A New Productivity Formula for Gas Reservoirs with Low Permeability

In response to the gas reservoirs with slippage effect,threshold pressure gradient and high-speed non-Darcy effect,based on analyzing synthetically those three effects,a new productivity formulae is deduced according to the fundamental principle of seepage mechanic in porous medium.In flow performance curves are comparatively analyzed under different slippage effects and threshold pressure gradients.Under the same downhole flowing pressure,the productivity is higher with the influence factor of the slippage effect increasing and the productivity is lower with the threshold pressure gradient increasing.