Bio-inspired superhydrophobic interface of nano-gaseous film for reducing injection pressure in oil reservoirs

Superhydrophobic wettability inspired by the "lotus effect" is an intriguing property in nature, but it is rarely applied in oilfield development. Superhydrophobic nanomaterials can effectively solve the problem of "high injection pressure and insufficient water injection" in low permeability oilfields by changing the properties of the core surface, which is of great significance to the development of low permeability oilfields. Herein, we report a novel type of superhydrophobic nanoparticle (SHNP) simply modified by fluorinated long chains, and a stable nanofluid is successfully prepared by compounding surfactant. The prepared SHNP nanofluid has an excellent core drag reduction effect, and the drag reduction rate is 1.35 times that of conventional NPs under the same conditions. The SHNPs assemble on the core surface to form a large number of micro/nanorough structures, which can effectively reduce the surface roughness of the core. The PIV experimental results show that compared with the injection of pure water, the center flow velocity in the subsequent water flooding center increases by 98.27% after the injection of SHNPs nanofluid (the flow velocity decreases by 53.45% after the injection of NPs). Moreover, bubble probe AFM technology has successfully shown that bubbles can be captured through the SHNPs superhydrophobic interface to form a gaseous film. By using the barrier effect of the gaseous film, the liquid-solid interface is converted to a liquid-gas-solid interface, thereby reducing the large resistance caused by the direct contact between the liquid and solid. Such SHNPs with simple modification and low cost have broad application potential in oilfield development.