Reservoir modeling is an important feature to understand the reservoir and predict its future performance using the available software. The main objective of this study is to estimate water influx, calculate OIIP thus the reserve and predict future performance (oil flow rate). The model has been built using MBAL software (which is a material-balance based on software with several different tools). The MBAL software uses the data collected (from “X” Field concession XX-25 of with three producing wells) to design the model, which is used to achieve the project objectives. The Oil initially in place (OIIP) was about 29.8 MMSTB (calculated by volumetric method and material balance equation gives 30 MMSTB). However, the nine models of water influx were tested. For water influx modeling with different techniques, all models show poor matching just the Fetkovitch model gave a good regression, with an error of about (0.8). Several reservoir fluid models and reservoir rock models and history matching were made to fulfill the requirement to have good and matching results that was used in water injection prediction model. No good response obtained by injection gas, with MBAL oven the type of gas was not specified with the software, so it is recommended to use another software to forecast future prediction using any evaluation oil recovery method, especially the gas miscible process.................. Keywords: ..........Water influx, Oil Simulation, reservoir modeling, history matching