The most obvious use of drillstem test data is for reservoir evaluation purposes. A DST has often been called a short duration temporary, open hole production test. As such, the data collected can be used to estimate reservoir properties such as initial reservoir pressure, permeability, skin damage and deliverability. (see Introduction to Quantitative Formulas)
It is not a substitute for a full scale production test, however. Keep in mind that a DST has limitations in this area. Flow times are usually short, in the order of one or two hours. This means that the volume of rock investigated is relatively small. This in turn means that interpretations must be judged in this context, i.e., it is not possible to infer a reservoir boundary or fluid contact 500 m from the wellbore with a test that has a radius of investigation of 10 m.