Abstract: In view of the fact that many gas wells often blowout immediately after fracturing, a pseudo-three-dimensional draw down analysis model in forced closure conditions is built based on the material balance theory and correlation analysis model. Filtration height is introduced into the model and the s tress contrast between pay zone and the upper and lower barriers is comprehensively taken into consideration, so that the real situations of the formation can be better simulated and more accurate parameter interpretations can be achieved. Pressure derivatives are used, for the first time, to perform curve fitting. Because the amplitude of pressure variation is enlarged, the linear relationships are different before and after closure. The crossover of the two linear relationships is used to calculate closure pressure and filtration coefficient. Drawdown analysis and interpretation with this model is more simple, straightaway and accurate. As the influences of blowout immediately after fracturing on fracture parameter interpretation are taken into consideration, this model has field practicability and is also applicable to natural closure of fractures. The relevant interpretation software is programmed with the Visual Basic6. O. A field case is presented to illustrate the accuracy of the model and the rationality of the software programmed.
Key words: shale reservoir; stimulated reservoir volume; micro-seismic; horizontal well; natural fracture; clustering perforation; water