a brief intro about well testing Well testing is an important process and it is needed in order to evaluate the reservoir production potential. It consists in fluid production during a relatively short period and measuring the three main variables for evaluation, time, flow rate and pressure. Well testing is usually done during exploration, development and production periods in an oil field, always in order to collect data that clarifies knowledge about the field and economic viability of its production. Important quantitative parameters are estimated through well testing such as absolute permeability, skin factor, wellbore storage coefficient, reservoir volume, average pressure, etc. These parameters are estimated by comparing the measured field data to theoretical mathematical models based on continuity equation and Darcy’s Law, that lead to the diffusivity equation, and a set of boundary conditions.