Abstract: To solve the problems of development in the Bannan fault block, Banqiao Oilfield, including low productivity, high water cut, low degree of production, and lacking formation energy, the CO₂ huff and puff technology was applied to the horizontal well 45H of Ban14-1 block in December 2018. The production data indicated that this technology can reduce water cut and recover deliverability effectively. In order to promote this technology in Bannan fault block, the effect of static parameters of CO₂ huff and puff was studied. According to the general geological characteristics of the Bannan fault block, the influencing factors of CO₂ huff and puff of horizontal wells were investigated by comparing cumulative oil increment and oil exchange rate in different conditions with the reservoir numerical simulation methods. The result shows that the formation oil viscosity and the height of horizontal well avoidance have a significance influence on CO₂ huff and puff of conventional heavy oil reservoirs with active bottom water energy. However, the influence of reservoir porosity, permeability and horizontal well length is weak.For the Bannan fault block, the block suitable for CO₂ huff and puff should have a porosity of 30%~35%, a permeability of (1 300~1 900)×10^-3 μm², a formation oil viscosity of 50~65 mPa·s, a horizontal well length of 200~230 m, and a horizontal well avoidance height between 4~6 m.