Biomimetic inspired superhydrophobic nanofluids: Enhancing wellbore stability and reservoir protection in shale drilling

Shale oil and gas, as typical unconventional resources, have gradually altered the global energy supply and demand landscape, attracting significant attention over recent decades. However, challenges such as wellbore instability and reservoir damage caused by drilling fluids invasion during shale drilling remain unresolved. In this study, we reported the synthesis and preparation of biomimetic inspired superhydrophobic nanofluids (SHN) with multiple functions by utilizing nano-silica, low surface energy fluorinated compounds, and cationic compounds with adsorption capabilities. Firstly, SHN with nano effects could plug micro-nano pores in shale, thereby reducing the filtration loss of drilling fluids (from 24 to 11 mL). Furthermore, SHN could adhere to shale surfaces through electrostatic interactions to increase its roughness from 1.121 to 3.567 μm, thereby transforming the shale surface from hydrophilic (26.4°) to superhydrophobic (152.8°). This not only reduced self-priming by 83.7% and decreased the capillary rise height to 5 mm below the liquid surface but also suppressed hydration expansion and improved the rolling recovery rate by 84.74%. Overall, this study provided new insights into the design and manufacturing of high-performance drilling fluids materials that could support wellbore stability and reservoir protection during shale oil and gas drilling processes.