A production engineer is responsible for generating the production forecast for a well or a field. Once production drops from the peak or plateau rate, the engineer needs an estimate of decline rate. Production forecasts use risk analysis techniques to help quantify the uncertainty. History matching is the process of building one or more sets of numerical models representing a reservoir which accounts for observed and measured data. The assessment of uncertainty is always subjective; history matching should assist in creating the model of uncertainty, which is subsequently used for decision making. This study makes use of the ECLIPSE simulator in which different runs of reservoir simulations were performed. The data were obtained from well XYZ in the Niger Delta region which is currently under natural depletion and requires a measure to enhance the amount of oil to be recovered, and then predict future performance and analysis. This model is based on the physical model that emerges from data obtained from the geological, geophysical, petrophysical, and log information.