The production behavior of horizontal wells producing from Marcellus shale has not been well established due to limited production history. As a result a simple method for predicting the long-term production would be of interest to the industry. Several DCA models have been proposed specifically for unconventional gas reservoirs. However, their reliability to predict the long-term production for Marcellus shale horizontal wells has not been established. In this study, production and completion data from a number of horizontal wells completed in Marcellus shale were collected. In addition, the properties of Marcellus shale were measured in laboratory with precision equipment designed for unconventional formations. The field data as well the laboratory measured properties were utilized in conjunction with a commercial numerical simulator to predict the long-term production behavior of horizontal wells producing from Marcellus shale. The numerical model allowed for inclusion of adsorbed gas, multiple hydraulic fracture stages, as well as dual porosity behavior. The predicted production profiles were then utilized to evaluate the applicability of the various DCA models. Subsequently, a technique was developed to estimate the parameters of the DCA model to predict the long-term production based on the early production history as well as the key reservoir parameters. Finally, the results of the DCA model predictions were compared to the history-matched simulation model predictions for confirmation.