5.3. Level gauge operation
5.3.1. Function
When monitoring the fluid level, а wave metering method is used.
The operation process is rendered automatically.
The participation of the
operator (after mounting the device) is required only to generate an
acoustic pulse using the level gauge outlet valve, or additional devices for
generating acoustic pulses (ball-type nozzle, GAI-01).
After an acoustic pulse is generated by a solenoid or manual valve,
the acoustic signal travels down the wellbore, is reflected off the liquid
level and returns to the wellhead, the signal is amplified and stored.
The
tool monitors an acoustic signal during 20 seconds, amplifies it and
records it in its storage.
Simultaneously the gas pressure in the annulus is
also determined and recorded in the storage. While analyzing and
processing the recorded data, the fluid level in the well is determined, then
shown on the display, and automatically stored in an nonvolatile memory
of the tool as a symbol report. Recorded results including a complete
echogram of the acoustic signal can be transferred to a computer database.
When calculating the fluid level, the tool automatically selects an
acoustic pulse velocity according to one of the sound velocity tables
recorded in it. The number of the correction table is selected by the
operator. In addition to it, it is possible not to use the tables, but to set a
sound speed (irrespective of pressure and level) manually using the
keyboard.
According to our experience, the sound speed in wells саn greatly
vary even within one and the same field. Therefore, it is highly
recommended to use the correction table applied for your region for
an individual field or а group of wells within the field. In any case, the
tool will display а level based only оn the sound speed that has been set
in it!
The tool automatically analyses the level of all signals including
noise signals, as well as it evaluates a degree of an interference effect, and,
when it is necessary, automatically activates (or deactivates) a program
interference filter.
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