A Study on the Mechanism of Urea-assisted Steam Flooding in Heavy Oil Reservoirs

The Biqian-۱۰ block, located in Henan Oilfield of Sinopic, contains many thin and interbedded reservoirs, which have been operated by cyclic steam stimulation for ۲۰ years or more. Therefore, it is a challenge to implement the conventional steam flooding. In order to improve the recovery of steam flooding, urea was used to assist steam flooding. Urea can decompose into CO۲ and NH۳, which are beneficial to enhance oil recovery (EOR). For the sake of exactly quantifying the mechanism of urea assisted steam flooding (UASF), the UASF model was built according to the experimental results. The simulation results show that CO۲ is the key point for EOR, and its pressurization function is more effective than the decrease in oil viscosity by dissolving CO۲. The emulsification of crude oil for NH۳ is weak in interfacial tension tests; thus the effect of emulsification can be ignored in the simulation. The UASF can improve the recovery by about ۱۷.۴%, which is ۶.۸% higher than steam flooding.

کلیدواژه ها:

heavy oil ، urea assisted steam flooding ، CO۲ ، Mechanism ، EOR