Abstract: Fengshen well1 gas condensate reservoir is the first discovery of Paleogene deep gas condensate reservoir in Jiyang Depression.The authors of this paper study in detail on the phase behavior of gas condensate reservoir of Fengshen well1 based on the analysis of formation fluid composition,experiment of constant composition expansion and constant volume depletion,along with continuous measurement of downhole temperature and pressure.The results suggest that the reservoir of Fengshen well1 belongs to unsaturated gas condensate one with high temperature and high pressure,but without oil ring.The content of intermediate and heavy hydrocarbon composition is high.The content of oil is 606g/cm³,which shows that the gas condensate reservoir is rich of condensate oil.The difference between formation pressure and dew point pressure is 6.70MPa,and with natural depletion drive,the formation pressure drops sharply.When producing with 6mm flow nipple,formation pressure near well bore decreases below dew point pressure in the early production period,the retrograde condensate phenomenon occurs.Due to the serious loss of retrograde condensation,low recovery of heavy hydrocarbon component and the increase of filtrational resistance caused by oil/gas twophase flow,the production of individual well decreases.Study on the phase behavior provides the basis for reserve evaluation of hydrocarbonbearing glutenite and profiling of development program,and can guide significantly the exploration and development of the same types of reservoirs in Jiyang Depression.

Key words: gas condensate resrvoir, fluid phase behavior, constant composition expansion, constant volume depletion, Jiyang Depression