Well-forming and sampling method for one-hole double-layer underground water environment monitoring well

Abstract

The invention discloses a one-hole double-layer underground water environment monitoring well completion and sampling method. The method comprises the following steps: S1, drilling to form a well; s2, assembling a well casing; s3, well descending construction is carried out; s4, lifting and waiting for coagulation; s5, pumping water from the upper part and sampling; s6, pumping water from the lower part and sampling; and S7, lifting and resetting. When the well casing module of the monitoring well descends, the temporary outer pipe, the water stopping tray and the well casing module are combined into a whole to descend, well cementation cement paste is injected in advance, the cement paste is prevented from penetrating through a holed pipe to flow into a water-bearing stratum in the well entering process to cause blockage, the layered packing water stopping quality is improved, and the upper water-bearing stratum and the lower water-bearing stratum are prevented from being communicated; the water isolation device is additionally arranged in the well casing module to dynamically isolate the two aquifers, and two functions can be achieved through cooperation of the water pumping device and the water isolation device, one function is that the upper aquifer is independently pumped when the lower aquifer is in a closed state, and the other function is that the lower aquifer can be opened and the upper aquifer can be synchronously closed. The purpose of independently extracting the upper aquifer or the lower aquifer is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of underground water environment drilling monitoring, in particular to a method for drilling and sampling underground water environment monitoring wells. Background Art

[0002] In groundwater environmental monitoring wells, in order to ensure that the collected water samples can represent the actual water quality of the aquifer, relevant specifications require the use of a submersible pump to extract water 3-5 times the volume of the wellbore before taking water samples. To ensure that the submersible pump can be lowered into the well to pump water, the borehole diameter is generally large, and the well pipe diameter generally needs to be no less than 100mm.

[0003] Traditional groundwater environmental monitoring wells monitor only one aquifer, or one well monitors the parameters of two or more mixed aquifers. To enable a single well to monitor multiple, unmixed aquifers, nested groundwater monitoring wells or clustered monitoring wells are commonly used. This involves running multiple sets of well pipes into a single well and sealing them off in separate layers. However, these monitoring wells have the following disadvantages: 1. It is impossible to lower a submersible pump to carry out water sampling. Due to the limitation of the borehole diameter, the well pipe is generally a small diameter PVC-U pipe of 50mm. Because the well pipe diameter is very small, if the water level in the well is very low, it is impossible to pump water outside the well. In this case, this type of monitoring well can only be sampled by lowering a Beyler pipe with a rope, which obviously does not meet the requirements of the technical specifications for groundwater environmental monitoring sampling. In order to meet the requirements of using a submersible pump to pump water and sample two or more aquifers, it is necessary to construct a separate monitoring well for each aquifer, or expand the borehole diameter to increase the diameter of the nested groundwater monitoring well pipe. In order to implement the submersible pump pumping method to monitor two aquifers, the conventional method of increasing the number of monitoring wells or expanding the borehole diameter and well pipe diameter is bound to increase the construction cost; 2. The well pipes of nested or clustered monitoring wells are composed of multiple pipes with a relatively complex structure. Clay balls and expanding waterstop rubber are mostly used to seal and stop water between each aquifer. The reliability of the waterstop effect is low, especially when the head pressure of the lower pressure aquifer is large. Under the action of pressure difference, the aquifer often breaks through, resulting in failure of stratified waterstopping. Summary of the Invention

[0004] The purpose of the present invention is to provide a double-layer groundwater environment monitoring well drilling and sampling method, which can realize separate pumping and sampling of two groundwater aquifers in the same environment monitoring well and avoid upward channeling of the lower aquifer.

