Study of Desorption in a Vapor Dominated Reservoir with Fractal Geometry

This paper is an at tempt to model well decline in a vapor dominated reservoir with fractal geometry. The fractal network of fractures is treated as a continuum with characteristic anomalous diffusion of pressure. A numerical solver is used t o obtain the solution of the partial differential equation including adsorption in the fractal storage space. The decline of the reservoir is found t o obey the empirical hyperbolic type relation when adsorption is not present. Desorption does not change the signature of the flow rate decline but shifts it on the time/flow rate axis. Only three out of six model parameters can be estimited from field data , due to the linear correlation between parameters. An application t o real well da ta from T h e Geysers field is presented together with the estimated reservoir, fractal space and adsorption parameters. Desorption dominated flow is still a questionable approximation for flow in fractal objects.