PROSPER is a well performance, design and optimisation program for modelling most types of well configurations found in the worldwide oil and gas industry today. PROSPER can assist the production or reservoir engineer to predict tubing and pipeline hydraulics and temperatures with accuracy and speed. PROSPER’s sensitivity calculation features enable existing well designs to be optimised and the effects of future changes in system parameters to be assessed. PROSPER is designed to allow building of reliable and consistent well models, with the ability to address each aspect of well bore modelling viz; PVT (fluid characterisation), VLP correlations (for calculation of flowline and tubing pressure loss) and IPR (reservoir inflow). By modelling each component of the producing well system, the User can verify each model subsystem by performance matching. Once a well system model has been tuned to real field data, PROSPER can be confidently used to model the well in different scenarios and to make forward predictions of reservoir pressure based on surface production data. With PROSPER detailed flow assurance can be studied at well and surface pipeline level. PROSPER provides unique matching features which tune PVT, multiphase flow correlations and IPR to match measured field data, allowing a consistent model to be built prior to use in prediction (sensitivities or artificial lift design).