Ground collapse experimental device and simulation method

Abstract

The invention discloses a formation collapse experimental device and a simulation method, the experimental device comprises: a transparent side wall of a container, a drain port is arranged on the side wall; a formation model is arranged in the container, and includes an artificial core layer, a natural gas hydrate reservoir layer, and a water layer from bottom to top; a wellbore is vertically arranged in the container, and the lower end of the wellbore is located above the artificial core layer; a water jet device comprises a sleeve, a high-pressure hose and a water jet drill bit, the sleeve is rotatably arranged in the wellbore, the high-pressure hose is arranged in the sleeve, the water jet drill bit is connected to the bottom end of the high-pressure hose, the bottom end of the sleeve extends outside the wellbore and tilts radially outward, so that the axial direction of the bottom end of the sleeve forms an angle with the vertical direction, and the drilling direction of the water jet drill bit is consistent with the axial direction. The formation collapse experimental device can better restore the formation structure and simulate the reservoir mining process, and form an artificial skeleton in the reservoir to increase the strength of the reservoir rock frame, effectively simulating the artificial skeleton formation process and support effect.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas reservoir development, and more specifically, relates to a formation collapse experimental device and a simulation method. Background Art

[0002] Natural gas hydrate is a new type of unconventional resource, a white crystalline compound formed by hydrocarbon gases such as methane and water under high pressure and low temperature conditions, also known as "combustible ice". Usually, the decomposition of one unit volume of natural gas hydrate can produce 164-180 units of methane gas. Natural gas hydrate resources are mainly distributed in deep waters with a depth of 300-3000 meters on coastal continental shelves such as the Arctic tundra, the Indian Ocean, the Pacific Ocean, the Arctic Ocean, and the Atlantic Ocean. It is preliminarily estimated that its resource volume is nearly 100 times that of conventional oil and gas, of which about 95% is stored in deep sea areas.

[0003] In the patent "A method for exploiting muddy silt-type natural gas hydrates based on foam mortar injection technology (CN201810054044.0)", the stability of the reservoir near the wellbore is improved by forming foam mortar jet jet piles around the well, and its effectiveness is focused on the wellbore stability of a single well.

[0004] In the patent "Method for Exploiting Natural Gas Hydrates (CN201919198515.6)", three fluids are introduced in sequence through the injection and production well group to achieve the replacement of natural gas in the reservoir, and at the same time fill the deficit caused by the exploitation of natural gas in real time.

[0005] In the invention patent "Deepwater Natural Gas Hydrate Extraction System and Extraction Method" (CN201910606033.3), with the vertical well as the core, radial wells are drilled in the upper and lower parts of the reservoir respectively, and two sets of circuits of oil pipes and casing are used to realize the displacement and replacement circulation extraction of the radial wells in the upper and lower parts of the reservoir in the same vertical well. At the same time, the stability of the well wall is achieved by relying on the concrete cementing technology.

[0006] In the invention patent "A system and method for exploiting natural gas hydrates in permafrost with a horizontal branch well network" (CN201910035958.7), through the coordinated production of well groups, exploitation and backfilling are carried out in sequence according to predetermined procedures to realize the utilization of the reservoir while ensuring the stability of the reservoir.

[0007] In the patent "A method for drilling and producing non-diagenetic natural gas hydrates in the sea" (CN201910293688.X), after drilling a horizontal well in the reservoir, foamed cement is sprayed laterally to form a honeycomb structure to provide support for the horizontal well and the formation, thereby achieving well wall stability.

[0008] In the invention patent "Device and working method for drilling hydrate micro-wellbores and quickly completing wells" (CN201910274015.X), a larger reservoir contact area is obtained by drilling a small wellbore laterally in a vertical well, and at the same time, a sand filter is carried into the small wellbore to achieve sand prevention, effectively improving the development effect.

[0009] At present, the contents of various patents on development methods and devices are mainly concentrated on specific development methods, which are still specific process forms of mainstream ideas such as pressure reduction, heating, replacement, and solid crushing. Among them, there is only one way to deal with the formation deficit caused by mining, which is "backfilling", and its operability still needs to be demonstrated. In non-diagenetic reservoirs or reservoirs with insufficient rock frame strength, the method of mining first and then backfilling cannot effectively reduce the risk of reservoir collapse and is not feasible. Regardless of the marine or frozen soil environment, geological phenomena such as landslides caused by formation collapse will have serious consequences.

