Split type high temperature resistant geothermal well radial extraction simulation test device and method

Abstract

The application discloses a split type high-temperature-resistant geothermal well radial extraction simulation test device and method, and belongs to the technical field of geothermal well simulation extraction. The test device comprises a pressure vessel which can be opened and closed; a water circulation cavity, a seepage cavity and a sample cavity are arranged in the pressure vessel body; the sample cavity is arranged along a central axis of the pressure vessel; a plurality of stacked rock samples are arranged in the sample cavity; the seepage cavity is coaxially arranged with the sample cavity and surrounds the outside of the sample cavity; a plurality of conical seepage holes are uniformly arranged on the cavity wall of the sample cavity; the seepage cavity and the sample cavity are communicated through the conical seepage holes; the cross-sectional area of the conical seepage hole decreases from one side of the sample cavity to the other side of the seepage cavity; the application can realize radial seepage path simulation, and the trinity design of 'central injection-radial diffusion-cone hole flow guide' is close to the radial flow mode of fluid in the rock stratum during geothermal exploitation and reinjection, and the test result is more accurate.

Description

Technical Field

[0001] This invention belongs to the field of geothermal well simulation extraction technology, specifically a split-type high-temperature resistant geothermal well radial extraction simulation test device and method; it is especially suitable for seepage simulation of ultra-high temperature dry hot rock (>550℃). Background Technology

[0002] Geothermal energy, mostly derived from renewable thermal energy deep within the Earth, is transferred to near-surface levels through groundwater circulation and lava flow. Geothermal reserves are vast and it is a clean energy source; if extracted rationally, it can generate a continuous supply of heat. As a purely natural and clean energy source, geothermal energy has become a new direction in energy research. The rational application of geothermal energy can alleviate the current shortage of traditional energy sources such as oil and coal in the country, and can also serve as an opportunity for industrial upgrading and transformation. Therefore, exploring geothermal energy development and utilization technologies is crucial in line with the needs of sustainable development.

[0003] Testing the seepage capacity of rock masses requires the use of pre-fabricated fractures. Existing devices rely on axial seepage, which cannot simulate the radial extraction path of geothermal wells, resulting in large prediction errors. Furthermore, existing seepage testing devices have complex structures, making it difficult to obtain complete samples after the test, which is not conducive to accurate evaluation and research of seepage experiments. Summary of the Invention

[0004] This invention overcomes the shortcomings of existing technologies and proposes a split-type high-temperature resistant geothermal well radial extraction simulation test device and method; this invention is achieved through the following technical solution:

[0005] A split-type high-temperature geothermal well radial extraction simulation test device includes a pressure vessel; the pressure vessel includes a first vessel body, a second vessel body, and an axial pressure head; the first and second vessel bodies are combined to form an openable and closable pressure vessel body; the pressure vessel body is provided with a water circulation chamber, a seepage cavity, and a sample cavity; the sample cavity is arranged along the central axial direction of the pressure vessel and is used to place multiple stacked rock samples; the seepage cavity is coaxially arranged with the sample cavity and surrounds the outside of the sample cavity, and multiple conical seepage holes are uniformly opened on the cavity wall of the sample cavity, with each conical seepage hole positioned at a position corresponding to each The bottom of the rock sample; the seepage cavity and the sample cavity are connected by a conical seepage hole; the cross-sectional area of ​​the conical seepage hole decreases from one side of the sample cavity to the other side of the seepage cavity; the seepage cavity is provided with an inlet and an outlet; the water circulation cavity is located above the sample cavity and the seepage cavity; the inlet and outlet are not connected to the water circulation cavity; multiple heating rod holes are provided axially in the cavity wall of the sample cavity, and heating rods are inserted into the heating rod holes; an axial pressure head is inserted into the sample cavity from the top and applies axial pressure to the rock sample; the axial pressure head is provided with seepage channels, and a sealing pressure head is connected to the outer wall of the axial pressure head.

