Abstract: Hydraulic fracturing has become a common and quite effective well stimulation technology to explore and develop low permeability reservoirs.The deliverability prediction theoretic curve of fractured well in low permeability reservoirs with threshold pressure effect is studied in this paper.The result shows that the skin factor has a relative big effect on the initial output of a fractured well，the bigger the skin factor，the lower the initial output is.However，the effect of
skin factor will disappear gradually with the increase of production time.The threshold pressure gradient affects mainly the middle-late period output of a fractured well，the higher the threshold pressure is，the faster the output declines.As a result，the effect of threshold pressure gradient must be considered when the deliverability analysis is carried out on a vertical fractured well in low permeability reservoirs.

Key words: threshold pressure gradient, vertical fracture well, deliverability prediction, skin effect, fracture