Abstract: Gas injection EOR experiments are carried out in single wells after waterflooding development in fractured-vuggy reservoirs in Tahe oilfield and good results have been gained. But the effects of waterflooding and gas injection in single wells are becoming worse at the middle-late development stage, causing large amounts of remaining oil can’t be produced after waterflooding. To improve the development effects of gas injection in this kind of reservoirs, the study on the mechanism of gas injection EOR in multiple wells needs to be carried out. Through gas drive simulation experiments on the basis of visualized models, the paper discusses the remaining oil distribution and its influencing factors after gas drive in fractured-vuggy reservoirs. The experiment results show that N2 flooding after waterflooding can effectively improve oil displace efficiency, and gas injection mode, injection point and model filling can influence the gas drive effects; gas drive effects can be improved by using continuous and stable gas injection, and gas injection at high positions of structures and producing oil at low positions of structures, which can provide basis for remaining oil production in similar reservoirs after waterflooding