A layered monitoring well for constructing underground coal gasification furnaces

Abstract

This utility model relates to the field of underground coal gasification technology, and discloses a stratified monitoring well for constructing an underground coal gasifier. The stratified monitoring well includes a wellhead, surface casing, cementing sheath, completion tubing, formation water channel, monitoring instruments, and data transmission and display equipment. A packer divides the annular space of the wellbore into multiple independent sections, corresponding to monitoring areas of aquifers at different depths. Combined with the formation water channel and stratified monitoring instruments, independent monitoring of each aquifer is achieved, accurately locating pollution sources and avoiding data distortion caused by the mixing of formation water at different depths. When an anomaly is detected, an interlocking device enables emergency shutdown of the gasifier.

Description

Technical Field

[0001] This utility model relates to the field of underground coal gasification technology, and more specifically, it relates to a stratified monitoring well for underground coal gasification technology. Background Technology

[0002] Underground coal gasification technology is a process that directly converts coal into product gas through combustion and gasification reactions in underground coal seams in the presence of an oxidant. During the gasification process in an underground coal gasifier, to ensure the continuous gasification reaction, the internal pressure of the gasifier needs to be slightly higher than the hydrostatic pressure of the formation. This pressure difference causes a tendency for substances inside the gasifier to seep outwards. Simultaneously, the gasification process produces various byproducts, including coal tar, carbon monoxide, and carbon dioxide. If these substances leak into the surrounding aquifers, they will cause serious groundwater pollution. To prevent groundwater pollution, monitoring wells need to be installed around the gasification area to monitor the groundwater.

[0003] Existing monitoring wells typically employ a single monitoring method, making it impossible to effectively and independently monitor multiple aquifers at different depths. When aquifers at a specific depth become contaminated, the lack of stratified isolation prevents monitoring data from accurately pinpointing the specific stratum where the pollution source is located, and also hinders timely determination of the pollution diffusion path. Furthermore, traditional monitoring wells lack effective interlayer sealing structures within the wellbore, leading to cross-contamination of formation water from different aquifer depths within the wellbore. This distorts the monitoring data, failing to reflect the true water quality conditions of each aquifer.

[0004] Therefore, existing technologies have problems such as the inability to independently monitor aquifers at different depths, the inability to accurately locate pollution source layers, and the distortion of monitoring data, which lead to technical problems in the inability to effectively protect groundwater resources. Utility Model Content

[0005] This invention provides a stratified monitoring well for underground coal gasification technology, which solves the technical problems in related technologies such as the inability to independently monitor aquifers at different depths, the inability to accurately locate pollution source layers, and the distortion of monitoring data.

[0006] This utility model discloses a stratified monitoring well for underground coal gasification technology, comprising: wellhead, surface casing, cementing sheath, completion string, formation water channel, monitoring instruments, and data transmission and display equipment; The wellhead is located on the ground, and a through hole is formed inside the wellhead; The surface casing is a tubular structure. The upper end of the surface casing is connected to the lower end face of the wellhead, and the lower end extends to the top plate of the coal seam where the gasifier is located. The interior of the surface casing forms a wellbore channel, and the exterior forms an annular space with the borehole wall. The cementing sheath fills the annular space between the outer surface casing and the borehole wall, and covers the entire length of the surface casing. Formation water channels are channels that penetrate the cement sheath and the surface casing. Formation water channels connect the water-bearing formation with the wellbore channel. At least one set of formation water channels is set up for each water-bearing formation that needs to be monitored. The completion string is suspended inside the wellhead and extends along the wellbore passage to the coal seam where the gasifier is located. The completion string includes tubing, multiple packers, and screen pipe. The tubing has a tubular structure, with the upper end fixed to the wellhead and the lower end extending to the depth of the coal seam where the gasifier is located. The packer is installed on the outer surface of the tubing. The packer forms a mechanical seal in the annular space between the tubing and the surface casing, dividing the annular space into multiple independent segments. Each independent segment corresponds to a monitoring area of ​​a water-bearing formation. The screen tube is connected to the lower end of the oil pipe, and multiple filter holes are opened on the screen tube; The monitoring instruments are set in the annular space between the tubing and the surface casing. At least one monitoring instrument is set for each water-bearing formation that needs to be monitored. The monitoring instruments are located near the corresponding formation water channels. The data transmission and display device is installed on the ground and is connected to the monitoring instrument via a transmission line.