[0005] To achieve the above-mentioned purpose, a method for drilling and sampling a double-layer groundwater environment monitoring well is provided, which comprises: S1. Drilling and well completion: Use the first drill bit to expose the upper aquifer, expose the impermeable rock layer at the bottom of the upper aquifer by 5-10m, then change the drill diameter and replace it with the second drill bit to continue drilling and expose the lower aquifer; S2. Well pipe assembly: Assemble the well pipe module and the water riser, slide a water stop tray and a temporary outer pipe onto the outside of the well pipe module, and inject cement slurry between the well pipe module and the temporary outer pipe. The well pipe module has both blind and eyed pipes, with the water riser located inside the blind pipe and the temporary outer pipe connected to the top of the water stop tray. S3. Construction of lowering the well: lower the well pipe module and the temporary outer pipe into the well, lower the water stop tray to the diameter change point in the well; continue to lower the well pipe module until it touches the bottom of the well, lower the eye pipe into the corresponding position of the upper and lower aquifers, and lower the water stop into the water-blocking rock layer between the upper and lower aquifers; S4, lifting and solidifying: the temporary outer pipe is separated from the water stop tray and lifted out of the well. After the cement slurry solidifies, a cement ring stone is formed between the well pipe module and the well wall; S5. Upper water sampling: lower the assembled pumping device into the well pipe module and stop it above the water stopper, and use the submersible pump in the pumping device to extract water samples above the water stopper; S6. Pumping water from the lower part for sampling: The pumping device is further moved downward, and the lower part of the pumping device pushes the water stopper to connect the lower part of the pumping device to the space below the water stopper. The hydraulic connection between the upper and lower aquifers is blocked by the pumping device, and the water sample below the water stopper is pumped out by the submersible pump in the pumping device; S7. Lift and reset: lift the pumping device upward and reset the water stop to block the hydraulic connection of the lower aquifer again.

[0006] According to the well construction and sampling method for a double-layer groundwater environment monitoring well, in S1, the first drill bit drills a hole with a diameter of 160 mm, and the second drill bit drills a hole with a diameter of 130 mm.

[0007] According to the well construction and sampling method of a double-layer groundwater environment monitoring well, the water stopper includes an outer body, a lower cone, a guide rod, a bottom plate and a spring member. The outer body has an upper cone groove, a first channel, a lower cone groove and a second channel from top to bottom. The upper cone groove is wide at the top and narrow at the bottom, and the lower cone groove and the lower cone are narrow at the top and wide at the bottom. The lower cone is arranged in the lower cone groove, the guide rod is arranged at the bottom of the lower cone, the bottom plate is arranged at the bottom of the outer body and is sleeved on the guide rod, and the bottom plate is provided with a first water outlet. The spring member is sleeved on the guide rod between the lower cone and the bottom plate. The pumping device includes a water tank, a pump pipe, a submersible pump, a cable, an upper cone and a top pipe. The top of the water tank is connected to the pump pipe. The submersible pump is arranged in the water tank and is connected to the pump pipe. The cable is passed through the top wall of the water tank and connected to the submersible pump. The upper cone is arranged at the bottom of the water tank and is wide at the top and narrow at the bottom. The top pipe is arranged at the bottom of the upper cone. The side wall of the top pipe is provided with a sieve hole, and the inner cavity of the top pipe extends upward to connect to the water tank.

[0008] According to the well drilling and sampling method for a double-layer groundwater environment monitoring well, in S5, when the water sample above the water separator is extracted by the submersible pump in the pumping device, the top pipe and the lower cone are arranged at intervals, and the lower cone fits in contact with the inner wall of the lower cone groove to block the hydraulic connection between the upper and lower aquifers.

[0009] According to the well construction and sampling method of a double-layer groundwater environment monitoring well, in S6, the pumping device continues to move downward, the lower part of the pumping device pushes the water stop to connect the lower part of the pumping device to the space below the water stop, and the hydraulic connection between the upper and lower aquifers is blocked by the pumping device: the lower cone of the water stop is pushed downward by the jacking pipe, the lower cone is disengaged from the abutment with the inner wall of the lower cone groove, the inner cavity of the jacking pipe is connected to the space below the water stop, and the upper cone fits and abuts the inner wall of the upper cone groove. The pumping device stops moving after the upper cone fits and abuts the inner wall of the upper cone groove to block the hydraulic connection between the upper and lower aquifers.

[0010] According to the well construction and sampling method for a double-layer groundwater environment monitoring well, in S2, a support ring is fixedly mounted on the outside of the well pipe module, and the support ring is wide at the top and narrow at the bottom; When the water-stop tray and the temporary outer pipe are slidably sleeved on the outer side of the well pipe module, the water-stop tray is located above the supporting ring.

