A method of estimating an influx profile (q i) for at least one of the well fluids, oil, gas, or water, to a producing petroleum well with two or more influx zones or influx locations (3, 31, 32, 33) to a production flow, comprising the following steps: - arranging tracer sources (4, 41, 42, 43) with distinct tracer materials (4m, 41m, 42m, 43m) 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 (3, 31, 32, 33), - each said tracer sources (4, 41, 42, 43) having even release rate (q t41, q t42, q t43...) to said well fluid, - inducing a transient in the production rate (q) of the entire production flow, thereby changing the local exposure times of the tracer sources to the fluid, - collecting samples (c), downstream at known sampling times (t), - analysing said samples (c) for concentration and type of tracer material from said possible tracer sources (4, 41, 42, 43), - based on said measured concentrations (4 c, 41 c, 42c, 43c) and their sampling sequence and the well geometry, calculating said influx volumes (q i) from transient flow models, characterized by - establishing in said calculation of said influx profile (q i), a model well of said well, including a model transport path (P') corresponding to said well's transport path downstream of said influx profile (q i), said model well having model influx rates (q'21, q'22, q'23...) to corresponding model influx locations (31', 32', 33',...) corresponding to said real influx locations (31, 32, 33), with model tracer sources (4',41',42',43') with distinct tracer materials (4'm, 41'm, 42'm, 43,m) in known levels of said model well corresponding to said real tracer sources (4, 41, 42, 43), - each said model tracer sources (4', 41', 42', 43') having even model leak rate (q't 41, q't 42, q't 43...) to a model fluid of said model well, - whereby model concentration (4'c, 41'c, 42'c, 43'c) for each tracer material (4'm, 41'm, 42'm, 43'm) is calculated in said modelled downstream well flow transport path (P') as a function of time under a modelled transient occurring in said model, - comparing said measured concentration (4c, 41c, 42c, 43c) and type of tracer material (4m, 41m, 42m, 43m) with said calculated model concentration (4'c, 41'c, 42'c, 43'c) for a corresponding model type of tracer material (4'm, 41'm, 42'm, 43'm), and adjusting said model influx rates (q'21, q'22, q'23...) so as for improving the consistency between said model influx profile (q i, q'21, q'22, q23...) and said influx profile (q i) - using the calculated influx volumes (q i) as parameters for controlling the production flow or for characterizing the reservoir. - arranging tracer sources (4, 41, 42, 43) with distinct tracer materials (4m, 41m, 42m, 43m) 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 (3, 31, 32, 33), - each said tracer sources (4, 41, 42, 43) having even release rate (q t41, q t42, q t43...) to said well fluid, - inducing a transient in the production rate (q) of the entire production flow, thereby changing the local exposure times of the tracer sources to the fluid, - collecting samples (c), downstream at known sampling times (t), - analysing said samples (c) for concentration and type of tracer material from said possible tracer sources (4, 41, 42, 43), - based on said measured concentrations (4 c, 41 c, 42c, 43c) and their sampling sequence and the well geometry, calculating said influx volumes (q i) from transient flow models, - establishing in said calculation of said influx profile (q i), a model well of said well, including a - each said model tracer sources (4', 41', 42', 43') having even model leak rate (q't 41, q't 42, q't 43...) to a model fluid of said model well, - whereby model concentration (4'c, 41'c, 42'c, 43'c) for each tracer material (4'm, 41'm, 42'm, 43'm) is calculated in said modelled downstream well flow transport path (P') as a function of time under a modelled transient occurring in said model, - comparing said measured concentration (4c, 41c, 42c, 43c) and type of tracer material (4m, 41m, 42m, 43m) with said calculated model concentration (4'c, 41'c, 42'c, 43'c) for a corresponding model type of tracer material (4'm, 41'm, 42'm, 43'm), and adjusting said model influx rates (q'21, q'22, q'23...) so as for improving the consistency between said model influx profile (q i, q'21, q'22, q23...) and said influx profile (q i) - using the calculated influx volumes (q i) as parameters for controlling the production flow or for characterizing the reservoir.