[0007] Furthermore, the packer includes an external packer and a through-tube external packer; the external packer forms a mechanical seal in the annular space between the tubing and the surface casing; the through-tube external packer, while achieving the sealing function, also has a structure that allows the transmission lines of monitoring instruments to pass through.

[0008] Furthermore, a wire-passing hole is provided on the outer packer of the through-pipe. The wire-passing hole penetrates the radial thickness of the outer packer of the through-pipe. The transmission line of the monitoring instrument passes through the wire-passing hole, and a sealing structure is provided around the wire-passing hole.

[0009] Furthermore, the monitoring instrument is installed adjacent to the packer outside the pipe, and the transmission line of the monitoring instrument extends into the oil pipe through the wiring hole of the packer outside the pipe, and then extends to the ground through the oil pipe.

[0010] Furthermore, the inner surface of the packer is tightly fitted to the outer surface of the tubing, and the outer surface is tightly fitted to the inner surface of the surface casing, so that water-bearing formations at different depths, after entering the annular space through the formation water channel, are each kept in an independent space defined by the packer.

[0011] Furthermore, the monitoring instruments include one or more of the following: water level monitoring instruments, water temperature monitoring instruments, water quality monitoring instruments, or water quantity monitoring instruments.

[0012] Furthermore, the data transmission display device is connected to an interlocking device, which is connected to the gasifier's production control system. When the monitoring data received by the data transmission display device exceeds a preset abnormal threshold, the data transmission display device triggers the interlocking device, which then sends a shutdown command to the gasifier's production control system.

[0013] Furthermore, the filter holes on the screen tube allow formation water to enter the screen tube while blocking particulate matter from entering.

[0014] Furthermore, at least one packer should be installed between every two adjacent water-bearing strata that need to be monitored.

[0015] Furthermore, a through channel is formed inside the oil pipe to accommodate the transmission lines of the monitoring instruments.

[0016] This invention, by setting multiple packers on the completion string, divides the annular space between the tubing and the surface casing in the wellbore into multiple independent sections, so that the formation water of different depth aquifers remains independent in the wellbore, avoiding the problem of mixed formation water of different depths causing distortion of monitoring data. It solves the technical problem of being unable to accurately monitor the true water quality of each aquifer and achieves the technical effect of improving the accuracy of monitoring data.

[0017] This invention enables independent real-time monitoring of each aquifer by setting up monitoring instruments in each independent monitoring area. When an aquifer at a specific depth is polluted, an anomaly can be detected immediately. This solves the technical problems of not being able to accurately locate the specific layer of the pollution source and not being able to determine the pollution diffusion path in a timely manner, and achieves the technical effect of accurately locating the pollution source and timely monitoring the pollution diffusion.

[0018] This invention employs an external packer that allows the transmission lines of monitoring instruments to pass through the packer while achieving interlayer isolation. This enables the monitoring instruments to be placed in an annular space and directly contact the formation water, solving the technical problems of low monitoring sensitivity and untimely monitoring response caused by the limited placement of monitoring instruments. It achieves the technical effect of improving monitoring sensitivity and monitoring response speed.

[0019] This invention connects the data transmission and display device with an interlocking device, enabling real-time analysis of monitoring data and automatic response to abnormal situations. When aquifer pollution is detected, it can immediately trigger the emergency shutdown of the gasifier, solving the technical problems of delayed response leading to pollution expansion and inability to control pollution spread in a timely manner in traditional monitoring methods. It achieves the technical effect of rapid response and effective control of pollution spread. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a stratified monitoring well used in underground coal gasification technology. Detailed Implementation

[0021] Underground coal gasification technology is a process that directly converts coal into product gas through combustion and gasification reactions in underground coal seams in the presence of an oxidant. During the gasification process in the underground coal gasifier 3, to ensure the continuous gasification reaction, the internal pressure of the gasifier 3 needs to be slightly higher than the hydrostatic pressure of the formation. This pressure difference causes a tendency for substances inside the gasifier 3 to seep outwards. Simultaneously, the gasification process produces various byproducts, including coal tar, carbon monoxide, and carbon dioxide. If these substances leak into the surrounding aquifers, they will cause serious groundwater pollution.