[0006] Furthermore, the contact surfaces of the first and second vessel bodies are provided with an interlocking groove-boob structure, and a metal sealing gasket is installed in the groove. After the first and second vessel bodies are fastened and sealed by multiple flange bolts, a cylindrical sealed cavity is formed.

[0007] Furthermore, the water inlet is located at the bottom of the first vessel body, and the water outlet is located at the top of the second vessel body.

[0008] Furthermore, the water circulation chamber is provided with a water circulation chamber inlet and a water circulation chamber outlet located opposite each other. The water circulation chamber inlet is located on the side wall of the second vessel body, and the water circulation chamber outlet is located on the side wall of the first vessel body.

[0009] Furthermore, each heating rod hole is positioned 24° apart from the conical permeation holes, and does not contact the conical permeation holes. The heating rod penetrates the metal wall between the sample cavity and the permeation cavity.

[0010] Furthermore, the inner radius of the sample cavity is R, and N rock samples are prefabricated. Each rock sample has a height of H and a radius of r, achieving an interference fit where r > R, so that the rock sample is tightly squeezed inside the sample cavity. The rock sample is axially fixed and constrained by the sample cavity, and under the action of axial pressure, the rock sample expands radially. The interference-fit rock sample automatically generates a high confining pressure loading state.

[0011] Furthermore, one end of the seepage channel is located on the sidewall near the top of the axial pressure head, and the other end of the seepage channel is located at the center of the bottom of the axial pressure head.

[0012] Furthermore, the bottom boss of the sealing head is sealed to the upper groove of the vessel body using graphite packing.

[0013] Furthermore, it also includes a base, with the first and second vessel bodies, after being closed and connected, fitting into a groove in the base.

[0014] A method for simulating radial extraction of a split-type high-temperature resistant geothermal well, employing the aforementioned split-type high-temperature resistant geothermal well radial extraction simulation device, includes the following steps:

[0015] Step 1: Rock Sample Processing

[0016] Multiple standard rock samples were prepared by taking dry hot rock cores, and radial cracks were pre-fabricated on the rock samples to simulate natural fractures;

[0017] Step 2: Device Assembly

[0018] A rock sample is placed into the sample cavity on one side of the first vessel body, and the second vessel body is closed and fixed.

[0019] Step 3: Preparation before the experiment

[0020] Water is injected from the inlet until it overflows from the outlet and no more bubbles emerge. Then, the inlet and outlet are closed to ensure that the internal seepage cavity is full of water. The axial pressure head and the sealing pressure head are inserted, and the heating rod is inserted into the heating rod hole. The whole unit is placed on the uniaxial testing machine, with the axial pressure head aligned with the axial pressure and the sealing pressure head aligned with the ring pressure.

[0021] Step 4: Experimental Operation

[0022] Turn on the cooling circulating water, and the water flows through the water circulation chamber. Turn on the heating rod to heat the rock sample until it reaches the required experimental temperature. Apply axial stress through the uniaxial testing machine using the axial pressure head. Inject simulated geothermal water into the seepage channel, and the geothermal water flows out from the outlet. Record the flow rate and calculate the permeability coefficient.

[0023] The fluid path of the injected simulated geothermal water is: axial pressure head → seepage channel → center of rock sample → radial diffusion → conical seepage hole → seepage cavity → outlet;

[0024] Step 5: Disassembly and Sampling after Testing

[0025] After stopping heating, maintain water circulation, stop axial pressure, open the second reactor, and completely remove the rock sample for subsequent structural analysis.

[0026] The beneficial effects of this invention compared to the prior art are as follows:

[0027] 1. This invention can realize the simulation of radial seepage path, and the three-in-one design of "central injection-radial diffusion-cone hole guidance" closely resembles the radial flow pattern of fluid in rock strata during geothermal extraction and reinjection.

[0028] 2. The reactor designed for this device can be opened and closed, avoiding sampling damage caused by traditional one-piece reactors.

