Comparison of Steam Front Shape During Steam Flooding Process Under Varying Steam State Condition: Numerical Analysis

It has been reported that superheated steam can greatly increase the oil recovery efficiency. After superheated steam injection, the viscosity of heavy oil is greatly reduced. Besides, the permeability of the rock is increased. However, this previous works were focused on the chemical respects of oil displacement mechanisms by superheated steam injection. The difference in physical heat transfer between superheated steam and wet steam has not been revealed. At present, there is a lack of study of its physical heating on the increase of productivity. In this paper, a numerical study is conducted to reveal the difference between superheated steam and wet steam during the steam flooding process. The contribution of physical heating on the productivity is studied. Simulation result show that: (a) The effect of physical heating of superheated steam can be neglected. The contribution of chemical reactions of superheated steam with heavy oil and rock minerals is the dominant factors for oil recovery mechanisms under superheated steam injection. (b) When the temperature is higher, the pressure wave propagates more widely. However, the difference in pressure field between superheated steam and wet steam with a steam quality of 1.0 is negligible. (c) There exists severe steam fingering phenomenon under superheated steam injection. This is because the superheated steam is completely vaporized which greatly increases its percolation capacity. This work sheds light on the contribution of physical heat transfer on temperature spread in reservoir under varying steam state during the steam flooding process. This work pointed out that the study of chemical reactions should be the research direction of the next step in oil displacement mechanisms by superheated steam injection.