The thesis addresses challenges and possibilities supplied by multilateral well technology due to the fact that multilateral drilling and completion might increase the earning potential enormously. Basic requirements for selection of appropriate candidates for multilateral wells as well as completion design considerations respectively application of an adequate TAML level (Technical Advancement of Multilaterals) are being discussed. A flowchart, which enables a pre-determination of the TAML level, has been created on the basis of different criteria the multilateral well has to fulfil. Such criteria are for example: Sand control, stability of the producing formation, junction stability or hydraulic isolation between the laterals. OMV-Austria constructed three horizontal oil producing wells from the same rig-site in the Vienna basin. A theoretically substitution of these conventional wells by one multilateral well has been analysed within this thesis. Thereby alternative borehole geometries as well as an almost unchanged borehole geometry of the existing horizontal wells have been evaluated according to their viability. Due to comparability, the scenario with almost unchanged borehole geometries has been selected for further analysis. The surface locations have been tied together into one point, which means a disarrangement of two wells of just a few meters. Afterwards, the resulting multilateral well has been analysed regarding to drilling procedures and completion design. For an economic evaluation the anticipated costs for the multilateral project have been calculated on the basis of proportional data resulting from conventional wells. The main reason of this thesis was to gain basic data of multilateral projects for potentially prospective intentions.