In recent decades, the evaluation of tight formations has become a challenge for many petrophysicists. The interpretation of electric logs in these types of unconventional reservoirs becomes difficult because of the low porosity and permeability that they represent. Quite often, because of drilling problems or simply because of the nature of the reservoir, the well must be cased without the possibility of obtaining open-well records, which are a key requirement to define the correct petrophysical interpretation. In light of this situation, how difficult does the analysis for this type of formation become when we do not have open hole logs? In other words, how can we evaluate whether or not the zone of interest will produce water when we do not have the critical information? This paper demonstrates how, through the use of pulsed neutron and complete-wave sonic logging, it is possible to determine the principal characteristics of a tight reservoir. With those logs, the fundamental parameters can be obtained with which to develop the completion of the well (effective porosity, volume of clay, water saturation, VP/VS ratio, and other parameters) to thereby select the "pay" zones to be fractured. This work presents a concrete solution for the efficient evaluation of tight gas reservoirs, using cased well logging.