[0010] Therefore, a formation collapse experimental device and a simulation method are needed to reduce the collapse risk of the reservoir and realize the effective utilization of the reservoir. Summary of the invention

[0011] The purpose of the present invention is to provide a formation collapse experimental device and a simulation method, so as to achieve better restoration and simulation of the prevention of collapse of the formation to be developed, and effectively reduce the risk of reservoir collapse.

[0012] In order to achieve the above object, according to one aspect of the present invention, a stratum collapse experimental device is provided, comprising:

[0013] A container, wherein the side wall of the container is transparent and a drain port is provided on the side wall;

[0014] A formation model, the formation model is arranged in the container and includes, from bottom to top, an artificial core layer, a natural gas hydrate reservoir, and a water layer;

[0015] A wellbore, wherein the wellbore is vertically arranged in the container, and the lower end of the wellbore is located above the artificial core layer;

[0016] A water jet device, the water jet device comprising a sleeve, a high-pressure hose and a water jet drill bit, the sleeve being rotatably disposed in the wellbore, the high-pressure hose being disposed in the sleeve, the water jet drill bit being connected to the bottom end of the high-pressure hose, the bottom end of the sleeve extending beyond the wellbore and tilted radially outward, so that the axial direction of the bottom end of the sleeve forms an angle with the vertical direction, and the drilling direction of the water jet drill bit is consistent with the axial direction.

[0017] Preferably, the artificial core layer is made of a whole cement block or a sandstone block; and the natural gas hydrate reservoir is made of a mixture of sand and a cementing agent.

[0018] Preferably, a cap layer is provided above the natural gas hydrate reservoir; and a transparent glass layer is provided above the water layer.

[0019] Preferably, the angle ranges from 40° to 50°.

[0020] Preferably, the drain port is located at the bottom of the natural gas hydrate reservoir, and the lower end of the wellbore is higher than the drain port.

[0021] Preferably, the outer wall of the shaft is in close contact with the inner wall of the container, and the shaft is made of a transparent material.

[0022] According to another aspect of the present invention, a method for simulating stratum collapse is provided, comprising the following method:

[0023] Step 1: a water jet drill bit drills into the natural gas hydrate reservoir from the bottom end of the sleeve in an inclined manner downward to form a drilled area in the natural gas hydrate reservoir;

[0024] Step 2: injecting concrete into the drilled area through a high-pressure hose to form an artificial skeleton;

[0025] Step 3: Repeating steps 1 and 2 multiple times along the circumferential direction of the wellbore until a plurality of artificial skeletons are formed;

[0026] Step 4: Simulate natural gas hydrate mining on the natural gas hydrate reservoirs inside the plurality of artificial skeletons to form goaf areas in the natural gas hydrate reservoirs;

[0027] Step 5: Repeat step 4 until collapse or water seepage occurs.

[0028] Preferably, the simulated natural gas hydrate production comprises:

[0029] The water jet drill bit performs hydraulic jetting to break the natural gas hydrate reservoir, wherein the liquid jetted by the water jet drill bit includes a gel-breaking substance;

[0030] The discharge port is opened to discharge the broken natural gas hydrate reservoir.

[0031] Preferably, the method further includes recording the scope of the goaf.

[0032] Preferably, in step 5, step 4 is repeated, and the mined-out area is backfilled through the wellbore before collapse or water seepage occurs.

[0033] The beneficial effects provided by the present invention are: through the formation collapse experimental device, the formation structure and the reservoir exploitation process can be better restored, and an artificial skeleton can be formed in the reservoir to increase the strength of the reservoir rock frame, effectively simulating the artificial skeleton formation process and support effect. The process of forming the artificial skeleton has little disturbance to the reservoir and low risk, effectively reducing the collapse risk of the reservoir, and also simulating the effect of the extreme safe goaf and overlying stress on the formation collapse during the exploitation process, which can provide guidance and reference for actual production.

[0034] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other purposes, features and advantages of the present invention will become more apparent by describing the exemplary embodiments of the present invention in more detail in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments.

[0036] Figure 1 A schematic structural diagram of a formation collapse experimental device in one embodiment of the present invention is shown.

