Abstract: The pressure drop equation was derived from the volume balance principle in allusion to the characterization with abnormity of pressure-drop plot and constant-volume in overpressure gas reservoir. And by combining the binomial seepage equation of gas wells with the well-bore flow equation, the basic performance prediction model was established. The model gives consideration to the compaction of gas-bearing reservoir, the elastic expanding of rock grains and the elastic expanding of formation irreducible water. And with the model, the detailed dynamic prediction has been conducted on the actual overpressure gas reservoir. The calculation results show that the methods presented in this paper are reliable and correct. The model can preferably predict the production performance in the stable production period and the production decline period of overpressure gas reservoir.

Key words: overpressure gas reservoir, volume balance, mathematical model, dynamic prediction