Spectral noise meter (SNM)
The autonomous digital spectral noise meter (hereinafter referred to as the device) is designed to record the intensity and spectral characteristics of acoustic noise along a wellbore in order to identify intervals of fluid and gas inflow, as well as behind-the-casing flows accompanied by acoustic noise in the well during hydrodynamic and geophysical studies of drilling, production and injection wells. The device records a signal from a piezoelectric sensor at specified equal time intervals and records them in 512 frequency bands. Information is recorded in digital form in the internal non-volatile memory of the device. Flash memory is used as memory chips, which allows storing information when the power sources are turned off. After the measurement process, the information is read into a computer for processing and analysis. The data can be saved on a computer and transferred to other data processing programs. The device does not require erasing the memory. To increase the dynamic range, the device uses two channels with different gain factors. This allows, when the channel with high gain is overloaded, to use data from the channel with lower gain. The video shows how to process the data of the spectral noise meter when performing point measurements by depth. The depth is imported from the LAS file received from the logging control system (depth recording system).
Characteristic
Noise meter channel
Sampling interval, sec 0,25 – 99
Input signal conversion frequency (ADC), Hz 125 000 (12500 for low
frequency channel)
ADC bit depth 24
Number of frequency bands 512
Number of analog channels for recording 2 or 4
Measuring channels and their frequency ranges, kHz:
a) low-frequency signal channel 0.012 – 6.25 Gain factor ~ 60
b) small-signal channel 0.1 – 62.5 Gain factor ~ 6
c) large-signal channel 0.1 – 62.5 Gain factor ~ 60
d) high-frequency signal channel 0.1 – 62.5 Gain factor ~ 726
Error of internal clock per day, sec, no more than ± 5
Device memory
Device memory capacity 4 GB
Memory filling time
from 97 hours (polling
cycle 1s, 4 channels,
512 frequency bands)
Time to read the entire memory about 10 minutes
Information storage time 10 years
Number of recording cycles to internal memory 100000
Number of operating programs, max 8
Maximum operating parameters
Operating temperature range, °C* 0-150
Maximum pressure, kgf/cm2 800
*depends on the version, indicated in the passport
Power supply of the device
The device is powered by a 6 V DC source (standard version – 2 batteries
with a diameter of 14.5 mm and a length of 50 mm)
Minimum supply voltage at which the device’s operating characteristics
are maintained, V 5
Storage mode consumption current, μA not more than 100
Average current consumption in operating mode depends on the set
polling cycle (1 s – 12 mA; 2 s – 24 mA)
The duration of the device’s operation depends on the type of batteries and
the set polling time: for example, with a battery capacity of 1 A/h and a
polling time of 1 s, the device will operate for 1000/12 = 83 hours
The device allows you to monitor the battery status during a
communication session with a computer
The software allows
Turn the device on and off in recording mode using a computer
View real values by channels and power supply voltage when checking
the device
Set the polling cycle from 0.25 to 99 sec, program the device operating
mode (up to 8 programs)
Set the start delay for each program up to 180 days
Output information with measurement data from the device to the
computer
View the received data on the computer screen and output to the printer in
numerical and graphic form
Communication with the PC USB2.0, USB3.0
Reliability indicators of the device
Mean time between failures, not less than, h 20000
Mean time to restore functionality, not more than, h 4
Overall dimensions and weight
Length, mm 870
Diameter, mm 42
Weight, kg, not more than 6,2
