Gas-lift deliquification in multiphase wells can be hindered by wall-adhered droplets and persistent liquid films, increasing hydraulic resistance and reducing liquid transport. Here, a SiO2/epoxy superamphiphobic coating was developed to regulate the phase-specific near-wall transport of water and crude-oil droplets under upward gas flow. PFOTS 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) reduced surface energy, while 3-glycidoxypropyltrimethoxysilane (KH-560) promoted interfacial coupling between SiO2 particles and the epoxy matrix, producing a hierarchical fluorinated surface. The coating exhibited static contact angles of 155° for water and 153° for crude oil, with contact-angle hysteresis below 9°. Experimentally measured advancing and receding contact angles were incorporated into the level set wall-wetting condition to represent macroscopic contact-angle hysteresis. Shear-rate-dependent constitutive models were further introduced for heavy and extra-heavy crude oils to account for non-Newtonian rheology. Simulations showed that the normalized near-wall migration metric for water increased from 1.22% on bare steel to 1.87% on the coated surface, while the recalculated values for heavy and extra-heavy crude oils were 0.98% and 0.81%, respectively. The results indicate that reduced interfacial retention promotes droplet migration, whereas shear-rate-dependent rheological resistance becomes increasingly important in high-viscosity oils. These findings highlight the coupled roles of wall wettability and liquid rheology in near-wall droplet transport. Simultaneous oil–water coexistence, competitive wetting, and emulsification remain outside the present scope.

Under artificial-lift conditions in oil and gas wells, gas-anchor separation efficiency is highly sensitive to variations in the gas–liquid ratio, stroke rate, and flow velocity. We propose an amphiphobic inner-wall coating for gas anchors to improve wall wettability and thereby enhance separation and pump efficiencies across a wide range of operating conditions. Nano-SiO2, synergistically modified with sodium dodecylbenzenesulfonate (SDBS) and 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS), was incorporated into an epoxy resin matrix, and the formulation was optimized. The mass ratio of modified nano-SiO2 to epoxy resin strongly influenced the coating microstructure and surface performance. At a nano-SiO2/epoxy mass ratio of 1:2, the water and oil contact angles reached 165.4° and 159.1°, respectively, indicating excellent amphiphobicity. Corrosion and adhesion tests further showed that the coating remained stable under high-temperature, high-pressure CO2 conditions, with a minimum corrosion rate of 0.0074 mm·a−1 and an adhesion rating of 4B. Gas-anchor separation tests confirmed the engineering benefits of the amphiphobic coating, yielding higher gas-separation and pump efficiencies across a range of gas–liquid ratios. The improvement was most pronounced at high gas–liquid ratios, where the maximum gas-separation efficiency reached 83.0%, outperforming the benchmark coatings. Overall, these results provide a practical materials and interfacial-regulation strategy to enhance gas-anchor separation and extend service life in oil and gas wells.

Sucker rods operate under long-term cyclic loading while exposed to corrosive produced fluids, making corrosion–fatigue damage a major integrity concern. This study examined produced-fluid samples from 16 wells with sucker-rod failures and 16 corresponding failed rods from a Daqing oil production plant using ionic-composition analysis, SEM/EDS, bulk chemical analysis, metallography, axial tensile tests, exploratory fatigue tests, and field load analysis. The fluids were HCO₃⁻-dominated, with average HCO₃⁻, Cl⁻, and SO₄²⁻ concentrations of 345.7, 0.129, and 2.55 mg/L, respectively. Representative fracture surfaces showed corrosion pits, corrosion products, secondary cracks, and lamellar or step-like morphologies, while corroded microregions were enriched in O and contained detectable Cl and S. Local discontinuities, including decarburization, inclusions, and scratches, were also observed. Residual tensile strength varied substantially with service history, and exploratory fatigue results showed considerable scatter. The actual field fracture location did not coincide with the maximum nominal axial stress. The combined evidence supports a representative sequence of localized corrosion and pit formation, crack-susceptible region development, microcrack initiation, cyclic crack propagation, crack coalescence, loss of effective load-bearing area, and final rapid fracture.