An analysis of the automatic water level monitors data at different positions in a pumping test

Abstract

In a pumping test, recording and analysis of the dynamic water level data are of great significance in the calculation of hydrogeological parameters. In recent years, automatic water level monitors have been widely used in pumping tests, and the pressure head change value of the pressure sensor is regarded as the drawdown of water level. Due to the water flowing in the well pipe can cause head loss, the automatic water level monitors at different positions can also obtain different drawdowns of water level, which are different from the drawdown of well water surface level measured by the traditional method and also has some influence on the calculation of hydrogeological parameters. Therefore, it is urgent to carry out experimental researches on how to place automatic water level monitors reasonably and how to apply the drawdown data from the automatic water level monitors in hydrogeological parameter calculation. In the large thickness aquifer area of Quaternary system in the Heihe River Basin, a typical single-layer test hole and a multi-layer test hole are selected for experimental studies, in which the multi-layer hole is a pumping test hole with the same diameter layered by the Parker technology. Under the dynamic water level, automatic water level monitors are placed in the upper, middle and lower parts of the pumping test section and the upper and lower parts of the pump for systematic data collection and analysis. The results show that in the pumping test, water flowing in the well pipe can cause head loss and velocity head difference, so the pressure head change value obtained by the automatic water level monitors at different positions are different. The well loss values at different parts of the wellbore are measured in this test. At the inlet of the submersible pump the well loss value is the largest, and decreases with the increasing distance from the submersible pump. To avoid the influence of bigger well loss on parameter calculation, the automatic water level monitors are preferably placed in the upper part of the pump close to the dynamic water level. When the steady flow formula is used to calculate the hydrogeological parameters in the single hole pumping test, the drawdown of the automatic water level monitor contains well loss, which cannot be ignored and needs to be deducted by the multiple drawdown pumping tests data. Moreover, the data analysis of the automatic water level monitors at different positions can provide a basis for better understanding the head loss in the well.

Keywords

• drawdown of automatic water level monitor
• drawdown in pumping well
• aquifer level fall
• hydrogeological parameters