The economic model is constructed for evaluate of feasibility studies to investment or divestment the projects. This calculated from the reservoir simulator’s results; optimum oil, gas and water production rate, cumulative oil production recovery and the gathering of much information, such as capital costs, operating costs, anticipated revenues, contract terms, fiscal (tax) structure, forecast oil prices, the timing of the project, and the expectation of the company in the investment. The difference bottom waterflooding scenarios depended on time to start water injection for each reservoir sizes, were simulated and analyzed to determine the suitable time that meet the economic criteria for each projects.