Effect of pressure, temperature and gas phase composition on the rheological properties of heavy crude oil

Influence of pressure, temperature and the nature of gas on the viscosity of heavy crude oil from the Tatarstan field was studied using rheology method (rheometer MCR 302). The effect of temperature from 25 to 125 °C and pressure from 0.1 to 12.5 MPa on crude oil viscosity was investigated. It was found that an increase in temperature of 125 °C leads to a decrease of viscosity by 8 times. At the same time, an increase of pressure up to 10 MPa leads to an increase in viscosity by 38% at low temperatures. Also the influence of the nature of gas (nitrogen, argon and air) on the viscosity of crude oil at different temperatures and pressures was analyzed. It is shown that crude oil viscosities depend on gas composition. On the other hand, the influence of the composition of binary gas mixtures in a wide range of temperatures and pressures on the viscosity of heavy oil has been studied. The activation energies of flow are calculated for two types of gas mixture. It is shown that the gas phase at different ratios of the components does not significantly affect the rheological parameters of crude oil.