Abstract
Thermal recovery is one of the most effective techniques for viscous oil production, which has been widely used in the heavy oilfield development. The mechanisms and percolation characteristics of thermal recovery have attracted a lot of attention. However, the displacement characteristics and produced oil properties in the steam flood heavy oil process are rarely addressed. In this paper, steam flooding experiments with two heavy oil viscosities under the temperatures from 120 to 200 °C and velocities from 1 to 3 mL/min were carried out to examine the oil displacement efficiency and the produced oil properties. The results show that the majority of the oil is produced in the low water cut stage. Temperature increment is helpful for prolonging the water breakthrough time. The high injection velocity of steam contributes to a high recovery factor, even if it enters into the high water cut stage. The rheology of the produced oils severely changes because the SARA composition changes, and emulsification occurs during the steam flooding heavy oil process. With the increasing steam temperature, the relative content of resins in the produced oils decreases, and asphaltenes increase. With the increase in the injection volume and the injection velocity of steam, the content of resins and asphaltenes increases. This leads to an increment in the produced oil viscosities. The effect of injection velocity on the rheology properties of the produced oils increases with temperature increment. The finding of this work will provide the technical support for heavy oilfields development.