Recourse to timed borehole fluid logging after tracer tests (dilution technique) makes it possible to determine, in a mathematical manner, the flow rate and filtration speed up to values of 10-5 m/sec in the case of an induced or natural flow. It also makes possible the continuous recording of variations in these parameters according to the depth. With the help of a tracer, usually NaCI, the variation over time of the electrolytic borehole fluid is studied.
