Mechanistic insights into amine-oxide-modified silica nanoparticle-stabilized Pickering emulsions for enhanced heavy oil recovery in heterogeneous reservoirs

To address the critical stability and mobility control limitations of conventional surfactant-stabilized emulsions, this study introduces a novel Pickering emulsion system stabilized by lauramidopropylamine oxide (LAO)-modified SiO 2 nanoparticles for enhanced heavy oil recovery. An aromatic hydrocarbon mixture was used as the oil phase, and the emulsion formulation (0.05 wt% LAO, pH 7.0) was systematically optimized through stability evaluations and rheological analyses. The optimized emulsion exhibited high stability, reversible shear-thinning behavior (> 90% viscosity recovery post-shearing), and predominantly elastic viscoelastic characteristics ( G′ / G″ > 10), which are attributed to the rigid interfacial film formed by LAO-modified SiO 2 nanoparticles. Core flooding tests demonstrated exceptional plugging performance (resistance coefficient, F R =124.3; residual resistance coefficient, F RR = 24.1) and achieved 29.6% incremental oil recovery—significantly exceeding conventional surfactant-stabilized emulsions (11.1%). A heterogeneous dual-core flooding experiment (permeability contrast = 5:1) confirmed superior conformance control with 33.6% tertiary oil recovery. Microscopic visualization revealed three synergistic mechanisms: (1) viscosity reduction and emulsification for enhanced heavy oil mobility; (2) flow diversion via Jamin effect-induced pore-throat blockage; and (3) pore-scale viscoelastic mobilization of residual oil. These mechanisms collectively enhanced macroscopic sweep efficiency and microscopic displacement efficiency, substantially improving heavy oil recovery in heterogeneous reservoirs. This work provides fundamental insights into Pickering emulsion transport in porous media and establishes a practical strategy for enhanced heavy oil recovery in heterogeneous reservoirs.