Hydrate formation and agglomeration in Pickering emulsions stabilized by hydrophilic and hydrophobic nano-CaCO3 particles

The stability of oil-dominated emulsions, including oil-based drilling fluids and crude oils, is crucial for mitigating gas hydrate risks in the petroleum and natural gas industries. Nanoparticles can stabilize oil-water systems (Pickering emulsions) by residing at the oil-water interface. However, their effects on the kinetics of hydrate formation in these systems remain unclear. To address this, we experimentally investigated how hydrophilic and hydrophobic nano-CaCO 3 influence CH 4 hydrate formation within dynamic oil-water systems. A series of hydrate formation experiments were conducted with varying water cuts and different concentrations of nano-CaCO 3 at a particle size of 20 nm, under 3 °C and 6 MPa. The induction time, hydrate formation volume, and hydrate growth rate were measured and calculated. The results indicate that hydrophilic nano-CaCO 3 generally inhibits hydrate formation, particularly at high water cuts, while hydrophobic nano-CaCO 3 can significantly inhibit or even prevent hydrate formation at low water cuts. Water cut strongly influences the kinetics of hydrate formation, and nanoparticle concentration also impacts the results, likely due to changes in oil-water interface stability caused by nanoparticle distribution. This study will offer valuable insights for designing deepwater oil-based drilling fluids using nanoparticles and ensuring safe multiphase flow in deepwater oil and gas operations.