The experience of using fiber-optic distributed acoustic sensing (DAS) for spectral noise logging based on a geophysical cable when monitoring the development of a gas condensate field is considered. Studies have been carried out to assess the spectral sensitivity of the DAS method. A technique has been developed for filtering the original signal with calculation of the signal energy in various frequency ranges, which carries information about the movement of fluid inside the well. Using these methods, the moment of stopping the well is clearly identified. By combining sound logging of wells with studies based on a fiber-optic system of distributed temperature sensing (DTS), intervals of gas-saturated formations operating in the well were identified.

It has been established that the information content of the DAS and DTS systems depends on the location of the cable. For monitoring development using the DTS technology, it is optimal to place the cable inside or outside the production casing. When the cable is located inside the tubing, the temperature field is distorted by counter-current fluid flows. The sensitivity of the DAS system to noise from the rock and the production casing can also be increased by optimizing the cable location, which can be justified with a wider implementation of this technology in production.

To be able to record noise from fluid movement behind the column and in the rock, it is necessary to expand the frequency range of the recorded vibrations by using special cables with increased sensitivity and an expanded directional diagram.

Keywords: spectral noise logging, fiber optic distributed acoustic sensing, gas-saturated formations, frequency range

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