stability of hydrophobicity was obtained, and the contact angle did not significantly decrease within 5 minutes. In contrast, using FC-A and SiO2@KH550 individually, the contact angle of the hydrophilic surface could not be increased to over 90°. The SEM results showed that after treatment with the composite system, a layer of micro–nanoscale particles was attached to the hydrophilic surface. It was proved that SiO2@KH550 and FC-A were adsorbed on the surface, forming a low surface free energy solid interface at the micro and nano scales, which greatly improved the surface hydrophobicity. Furthermore, after the composite system was used to treat tight sandstone cores aged at 100° for 16 hours, the amount of imbibition of the core samples treated with SiO2@KH550/FC-A significantly decreased from 2.6 mL of brine to only 0.5 mL after 8 hours. The core spontaneous imbibition rate was also reduced to 0.0004 g min−1 within 5 minutes, while the maximum brine water spontaneous imbibition rate was 0.27 g min−1. The core displacement experiment further showed that the fluid in the core pores can be more easily flowed back under gas displacement after wetting modification. The water saturation of the core samples decreased to 16.3% after displacement, and the core permeability recovered to 88.4%, indicating that the SiO2@KH550/FC-A composite system can significantly improve the liquid phase flowback ability.

Graphical abstract: Wettability modification of a nano-silica/fluoro surfactant composite system for reducing the damage of water blocking in tight sandstone reservoirs

Article information

Article type
Paper
Submitted
04 Dec 2024
Accepted
27 Jan 2025
First published
17 Feb 2025
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2025,15, 5264-5276

Wettability modification of a nano-silica/fluoro surfactant composite system for reducing the damage of water blocking in tight sandstone reservoirs

C. Chen, S. Zhuo, S. Li, N. Yin, C. Luo, H. Ren, M. Jia, X. Wang and Q. Cheng, RSC Adv., 2025, 15, 5264 DOI: 10.1039/D4RA08564G

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