Research Info

This study investigates the influence of asphaltene as a natural surfactant on the formation and stability of water-in-oil (W/O) emulsions under both ambient (27°C, 14.7 psi) and reservoir conditions (up to 80°C and 4500 psi). Emulsions were formulated using synthetic oil composed of toluene and paraffin (60:40), with variable water volumes (10%–50%), asphaltene concentrations (1000–50,000 ppm), and salt types (NaCl, Na2SO4, CaCl2, and MgCl2) at six different concentrations (1000–50,000 ppm). The findings reveal that a water content of 30% yields the most stable emulsion, with the smallest average droplet area of 1.144 μm2 observed in the presence of MgCl2 at 10,000 ppm. Increasing asphaltene concentration from 1000 to 10,000 ppm reduced average droplet size from 3.45 to 1.19 μm2 and increased phase separation resistance, as confirmed by centrifuge tests. Under reservoir conditions, increasing pressure from 1500 to 2500 psi enhanced emulsion stability, with the viscosity rising from 3.012 to 3.183 cP. However, at higher pressures (3500–4500 psi), viscosity decreased to 2.33 and 1.79 cP, respectively, indicating reduced stability due to asphaltene precipitation and reduced interfacial activity. Temperature rises also had a destabilizing effect: instability at 40°C increased 2.94 times, and at 80°C, it rose 4.66 times compared to ambient temperature, based on water droplet area and distribution. These insights emphasize the sensitivity of W/O emulsions to salinity, pressure, and temperature, offering valuable implications for the design of effective emulsion-based enhanced oil recovery (EOR) processes.