Echometer Company
Model – H Manual
Phone: (940) 767-4334
5001 Ditto Lane
Page 69
Fax: (940) 723-7507
Wichita Falls, Texas 76302, U.S.A.
E-Mail:
The program is designed to be easy to use and require a minimum of data. The user should remember,
however, that the results from computer calculations are only as good as the data that is entered. Thus, make
sure that the data input is accurate or the results will be meaningless.
Fluid Level Acquisition in Problem Wells
Obtaining a good record is made more difficult by excessive surface vibrations, excessive down-hole noise from
gaseous liquid columns, improper wellhead connections, dirty microphone and electrical connections, or low
casing pressure.
Excessive surface vibrations and downhole noise should be reduced as much as possible.
Any well venting gas to the atmosphere, venting gas to the flow line or using casing gas to operate an engine,
will have a gaseous liquid column if liquid exists above the pump or formation. The amount of liquid present in a
gaseous liquid column can be determined by a casing pressure build-up test. Another technique is compression
of the gaseous column with casing pressure to determine the gaseous column gradient. Additional information is
presented in the papers "Producing Bottom Hole Pressures" and "Acoustic Foam Depression" in the appendix.
Gaseous columns caused by gas bubbling through oil cause excessive down-hole noise and can be a problem in
obtaining clear records of deep collars and liquid levels. Increasing the casing pressure by closing the flow line-
casing valve will generally result in much improved signals. The pressure in the gas gun volume chamber may
have to be increased to the maximum so as to increase the signal to noise ratio.
Whenever there are doubts that the correct liquid level signal has been identified the best way to differentiate it
from other signals (such as signals from liners, paraffin rings, or liquid influx from perforations) is to cause the
liquid level to move. The liquid level signal is the only signal that can move in a well and such movement
identifies the liquid level. A high fluid level can be depressed by increasing the casing pressure. An increase of
10-psi in the casing pressure will depress a gas-free liquid level by approximately 30 feet. The liquid level will rise
when a producing well is shut down. The rate of fill-up will vary with the productivity of the well and the annular
volume. A Rate of Fill-up chart is presented in the appendix and may be used to estimate the amount of time
required for liquid level rise. Note also that this chart may be used to estimate the production rate from a well by
shutting in the well and measuring the change in fluid level as a function of time, then using the chart to estimate
the production rate.
If a record shows numerous "kicks" which are difficult to interpret, the shot should be repeated and the new chart
compared with the first recording. All "kicks" should be duplicated on each record. Signals that are not duplicated
correspond to stray noises and other random signals. The source of these noises should be identified so as to
eliminate them as described above.
The effect of casing pressure on signal quality is very important. Stronger signals are returned in high-pressure
wells. It is especially difficult to obtain good recordings in deep wells with the casing pressure near or below
atmospheric pressure.
On rare occasions, paraffin deposits, scaling, dirty tubing or other conditions can result in additional down-hole
signals, which make it difficult to count collars or to determine the fluid level depth. In extreme cases it may be
necessary to clean the tubing and casing to remove the foreign material.