Indoor Test of Heavy Oil Recovery by Gravity Drainage with Solvent

VAPEX in Hele-Shaw and porous media are different in mechanism,we are especially uncertain whether their pressure ranges of deasphalting are the same and the degree of difference in increasing oil production.In order to study the mechanism of VAPEX in porous media,a three-layer sand-packed physical model for VAPEX was built.VAPEX tests in high permeability cores were conducted to find the relationship between operating pressures and production rates,and several tests were conducted to study the effect of asphaltene precipitation on different permeability of cores under the same pressure.The experiment results show that deasphalting in porous medium happens near saturated vapour pressure,oil drainage ratio increased by three times,but deasphalt appeared in narrow pressure ranges,the asphaltene deposition would plug part of the pore throats,so the operating pressure should be lower than the solvent’s saturated vapour pressure,but for high permeability formations,the lower viscosity in deasphalting can be fully used to improve production rate.