This thesis will present the technical improvements, which have been developed by engineers of OMV Austria within the last 15 years. Those developments will mainly examine production engineering topics, which can be applied in mature oil fields. The merger with the Romanian oil and gas company Petrom increased OMVs portfolio of those fields. The knowledge gained in Austria will be applied at the Romanian fields. The two companies will be compared concerning their financial situation and their oil and gas fields. The post merger situation is explained and potential challenges and possibilities are discussed. The main part of that thesis describes the successful implemented processes in the Vienna Basin. Advantages and drawbacks are compared. Important optimizations of lifting methods are discussed and the procedures to increase the lifetime of installations are examined. Further, methods will be discussed which have an impact not only at a well, but rather effect the entire Vienna Basin. At the end all procedures and methods are compared and ranked. Due to that they can be evaluated concerning their importance. A set of proposal is outlined for processes, which should be applied in mature oil fields.