Welltest 103: Acoustic Well Sounder Surveys

Factory setting paper chart speed for an Echometer™ model D #AWS is 9.2075 cm/s. This can change with age, environment, level of use, and battery charge. Don’t pull on the chart as it comes off the machine. Some models place a tick mark every second, Sage™ machines mark charts every ¼ second. If you don’t have marked charts, verify your chart speed near a reliable electrical source (i.e. in the office, not out on a lease). Stick something metal (pen knife or paper clip) into the microphone input port, turn on the machine, and run it for over one  second, before turning off. Note the regular cycle of the pen trace (60 Hz in North America). Count off 60 spikes, that’s exactly one second, measure the length with a ruler (cm), that’s the chart speed (cm/s).

Depending on wellbore configuration and where the liquid level is, one may observe kicks besides tubing collars and fluid level. Some of these kicks have the potential to be misinterpreted as the liquid level. Please review the examples in appendix 1 for different scenarios.

To be sure your interpretation is correct, run the chart or computer at least twice as long as it takes to observe the liquid level. In other words, run the chart until the impulse hits surface again. The paper chart can then be folded in half to verify your reading (on a computer a doubling of the travel time can be confirmed).