Fluid flow in a petroleum reservoir is a very complex phenomenon and it is impossible to develop analytical solutions for practical issues due to the complex behaviour of multi-phase flow. Reservoir simulation study the behaviour of fluid flow and provides numerical solutions to hydrodynamic problems of fluids in the petroleum reservoir-well systems with the help of a simulator. Reservoir simulation is used to predict the future performance of the reservoir so that intelligent decision can be made to optimize the economic recovery of hydrocarbons from the reservoir. In this study MBal software was the simulator tool used. The study shows the application of MBal in predicting the future performance of the well. A work flow was applied for this study and Data was gotten from RZD field and inputted to MBal, where result was gotten. MBal software calculation estimated STOIP as 149.184MMSTB, predict volume of the water influx as 47268.8MMft3, also show the effect of aquifer on the pressure of the reservoir and show that water drive is the predominant drive mechanism responsible for production. Also history matching and prediction run was done and it was predicted that the reservoir was to have a life span of 33 years with a recovery factor of 81.7%. This project show the importance of MBal in prediction of future performance.