[0022] Existing monitoring wells typically employ a single monitoring method, making it impossible to effectively and independently monitor multiple aquifers at different depths. When aquifers at a specific depth become contaminated, the lack of stratified isolation prevents monitoring data from accurately pinpointing the specific stratum where the pollution source is located, and also hinders timely determination of the pollution diffusion path. Furthermore, traditional monitoring wells lack effective interlayer sealing structures within the wellbore, leading to cross-contamination of formation water from different aquifer depths within the wellbore. This distorts the monitoring data and fails to reflect the true water quality conditions of each aquifer.

[0023] Therefore, a layered monitoring well structure is needed that can independently monitor multiple aquifers 2 at different depths around the gasifier 3 and provide timely warnings when anomalies are detected.

[0024] According to this embodiment, a stratified monitoring well for underground coal gasification technology is provided, which includes a wellhead 5, a surface casing 6, a cementing sheath 7, a completion string, a formation water channel 10, a monitoring instrument 9, and a data transmission and display device 4.

[0025] Wellhead 5 is a structure connecting the surface and underground wellbore. The upper end of wellhead 5 is exposed to the surface, and the lower end is connected to the surface casing 6. The material grade of wellhead 5 is selected according to API standard DD grade, and the pressure rating is selected according to formation conditions, including 2000 psi or 3000 psi. A through-hole is formed inside wellhead 5, which is used to suspend the completion string and allows the transmission line of monitoring instrument 9 to pass through.

[0026] The surface casing 6 is a tubular structure, with its upper end connected to the lower end face of the wellhead 5 and its lower end extending to the roof of the coal seam where the gasifier 3 is located. The surface casing 6 is made of N80 grade steel casing, but stainless steel can also be used according to monitoring requirements. The interior of the surface casing 6 forms a through-hole channel, and the exterior forms an annular space between it and the borehole wall.

[0027] The cement sheath 7 fills the annular space between the outer surface casing 6 and the borehole wall. The cement sheath 7 is formed using oilfield G-grade cement and covers the entire length of the surface casing 6. The function of the cement sheath 7 is to fix the surface casing 6 to the formation and form a sealing structure to prevent fluid cross-contamination between formations of different depths through the annular space.

[0028] After the cementing sheath 7 has solidified and the well has been flushed, perforations are made on the surface casing 6 and the cementing sheath 7 at locations corresponding to the water-bearing formation 2, forming formation water channels 10. Formation water channels 10 are passages penetrating the cementing sheath 7 and the surface casing 6, connecting the water-bearing formation 2 to the wellbore channel inside the surface casing 6, allowing formation water to flow from the water-bearing formation 2 into the wellbore channel. At least one set of formation water channels 10 is provided for each water-bearing formation 2 that needs to be monitored.

[0029] The completion string is a tubular assembly structure that is suspended inside the wellhead 5 and extends along the wellbore passage to the coal seam where the gasifier 3 is located. The completion string includes tubing 12, multiple packers, and screen pipe 13.

[0030] The tubing 12 is a tubular structure that forms the main part of the completion string. The upper end of the tubing 12 is fixed to the wellhead 5, and the lower end extends to the depth of the coal seam where the gasifier 3 is located. The interior of the tubing 12 forms a through channel to accommodate the monitoring instrument 9 and its transmission line.

[0031] The packer is installed on the outer surface of the tubing 12, forming a mechanical seal within the annular space between the tubing 12 and the surface casing 6. The inner surface of the packer is in close contact with the outer surface of the tubing 12, and the outer surface is in close contact with the inner surface of the surface casing 6, thereby dividing the annular space into multiple independent segments. This ensures that after water-bearing formations 2 at different depths enter the annular space through the formation water channel 10, they remain within their respective independent spaces defined by the packer, preventing cross-contamination.

[0032] In some embodiments, the packer includes an external packer 11 and a through-tube external packer 8. The external packer 11 is a conventional packer structure that forms a mechanical seal within the annular space between the tubing 12 and the surface casing 6. The through-tube external packer 8, while providing a sealing function, also has a structure that allows the transmission line of the monitoring instrument 9 to pass through. The through-tube external packer 8 has a through-hole that extends through the radial thickness of the through-tube external packer 8. The transmission line of the monitoring instrument 9 passes through the through-hole, and a sealing structure is provided around the through-hole to ensure that the sealing function is maintained even when the transmission line passes through.

[0033] The screen pipe 13 is connected to the lower end of the tubing 12. Multiple filter holes are provided on the screen pipe 13. The filter holes allow formation water to enter the interior of the screen pipe 13 while blocking particulate matter from entering and preventing wellbore blockage.

