Coupling of steam chamber and liquid pool during steam-assisted gravity drainage process in heavy oil reservoirs

The flow mechanism between the injector and producer is different from the flow in the steam chamber in the Steam-Assisted Gravity Drainage (SAGD) process. The interwell flow between the injector and producer is determined by both gravity and the pressure difference. In this study, the interwell flow model is improved by introducing a relative permeability model and an oil viscosity linearity assumption, considering the availability of input data. The interwell flow in the liquid pool is coupled with the gravity drainage in the steam chamber throughout the entire SAGD process. And the liquid level calculated by the new model is validated by field data. The results show that the subcool gradient is larger in the earlier stage and smaller in the later stage. The liquid level, subcool, pressure difference and wellbore liquid rate are interacted and should be matched to each other. In field applications, the subcool should be controlled differently according to its development stage. The subcool of the hottest spot should be near zero to maximize the well productivity and the steam chamber supply capacity. The results of this study provide theoretical guidance for the evaluation and adjustment of field dual-horizontal SAGD well pairs.