[0037] Figure 2 A front view of a formation collapse experimental device in one embodiment of the present invention is shown.

[0038] Figure 3 A schematic structural diagram of a water jet device in one embodiment of the present invention is shown.

[0039] Figure 4 A schematic diagram of drilling with a water jet device in one embodiment of the present invention is shown.

[0040] Figure 5 Schematic diagram of water jet mining in one embodiment of the present invention.

[0041] Figure 6 Schematic diagram of water jet mining of goaf in one embodiment of the present invention.

[0042] Description of reference numerals:

[0043] 1. Container; 2. Wellbore; 3. Outflow port; 4. Artificial skeleton; 5. Water layer; 6. Cap layer; 7. Natural gas hydrate reservoir; 8. Artificial core layer; 9. Goaf; 21. Water jet device; 22. High-pressure hose; 23. Sleeve; 24. Water jet drill bit; 25. Water jet waterline direction. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0045] An embodiment of the present invention provides a stratum collapse experimental device, comprising:

[0046] A container, wherein the side wall of the container is transparent and a drain port is provided on the side wall; a formation model, wherein the formation model is arranged in the container and comprises, from bottom to top, an artificial core layer, a natural gas hydrate reservoir layer and a water layer; a wellbore, wherein the wellbore is vertically arranged in the container and the lower end of the wellbore is located above the artificial core layer; a water jet device, wherein the water jet device comprises a sleeve, a high-pressure hose and a water jet drill bit, wherein the sleeve is rotatably arranged in the wellbore, the high-pressure hose is arranged in the sleeve, the water jet drill bit is connected to the bottom end of the high-pressure hose, the bottom end of the sleeve extends beyond the wellbore and is inclined radially outward, so that the axial direction of the bottom end of the sleeve forms an angle with the vertical direction, and the drilling direction of the water jet drill bit is consistent with the axial direction.

[0047] Specifically, an artificial core layer, a natural gas hydrate reservoir layer, and a water layer are sequentially arranged in a container from bottom to top to form a formation model, a wellbore is arranged above the artificial core layer of the formation model, and a water jet device is arranged in the wellbore. The water jet device includes a sleeve, a high-pressure hose and a water jet drill bit. The sleeve is rotatably arranged in the wellbore and can drive the high-pressure hose and the water jet drill bit to move along the wellbore. The bottom end of the sleeve extends outside the wellbore and is radially inclined outward so that the bottom end of the sleeve forms an angle with the vertical direction. The water jet drill bit controls the initial orientation and direction of the drill bit through the bottom end of the sleeve, thereby achieving consistency between the water jet waterline direction, the drill bit positive direction and the drill bit drilling direction. The water jet drill bit drills forward and carries the high-pressure hose forward at the same time, forming a drilled area along the way. The drilled area is backfilled with concrete through the high-pressure hose, thereby forming an artificial skeleton, which has a supporting effect on the subsequent exploitation of the natural gas hydrate reservoir, effectively reduces the collapse risk of the reservoir, and realizes the effective development of the reservoir.

[0048] As a preferred solution, the artificial core layer is made of a whole cement block or a sandstone block; and the natural gas hydrate reservoir is made of a mixture of sand and cement.

[0049] As an example, a hard artificial core layer is placed at the bottom of the container, such as a whole cement block or a sandstone block, or a plurality of cement blocks spliced ​​together, but not gravel or other crushed stones.

[0050] As an example, a natural gas hydrate reservoir is placed on an artificial core layer, and a cementing agent is mixed into the sand in proportion to simulate a natural hydrate reservoir. The proportion of sand and cementing agent needs to be confirmed by a preliminary rock sample preparation experiment. The preliminary rock sample preparation experiment includes: mixing sand and cementing agents in different proportions, comparing them with the real reservoir core after cementation, and selecting a formula with similar rock properties such as elastic modulus, Poisson's ratio, and compressive strength as the formula for subsequent experiments.

[0051] As a preferred solution, a cap layer is provided above the natural gas hydrate reservoir; and a transparent glass layer is provided above the water layer.

