A tracer method for online monitoring of downhole zonal contributions of oil, condensate, gas, or water mass flux (Foz, Fcz, Fwz, Fgz) of a production flow in a petroleum production well wherein said well having different well components with different behavior, and acting as delay chambers during flush out and comprises - production tubing, - completion void, - gravel pack, and the surrounding permeable geological formation, comprising a) arranging one or more distinct tracer carrier systems (Trs1, Trs2,..) each in different production zones (Z1, Z2,...) in said well, b) said distinct tracer carrier systems (Trs1, Trs2,...) arranged for releasing tracers (Tr1, Tr2,..) to a fluid of said production zones (Z1, Z2,...); characterized by c) said tracers (Tr1, Tr2,..) having affinity after downhole release to separate phases of oil, condensate, gas, or water with corresponding zonal mass fluxes (Fo, Fc, Fw, Fg), conducting a continuous loop of the following steps (e) - (f), comprising: e) using an online tracer monitor, conducting sampling of tracer concentrations (c1, c2,...) for at least one of the tracers (Tr1, Tr2,...) in said zonal mass fluxes (Fo, Fc, Fw, Fg) at a high sampling and analysis rate up to 1 sampling/ 5 seconds set and conducted at a time rate obeying Nyquist sampling of information related to one or more Flow Physical Events and noise, f) based on said concentration values (c1, c2,..) and retention times (tr) for the different delay chambers, estimating corresponding zonal tracer fluxes and zonal mass flux of oil, condensate, gas, or water (Foz, Fcz, Fwz, Fgz) as often as once per hour, using said one or more estimated zonal mass fluxes (Foz, Fcz, Fwz, Fgz) as input to control said production well. - production tubing, - completion void, - gravel pack, a) arranging one or more distinct tracer carrier systems (Trs1, Trs2,..) each in different production zones (Z1, Z2,...) in said well, b) said distinct tracer carrier systems (Trs1, Trs2,...) arranged for releasing tracers (Tr1, Tr2,..) to a fluid of said production zones (Z1, Z2,...); characterized by c) said tracers (Tr1, Tr2,..) having affinity after downhole release to separate phases of oil, condensate, gas, or water with corresponding zonal mass fluxes (Fo, Fc, Fw, Fg), conducting a continuous loop of the following steps (e) - (f), comprising: e) using an online tracer monitor, conducting sampling of tracer concentrations (c1, c2,...) for at least one of the tracers (Tr1, Tr2,...) in said zonal mass fluxes (Fo, Fc, Fw, Fg) at a high sampling and analysis rate up to 1 sampling/ 5 seconds set and conducted at a time rate obeying Nyquist sampling of information related to one or more Flow Physical Events and noise, f) based on said concentration values (c1, c2,..) and retention times (tr) for the different delay chambers, estimating corresponding zonal tracer fluxes and zonal mass flux of oil, condensate, gas, or water (Foz, Fcz, Fwz, Fgz) as often as once per hour, using said one or more estimated zonal mass fluxes (Foz, Fcz, Fwz, Fgz) as input to control said production well. e) using an online tracer monitor, conducting sampling of tracer concentrations (c1, c2,...) for at least one of the tracers (Tr1, Tr2,...) in said zonal mass fluxes (Fo, Fc, Fw, Fg) at a high sampling and analysis rate up to 1 sampling/ 5 seconds set and conducted at a time rate obeying Nyquist sampling of information related to one or more Flow Physical Events and noise, f) based on said concentration values (c1, c2,..) and retention times (tr) for the different delay chambers, estimating corresponding zonal tracer fluxes and zonal mass flux of oil, condensate, gas, or water (Foz, Fcz, Fwz, Fgz) as often as once per hour,