Temperature effects on alkaline flooding for heavy oil recovery in heterogeneous and homogeneous porous media: Pore scale evaluation

ABSTRACT

Among the various methods of chemical enhanced oil recovery, alkaline flooding has a better potential to increase oil recovery in reservoirs containing acidic crude oil. This research investigated the effect of temperature on alkaline flooding (sodium hydroxide and sodium carbonate) on the enhanced oil recovery in two homogeneous and heterogeneous micromodels at temperatures of 25, 50, 75 and 90°C. Evaluation of the effect of temperature on oil recovery in micromodel experiments showed that sodium hydroxide increased the pH of the environment at low temperatures (25 and 50°C) due to its higher alkalinity and, this issue shows greater ability to emulsification and reduce interfacial tension, which ultimately increases oil recovery. In contrast, high temperatures (75 and 90°C) have a negative effect on oil recovery, so that oil recovery is greatly reduced. The high temperature causes the increased rate of the reaction between the crude oil sample and alkaline solutions, which in turn reduces the effect of IFT and, weakening the uniform enrichment of in situ surfactants cause problem for making water droplets within the oil phase. Finally, the increase in temperature to 90°C showed that the oil recovery rate was reduced to about 42% in the homogeneous model and 51% in the heterogeneous model. The achievements of this research lead to a better understanding of the effect of temperature parameter on various mechanisms of increasing heavy oil recovery such as reducing the IFT of oil/injectable solutions and producing W/O emulsion during alkaline flooding under different wetting conditions. Studies show that injecting alkaline by creating a W/O emulsion prolongs the breakthrough time and changes the finger pattern created during water flooding in a way that reduces the amount of oil bypassed, so that a significant increase is observed in the oil recovery factor.

KEYWORDS:

• Alkaline flooding
• high temperature
• homogeneous and heterogeneous micromodels
• interfacial tension
• viscosity

Disclosure statement

No potential conflict of interest was reported by the authors.