During N₂ injection process in Tahe Oilfield to enhance oil recovery，asphalt deposition may occur and cause reservoir damage problem. To solve this problem，through gas injection phase analysis test and viscosity test，the influence of N₂ injection on crude oil composition and property was analyzed，the influence of the N₂ injection on the permeability of reservoir was studied through gas injection huff and puff asphalt deposition experiment with core flow device，the degree of reservoir damage was evaluated by the index of fracture width，and the measures of reducing the deposition of asphalt were put forward. Experimental results showed that N₂ huff and puff would destroy the original balance state of crude oil，increasing heavy component content in oil，decreasing light component，thus increasing viscosity of crude oil. The asphalt precipitation degree would be influenced by gas injection rounds，crack width and well bottom hole flowing pressure. The asphalt deposition was not obvious when the bottom hole flowing pressure was higher than the saturation pressure，while there were more asphalt depositions when that was lower than saturation pressure. It was suggested that the reasonable production differential pressure should be maintained to prevent the asphalt deposition in the field of gas injection production，and suitable chemical plugging agent could effectively relieve the asphalt precipitation. During N2 injection process in Tahe Oilfield to enhance oil recovery，asphalt deposition may occur and cause reservoir damage problem. To solve this problem，through gas injection phase analysis test and viscosity test，the influence of N2 injection on crude oil composition and property was analyzed，the influence of the N2 injection on the permeability of reservoir was studied through gas injection huff and puff asphalt deposition experiment with core flow device，the degree of reservoir damage was evaluated by the index of fracture width，and the measures of reducing the deposition of asphalt were put forward. Experimental results showed that N2 huff and puff would destroy the original balance state of crude oil，increasing heavy component content in oil，decreasing light component，thus increasing viscosity of crude oil. The asphalt precipitation degree would be influenced by gas injection rounds，crack width and well bottom hole flowing pressure. The asphalt deposition was not obvious when the bottom hole flowing pressure was higher than the saturation pressure，while there were more asphalt depositions when that was lower than saturation pressure. It was suggested that the reasonable production differential pressure should be maintained to prevent the asphalt deposition in the field of gas injection production，and suitable chemical plugging agent could effectively relieve the asphalt precipitation.During N2 injection process in Tahe Oilfield to enhance oil recovery，asphalt deposition may occur and cause reservoir damage problem. To solve this problem，through gas injection phase analysis test and viscosity test，the influence of N2 injection on crude oil composition and property was analyzed，the influence of the N2 injection on the permeability of reservoir was studied through gas injection huff and puff asphalt deposition experiment with core flow device，the degree of reservoir damage was evaluated by the index of fracture width，and the measures of reducing the deposition of asphalt were put forward. Experimental results showed that N2 huff and puff would destroy the original balance state of crude oil，increasing heavy component content in oil，decreasing light component，thus increasing viscosity of crude oil. The asphalt precipitation degree would be influenced by gas injection rounds，crack width and well bottom hole flowing pressure. The asphalt deposition was not obvious when the bottom hole flowing pressure was higher than the saturation pressure，while there were more asphalt depositions when that was lower than saturation pressure. It was suggested that the reasonable production differential pressure should be maintained to prevent the asphalt deposition in the field of gas injection production，and suitable chemical plugging agent could effectively relieve the asphalt precipitation.