A Study of the Effect of Gas Condensate on the Viscosity and Storage Stability of Omani Heavy Crude Oil

Heavy crude oil (density of 0.9571 g/cm3 at 288 K and kinematic viscosity of 7160 mm2/s at 303 K) and natural gas condensate (density of 0.7848 g/cm3 at 288 K and kinematic viscosity of 0.764 mm2/s at 303 K) were sampled from Omani oil fields. The oil was mixed with condensate (5−50 vol %), and the mixture viscosities were measured at the temperature range of 293−348 K. A drastic decrease in kinematic viscosity was achieved. An addition of about 12 vol % of condensate gave a viscosity of 265 mm2/s at 303 K. This made it easier to transport the heavy oil mixtures. The experimental data for the kinematic viscosity [ν (mm2/s)] as a function of the gas-condensate fraction (φ) and temperature [T (K)] could be described by an equation: ln(ln(ν)) = (k 1 + k 2·T) + (k 3 + k 4·T)·φ, with a high accuracy. Blends of the heavy oil and the gas condensate were stored to evaluate their stability. Results showed less than 0.05 wt % sludge formation after 2 months.