[0052] As an example, a cap layer is set above the natural gas hydrate reservoir. The cap layer is made of a mixture of sand and cement in different proportions. The ratio of sand and cement needs to be confirmed by a preliminary rock sample preparation experiment. The preliminary rock sample preparation experiment includes: mixing sand and cement in different proportions, comparing with the real cap layer core after cementation, and selecting a formula with similar rock properties such as elastic modulus, Poisson's ratio, and compressive strength as the formula for subsequent experiments.

[0053] As an example, fresh water is introduced into the upper part of the simulated caprock to simulate a deepwater environment. The magnitude of the overburden stress can be adjusted by the water depth, and the adjustment is close to the real stratum structure.

[0054] As a preferred solution, the angle ranges from 40° to 50°.

[0055] As an example, a water jet device is placed in the wellbore. The water jet device controls the initial position and direction of the drill bit through a sleeve. The axial direction of the bottom end of the sleeve forms an angle with the vertical direction, which is 45° downward from the horizontal. The water jet waterline direction, the positive direction of the drill bit and the drilling direction are consistent.

[0056] As a preferred solution, the drain port is located at the bottom of the natural gas hydrate reservoir, and the lower end of the wellbore is higher than the drain port, which is used to simulate the exploitation of the natural gas hydrate layer and discharge the reservoir broken by the water jet drill bit out of the container to form a goaf.

[0057] As a preferred solution, the outer wall of the well is in close contact with the inner wall of the container, and the well is made of a transparent material.

[0058] As an example, the container is made of a transparent glass plate and is ensured to be leak-proof at the bottom and around the container under normal pressure.

[0059] As an example, when laying a natural gas hydrate reservoir, a wellbore is placed, the well wall is close to the inner wall of the container, and the simulated wellbore is made of transparent plastic.

[0060] According to another aspect of the present invention, a method for simulating stratum collapse is provided. Using the above, the method comprises the following steps:

[0061] Step 1: The water jet drill bit drills into the natural gas hydrate reservoir from the bottom end of the sleeve in an inclined manner downward to form a drilled area in the natural gas hydrate reservoir;

[0062] Specifically, the water jet drill bit drills forward along the bottom end of the sleeve, while carrying the high-pressure hose forward, forming a drilling gap along the way; when the drill bit drills to the artificial core layer and cannot drill further, the water jet drilling stops;

[0063] Step 2: Inject concrete into the borehole area through a high-pressure hose to form an artificial skeleton; specifically, inject concrete through the high-pressure hose at a low speed, and pull the high-pressure hose up at a low speed. When the drill bit is recovered into the wellbore, the borehole area is filled with concrete, wherein the concrete is a mixture of cement and fine sand.

[0064] Step 3: Repeat steps 1 and 2 multiple times along the circumferential direction of the wellbore until multiple artificial skeletons are formed; specifically, repeat steps 1 and 2 multiple times until all artificial skeletons are drilled, and wait for the concrete to solidify.

[0065] Step 4: Simulate natural gas hydrate exploitation on the natural gas hydrate reservoirs inside the multiple artificial skeletons to form goaf areas in the natural gas hydrate reservoirs.

[0066] Specifically, a water jet drill is used to perform hydraulic jetting in the natural gas hydrate reservoir to break up the natural gas hydrate reservoir, and the mining operation is cyclically repeated in sequence until a goaf is formed.

[0067] As a preferred solution, the simulation of natural gas hydrate exploitation includes: a water jet drill performs hydraulic jetting to break up the natural gas hydrate reservoir, wherein the liquid jetted by the water jet drill includes gel-breaking substances; and opening a drain port to discharge the broken natural gas hydrate reservoir.

[0068] Specifically, mixing a small amount of cement-breaking material into the hydraulic jetting liquid can accelerate the fragmentation and degradation of the simulated reservoir.

[0069] Specifically, the valve of the discharge port is opened to discharge the crushed sand and liquid, and the hydraulic jet cycle operation is performed in sequence until a goaf is formed.

[0070] As a preferred solution, it also includes recording the scope of the goaf.

[0071] Step 5: Repeat step 4 until collapse or water seepage occurs.

[0072] Specifically, the gas hydrate reservoir is mined until reservoir collapse or massive infiltration of upper water occurs, indicating that the ultimate safe goaf area has been reached.

[0073] As a preferred solution, in step 5, step 4 is repeated, and the mined-out area is backfilled through the wellbore before collapse or water seepage occurs.

