More and more gas wells suffer from liquid loading. This effect comes along with decreasing reservoir pressure and increasing liquid production. At some point a gas well is no longer able to transport the produced liquids up to the surface, which results in a reduction of gas production. In order to accomplish this problem several methods to unload gas wells are available. Dependent on the method used different sources to solve the liquid loading problem are addressed. One specific method utilizes a capillary string to inject surfactant into the wellbore at a desired depth. The capillary string technology consists of a chemical injection valve that is attached to the lower end of the capillary string which is hung of at the wellhead. The capillary string is installed under life-well conditions through the wellhead and the tubing where the surface end is attached to an injection unit. The surfactant is pumped from the surfactant tank through the filter, down the capillary string and enters the wellbore through the chemical injection valve. The surfactant, a wetting agent that lowers the surface tension of a liquid, causes the formation of foam. Foam has a lower hydrostatic and therefore can be removed more easily from the wellbore. Now the gas well is able to remove the liquids out of the wellbore again by its own. In order to become the application of foamer a success a suitable candidate well has to be selected. Certain criteria have to be met during the evaluation process.