Method for interpreting gas well productivity of low-permeability heterogeneous water-containing gas reservoir

The invention discloses a gas well productivity interpretation method for a low-permeability heterogeneous water-containing gas reservoir. The method comprises the steps that a binary function between the starting pressure gradient and permeability and a binary function between the starting pressure gradient and water saturation are built; collecting gas well productivity well test data, and calculating the production pressure difference of different test points; determining the drainage radius of the gas well; starting pressure of different small layers is calculated; judging whether each small layer under each measuring point participates in flowing or not according to the production pressure difference and the starting pressure, and calculating the thickness of the producing layer, the stratum coefficient and the average permeability; calculating a laminar flow and turbulent flow contrast coefficient of the productivity equation of each measuring point; and drawing a productivity indication curve, determin