Sage Technologies logo

Sage Technologies, Inc.
 (817) 488-2579
toll-free in U.S. (877) 488-2579

Acoustic Fluid Logger III

The Acoustic Fluid Logger III is straightforward and simple to use.

No computer is required for the AFL III, making it a good option for situations where weather, location or personnel situations make computer use difficult. It records fluid levels with the one self-contained logger that prints the fluid levels and collars on paper tape for easy calculation.Acoustic Fluid Logger III printing fluid level tape

Special features of the AFL III:

  • Microprocessor based multichannel recorder
  • Automatic gain control
  • Analog to digital converter, thermal printer, embedded signal acquisition software
  • Internal filter network reduces unwanted noise and highlights collar and fluid signals
  • Precision one-second timing marks displayed on tape
  • Compressed mode shortens tapes to up to one-eighth original size, keeps one-second timing marks, and makes tapes easier to handle in the field, while offering a condensed view of events inside the wellbore
  • Tape reprint allows multiple copies of the same tape
  • Extremely rugged and reliable

AFL III fluid level tapeThe Acoustic Fluid Logger III identifies the distance to the liquid level in the casing annulus of a well. It works by using the Pressure Pulse Gas Gun -- 1,500 or 3,000 psi -- to send a compressed gas pulse down the annulus of the well. The microphone inside the gas gun registers the returning echoes from the collars and the fluid. A microphone cable delivers the signal to the Acoustic Fluid Logger III. A microprocessor uses the analog to digital converter to gather all reflections from the collars and the fluid, and then plots them on thermal paper tape.

Each time the operator shoots a fluid level, the Acoustic Fluid Logger III automatically gathers the echo with seven different gain settings. During the fluid level test, this allows you to print up to seven fluid level tapes with different amplifications of the fluid level signal, without reshooting the gas gun. The signal amplification that occurs with the multichannel filter operation increases your ability to pinpoint the fluid level even more when combined with the compressed mode feature, which produces a shorter tape with a compressed signal for easy visual recognition of the fluid level.

Compressed AFL III tape

This compressed mode feature is unique to the Acoustic Fluid Logger III. Compressed mode allows you to shorten the fluid level tape to 1/2, 1/4, or even 1/8 the original size, still overlaid with the 1-second timing marks. The shorter tape conserves paper, prints a condensed view of the fluid level, and makes fluid level determination quicker and easier. When testing the same wells over time, compressed mode allows a quick check for a change in the fluid depth. (Notice on the tape above that the header portion of the tape offers you a place to record well information and also shows you the voltage currently on your AFL III battery.)

How does the AFL III work?

During a fluid level test, the Pressure Pulse Gas Gun delivers a shot of compressed gas down the annulus of the oil or gas well. Echoing reflections return from the collars and tubing to the gas gun, and register as vibrations on the internal microphone. Those echoes are gathered by the fluid logger unit, processed and amplified to reduce noise, and then printed to a paper tape.

On the paper tape chart, a single printed echo shows collars and fluid inside the wellbore. The AFL III recorder registers any narrowing of the annular area by kicking down for liner tops, wellbore obstruction and liquid level. The recorder displays kicks in the opposite direction (upkick) for enlargement of the annulus, such as open hole sections and perforations. The echo is overlaid with one-second timing marks, which help in calculating the distance to the fluid in hard-to-determine wells.

Counting the timing marks to find the fluid level

Mark AFL III tape from start with Acoustic Fluid Logger IIIMarked fluid level on AFL III tapeA simple count of tubing collars between the gas shot and the fluid level kick determines the distance to the fluid. Eleven-point dividers are included with the system to aid in fluid level calculation. Starting from the point where the fluid level shot is taken, the dividers are expanded to the point where each tip of the divider roughly meets a peak (well collar) on the echo trace. The collars can then be marked and counted quickly by tens, and then counted individually to the exact fluid level. Multiplying the collar count by the known joint length in the well determines the distance to the fluid.

The tape below shows an actual fluid level test. To find the fluid level, eleven-point dividers are used to count the collars from the start of the shot -- the first kick up on the graph -- to the fluid level -- the last point before the first big kick down on the tape.

The dividers are used to quickly count the collars in sets of ten, then the collars are counted individually to the fluid level. The total collar count is then multiplied by the average joint length in the well, and that determines the distance to the fluid.

Counting the collars to the fluid on AFL III tape

Fluid level amplification examples

Assume there is an echo in memory. You are at the well, have taken a gas shot on the well, and now can adjust the printout of the tape. The seven amplifications are akin to looking at the fluid level through a series of magnifying glasses of increasing power, and you may pick the amplification you prefer for clarity on each well.

Once you have determined the proper tape for a well, you can specify that tape using the keypad, so that it will be the first tape printed.

 Following are three example amplifications of fluid levels:

Command - Print. This is the default plot for the AFL III. This plot of the fluid level uses the square root of the largest amplitude of the signal.Square root of amplitude plot on AFL III

Command - 1 Print. This is the minimum amplification of the signal.Command - 1 Print for AFL III Fluid level

Command - 6 Print. This is the maximum amplification of the signal.Command 6 amplification of the AFL III fluid level shot

How do you set up the AFL III on a well?

Pressure Pulse Gas GunSet-up of the AFL III is quick and easy. Simply screw the Pressure Pulse Gas Gun to the wellhead with the included spanner wrench. Pressure up the gun with a quick stab-in connection of the gas charge hose. Connect the gun to the Acoustic Fluid Logger III; turn on the instrument. Compress the tape, if desired, by entering simple key commands before the shot: 4 C Start will print an echo 1/4 the normal tape length. Push the gun's load fire shuttle valve. The gun will fire, and the fluid logger will quickly print out the fluid level tape. Starting a fluid level test with the Acoustic Fluid Logger III

The power behind the gas gun is compressed CO². Our system includes a 2.5 lb. aluminum bottle, shipped empty with the system. This size of cylinder is easily transported, and can hold about 200 shots of carbon dioxide gas, depending on well depth. In cold weather conditions, compressed nitrogen gas is preferable; nitrogen adapters are available for the charge hose and gas guns.


Thermal paper is available from Sage Technologies, with quantity discounts. The special uncoated thermal paper allows optimum use of the AFL III integral printer, which never requires ink. Coatings and plastics contained on alternate papers may damage the printhead, so only paper from Sage Technologies is recommended. 

Compressed gas (CO²) for the bottle can be found from industrial gas suppliers. Simply look for a local oilfield, industrial, medical or beverage gas supplier. The 2.5 lb. bottle should be weighed empty, then filled with 2.5 lbs. of compressed gas.

See the Supplies tab for more parts and accessories for the Acoustic Fluid Logger III.


Go to the Downloads section of click here for a .pdf of the operator's manual: Acoustic Fluid Logger III Manual

Click for a .pdf of the brochure: Acoustic Fluid Logger III Brochure

AFL III system components:AFL III components

Included with AFL III system:

  • Acoustic Fluid Logger III
  • Pressure Pulse Gas Gun rated 1,500 or 3,000 psi
  • 200 psi gauge with quick connect
  • CO2 bottle
  • CO2 charge hose
  • CO2 refill adapter
  • 25-ft. microphone cable
  • 10 rolls thermal paper
  • Wellhead connection tools
  • O-ring kit and maintenance tools
  • Carrying case
  • Operator's manual

Options and accessories (see Supplies tab):