Water-saturated lean zones are notoriously challenging for steam-assisted gravity drainage (SAGD) operations since they increase heat loss and impair the SAGD performance. This study proposes mitigating lean zone effects using gas/water displacement to reduce lean zone impacts and improve SAGD performance. At the beginning of this study, we conduct a literature review on lean zones and gas-water displacement. We then develop a three-dimensional homogenous model to simulate SAGD scenarios with and without lean zone mitigation (LZM). Our findings reveal that lean zones have negative effects on SAGD performance, mostly owing to the pressure imbalance between lean and rich zones, which causes steam channelling and energy loss. LZM demonstrates significant advantages of using non-condensable gases (NCG) to displace water and balance pressure between the rich and lean zones, hence minimizing steam channelling and saving energy.