A method of estimating an influx pr

A method of estimating an influx profile for at least one well fluid to a producing petroleum well with two or more influx zones or influx locations to a production flow, wherein the well comprises tracer sources with distinct tracer materials in known levels of the well, at least one of said tracer sources arranged downstream and exposed to the fluids in at least one of said influx zones, wherein each said tracer source has an even release rate to said well fluid, characterised in that one or more of the tracer sources is provided in one or more delay chambers for ventilating out fluid with leaked tracer material at a time constant which is significantly longer than the diffusion rate from the tracer source to the well fluid, wherein the method further comprises: providing samples, the samples collected from the production flow at a location downstream of the tracer sources during a time period in which the tracer transient is detectable at the downstream location, analysing said samples for concentration and type of tracer material from said possible tracer sources as a function of sampling time or cumulative produced volume; and based on said measured concentrations and their sampling time or cumulative produced volume, calculating said influx volumes.