Real time radioactive

A method of characterizing flow behavior of a petroleum well, comprising:

• a) using at least two locally arranged injection devices, each of the injection devices provided at an injection position along the petroleum well, each of the injection positions being associated with a local production flow, wherein each of the injection devices injects a set of at least a first tracer with water-affinity and a second tracer with hydrocarbon-affinity into a base pipe of the petroleum well, the first and the second tracers being detectable downstream by an online detector, the injections by the injection devices occurring simultaneously into water and hydrocarbon-containing fluids present in the local production flow associated with each of the injection position, and wherein overpressure in each of the injection devices during the injection is at least 5 bars relative to the pressure in the base pipe;
• b) allowing transport of each of the local production flows to the online detector at a detection point downstream of the injection positions;
• c) at the detection point, conducting monitoring for detection of the first and the second tracers in a production flow comprising one or more of the local production flows to determine arrival time of the first and second tracers;
• d) calculating detection point slip times between corresponding arrival times of the first and the second tracers as measured at the detection point;
• e) based on the detection point slip times, determining transport times and local zonal slip times for the first and second tracers;
• and
• f) based on the determined transport times and local zonal slip times, characterizing the flow behavior of the petroleum well.