A computer-implemented process simulates production of oil and gas from hydrocarbon reservoirs. The process is used to help forecast the optimal future oil and gas recovery from large hydrocarbon reservoirs. At the same, this process is flexible to allow for further addition of new options; robust and reliable; and easy to use. The process is also comprehensive in that it allows a forecast of future performance of a wide range of reservoirs and future operation scenarios. By using the high-resolution models provided, a reservoir can be described much more accurately.