PRACTICAL FIELD METHODS FOR TRANSDUCER INSTALLATION DURING WINTER DRILLING OPERATIONS
Multi-year project involved drilling and testing of ground water wells that had to be performed during winter when ice roads allowed mobilization of drilling and pumping rigs over muskeg in northern Alberta. Installing pressure transducers in observation wells in extreme (up to -52°C) winter conditions in a simple, repeatable manner is key to maintaining the integrity of data collection. Operating in these conditions poses a variety of safety and technical concerns. As many different personnel from widely varying backgrounds converged on this site to perform the work, initially a variety of methods were used to install and secure transducers in observation and pumping wells, which yielded inconsistent results, and often led to damage of cables in the extreme cold, as well as premature battery drainage in laptop or handheld PC.
The Solution:
For this project, InSitu® LevelTroll 500®non-vented pressure transducers were used, connected to non-vented direct-read cables. Non-vented cables were selected due to the possible introduction of water vapour into the vent line which would freeze when exposed to ambient conditions. Installation depths were critical, as 10.9-meter range transducers were used limiting the amount of head change that could be experienced during the testing and recovery periods. In pumping wells, and in some observation wells, 60.1-meter range transducers were installed.
The critical part of the process involved performing as much of the preliminary setup as possible in a climate controlled-area, minimizing exposure of personnel and sensitive equipment to the extreme temperatures. A number of techniques were field proven to deal with the extreme weather conditions, and were then exercised as a standard approach on this project.
The Result:
This project provided empirical evidence that the low end of the manufacturer rating for operating temperature of the transducer, cabling, and handheld and laptop PC instrument (published as between -30°C and -20°C) could be extended, provided the length of exposure to extreme cold was limited. Data were repeatable, installations were uniform, and cable damage was minimized.