In the course of the redevelopment project of the 16th Tortonian Horizon, three horizontal infill wells were drilled. These wells targeted the attic oil in the top region of the reservoir and, as result, increased the oil production for this production unit. Out of this redevelopment project, the idea was born to compare the production performance of these oil wells. The western part of the 16th Tortonian is called Bockfliess and is the main target of the infill wells. It was the first time that OMV Austria drilled horizontal wells in this reservoir region; therefore, it was decided to vary the type of completion depending on the geological setting and the presence of a gas cap. In the case of Bockfliess 204 and Bockfliess 208, no significant amount of gas presence was given, therefore well BO 204 was completed with a slotted liner while the other one (BO 208) was completed with a combination of blank pipes and autonomous inflow control devices (AICDs). Bockfliess 205 showed the presence of a gas cap, and therefore a standard cemented cased hole completion was implemented. This thesis generates information about the production performance difference between horizontal and vertical wells and in addition how efficient the newly introduced AICD completion works. In order to reprocess all the necessary data, this thesis overviews the theoretical information about the reservoir, completion types, and artificial lift systems, including inflow control devices. In addition, it also discusses the mathematical methods used to estimate the production performance of horizontal and vertical wells. All necessary analyses were performed with applications such as NEToolTM and MS Excel®. The analysis covers three horizontal and six vertical wells and uses the production data of each well from the last 30 months. With this data it was observed that the cumulative oil production rate of the horizontal wells was approximately 2.2 times higher compared to the neighbouring vertical well. The results from the BO 208 analysis were notable. The AICDs, which were mounted at the horizontal section, choked the production fluid in such a way that the water cut trend maintained a constant rate compared to all other wells, where the water cut constantly increased. Through the different analytical methods of the production data and the investigation of the completion types, it was determined that a static NETool(TM) model does not provide clear information about the production behaviour of the horizontal wells. A study of the cumulative oil production showed that the application of horizontal wells is more efficient than vertical ones. Several completion types were examined, and the use of AICDs in horizontal sections showed the ability to flatten the increasing water cut trend, which will be even more useful for future wells in Austria.