Enhancing Anticondensate Stability of Pickering Foam through Short-Chain Fluorinated Silane-Modified Nanosepiolite

The extraction of natural gas from condensate-bearing wells urgently requires foam systems with superior oil tolerance. However, conventional surfactant foams suffer from rapid collapse due to hydrocarbon displacement at gas-liquid interfaces. Herein, we develop an oil-resistant Pickering foam with high stability using short-chain fluorinated silane-modified nanosepiolite (designated as FHTES@NSP, where FHTES triethoxy (1H,1H,2H,2H-nanofluorohexyl) silane and NSP denotes nanosepiolite) combined with AOS surfactant for foam drainage gas recovery. Resultantly, The AOS/FHTES@NSP foam system demonstrates exceptional stability across 0-80% condensate content, with half-life extending from 23.1 to 44.6 min and liquid unloading efficiency reaching 68.32% at 10% condensate. The system maintains robust performance under high salinity (100,000 mg·L^-1 NaCl), high temperature (90 °C), and in Ca²⁺-rich brine with the green chelating agent IDS-Na₄. We propose that the coadsorption of FHTES@NSP and AOS at the air-water interface forms an elastic, robust composite film that resists oil displacement, while the nanofibers construct a three-dimensional network within Plateau borders to trap emulsified oil droplets, synergistically enhancing foam stability and drainage retardation.