Echometer Company
Model – M Manual
Phone: (940) 767-4334
5001 Ditto Lane
Page
15
Fax: (940) 723-7507
Wichita Falls, Texas 76302, U.S.A.
E-Mail:4 - Operation
Operation of the instrument is simple. First the acoustic wellhead should be attached to the casing annulus valve,
and the cable connected between the microphone and the instrument. The valve between the casing annulus and the
flow line should be closed to prevent the casing annulus gas from venting into the flow line causing excessive
noise.
General Recording Procedure
When the power switch is turned on, a red LED light indicates that the battery is powering the electronics. The
chart drive turns on and a header is printed as shown in Figure 3 in the appendix. Next, a system test is performed
which also displays the battery voltage. If the battery voltage is low, a message to charge the battery is displayed.
Then, the message is printed to "Turn on the chart drive to test well" and the chart drive stops until the chart drive
switch is turned to the ON position. At this point the operator selects the type of collar response (filter) desired.
Sharp upper collars can be selected for special applications such as shallow wells, irregular tubing length, dual
tubing strings and other special applications. The lower collar position is selected for most deep wells especially
with low casing pressure. Normally, both gain controls are set to the AUTO position and only changes from these
settings are necessary for those cases when satisfactory recordings are not obtained in the automatic position. When
the chart drive is activated, the form shown in Figure 4 is printed on the strip chart. This form is designed to insure
that the operator will write all the pertinent information about the well and the test. This includes the well
designation, the casing pressure, the casing pressure buildup rate and the latest well production test results. The
universal coordinated time stamp is beneficial for tracking the sequence of shots and calculating the exact time
interval between shots. The time interval is necessary when calculating rate of change in liquid level from which
can be computed the well influx (or injectivity) rates or to compute pressure buildup rates. Next, the acoustic
analysis form is printed on the strip chart. During the time that the forms are being recorded on the strip chart, the
instrument measures the background noise on both channels and then analyzes the noise in terms of peak to peak
amplitude and records the AUTO position when the chart drive is turned on, later adjustment of the gain control
does not affect amplifier gain. Then, a message to generate the pulse is printed on the strip chart. When the shot is
generated, the instrument detects the large signal and prints a vertical dotted line to mark zero time on the chart.
Each second thereafter another mark is recorded and labeled with the corresponding elapsed time in seconds. If
the “shot” is not detected by the electronics (which is indicated by the zero time mark), a larger pulse must be
generated so that the electronics will detect the initial pulse. After the zero time mark is printed on the chart,
operator adjustments of the gain control do not affect amplifier gain. This prevents the operator from increasing
the gain, which might result in noise being mistaken for a liquid level kick. The operator turns off the chart drive
after the liquid level response and other desired information is observed on the chart. The acoustic liquid level test
can be repeated by reloading the gas chamber, turning on the chart drive, and generating another acoustic pulse. If
the operator desires to manually select the amplifier gain, the gain control knob must be set at a value greater than
one before the chart drive is turned on. The collar channel gain should be set so that the response is approximately
1/8 inch (3 mm) before the shot. The liquid level channel gain should be set so that the response is 1/16 inch (1
mm) before the shot. Operator adjustment of the gain control after the “shot” is detected and the zero time mark is
recorded does not affect amplifier gain. If the recording level is excessive from downhole anomalies such as a
tubing anchor or perforations, a lower gain setting should be used. Both channels may be set in AUTO gain setting
mode or both in manual gain mode or one channel may operate in manual while the other is set to AUTO. Figure 5
shows two records. The upper record is with the filter setting on upper collars and the lower record shows the
response when the filter setting is lower collars.