Experimental studies on fire and explosion characteristics of natural gas with carbon dioxide

China has started developing CO2 sour gas fields. While developing this kind of gas field,explosion characteristic of the fire accidents and asphyxiation accidents caused by natural gas should be attached with great importance. To identify the threshold concentration of CO2 and to figure out the corresponding protective measures are of great practical significance. This paper performed some researches into the explosion limits of natural gas which contains CO2. The obtained graphs present the explosion ranges of CH4,air and CO2. The results show that while air blend's CO2 content reaches 13.86%,and that of CH4 reaches 7.48%,then the lower explosion limit and the upper explosive limit of CH4 are the same. While air blend's CO2 content is higher than 13.86%,people should pay more attentions to asphyxiation accidents which might be caused by CO2. While CO2 content is lower than 13.86%,people should pay more attentions to fire and explosion risks. In addition,this paper puts forward some countermeasures in accordance with the safety production status at gas fields.