An appropriate injection well completion design requires a knowledge of pressure and temperature profiles along the depth of the well. The results of sensitivity analysis can be used for preliminary design calculations of injection wells to find the optimum injection surface parameters and wellbore completion. In this study, the surface injection parameters and wellbore geometry are varied to examine the sensitivity of the results for various parameters by using the numerical model during water and gas injections. The results revealed that the temperature profile can be calculated for a single phase with a small error in absence of the pressure profile, the error is less than 3 . It is found that the contribution of the acceleration term is too weak for building pressure and tem-perature profiles (less than 0.001). Further, those comparisons of the results showed that except near the critical point, the pressure profile is not sensitive to the wellhead injection temperature (less than 1 ). © Pet Coal 2018.