Many methods have been investigated in the laboratory and in the field for improving oil recovery. Today technology and economics on the average leaves two barrels of oil in the ground for each barrel recovered worldwide. On the other hand the recovery factor of Bu Attifel field is around 50% which indicates a substantial amount of oil remains in the ground after primary & secondary recovery processes are completed. This remaining oil is an EOR target. Many techniques have been proposed and used to recover the remaining oil such as chemical, miscible & thermal flooding techniques. Due to the nature of the reservoir and the current state of economics and technology miscible flooding has been selected to be investigated to improve the oil recovery in Bu Attifel field. The work used laboratory measurements to investigate the possible use of lean gas, rich gas or CO2 in Bu Attifel field. The work consist of phase behavior, minimum miscibility pressure determination of Bu Attiful oil and lean gas, minimum miscibility composition determination of enriched gas.