[en] Due to their physical properties (viscosity, density), the alternative frac fluids mentioned above present some technical challenges, such as high pressures at the wellhead. In this project, different scenarios are to be simulated on a case study in order to verify the feasibility for German tight gas deposits and to optimise the processes. The use of water-based frac fluids has a long history. Their disadvantages become more and more obvious as the development of tight gas formations progresses. The main problem is the slow flow-back, which allows the support fluid to settle. The solution to these problems is to replace the water-based frac-fluids with alternative frac-fluids, such as liquid gas (CO${}_2$, N${}_2$), LPG (Liquefied Petroleum Gas e.g. propane or butane), foam, energised fluids, methanol or emulsions. Although these alternative frac fluids have different properties, they have in common the use of gas as the main component of the frac fluid. Gas usually has a low viscosity and a high expansion capability, so that the frac closure can be accelerated and the lowering of the supporting fluid can be prevented.