[0074] Specifically, when the reservoir has not collapsed, the backfilling of the goaf can be simulated by injecting concrete from the wellbore to backfill until the goaf is filled.

[0075] Example 1

[0076] Figure 1 The schematic diagram of the structure of the ground collapse experiment device in one embodiment of the present invention is shown. Figure 2 The figure shows a front view of a ground collapse experimental device in one embodiment of the present invention. Figure 3 FIG. 1 shows a schematic structural diagram of a water jet device in one embodiment of the present invention. Figure 4 A schematic diagram of drilling with a water jet device in one embodiment of the present invention is shown.

[0077] like Figures 1 to 4 As shown, the embodiment provides a formation collapse experimental device, comprising:

[0078] A container 1, wherein the side wall of the container 1 is transparent and a drain port 2 is provided on the side wall 1; a formation model, wherein the formation model is arranged in the container 1 and comprises, from bottom to top, an artificial core layer 8, a natural gas hydrate reservoir 7 and a water layer 8; a wellbore 2, wherein the wellbore 2 is vertically arranged in the container 1 and the lower end of the wellbore 2 is located above the artificial core layer 8; a water jet device 21, wherein the water jet device 21 comprises a sleeve 23, a high-pressure hose 33 and a water jet drill bit 24, wherein the sleeve 23 is rotatably arranged in the wellbore 2, the high-pressure hose 22 is arranged in the sleeve 23, the water jet drill bit 24 is connected to the bottom end of the high-pressure hose 22, the bottom end of the sleeve 23 extends outside the wellbore 2 and is radially inclined outward, so that the axial direction of the bottom end of the sleeve 23 forms an angle of 45° with the vertical direction, and the drilling direction of the water jet drill bit 24 is consistent with the axial direction. The artificial core layer 8 is made of a whole cement block or a sandstone block; the natural gas hydrate reservoir 7 is made of a mixture of sand and a cementing material; a cap layer 6 is provided above the natural gas hydrate reservoir 7; and a transparent glass layer is provided above the water layer 9.

[0079] The leakage port 3 is located at the bottom of the natural gas hydrate reservoir 7, the lower end of the wellbore 2 is higher than the leakage port 3, the outer wall of the wellbore 2 is in close contact with the inner wall of the container 1, and the wellbore 2 is made of transparent material.

[0080] like Figure 4 As shown, a water jet device 21 is placed in the wellbore 2. The water jet device 21 controls the initial position and direction of the water jet drill bit 24 through the sleeve 23. The water jet waterline direction 25, the positive direction of the water jet drill bit 24 and the drilling direction are consistent.

[0081] Example 2

[0082] Figure 5A schematic diagram of water jet mining in one embodiment of the present invention, Figure 6 Schematic diagram of water jet mining of goaf in one embodiment of the present invention.

[0083] like Figure 5 and Figure 6 As shown, the embodiment provides a method for simulating formation collapse, the method comprising the following steps:

[0084] Step 1: The water jet drill bit 24 drills into the natural gas hydrate reservoir 7 from the bottom end of the sleeve 23 in an inclined manner downward to form a drilled area in the natural gas hydrate reservoir 7;

[0085] The water jet drill 24 drills forward while carrying the high pressure hose 22 forward, forming a drilling gap along the way; when the water jet drill 24 drills to the artificial core layer 8 and cannot drill further, the water jet drilling is stopped.

[0086] Step 2: inject concrete into the drilled area through a high-pressure hose to form an artificial skeleton 4;

[0087] Concrete is injected at a low speed through the high-pressure hose 22, and the high-pressure hose 22 is raised at a low speed. When the water jet drill bit 24 is recovered into the wellbore 2, the drilled area is filled with concrete.

[0088] Step 3: Repeat steps 1 and 2 several times along the circumferential direction of the shaft 2 until multiple artificial skeletons 4 are formed, and wait for the concrete to solidify, finally forming a Figure 1 and Figure 2 The artificial skeleton 4 is shown.

[0089] Step 4: Simulate the exploitation of natural gas hydrate in the natural gas hydrate reservoir 7 inside the plurality of artificial skeletons 4, and form a goaf 9 in the natural gas hydrate reservoir 7, such as Figure 6 shown.

