The peripheral reservoirs of the Daqing Oilfield exhibit low permeability and partial heterogeneity, resulting in a rapid injection pressure increase, limited sweep efficiency, and significant residual oil retention. To enhance recovery, this study synthesized a fluorocarbon siloxane (FHB) via free radical addition for rock surface wettability modification. At a concentration of 0.1 wt%, FHB increased water and oil contact angles to 136° and 117°, respectively, at 60 °C. Fourier transform infrared spectroscopy, thermogravimetric analysis, and aging tests confirmed stable hydrophobic/oleophobic properties through chemical bonding to the rock. Furthermore, the low surface energy FHB significantly reduced adhesion work and decreased oil-water interfacial tension from 27 mN/m to 0.55 mN/m, thereby improving fluid transport in pore throats and promoting residual oil mobilization. Core flooding experiments resulted in an increase in total recovery by 11%, with low-field NMR analysis confirming reduced oil saturation across various pore sizes. A field trial in a production well in Daqing Oilfield successfully increased output from 3.1 t/d to 4.9 t/d, validating the efficacy of this strategy under real reservoir conditions—representing the first successful field application of a fluorocarbon-based modifier for wettability alteration and oil production enhancement in China. This study provides valuable experimental data and a practical framework for implementing chemical-enhanced recovery.

This study establishes a covalently anchored wettability alteration strategy for enhanced oil recovery (EOR) using perfluorinated siloxane (CQ), addressing limitations of conventional modifiers reliant on unstable physical adsorption. Instead, CQ forms irreversible chemical bonds with rock surfaces via Si-O-Si linkages (verified by FT-IR/EDS), imparting durable amphiphobicity with water and oil contact angles of 135° and 116°, respectively. This modification exhibits exceptional stability: increasing salinity from 2536 to 10,659 mg/L reduced angles by only 6° (water) and 4° (oil), while 70 °C aging in aqueous/oleic phases preserved amphiphobicity without reversion—supported by >300 °C thermal decomposition in TGA; confirming chemical bonding durability. Mechanistic analysis identifies dual EOR pathways: amphiphobic surfaces lower rolling angles, surface free energy (SFE), and fluid adhesion to facilitate pore migration, while CQ intrinsically reduces oil-water interfacial tension (IFT). Core displacement experiments showed that injecting 0.05 wt% CQ followed by secondary waterflooding yielded an additional 10–18% increase in oil recovery. This improvement is attributed to enhanced mobilization of residual oil, with greater EOR efficacy observed in smaller pore throats. Field trials at the Huabei Oilfield validated practical applicability: Production rates of test wells C-9 and C-17 increased several-fold, accompanied by reduced water cuts. Integrating fundamental research, laboratory experiments, and field validation, this work systematically demonstrates a wettability-alteration-based EOR method and offers important technical insights for analogous reservoir development.