[0034] The monitoring instrument 9 is installed in the annular space between the tubing 12 and the surface casing 6. At least one monitoring instrument 9 is installed for each water-bearing formation 2 that needs to be monitored. The monitoring instrument 9 is located near the corresponding formation water channel 10, so that the formation water flowing in from the formation water channel 10 can be detected by the monitoring instrument 9. The monitoring instrument 9 is installed adjacent to the external packer 8. The transmission line of the monitoring instrument 9 extends through the wiring hole of the external packer 8 into the tubing 12, and then extends through the tubing 12 to the surface.

[0035] In some embodiments, the monitoring instrument 9 includes one or more of a water level monitoring instrument, a water temperature monitoring instrument, a water quality monitoring instrument, or a water quantity monitoring instrument. The appropriate type of monitoring instrument 9 is selected based on the design layout of the gasifier 3 and environmental protection requirements. The water level monitoring instrument is used to monitor changes in the water level of the aquifer 2, the water temperature monitoring instrument is used to monitor the temperature of the formation water, the water quality monitoring instrument is used to detect the pollutant components in the formation water, and the water quantity monitoring instrument is used to monitor the flow rate of the formation water.

[0036] The data transmission and display device 4 is installed on the ground and connected to the monitoring instrument 9 via a remote transmission system. The monitoring data acquired by the monitoring instrument 9 is transmitted to the data transmission and display device 4 via a transmission line, where the data transmission and display device 4 displays and analyzes the monitoring data.

[0037] Furthermore, to enable rapid response in abnormal situations, the data transmission display device 4 is connected to an interlocking device, which is connected to the production control system of the gasifier 3. When the monitoring data received by the data transmission display device 4 exceeds a preset abnormal threshold, the data transmission display device 4 triggers the interlocking device, which sends a shutdown command to the production control system of the gasifier 3, thereby achieving an emergency shutdown of the gasifier 3 and preventing the spread of pollution.

[0038] Step 1: Deployment and drilling of monitoring wells; Based on the design layout and environmental protection requirements of gasifier 3, the depth and location of the water-bearing strata 2 to be monitored are determined, and the deployment locations of monitoring wells are selected outside the gasification area. A drilling design for the monitoring wells is prepared, determining the wellbore structural parameters, including borehole diameter, casing size, and drilling depth.

[0039] The monitoring well is drilled using a two-stage wellbore structure. The first stage of drilling reaches the roof of the coal seam where the gasifier 3 is located. After the first stage of drilling is completed, the surface casing 6 is lowered. The lower end of the surface casing 6 reaches the roof of the coal seam, and the upper end is connected to the wellhead 5.

[0040] Step 2: Cementing and cement sheath formation; After the surface casing 6 is lowered into place, cementing operations are carried out throughout the well. Oilfield G-grade cement slurry is pumped into the annular space between the surface casing 6 and the borehole wall, filling the entire annular space and extending from the coal seam roof to the surface. After solidification, the cement slurry forms a cement sheath 7, firmly connecting the surface casing 6 to the formation and sealing the annular space to prevent fluid flow between formations at different depths.

[0041] Wait for the cement sheath 7 to set. The setting time depends on the cement properties and formation temperature, and usually takes 24 to 72 hours.

[0042] Step 3: Well cleaning and perforation; After the cement sheath has set, the wellbore is flushed to remove drilling fluid residue and cuttings, ensuring a clean wellbore.

[0043] After well washing, based on the predetermined depth of the water-bearing formation 2 to be monitored, a perforation device is used to perforate the surface casing 6 and cement sheath 7. The perforation device is lowered to the corresponding depth of the water-bearing formation 2, and a through hole is formed in the surface casing 6 and cement sheath 7 using a perforation gun or perforation projectile. This through hole serves as the formation water channel 10, connecting the water-bearing formation 2 to the inside of the wellbore. Perforation is performed on each water-bearing formation 2 to be monitored, forming multiple sets of formation water channels 10.

[0044] Step 4: Basic water sample collection; After perforation, water samples were collected from each aquifer 2. Using specialized sampling equipment, water samples were collected from the formation water flowing into each aquifer channel 10, ensuring that the samples from each aquifer did not mix. The collected water samples were then subjected to water quality testing to obtain basic water quality data for each aquifer 2, including pH value, dissolved oxygen, major ion content, and organic matter content. This basic data serves as a benchmark for subsequent monitoring.