[0090] The simulation of natural gas hydrate exploitation includes: a water jet drill 24 performs hydraulic jetting to break the natural gas hydrate reservoir 7, wherein the liquid jetted by the water jet drill 24 includes gel-breaking substances; and opening the discharge port 3 to discharge the broken natural gas hydrate reservoir 7.

[0091] Step 5: also includes recording the scope of the goaf 9.

[0092] Step 6: Repeat step 4 until collapse or water seepage occurs, indicating that the ultimate safe goaf area is reached. In step 6, step 4 is repeated, and the goaf area 9 is backfilled through the wellbore 2 before collapse or water seepage occurs.

[0093] In non-diagenetic reservoirs or reservoirs with insufficient rock frame strength, the method of mining first and then backfilling cannot effectively reduce the risk of reservoir collapse. The simulation method of the present invention provides a simulation method of pre-treating the reservoir first and then mining, which increases the strength of the reservoir rock frame by forming an artificial skeleton in the reservoir, and has the following characteristics: effectively simulates the formation process and support effect of the artificial skeleton; effectively simulates the effect of overburden stress on formation collapse; effectively simulates the extreme safety goaf area, providing guidance and reference for actual production; the whole process is visualized, and the simulation results are intuitive and reliable.

[0094] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A stratum collapse experimental device, characterized in that: include: A container, wherein the side wall of the container is transparent and a drain port is provided on the side wall; A formation model, the formation model is arranged in the container and includes, from bottom to top, an artificial core layer, a natural gas hydrate reservoir, and a water layer; A wellbore, wherein the wellbore is vertically arranged in the container, and the lower end of the wellbore is located above the artificial core layer; A water jet device, the water jet device comprising a sleeve, a high-pressure hose and a water jet drill bit, the sleeve being rotatably disposed in the wellbore, the high-pressure hose being disposed in the sleeve, the water jet drill bit being connected to the bottom end of the high-pressure hose, the bottom end of the sleeve extending out of the wellbore and tilted radially outward, so that the axial direction of the bottom end of the sleeve forms an angle with the vertical direction, and the drilling direction of the water jet drill bit is consistent with the axial direction; The simulation method of stratum collapse performed in the stratum collapse experimental device comprises the following steps: Step 1: a water jet drill bit drills into the natural gas hydrate reservoir from the bottom end of the sleeve in an inclined manner downward to form a drilled area in the natural gas hydrate reservoir; Step 2: injecting concrete into the drilled area through a high-pressure hose to form an artificial skeleton; Step 3: Repeating steps 1 and 2 multiple times along the circumferential direction of the wellbore until a plurality of artificial skeletons are formed; Step 4: Simulate natural gas hydrate mining on the natural gas hydrate reservoirs inside the plurality of artificial skeletons to form goaf areas in the natural gas hydrate reservoirs; Step 5: Repeat step 4 until collapse or water seepage occurs.

2. The ground collapse experimental device according to claim 1, characterized in that: The artificial core layer is made of a whole cement block or a sandstone block; The natural gas hydrate reservoir is made of a mixture of sand and cement.

3. The ground collapse experimental device according to claim 1, characterized in that: A cap layer is also provided above the natural gas hydrate reservoir; A transparent glass layer is arranged above the water layer.

4. The ground collapse experimental device according to claim 1, characterized in that: The angle ranges from 40° to 50°.

5. The ground collapse experimental device according to claim 1, characterized in that: The leakage port is located at the bottom of the natural gas hydrate reservoir, and the lower end of the wellbore is higher than the leakage port.

6. The ground collapse experimental device according to claim 1, characterized in that: The outer wall of the well is in close contact with the inner wall of the container, and the well is made of a transparent material.

7. The ground collapse experimental device according to claim 1, characterized in that: The simulated natural gas hydrate production comprises: The water jet drill bit performs hydraulic jetting to break the natural gas hydrate reservoir, wherein the liquid jetted by the water jet drill bit includes a gel-breaking substance; The discharge port is opened to discharge the broken natural gas hydrate reservoir.

8. The ground collapse experimental device according to claim 1, characterized in that: The simulation method of stratum collapse also includes recording the scope of the goaf.

9. The ground collapse experimental device according to claim 8, characterized in that: In step 5, step 4 is repeated, and the mined-out area is backfilled through the wellbore before collapse or water seepage occurs.

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