[0011] According to the well construction and sampling method for a double-layer groundwater environment monitoring well, the water-stop tray is provided with a slot for inserting a temporary outer pipe.

[0012] Beneficial effects: When the well pipe module of the monitoring well is lowered into the well, the temporary outer pipe, water stop tray and well pipe module are combined and lowered as a whole. Cementing cement slurry is pre-injected into the annular space between the temporary outer pipe and the well pipe module. This changes the conventional consolidation method of injecting cement slurry from the surface pipe after the pipe is lowered. This prevents the cement slurry from flowing through the perforated pipe into the aquifer during the well entry process, causing blockage or contamination of the water stopper with cement slurry. This improves the quality of stratified isolation and water stopping, and prevents the upper and lower aquifers from communicating with each other. Using the same monitoring well pipe channel, a water stopper is added to the well pipe module to dynamically isolate the two aquifers. The cooperation of the pumping device and the water stopper can achieve two functions: one is to independently extract the upper aquifer while the lower aquifer is closed; the other is to open the lower aquifer and simultaneously close the upper aquifer to achieve the purpose of independently extracting the upper or lower aquifer. The submersible pump of the pumping device can be lowered into the well to pump water, preventing the water level in the well from being too low to be pumped out; it avoids the cost increase caused by constructing large-diameter nested / clustered monitoring wells or increasing the number of monitoring wells, ensures that groundwater collection work complies with regulatory requirements, and improves the authenticity and accuracy of aquifer water quality.

[0013] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 is a flow chart of the method of the present invention; Figure 2 Schematic diagram of underground well construction for groundwater environment monitoring; Figure 3 Schematic diagram of collecting water samples above the water separator for groundwater environmental monitoring wells; Figure 4 Schematic diagram of collecting water samples below the water separator for groundwater environmental monitoring wells; Figure 5 This is a cross-sectional view of the water separator and pumping device. DETAILED DESCRIPTION

[0015] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0016] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0017] Reference Figure 1-5 A method for drilling and sampling a double-layer groundwater environment monitoring well includes the following steps: S1. Drilling and well completion: Use the first drill bit to expose the upper aquifer, expose the impermeable rock layer at the bottom of the upper aquifer by 5-10m, then change the drill diameter and replace it with the second drill bit to continue drilling and expose the lower aquifer; S2. Well pipe assembly: Assemble the well pipe module and the water riser 20, slide the water stop tray 12 and the temporary outer pipe 121 onto the outside of the well pipe module, and inject cement slurry between the well pipe module and the temporary outer pipe 121. The well pipe module includes a blank pipe 111 and a perforated pipe 112, with the water riser 20 located inside the blank pipe 111 and the temporary outer pipe 121 connected to the top of the water stop tray 12. S3. Lowering the well pipe module and the temporary outer pipe 121 into the well, lowering the water stop tray 12 to the diameter change point in the well; continuing to lower the well pipe module until it touches the well bottom, lowering the perforated pipe 112 into the corresponding positions of the upper and lower aquifers, and lowering the water stop 20 into the water-blocking rock layer between the upper and lower aquifers; S4, lifting and solidifying: the temporary outer pipe 121 is separated from the water-stop tray 12 and lifted out of the well, and after the cement slurry solidifies, a cement ring stone is formed between the well pipe module and the well wall; S5. Pumping water and sampling from the upper part: The assembled pumping device 30 is lowered into the well pipe module and stays above the water stopper 20. The submersible pump 33 in the pumping device 30 is used to pump water samples above the water stopper 20; S6. Pumping water and sampling from the lower part: The pumping device 30 is further moved downward. The lower part of the pumping device 30 pushes the water stop 20 to connect the lower part of the pumping device 30 to the space below the water stop 20. The pumping device 30 blocks the hydraulic connection between the upper and lower aquifers. The submersible pump 33 in the pumping device 30 is used to pump water samples from the lower part of the water stop 20. S7. Lift and reset: lift the pumping device 30 upward and reset the water stop 20 to block the hydraulic connection of the lower aquifer again.

