A new productivity formula for horizontal well in low permeability gas reservoir

Low permeability gas reservoir usually features stress sensitivity,threshold pressure gradient and high velocity non-Darcy effect,which should be considered in analysis of the productivity of horizontal well in low permeability gas reservoir.A new productivity formula for horizontal well in low permeability gas reservoir has been derived through conformal transformation by taking account of high velocity non-Darcy effect,stress sensitivity and threshold pressure gradient.The result shows that high velocity non-Darcy effect,stress sensitivity and threshold pressure gradient will cause the decrease of horizontal well productivity in low permeability gas reservoir;under the same bottom hole pressure,the production of horizontal well will decrease with the increasing of stress sensitivity coefficient and threshold pressure gradient.The formula is of guiding significance to the development of low permeability gas reservoir with strong stress sensitivity.