Abstract: During the high water eut exploitation stage,a large amount of remaining oil will be left in the uper pant of a thick reservoiz with positive thgthmic sedimentation of Daqing oil field.When the gas injection was applied,it improves the developaneaat zesults.This paper studies the time of gas breakthrough and varying patterns of the gas and liquid ratio as well as the importance of the regine of the gas injection operation on the results of gas injecdons.A new conclusion and understanding obtained are sign ificant to the dynamic analysis of actual field gas injection test and the adjustment of gas injection programane for an optianal gas injection programme.