[0018] The water trap 20 includes an outer body 21, a lower cone 22, a guide rod 23, a bottom plate 24, and a spring member 25. The outer body 21 has an upper cone groove 211, a first channel 212, a lower cone groove 213, and a second channel 214 from top to bottom. The upper cone groove 211, the first channel 212, the lower cone groove 213, and the second channel 214 constitute a water channel located in the outer body 21 and running through from top to bottom. The upper cone groove 211 is wide at the top and narrow at the bottom, the lower cone groove 213 and the lower cone 22 are narrow at the top and wide at the bottom, the lower cone 22 is arranged in the lower cone groove 213, the guide rod 23 is arranged at the bottom of the lower cone 22, the bottom plate 24 is arranged at the bottom of the outer body 21 and is sleeved on the guide rod 23, and the bottom plate 24 has a first water opening 241. The spring member 25 is located between the lower cone 22 and the bottom plate 24, and is sleeved on the guide rod 23. The spring member 25 can push the lower cone portion 22 to fit the inner wall of the lower cone groove 213, thereby blocking the hydraulic connection between the upper and lower aquifers, preventing the water in the lower aquifer from flowing upward, and preventing the water in the upper and lower aquifers from mixing.

[0019] The pumping device 30 includes a water tank 31, a pump pipe 32, a submersible pump 33, a cable 34, an upper cone 35, and a top pipe 36. The top of the water tank 31 is connected to the pump pipe 32. The submersible pump 33 is disposed within the water tank 31, and the water outlet of the submersible pump 33 is connected to the pump pipe 32. The cable 34 is passed through the top wall of the water tank 31 and connected to the submersible pump 33. The upper cone 35 is disposed at the bottom of the water tank 31 and is wide at the top and narrow at the bottom. The top pipe 36 is disposed at the bottom of the upper cone 35. The sidewall of the top pipe 36 is provided with a sieve hole 361. The inner cavity of the top pipe 36 extends upward to connect to the water tank 31. The outer diameter of the top pipe 36 is smaller than the inner diameter of the first channel 212. The top wall of the water tank 31 has a through hole for the cable 34 to pass through. The gap between the inner wall of the through hole and the cable 34 is filled with a sealing material.

[0020] In S1, the first drill bit drills a hole with a diameter of 160 mm, and the second drill bit drills a hole with a diameter of 130 mm. After the well is drilled, a step is formed at the diameter change position for the subsequent installation of the water stop tray 12 and the like.

[0021] In S2, the well pipe module is assembled according to the position of the upper aquifer, the impermeable rock layer, and the lower aquifer, and the length of the well. The well pipe module has a blind pipe 111 and a permeable pipe 112, which uses a φ110mm PVC-U casing. The pipe sections are connected by threaded connections. The permeable pipe 112 is lowered into the corresponding positions of the upper and lower aquifers to ensure that the aquifer water can smoothly enter the well pipe module; the blind pipe 111 is lowered into the impermeable rock layer section between the aquifers, and blind pipes 111 can also be used at other positions in the well. The water stopper 20 can be fixed in the blind pipe 111 when the well pipe module is assembled. The water stopper 20 and the well pipe module are lowered into the well together. The bottom of the well pipe module stops lowering after it contacts the bottom of the well. The water stopper 20 is lowered into the impermeable rock layer between the upper and lower aquifers along with the well pipe module. A water-stop tray 12 and a temporary outer pipe 121 are also slidably mounted on the outside of the well pipe module, and the temporary outer pipe 121 is connected to the top of the water-stop tray 12; before lowering the well, cement slurry is injected between the well pipe module and the temporary outer pipe 121, and the injection height of the cement slurry is lower than the eye pipe 112 corresponding to the upper aquifer.

[0022] Furthermore, in S2, a support ring 13 is fixedly mounted on the outside of the well pipe module. This support ring is wide at the top and narrow at the bottom, with a maximum outer diameter of less than 130 mm. When the water-stop tray 12 and the temporary outer tube 121 are slidably mounted on the outside of the well pipe module, the water-stop tray 12 is positioned above the support ring. The top of the water-stop tray 12 is provided with a slot (not shown) for inserting the temporary outer tube 121. This slot is annular to prevent cement slurry from overflowing from the bottom of the temporary outer tube 121.

