Echometer Company
Model – M Manual
Phone: (940) 767-4334
5001 Ditto Lane
Page
11
Fax: (940) 723-7507
Wichita Falls, Texas 76302, U.S.A.
E-Mail:Remote Fire Gas Gun
The remotely fired gas gun generates an acoustic pulse and detects the downhole reflections. The gas gun contains
a volume chamber, which is filled with compressed gas to deliver the acoustic pulse to the well. A microphone
housed in the gas gun detects the shot, collars and other wellbore reflections, and liquid level. The standard unit
has a working pressure of 1500 PSI.
Gas Valve and Solenoid
The solenoid serves as a trigger mechanism to initiate the acoustic pulse. When energized, the solenoid lifts a small
plunger and allows gas pressure to bleed off the top of the gas valve. Gas pressure then forces the gas valve open, causing
an acoustic pulse to be delivered to the well as the gas flows from the volume chamber into the well, (see the remote fire
gun diagram.) The gas valve does not hold pressure from the well. Therefore, gas pressure must be applied to the volume
chamber inlet port in order to close it. Whenever the valve is left open, well fluids will flow backwards through the gun
and into the volume chamber. This flow may entrain sand and other debris. These deposits may prevent the gas gun from
operating properly. To minimize this potential problem, it is advisable to charge the volume chamber with clean gas
before the casing valve is opened and as soon as the strip chart from any shot has been recorded. This will prevent the
well fluids and debris from entering the solenoid gas valve mechanism and causing a malfunction of the firing mechanism.
Volume Chamber Pressure Gauge
The volume chamber pressure gauge measures the pressure in the gas gun volume chamber. It should be used to
determine if the chamber pressure is sufficiently high (explosion mode) to generate the acoustic pulse. The volume
chamber pressure should be approximately 100-psi in excess of casing pressure unless additional pressure is required to
obtain desire results.