Abstract: In the paper, the interfacial phenomena and their relations are analyzed, and the mechanisms of porous media influencing on dew point are studied. It is concluded that porousmedia affecting dew point is characterized by capillary condensation and gas adsorption, and the influencing degree is dependent on the fluid composition, status and the pore structure characters. Both
capillary condensation and gas adsorption make dew point pressure increase. Rich gas condensate reservoir is strongly affected by adsorption, and the increase degree ofdew point is high. The smaller the pore radius is, the stronger the effect of capillary condensation is, and the higher the increase degree ofdew point is, andwhen the pore radius is less than 5×10-6cm, the influence of capillary condensation can′t be neglected. For low permeability gas reservoir, the proportion of adsorbed fluid in total gas is relatively high, and the influence of adsorption is strong. The higher the difference between the initial formation pressure and the dew pointpressure is, the stronger the effect of adsorption is. For the same system, the higher the reservoir tempera
ture is, the smaller the changes in dew pointpressure caused by adsorption and capillary condensation.

Key words: porousmedium, gas condensate reservoir, adsorption, dew point pressure, capillary condensation, Interfacial Phenomenon