The interpretation of WT data in gas condensate formation with stress sensitive rock is very complex problem due to simultaneous effect of several phenomena on fluids flow in the near wellbore area such as: "formation damage skin", non-Darcy flow effect, condensate bank and permeability changing due to rock deformation. In this case it's not possible to estimate the main reservoir properties and total skin with its components using only standard interpretation technique of the WT data. This problem can be solved on the basis of special approach of the joint treatment of the steady flow multirate test and pressure build up test data. The proposed WT data interpretation method allows to get the key formation parameters: "undamaged" formation permeability (permeability in area distant from well), permeability vs. formation pressure as exponential function, non-Darcy flow coefficient, total and "condensate bank" skins. Suggested approach was evaluated using synthetic production data for the reservoir model based on the Urengoyskoe field (Western Siberia, Russia) parameters.