Abstract: Steam Assisted Gravity Drainage（SAGD）technology is widely adopted for the development of terrestrial heavy oil reservoirs in Fengcheng oilfield. Due to the strong heterogeneity and low permeability of the reservoirs, the reservoir stimulation by water injection has been adopted to shorten the subsequent preheating period in SAGD wells. To quantitatively evaluate the shape of the stimulated region, the article proposed the concepts and calculation methods of floodable coefficient and squeezed fluid permeability in the swept area by water injection, derived the analytical solutions of the swept area in a single horizontal well and two horizontal wells, respectively, and finally used the model to predict the effects of field practices and verified the results by combining finite element calculation. It was concluded that the floodable coefficient in the studied reservoirs was about 0.27~0.30. Both the water swept radius and area of the dual-well injection system increased with the increase of the well spacing between the 2 wells, effective water permeability, horizontal section length and injection pressure under constant displacement conditions, and decreased with the viscosity of injected fluid. The viscosity of the injected fluid should be reduced as far as possible during field liquid-squeezing operation in SAGD wells. Meanwhile, the injection pressure and the near-wellbore reservoir permeability should be increased gradually to optimize the effect