“…Analytical solutions to these liquid equations are readily available in the form of type-curves, which have become one of the foundations of reservoir engineering analysis. Starting with the pioneering analytical solutions provided by Van Everdingen and Hurst (1949), the "liquid" pressure diffusivity equation have been extensively analyzed and solved for a myriad of reservoir models and boundary conditions for the case of oil systems, including the analysis of infinite-acting constant rate production in radial systems (Ramey, 1970;Gringarten et al, 1979;Bourdet et al, 1983a), hydraulic fractured wells (Cinco et al, 1978;Gringarten et al, 1974;Agarwal et al, 1979), naturally-fractured systems (Warren and Root, 1963;Bourdet et al, 1983b), horizontal wells (Giger et al, 1984;Odeh and Babu, 1990;Ozkan, 2001), among others. These applications have established the fundamental solutions to the "liquid" pressure diffusivity equation, and their results have been widely used in oil pressure transient analysis.…”