Noise Logging - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 121

Fig. 9.1 Noise log

Operating Principle

Through controlled experiments it is possible to derive noise amplitude-frequency
spectra that are characteristic of fl uid fl ow regimes. For example, Fig. 9.2 shows the
spectrum for 70 BWPD expanding across a 90 psi differential into a channel behind
the pipe. Note that the majority of the noise energy is concentrated in the frequency
range from 800 to 2,000 Hz.
By contrast, Fig. 9.3 shows the spectrum for sound emanating from 3.8 Mcf/D of
gas expanding across a pressure differential of 10 psi into a gas-fi lled channel
behind the pipe. Note the two peaks at 800 and 1,800 Hz.