In this work, we perform a comparative study of flow models and a sensitivity analysis concerning some parameters, considering the effects of slipping and gas adsorption in shale gas reservoirs, using numerical simulation. We use the Finite Difference Method, a linearization based on the Picard method, and the Conjugate Gradient method to obtain the reservoir and production well pressures. The results obtained demonstrate the importance of the effects of slipping and adsorption in the variation of pressure in a single-phase isothermal gas flow. Mainly because some parameters in the flow models, depending on their values, can act favoring (or disfavoring) the pressure drop.