Echometer Company
Model – M Manual
Phone: (940) 767-4334
5001 Ditto Lane
Page
35
Fax: (940) 723-7507
Wichita Falls, Texas 76302, U.S.A.
E-Mail:ACOUSTIC RESPONSES FROM DOWNHOLE ANOMALIES
Following are examples of the responses obtained from restrictions such as the liquid level and from
enlargements such as perforations. The initial pulse generated by the gun is a compression (explosion)
pulse; that is, the pressure in the gas gun volume chamber is in excess of well pressure. If the initial
pulse were a rarefaction (implosion) pulse, the responses would be reversed.
COMPRESSION RESPONSE
(Downward kick)
The liquid level, liners, gas mandrels and other anomalies causing a reduction in casing annulus
area will cause a reflected signal back to the surface that will be of the same type as the initial
pulse, which was a compression wave. The direction of the initial pulse is downward when the
top of the chart is to the operator’s left.
RAREFRACTION RESPONSE
(Upward kick)
Perforations, “shot” holes, a reduction in tubing size and other anomalies causing an increase in
casing annulus area will cause a reflected signal back to the surface that will be of the opposite
polarity as the initial pulse. Thus, the response from these anomalies will be upward when the
top of the chart is to the operator’s left.