Emulsification in steam flooding of extra-heavy oil resources

In situ emulsification is an essential process in thermal recovery techniques, yet few studies clarified its mechanism in steam flooding of extra-heavy oil resources. This study first analyzed the role of emulsification in steam flooding through laboratory physical experiments. Then, a new numerical model was established to characterize the in situ emulsification, which is validated through data matching and employed to do sensitivity analysis. The results show the following: First, water-in-oil (W/O) emulsion is generated and plugs channels in steam flooding; the resultant pressure difference in an extra-heavy oil test is about five times of that in a regular heavy oil test. In addition, in the early stage of steam flooding, emulsion plug is mainly influenced by perforation position, while in the middle and late stages, it is primarily affected by steam override. Moreover, the reason for “better recovery for higher temperatures” is that hotter steam generates more and stronger W/O emulsions, leading to better profile control and larger swept area. However, viscosity reduction of emulsions at higher temperatures is relatively less significant. This study clarifies the role of emulsification played in steam flooding of extra-heavy oil and provides theoretical support for efficient application of thermal recovery processes.