This thesis should help to find an optimum solution for workover projects that are in the tail-end phase, with low reservoir pressures and increasing water-gas ratios. Also future considerations, like possible artificial lift methods or foam injections, are discussed in this thesis to extend the well life. To identify future completion design standards besides the produced gas volumes the economics are calculated for the different completion possibilities and cost saving potentials. At the beginning of the thesis the importance of natural gas, as an energy source, but also for reducing carbon dioxide emissions is highlighted. Especially for Europe natural gas plays an important role and therefore the gas production, even in the tail end-phase has a high significance for the energy sector. To ascertain the most profitable completion designs, the evaluation parameters are identified and their advantages and disadvantages discussed. In a next step the costs that occur during the life cycle of a well are evaluated. For the most important factors for the life cycle costs; like gas price, inflation, or sulphur price development; the forecasts from ExxonMobil are compared to different industry standards. To figure out future completion designs two upcoming workover candidates were chosen, which are in the tail end phase, with low reservoir pressures and increasing liquid production. Based on the simulated production volumes for the different completion designs, an economic evaluation is performed, followed by a sensitivity analysis for the most economic designs.