[0023] In S3, the well pipe module and the temporary outer pipe 121 are lowered into the well until the water stop tray 12 reaches the φ130mm diameter step in the well. During this process, the water stop tray 12 is supported by the supporting ring 13; the well pipe module is continued to be lowered until it abuts the bottom of the well to lower the eye pipe 112 into the corresponding position of the upper and lower aquifers, and the water stop 20 is lowered into the water-isolating rock layer between the upper and lower aquifers; the temporary outer pipe 121 is separated from the water stop tray 12 and lifted up to the outside of the well. At this time, the supporting ring 13 is lowered into the φ130 wellbore with the well pipe module, and the supporting ring 13 is separated from the water stop tray 12.

[0024] In S4, the temporary outer tube 121 is removed from the slot of the water-stop tray 12 and slowly lifted upward. Once the temporary outer tube 121 is free of the cement slurry, the lifting speed is increased until the temporary outer tube 121 is lifted out of the well. After the cement slurry solidifies, a cement ring is formed, sealing the well pipe module with the well wall with cement, and cutting the channel between the upper and lower aquifers outside the well pipe module.

[0025] In S5, the assembled pumping device 30 is lowered into the wellbore module and positioned above the water stop 20. Power is supplied to the submersible pump 33 via a cable 34, causing it to operate. Water above the water stop 20 (corresponding to the water in the upper aquifer) flows through the screen tube into the water tank 31 and is then pumped out of the well via the pump pipe 32. During this process, the top pipe 36 is spaced from the lower cone 22, which abuts against the inner wall of the lower cone groove 213, thereby blocking the hydraulic connection between the upper and lower aquifers.

[0026] In S6, the lower cone 22 of the water stop 20 is pushed downward by the jacking pipe 36, and the lower cone 22 is disengaged from the inner wall of the lower cone groove 213. The inner cavity of the jacking pipe 36 is connected to the space below the water stop 20. After the upper cone 35 fits and abuts the inner wall of the upper cone groove 211, the pumping device 30 stops moving, and the upper cone 35 abuts the inner wall of the upper cone groove 211 to block the hydraulic connection between the upper and lower aquifers; after the lower cone 22 is pushed open, the water in the second aquifer can surge upward under the action of water pressure. When the submersible pump 33 is in operation, the water rising from the second aquifer can enter the jacking pipe 36 and the water tank 31 through the sieve hole 361, and finally be transported to the outside of the well for sampling through the pump pipe 32.

[0027] The above scheme has two main purposes: one is to provide a method for separately pumping and sampling two groundwater aquifers in the same environmental monitoring well; the other is to improve the quality of stratified sealing and water-stopping to ensure that there is no channeling between aquifers. The scheme overcomes the shortcomings of conventional nested groundwater monitoring wells or clustered monitoring wells that cannot implement water pumping and sampling, and avoids the increase in the cost of monitoring well construction due to the construction of two monitoring wells or the expansion of the borehole diameter. At the same time, it also ensures the effect of stratified sealing and water-stopping, so that the groundwater collection work meets the requirements of the specifications and improves the authenticity and accuracy of the aquifer water quality. In addition, cement consolidation sealing and water-stopping is achieved between the two aquifers, and the blockage caused by the flow of cement slurry into the aquifer is avoided, thereby improving the quality of stratified sealing and water-stopping.

[0028] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the scope of the present invention.

