How is pumping and sampling performed in multiple aquifers

Groundwater refers to the various forms of gravity water buried below the surface, so how does it exist underground? The answer is one layer on top of another, each layer, in the jargon, an aquifer, separated by a water barrier, as shown in Figure 1. The surface geology of the top layer of aquifer is generally quaternary stratum, which is mainly composed of loose gravel and clay material of different grain levels, and is a good place to store groundwater. The quaternary strata with groundwater are generally referred to as quaternary aquifers. Quaternary aquifer is closely related to soil, ecological tree planting and human activities, and is the key aquifer to maintain the function of the earth's ecosystem and human survival. Since the quaternary loose aquifer is composed of multiple aquifers and aquifer layers interpenetrating and superimposed, the water quality and quantity of groundwater at different depths are different, so it is necessary to know the water quality and quantity information of different aquifers by pumping test, sampling and laboratory testing.

According to the traditional stratified pumping and sampling test method, aquifers of different depths are usually drilled in the same borehole into different bore sections, and the water sealing pipe is divided into steps for water sealing treatment. In this case, the same borehole can only do 2-3 layers pumping test, and the operation is difficult, the cost of reaming is high, the water sealing effect is poor, and it is difficult to obtain accurate water quality and water quantity information of different aquifers.

By using the embolic stratified sampling system, it can realize the stratified pumping and sampling of the aquifer at any depth in the same bore hole.

The embolization system is mainly composed of inflation system, pumping system and pressure sensing system. Before sampling, the two emboli of the system are first placed in the upper and lower part of the sampling interval in the drilling hole, and then the two emboli are filled with high-pressure nitrogen, so that the two expanded emboli are in close contact with the well wall to produce water sealing effect. After the borehole is divided into three sections by two expanding emboli, the water level of the borehole can be measured separately by using a self-recording water level meter. The pump can pump the groundwater between the two emboli to the surface for hydrochemical parameter determination and sample collection (see Figure 2). The embolic stratified sampling system is used to collect and test the groundwater quality and quantity of aquifers at specific depth and level.

In short, the embolization stratified sampling technology can realize the same diameter water stop, stratified sealing, well washing, sampling and pumping test in the fourth series loose rock aquifer drilling, overcoming the difficulties faced by the traditional drilling pumping test method, and has the advantages of simplification, safety, efficiency and convenience in the implementation process. The hydrogeological parameters of different aquifers can be obtained more accurately and effectively, which has important guiding significance for drilling sampling and pumping test of quaternary loose rock strata.