Abstract: A method and a system determine multi-zones commingling in oil field production. The system includes a processing circuitry configured to: identify a plurality of zones in a well to be analyzed based on first differences in properties or flow performance; calculate a normalized bubble point pressure; define a first bottom hole flowing pressure for the well; define flowing pressures after excluding the zone with the highest saturation pressure; calculate a normalized bottom-hole flowing pressure and a corresponding flow rate ratio; plot the flow rate ratio versus the normalized bottom-hole flowing pressure and the flow rate ratio versus the bottom-hole flowing pressure in a Cartesian scale; and determine the feasibility to produce from all the zones.