Claims

1. A method for drilling and sampling a double-layer groundwater environment monitoring well, characterized in that: include: S1. Drilling and well completion: Use the first drill bit to expose the upper aquifer, expose the impermeable rock layer at the bottom of the upper aquifer by 5-10m, then change the drill diameter and replace it with the second drill bit to continue drilling and expose the lower aquifer; S2. Well pipe assembly: Assemble the well pipe module and the water riser, slide a water stop tray and a temporary outer pipe onto the outside of the well pipe module, and inject cement slurry between the well pipe module and the temporary outer pipe. The well pipe module has both blind and eyed pipes, with the water riser located inside the blind pipe and the temporary outer pipe connected to the top of the water stop tray. S3. Construction of lowering the well: lower the well pipe module and the temporary outer pipe into the well, lower the water stop tray to the diameter change point in the well; continue to lower the well pipe module until it touches the bottom of the well, lower the eye pipe into the corresponding position of the upper and lower aquifers, and lower the water stop into the water-blocking rock layer between the upper and lower aquifers; S4, lifting and solidifying: the temporary outer pipe is separated from the water stop tray and lifted out of the well. After the cement slurry solidifies, a cement ring stone is formed between the well pipe module and the well wall; S5. Upper water sampling: lower the assembled pumping device into the well pipe module and stop it above the water stopper, and use the submersible pump in the pumping device to extract water samples above the water stopper; S6. Pumping water from the lower part for sampling: The pumping device is further moved downward, and the lower part of the pumping device pushes the water stopper to connect the lower part of the pumping device to the space below the water stopper. The hydraulic connection between the upper and lower aquifers is blocked by the pumping device, and the water sample below the water stopper is pumped out by the submersible pump in the pumping device; S7. Lift and reset: lift the pumping device upward and reset the water stop to block the hydraulic connection of the lower aquifer again.

2. The method for drilling and sampling a double-layer groundwater environment monitoring well according to claim 1, characterized in that: In S1, the first drill bit drills a hole with a diameter of 160 mm, and the second drill bit drills a hole with a diameter of 130 mm.

3. The method for drilling and sampling a double-layer groundwater environment monitoring well according to claim 1, characterized in that: The water separator includes an outer body, a lower cone, a guide rod, a bottom plate and a spring member. The outer body has an upper cone groove, a first channel, a lower cone groove and a second channel from top to bottom. The upper cone groove is wide at the top and narrow at the bottom. The lower cone groove and the lower cone are narrow at the top and wide at the bottom. The lower cone is arranged in the lower cone groove. The guide rod is arranged at the bottom of the lower cone. The bottom plate is arranged at the bottom of the outer body and is sleeved on the guide rod. The bottom plate is provided with a first water outlet. The spring member is sleeved on the guide rod between the lower cone and the bottom plate. The pumping device includes a water tank, a pump pipe, a submersible pump, a cable, an upper cone and a top pipe. The top of the water tank is connected to the pump pipe. The submersible pump is arranged in the water tank and is connected to the pump pipe. The cable is passed through the top wall of the water tank and connected to the submersible pump. The upper cone is arranged at the bottom of the water tank and is wide at the top and narrow at the bottom. The top pipe is arranged at the bottom of the upper cone. The side wall of the top pipe is provided with a sieve hole, and the inner cavity of the top pipe extends upward to connect to the water tank.

4. The method for drilling and sampling a double-layer groundwater environment monitoring well according to claim 3, characterized in that: In S5, when the water sample above the water separator is extracted by the submersible pump in the pumping device, the top pipe and the lower cone are arranged at intervals, and the lower cone fits in contact with the inner wall of the lower cone groove to block the hydraulic connection between the upper and lower aquifers.

5. The method for drilling and sampling a double-layer groundwater environment monitoring well according to claim 4, characterized in that: In S6, the pumping device is further moved downward, and the lower portion of the pumping device pushes the water stopper to connect the lower portion of the pumping device to the space below the water stopper, and the hydraulic connection between the upper and lower aquifers is blocked by the pumping device: The lower cone of the water stop is pushed downward by the jacking pipe, and the lower cone is separated from the inner wall of the lower cone groove. The inner cavity of the jacking pipe is connected to the space below the water stop. After the upper cone fits and abuts the inner wall of the upper cone groove, the pumping device stops moving, and the upper cone abuts the inner wall of the upper cone groove to block the hydraulic connection between the upper and lower aquifers.

6. The method for drilling and sampling a double-layer groundwater environment monitoring well according to claim 1 or 3, characterized in that: In S2, a support ring is fixedly mounted on the outside of the well pipe module, and the support ring is wide at the top and narrow at the bottom; When the water-stop tray and the temporary outer pipe are slidably sleeved on the outer side of the well pipe module, the water-stop tray is located above the supporting ring.

7. The method for drilling and sampling a double-layer groundwater environment monitoring well according to claim 6, characterized in that: The water-stop tray is provided with a slot for inserting a temporary outer pipe.

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