

Abstract
This presentation shows that owing to the high conductivity and mobility of water, the latent heat of steam was lost into the lean zones significantly in the SAGD process. The lean zones also have negative effects on the ES-SAGD process. However, the mechanisms of the effect are different when compared to the SAGD process. The solvent acted in a crucial role in the growth of a steam chamber. It intrudes into the lean zone layers to prevent the mobile water flowing into the steam chamber.