Integrated asset modelling has become a standard in the oil and gas industry. It combines reservoir, production and surface models, which allows to simulate the whole oilfield system. An integrated asset model allows a very cost effective evaluation for different what-if cases of new projects and exploitation of existing fields: e.g. benefits of well intervention and work overs can be estimated, different artificial lift methods can be compared and redundant drilling costs can be prevented. For decisions on day to day development, maintenance and operational improvements, the accuracy of such models and the ability to analyse the whole production system is often underestimated. State of the art software allows creating models with high accuracy. In order to achieve this target, it is of utmost importance to use precise input data from regular production measurements, and to follow the correct model set-up workflow. The aim of the current thesis is to establish a process and procedure for a modelling approach. Beginning with a checklist for mandatory input data, a step by step guide to set up a new model within the Petroleum Experts software suite is provided. The MBAL model represents the reservoir and allows determining the original oil in place and reproduces the measured production history, which is essential for a reliable forecast. The well model is generated with Prosper and allows comparing the production rate among different reservoir conditions. Several cases for production improvement, using diverse artificial lift methods, can be investigated. GAP connects the stand-alone reservoir and well models and includes the surface equipment of the production system. Predictions over defined period of time can be calculated and upcoming bottlenecks displayed. Achieved improvements and lessons learned for using integrated asset modelling within the “OMV Head Office Production Technology” department are incorporated to become standard within “OMV Exploration and Production”.