Abstract: For the problem of CO₂ channeling happened in individual wells and its source coming unclear in Qiaojiawa oilfield, sulfur hexafluoride gas tracer monitoring using well 45543-01 as an injecting well and numerical analysis is carried out.Meanwhile, changing CO₂ injecting to WAS based on gas tracer monitoring result.The monitoring and analysis results show that there is one preferential migration passage between well 45543-01, well Qiao 46-01 and injecting well and two preferential migration passages between well Qiao 46-02, well 45545 and injecting well.The equivalent permeability is 44.13×10^-3 μm², 9.54×10^-3 μm²and 17.02×10^-3 μm², 136.15×10^-3 μm² and 184.87×10^-3 μm², 104.27×10^-3 μm².Besides, the effect of WAS injecting is obvious in well 45543-01 and well Qiao 46-01.