Talking about the Application of Pump Air Compressor Combined Washing Well in Old Well Repair Ding Dangpeng, You Feng (Shaanxi Nuclear Industry Geological Survey Institute, Xi'an 710054, China) After washing the well in a water source in Guanzhong Plain, after continuous exploration, In contrast, a new method of combined pumping air compressor combined with well washing is proposed, which is suitable for deep well washing in the water source, and has created good social and economic benefits. Old well repair; air compressor water pump combined washing; engineering application In recent years, with the rise of modern industry, the demand for water resources is growing. However, there is a shortage of water resources in northern China, and many companies use tube wells to extract groundwater. The life of a tube well is 20 years. Due to water shortages, most wells over 20 years are still in use after repeated repairs. Therefore, the repair of old wells is particularly important. Through engineering practice, for the deep well of 150 ~ 300m, by analyzing its plugging mechanism, selecting the best well washing process, the purpose of restoring the water output of the tube well and prolonging the service life of the tube well is achieved. 1 Water supply source water supply pipe water supply status The water source is located in the middle of the Guanzhong Plain, distributed along the river bank in the east-west direction, about 11.5km from east to west, about 2.7km wide from north to south, with an area of ​​about 25km2 and a water intake of less than 300m. A total of 60 water supply wells were distributed in the water source, which were put into trial operation in 1991 and 1995 respectively. Due to many factors such as geological structure, hydrogeological conditions and water chemistry characteristics, the pipe wells have been blocked by the filter pipe during the long-term use, and the water output is reduced; the water filter network is broken, the sand in the well is leaking; the well pipe is inclined, the well is well Collapse and other phenomena. Among them, the filter water pipe is seriously blocked, and the sharp drop of water output has become a widespread problem. The unit water inflow is generally attenuated to 30%~40% of the original well, and the individual pipe wells are only 5% of the original wells, resulting in a decline in the water supply capacity of the water source. . For tube wells with a depth of less than 150m, three joint washing wells, such as sulfamic acid washing, capsule closed washing and air compressor washing, can be used to improve the water output of the tube well. For the tube wells with a well depth of 150~300m, the liquid-carbon carbon dioxide closed well washing and the air compressor washing effect is not obvious. Therefore, how to improve the water output of wells with a depth of 150~300m is of great significance for solving the problem of water shortage. 2 Analysis of the cause of the blockage The pipe wells of the water source are mostly distributed in the Quaternary alluvial, alluvial and floodplain loose layers. The lithology of the aquifer is mainly gravel, coarse sand, medium sand, fine sand, silt, and partially sandy. Silt, the structure is loose, the thickness is not the same; the lithology of the water-repellent layer is clay, silty clay or silt, silt, etc., interbedded with the aquifer, the layer is unstable, and sometimes the lens body. Through the on-site well washing of multi-eye deep wells, when the pipe well is used for a long time and large amount of water is mined, as the water flow rate increases, the fine particles with poor stability in the aquifer flow to the well wall, and often accumulate and precipitate calcium deposits. Together, the formation of silt clumps affects the water output of the tube wells; due to the replenishment of river water, the groundwater in the tube wells is rich in dissolved, causing strong corrosion to the tube wells, which deepens with time and gradually becomes continuous One piece, severely blocking the water filter. 3 Water pump air compressor combined well washing process test For the above situation, for wells with a depth of 150 ~ 300m, the effect of sulfamic acid washing, liquid carbon dioxide closed washing, capsule closed washing and air washing is not ideal. Under the circumstances, the pump air compressor washing method is designed. This method belongs to a kind of mechanical washing. The equipment used is not much different from other mechanical washing methods, mainly water pump and air compressor. The pump air compressor washing method is basically the same as the air compressor capsule washing. The set of well washing test is to use the huge water pressure generated when pumping water, and the water flow is pressed into the aquifer through the capsule, impacting the aquifer and destroying the blockage, so that the various scales between the pores are completely removed; Fine sand particles that have been pumped and accumulated around the screen are also washed out in large quantities, allowing groundwater to flow in quickly. Combined with the segmental layered flushing action of the air compressor washing well, the purpose of dredging the inside and outside of the tube well is achieved. The construction process steps are: sulfamic acid immersion, a water pump cleaning, and an air compressor pumping. 4 Engineering application of water pump air compressor washing is a new method used in the past two years, and has been applied in the water source well washing project. The 14C2 and 22C water supply pipe wells of the water source cannot continue to operate due to the decrease of the water output. Party A requires the unit to recover the water inflow: *m. By using this method to wash the well, the 4C2 unit water inflow is 2.88L/s*m; 22C unit The water inflow is 3.8L/sm (see Table 1), and both wells meet the well washing requirements. At the same time, after adopting this method, the construction period is also earlier than other mechanical methods and chemical methods. Table 1 Well washing results Statistics table Well number Wells Year (year) Well Deep well diameter Water-bearing rock layer Before the well washing unit Unit water influx After the unit water inflow In the fine sand, the coarse sand 5 knot ~ 300m deep well adopts the pump air compressor combined washing method, which has obvious advantages in terms of effect and efficiency compared with other mechanical methods and chemical methods. At the same time, it also created and received good social and economic benefits, and found a set of effective construction methods for the repair of the old wells in the water source. The wafer Check Valve with double discs is light with a small body, but a kind of check valve that quickly develops, which functions to preventing media in pipes from back flowing. Check valve belongs to the category of automatic valves, mainly used on those pipes in which media flow unidirectional and to control the media to flow only one-way so as to prevent accident. 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