The real gas potential function presently being used in the oil and gas industry does not yield valid solutions when the reservoir pressure falls substantially below the initial value. To tackle this problem, a new real gas potential has been implemented. The effects of pressure-dependent fluid and rock properties such as gas viscosity, compressibility, porosity and permeability have been considered. Advanced mathematical derivations with respect to nonconstant hydraulic diffusivity have been performed, and an analytical solution has been obtained. Solutions for multiple-rate and multiple-well systems as well as bounded reservoirs of any shape have been successfully developed by using the principle of superposition and an unsteady-state bounding technique. Validation of the analytical solution has been favorably achieved by comparison with a finite-difference simulation. Reservoir pressures and flowing bottomhole pressures in gas wells calculated by the analytical solution presented in this paper are more accurate than by other analytical methods previously available in the literature.

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