For relative high condensate content gas reservoir, dry-gas reinjection is an effective way to increase condensate recovery. However, the fluid phase behaviors are complex, and it is much important to carry out detailed performance analysis which contributes to reasonable adjustment programs for better effectiveness. According to Yaha gas-condensate reservoir, this paper presents following detailed dynamic analysis methods in order to research the effect of dry-gas reinjection according to Yaha gas-condensate reservoir.

Firstly, the pressure decline rate is in inverse proportion to the injection ratio, and the rate of pressure depletion is 1.29MPa/year while the reinjection ratio is 60%. As a result of the pressure decline, the characteristics of formation fluid change in different scale: the content of condensate and the saturation of retrograde condensate decrease gradually, and the dew point pressure increases slightly. Through careful comparative analysis it is found that the rate of GCR of certain wells increases three times faster than that before dry-gas breakthrough. Confirmed by trace monitoring the high permeability zones of dry-gas migration could be identified more accurately. Based on material balance equation analysis and numerical reservoir simulation, Yaha gas reservoir is of strong water-drive, and the edge water has moved forward about 300m in average, while 900m for some zones after nine years' development. Furthermore, the relative production and injection rates of different layers are found to vary from 0 to 90% through production log analysis.

According to the findings of performance analysis, some measures, such as infill well drilling, have been applied to Yaha gas-condensate reservoir in order to increase condensate recovery.

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