The present invention concerns a method of quantifying, detecting and localizing leaks or flows of liquid, gasses, or particles, in an oil or gas producing well (230). The method utilizes an acoustic
transducer (150) arranged in the well (230). The method comprises steps of: (a) detecting signals (210) using the
transducer (150), wherein the signals (210) are generated by acoustic
noise from leaks (20) or flow of liquid, gasses, or particles in surroundings of the
transducer (150); (b) amplifying the signals (210) to generate corresponding amplified signals for subsequent
processing in a
processing unit (170) disposed locally to the transducer (150); (c) filtering the amplified signals (210) over several frequency ranges using
dynamic filtering for simultaneously detecting in these frequency ranges for better optimizing the
signal-to-
noise ratio by filtering away
background noise in the amplified signals (210), and thereby generating corresponding processed data; and (d) sending the processed data from the
processing unit (170) to a unit on the surface for storage and / or viewing of said data. The invention also comprises a corresponding
system for implementing the method. The method and
system are beneficially adapted for a
continuous measurement up and / or down the oil or gas producing well. (230) in a non-stepwise manner.