A method of estimating an influx profile (q i) for at least one well fluid (oil, gas, water) to a producing petroleum well with two or more influx zones or influx locations (3, 31, 32, 33) to a production flow; - analysing collected samples (c), the samples (c) previously collected by: - arranging new or selecting existing tracer sources (4, 41, 42, 43) with distinct tracer materials (4m, 41m, 42m, 43m) in known levels of the well, each of said tracer sources arranged at or immediately downstream of and exposed to the fluids in a corresponding influx zone (3, 31, 32, 33); - wherein each said tracer source (4, 41, 42, 43) has an even leak out rate (q t41, q t42, q t43...) to said well fluid; wherein - one or more of the tracer sources is arranged in a separate corresponding one or more delay chambers having one or more apertures to the fluid flow, the one or more delay chambers arranged 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; - the samples being collected from the production flow at a location downstream of the tracer sources at known sampling times after inducing a transient in the production rate of the entire production flow or for at least for one of the influx zones, thereby changing the local exposure times of the tracer sources to the fluid; - wherein analysing the collected samples (c) comprises: analysing the collected samples (c) for concentration and type of tracer material from said possible tracer sources (4, 41, 42, 43); and - based on the analysed concentrations (4c, 41c, 42c, 43c) and type of tracer materials in the samples as a function of the sampling times, calculating said influx profile (q i). - analysing collected samples (c), the samples (c) previously collected by: - arranging new or selecting existing tracer sources (4, 41, 42, 43) with distinct tracer materials (4m, 41m, 42m, 43m) in known levels of the well, each of said tracer sources arranged at or immediately downstream of and exposed to the fluids in a corresponding influx zone (3, 31, 32, 33); - wherein each said tracer source (4, 41, 42, 43) has an even leak out rate (q t41, q t42, q t43...) to said well fluid; wherein - one or more of the tracer sources is arranged in a separate corresponding one or more delay chambers having one or more apertures to the fluid flow, the one or more delay chambers arranged 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; - the samples being collected from the production flow at a location downstream of the tracer sources at known sampling times after inducing a transient in the production rate of the entire production flow or for at least for one of the influx zones, thereby changing the local exposure times of the tracer sources to the fluid; - arranging new or selecting existing tracer sources (4, 41, 42, 43) with distinct tracer materials (4m, 41m, 42m, 43m) in known levels of the well, each of said tracer sources arranged at or immediately downstream of and exposed to the fluids in a corresponding influx zone (3, 31, 32, 33); - wherein each said tracer source (4, 41, 42, 43) has an even leak out rate (q t41, q t42, q t43...) to said well fluid; wherein - one or more of the tracer sources is arranged in a separate corresponding one or more delay chambers having one or more apertures to the fluid flow, the one or more delay chambers arranged 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; - the samples being collected from the production flow at a location downstream of the tracer sources at known sampling times after inducing a transient in the production rate of the entire production flow or for at least for one of the influx zones, thereby changing the local exposure times of the tracer sources to the fluid; - wherein analysing the collected samples (c) comprises: analysing the collected samples (c) for concentration and type of tracer material from said possible tracer sources (4, 41, 42, 43); and - based on the analysed concentrations (4c, 41c, 42c, 43c) and type of tracer materials in the samples as a function of the sampling times, calculating said influx profile (q i).