Energy & Fuels, Vol.26, No.6, 3514-3520, 2012
Performance Enhancement of Vapex by Varying the Propane Injection Pressure with Time
Vapex or vapor extraction is an emerging green technology for heavy oil recovery. However, the oil production rates with Vapex are lower than those with the conventional recovery processes. This work aims at enhancing the oil production rates by investigating the effect of varying the injection pressure of solvent propane with time. For this purpose, experiments were designed and performed by injecting pure propane at injection pressures of 482.6, 551.6, 620.5, and 689.5 kPa and 21 degrees C into lab-scale physical models of heavy oil reservoirs. The physical models were packed with a porous medium and saturated with heavy oil. Three different permeabilities of the porous medium were used with heavy oils of two different viscosities and bed heights. The experiments were performed using different policies of solvent injection pressure versus time. Pressure variations were introduced by sudden release and re-injection of the solvent gas. In comparison to constant injection pressure, the pressure pulsing enhanced the oil production rate by 20-30%.