Injection of hot urea solutions as a novel process for heavy oil recovery ― A proof-of-concept experimental study

Abstract

We report a proof-of-concept experimental study of hot urea solutions injection as a new recovery process to extract highly-viscous oils. Eight flooding experiments were conducted to study the viability of hot urea solutions in displacing bitumen from cold sandpacks. Three injection rates (4, 8, and 12cm3/min), four injection temperatures (180, 200, 220, and 240°C), and three urea solution concentrations (5, 10, and 15wt%) were investigated. Another baseline experiment was conducted with fresh water for comparison with the urea solution scenarios. The results showed that the injection of hot urea solution into cold sandpack saturated with bitumen lead to a significant increase in the oil recovery due to the formation of in-situ water-in-oil emulsions. The results also reveal that the balance of the retention time and the amount of heat delivered to the sandpack leads to an optimum injection rate at which the oil recovery is improved considerably. Additionally, while the increment in injection temperature accelerates oil production, it decreases the ultimate oil recovery. These results pave the way for improving the existing recovery techniques and introducing chemical in-situ oil recovery processes for reservoirs that are not currently exploitable using existing recovery techniques.