[0045] In some embodiments, after water sampling, secondary drilling continues from the coal seam roof to the depth of the gasified coal seam where the gasifier 3 is located. Water sampling is also performed on the gasified coal seam to obtain basic water quality data of the gasified coal seam location.

[0046] Step 5: Well completion string running and installation; After water sampling is completed, the completion string is assembled. The completion string consists of tubing 12, multiple packers, monitoring instruments 9, and screen pipe 13. Packers and monitoring instruments 9 are installed at corresponding positions on the tubing 12 according to the depth of each water-bearing formation 2. At least one packer is installed between every two adjacent water-bearing formations 2 that need monitoring, and monitoring instruments 9 are installed at the corresponding depth position of each water-bearing formation 2 that needs monitoring.

[0047] The assembled completion string is lowered into the wellbore. The upper end of the completion string is suspended and fixed at the wellhead 5, and the lower end extends to the depth of the gasified coal seam. The screen pipe 13 is located at the bottom of the completion string. During the lowering process, the transmission line of the monitoring instrument 9 is kept to pass smoothly through the wire hole of the packer 8 outside the pipe to avoid tangling or damage to the transmission line.

[0048] After the completion string is lowered into place, the packer setting mechanism is activated, causing the packer to expand in the annular space between the tubing 12 and the surface casing 6. The outer surface of the packer is tightly fitted to the inner surface of the surface casing 6, achieving mechanical sealing and dividing the annular space into multiple independent segments. Each independent segment corresponds to a monitoring area of ​​a water-bearing formation 2.

[0049] Step Six: Monitoring System Debugging and Operation; After the completion string is installed, the transmission line of the monitoring instrument 9 is extended to the surface through the inside of the tubing 12 and connected to the data transmission and display device 4. The monitoring instrument 9 is then functionally tested to check whether each monitoring instrument 9 is working properly, whether the data transmission is stable, and whether the data transmission and display device 4 can correctly receive and display the monitoring data.

[0050] After debugging, the monitoring system began formal operation, continuously monitoring each aquifer 2 in layers. Formation water from each aquifer 2 enters its corresponding independent section through formation water channels 10. Due to the isolation effect of the packers, the formation water from aquifers at different depths remains independent and does not mix. Each monitoring instrument 9 detects the formation water parameters within its respective independent section, and the monitoring data is transmitted in real time to the data transmission and display device 4 via transmission lines.

[0051] In some embodiments, step six further includes: connecting the data transmission display device 4 to an interlocking device, and connecting the interlocking device to the production control system of the gasifier 3. An abnormal threshold for the monitoring data is set in the data transmission display device 4. When the monitoring data of any aquifer 2 exceeds the abnormal threshold, the data transmission display device 4 automatically triggers the interlocking device, which sends an emergency shutdown command to the production control system of the gasifier 3. The gasifier 3 immediately stops production to prevent further leakage and diffusion of pollutants.

[0052] The layered monitoring well provided in this embodiment divides the annular space between the tubing 12 and the surface casing 6 in the wellbore into multiple independent sections by setting multiple packers on the completion string. Each independent section corresponds to a monitoring area of ​​aquifer 2, ensuring that the formation water of aquifers at different depths remains independent within the wellbore and does not mix. Therefore, it overcomes the problem of data distortion caused by the mixing of formation water at different depths within the wellbore in traditional monitoring wells, and solves the technical problem of being unable to accurately monitor the true water quality of each aquifer.

[0053] By setting up monitoring instruments 9 in each independent monitoring area, each aquifer 2 can be independently monitored in real time. When an aquifer at a specific depth is contaminated, the monitoring instrument 9 in that layer can immediately detect the anomaly and accurately locate the layer where the pollution source is located. Therefore, this overcomes the problem that traditional monitoring wells cannot locate the specific layer of the pollution source and solves the technical problem of not being able to determine the pollution diffusion path in a timely manner.

[0054] By employing an external packer 8, interlayer isolation is achieved while allowing the transmission line of the monitoring instrument 9 to pass through the packer. This enables the monitoring instrument 9 to be positioned within the annular space and directly contact the formation water, improving the sensitivity and accuracy of monitoring. Therefore, this overcomes the problem of low monitoring sensitivity caused by limited instrument placement and solves the technical issue of untimely monitoring response.

