Preparation of fluoropolymer nanoparticles(FPNPs) dispersion and its application as a wetting adjustment agent for sandstone rocks

In this paper, a kind of fluoropolymer nanoparticles (FPNPs) with excellent dispensability and stability was prepared for sandstone wettability adjustment. FPNPs not only could adsorb on sandstone to form micro-nano structures but also reduce the surface free energy of sandstone. FPNPs could change the wettability of cores from super-hydrophilic to superhydrophobic. The formation water contact angle of cores from 7 degrees to 150 degrees (95.33 % in wettability alteration). The surface free energy of cores from 180.77 mN m(-1) to 0.817 mN m(-1) (99.54 % reduction). The temperature resistance experiments illustrate that the formation water contact angle was 139 degrees after 48 h aging at 150 degrees C, which is still a highly hydrophobic state. Ultrasonic cleaning experiments explain that after 45 min of ultrasonic cleaning, the formation water contact angle was 131 degrees, indicating that there is a strong adsorption force between the core and FPNPs. Core imbibition experiments demonstrate that the treated core imbibition rate reduced by 66 %. Core flooding experiments show that the core water permeability increased by 44.26 %, and the pressure reduction rate reached 29.62 %. Therefore, FPNPs have promising applications in the fields of removing water locking, reducing injection pressure, and increasing injection volume. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, fluoropolymer nanoparticles (FPNPs) were prepared and applied for the adjustment of sandstone wettability. The results showed significant improvement in wettability alteration and hydrophobicity enhancement on sandstone cores. Detailed experiments on core permeability and pressure effects demonstrated the potential of FPNPs in promoting oilfield injection processes.