What Is a Tube Well?

A well with a small diameter and a large depth, and a water intake building that draws deep or shallow groundwater. Pipe wells that are driven into confined aquifers are also called artesian wells when the head is above the ground. ^[1]

Tube wells are tubular structures that are vertically placed underground to take water or protect groundwater. It is a water supply and drainage facility for industrial and agricultural production, urban, transportation, and national defense construction.

Chinese name: Tube well
Foreign name: tube well

Structure: Wellbore pipe and filter are connected to form a string
Use: Industrial and agricultural production, urban and national defense construction

Tube well tube well type

Uses are divided into water supply wells, drainage wells, and recharge wells. According to the type of groundwater, it is divided into pressure wells (pressure wells) and pressureless wells (submersible wells). Artesian wells are known as pressure wells where groundwater can automatically eject from the surface. According to whether the well penetrates the aquifer, it is divided into complete well and incomplete well.

Tube well tube well structure

The well consists of a wellhead, a well wall pipe, a water filter pipe and a settling pipe (as shown in the overview picture). The periphery of the wellhead of the tube well is closed with an impervious material, crushed stone is laid around the wellhead of the artesian well and concrete is poured. The shaft wall can be made of steel pipe, cast iron pipe, reinforced concrete pipe or plastic pipe. Steel pipes are suitable for a wide range of well depths; cast iron pipes are generally suitable for well depths up to 250 meters; reinforced concrete pipes are generally used for well depths of 200 to 300 meters; plastic pipes can be used for well depths of more than 200 meters. ^{[1] The} well wall pipe and the filter are connected into a string and installed vertically in the well. The well wall pipe is installed at the non-aquifer, and the filter is installed at the water production section of the aquifer (see picture). Fill the aquifer section in the annular gap between the pipe string and the hole wall with screened gravel, and fill the non-aqueous section above the gravel or the planned aquifer section with waterstops such as clay, clay balls, or cement.

Tube well tube well design

Including well depth, opening and final hole diameter, types and specifications of well pipes and filters, installation location and water stop

Tube well , Closing wells, etc. The depth of the well depends on the burial depth of the aquifer and the requirements of the pumping equipment used. The diameters of the openings and final holes are determined according to the diameter of the well pipe where the pumping equipment is installed, the diameter of the filter installed and the thickness of the artificial filler. The types and specifications of well pipes and filters, the location of installation, the length of the sedimentation pipe and the type of the bottom of the well are mainly determined according to the local hydrogeological conditions, and according to the designed water output and water quality requirements. The diameter of the well pipe must be determined according to the type and specifications of the pumping equipment selected. Commonly used well pipes include seamless steel pipes, steel plate coil welded pipes, cast iron pipes, asbestos cement pipes, polyvinyl chloride, polypropylene plastic pipes, cement pipes, glass steel pipes, etc. Water stop and well closure depend on the water quality requirements, the location of the bad water source and the possibility of penetration and pollution. The design shall stipulate the location and method of water stop and well closure, and the quality of the materials used.

Quaternary loose-layer water intake wells are designed for high-pressure aquifers, water intakes above coarse sand, and some extremely fractured bedrock water wells. Wire wound filters or wire mesh filters can be used. Medium sand, fine sand, and silt layers can be wrapped with metal or non-metal tubular framework wrapped with metal or non-metal wires, and wrapped with gravel wrapped filter to prevent fine particles from flowing into the aquifer In the well, to ensure the service life of the well, it can also increase the porosity and water permeability around the filter, thereby reducing head loss during water inflow and increasing the water output of a single well. The thickness of gravel is determined according to the particle size of the aquifer, and is generally 75 to 150 mm. The length of the sedimentation tube is generally 2-10 meters, and its lower end should be installed at the bottom of the well.

In the design of the water pipe well in the bedrock, if all the rock formations are hard and stable rocks, it is not necessary to install a well pipe, and the hole wall is used as the well pipe. When the upper part is a cover layer or broken unstable rock, and the lower part also has broken unstable rock, a well pipe should be installed from the orifice until the rock is stabilized. Where there are broken zones, cracks, karst caves, etc. in the aquifer, wire wrap, net filter or round or strip filter should be installed according to the broken condition of the aquifer.

Tube well tube well construction

Including drilling, well pipe installation, gravel packing, water sealing and well washing, etc.

Tube well drilling method

Common drilling methods include percussion drilling, rotary drilling, and percussion rotary drilling (see Hydrogeological Drilling).

Tube well well pipe installation

Different installation methods are adopted according to different well pipes and drilling equipment. The main ones are: wire rope suspension down pipe method. Applicable to steel pipes with iron buckles, cast iron pipes, and glass steel pipes, polypropylene pipes and asbestos cement pipes with special joints, wire-free welded steel pipes with drawn plates, boltless non-wire-cast iron pipes, bonded glass steel pipes , Welded rigid PVC pipe. Floating plate down tube method. It is suitable for steel pipes whose total weight exceeds the load of the rig lifting equipment or cast iron well pipes with thread buckles that exceed the tensile force that the well pipe can bear. Tray down tube method. Suitable for cement well pipes, gravel cement filters and large diameter cast iron well pipes with riveted weld heads.

Gravel filling

Gravel filling methods are: still water filling method, suitable for shallow wells and stable aquifers; circulating water gravel filling method, suitable for deeper wells; pumping gravel filling method, suitable for deep wells with stable hole walls.

Water well sealing

According to the requirements of the water quality of the pipe well, the water stop and well closure shall be carried out. The position shall be selected as far as possible with good water insulation and regular well wall. Water supply wells shall be permanently stopped and sealed, and the effectiveness of water stopping and closing shall be guaranteed. The materials used shall not affect the water quality. The permanent water-stopping and well-sealing methods include: clay and clay ball filling method, and pressure grouting method. The materials used are clay, clay balls and cement.

Tube well washing

In order to remove the mud in the well, destroy the mud wall formed during the drilling process, extract the mud in the aquifer near the well wall, excessively fine particles and the fillings in the aquifer of the bedrock, so that a good water filter layer is formed around the filter. To increase the water output of the well. Common well-washing methods include: piston well-washing method, compressed air well-washing method, puncher well-washing method, mud pump and piston combined well-washing method, liquid carbon dioxide well-washing method, and chemical well-washing method. These well-washing methods are used in different hydrogeological conditions and different types of tube wells, and the well-washing effects are not the same. They should be selected according to local conditions.

Tube well maintenance

It is directly related to the service life of the well. Improper use and maintenance will reduce the water output of the tube well, deteriorate the water quality, and even cause the well to be scrapped. During the use period of the well, the pumping equipment of the well shall be properly selected according to the pumping test data. The maximum water output of the selected water pump cannot exceed the maximum allowable water output of the well. During the production period of pipe wells, it is necessary to ensure that the water is clear and free of sand; for wells containing sand, the water output shall be appropriately reduced. During the production period, a file for the use of pipe wells should also be established to carefully record changes in water output, water level, water temperature, water quality, and sand content during use, so that inspection and maintenance can be performed at any time. If you notice a sudden decrease in water output, an increase in gushing sand, or a deterioration in water quality, you should stop production immediately, carry out detailed inspection and repair, and then continue to use it. Generally, the depth of the well is measured once a year, and it is performed at the same time as the maintenance of the pump. If silt at the bottom of the well is found, it should be cleaned. Seasonal water supply wells can easily cause filter clogging and reduce water output. Therefore, during periods of inactivity, water should be pumped regularly to avoid clogging the filters.