[0055] By connecting the data transmission and display device 4 to the interlocking device, real-time analysis of monitoring data and automatic response to abnormal situations are achieved. When aquifer pollution is detected, the gasifier 3 can be immediately shut down to block the pollution source. Therefore, this overcomes the problem of pollution expansion caused by the delayed response of traditional monitoring methods and solves the technical problem of being unable to control the spread of pollution in a timely manner.

[0056] By adopting a two-stage wellbore structure, the surface casing 6 is first run in and cemented throughout the entire well section. Then, a formation water channel 10 is formed through perforation, ensuring the overall sealing of the wellbore and preventing fluid cross-contamination between formations through the wellbore. Therefore, this overcomes the problem of cross-contamination caused by traditional open wellbore structures and solves the technical problem that the monitoring well itself may become a contamination diffusion channel.

Claims

1. A monitoring well for constructing a coal underground gasification furnace, characterized by, include: Wellhead, surface casing, cementing sheath, completion string, formation water channel, monitoring instruments and data transmission and display equipment; The wellhead is located on the ground, and a through hole is formed inside the wellhead; The surface casing is a tubular structure. The upper end of the surface casing is connected to the lower end face of the wellhead, and the lower end extends to the top plate of the coal seam where the gasifier is located. The interior of the surface casing forms a wellbore channel, and the exterior forms an annular space with the borehole wall. The cementing sheath fills the annular space between the outer surface casing and the borehole wall, and covers the entire length of the surface casing. Formation water channels are channels that penetrate the cement sheath and the surface casing. Formation water channels connect the water-bearing formation with the wellbore channel. At least one set of formation water channels is set up for each water-bearing formation that needs to be monitored. The completion string is suspended inside the wellhead and extends along the wellbore passage to the coal seam where the gasifier is located. The completion string includes tubing, multiple packers, and screen pipe. The tubing has a tubular structure, with the upper end fixed to the wellhead and the lower end extending to the depth of the coal seam where the gasifier is located. The packer is installed on the outer surface of the tubing. The packer forms a mechanical seal in the annular space between the tubing and the surface casing, dividing the annular space into multiple independent segments. Each independent segment corresponds to a monitoring area of ​​a water-bearing formation. The screen tube is connected to the lower end of the oil pipe, and multiple filter holes are opened on the screen tube; The monitoring instruments are set in the annular space between the tubing and the surface casing. At least one monitoring instrument is set for each water-bearing formation that needs to be monitored. The monitoring instruments are located near the corresponding formation water channels. The data transmission and display device is installed on the ground and is connected to the monitoring instrument via a transmission line.

2. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, Packers include external packers and through-tube external packers; external packers form a mechanical seal in the annular space between the tubing and the surface casing; through-tube external packers, while achieving the sealing function, also have a structure that allows the transmission lines of monitoring instruments to pass through.

3. The layered monitoring well for constructing an underground coal gasification furnace according to claim 2, characterized in that, The outer packer of the through pipe has a through hole that extends through the radial thickness of the outer packer. The transmission line of the monitoring instrument passes through the through hole, and a sealing structure is set around the through hole.

4. The layered monitoring well for constructing an underground coal gasification furnace according to claim 2, characterized in that, The monitoring instrument is installed adjacent to the packer outside the pipe. The transmission line of the monitoring instrument extends into the oil pipe through the wiring hole of the packer outside the pipe, and then extends to the ground through the oil pipe.

5. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, The inner surface of the packer is in close contact with the outer surface of the tubing, and the outer surface is in close contact with the inner surface of the surface casing. This allows water-bearing formations at different depths to remain within their own independent spaces after entering the annular space through the formation water channels.

6. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, The monitoring instruments include one or more of the following: water level monitoring instruments, water temperature monitoring instruments, water quality monitoring instruments, or water quantity monitoring instruments.

7. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, The data transmission display device is connected to an interlocking device, which is connected to the gasifier's production control system. When the monitoring data received by the data transmission display device exceeds a preset abnormal threshold, the data transmission display device triggers the interlocking device, which then sends a shutdown command to the gasifier's production control system.

8. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, The filter holes on the screen tube allow formation water to enter the screen tube while blocking particulate matter from entering.

9. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, At least one packer should be installed between every two adjacent water-bearing strata that need to be monitored.

10. The layered monitoring well for constructing an underground coal gasification furnace according to claim 1, characterized in that, The inside of the oil pipe forms a through channel to accommodate the transmission lines of the monitoring instruments.

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