[0029] 3. The rock sample radius r > the cavity radius R, and the split design + interference fit rock sample does not require a traditional confining pressure loading system.

[0030] 4. The heating rod of this device is set inside the reactor, which has a higher heat transfer effect on the experimental sample, increases the heating rate (50%), and can achieve a higher maximum heating temperature (≥600℃); at the same time, its heat transfer efficiency to the outer wall of the reactor is low, the outer wall is less affected by temperature deterioration, the reactor structure is more stable, the sealing is stronger, and it can withstand a stronger maximum axial pressure (≥100MPa).

[0031] 5. All seals in this device are achieved by graphite packing or metal gaskets, completely replacing rubber seals, and can achieve higher experimental temperatures (≥500℃).

[0032] 6. This device has a higher degree of integration. The integrated design, in which the percolation, heating and cooling functions can all be realized by the reaction vessel, does not require any external devices, making the experimental loading and unloading simpler and faster.

[0033] 7. The inlet is designed at the bottom of the vessel and the outlet is designed at the top of the vessel. Gravitational potential energy is used to promote the directional flow of fluid to the outlet and eliminate the interference of sediment retention.

[0034] 8. The built-in heating + water cooling cavity design breaks through the temperature bottleneck while ensuring the life of the equipment. Attached Figure Description

[0035] Figure 1 Exploded view of the structure of a split-type high-temperature geothermal well radial extraction simulation test device;

[0036] Figure 2 Front view of a split-type high-temperature geothermal well radial extraction simulation test device;

[0037] Figure 3 for Figure 2 FF section view;

[0038] Figure 4 This is a front view of the first vessel body;

[0039] Figure 5 for Figure 4 AA section view in the middle;

[0040] Figure 6 for Figure 4 BB section view in the middle;

[0041] Figure 7 Right view of the split-type high-temperature geothermal well radial extraction simulation test device;

[0042] Figure 8 for Figure 7 EE section view;

[0043] Figure 9 This is a schematic diagram of the axial indenter.

[0044] In the figure: 1-Axial pressure head, 2-First vessel body, 3-Second vessel body, 4-Flange bolt, 5-Sample, 6-Metal sealing gasket, 7-Base, 8-Sample cavity, 9-Heating rod hole, 10-Water circulation cavity, 11-Sealing pressure head, 12-Graphite packing, 101-Seepage channel, 201-Seepage cavity, 202-Inlet, 301-Outlet, 801-Conical seepage hole, 1001-Water circulation cavity inlet, 1002-Water circulation cavity outlet. Detailed Implementation

[0045] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0046] Example 1

[0047] See Figures 1 to 9 This embodiment proposes a split-type high-temperature resistant geothermal well radial extraction simulation test device, including a pressure vessel, a rock sample 5, and a base 7.

[0048] The pressure vessel includes a first vessel body 2, a second vessel body 3, and an axial pressure head 1. Both the first vessel body 2 and the second vessel body 3 are semi-circular, and both have the same semi-cylindrical cavity structure inside. The first vessel body 2 and the second vessel body 3 are fastened together to form a cylindrical unit. The combination of the first vessel body 2 and the second vessel body 3 forms an openable and closable pressure vessel. The contact surfaces of the first vessel body 2 and the second vessel body 3 have an interlocking groove-boob structure, with a metal sealing gasket 6 installed in the groove. The first vessel body 2 and the second vessel body 3 are fastened and sealed by six flange bolts 4 to form a cylindrical sealed cavity, ensuring the stability and sealing of the internal structure. The opening and closing operation time is ≤5 minutes, and the rock sample recovery rate is 100% after high-temperature and high-pressure deformation. After closing, the vessel body fits into the groove of the base 7, providing auxiliary sealing and support.

[0049] The first vessel body 2 and the second vessel body 3 have the same cavity structure. The cylindrical cavity structure formed by their combination includes a water circulation cavity 10, a seepage cavity 201, and a sample cavity 8. The sample cavity 8 is arranged along the central axis of the pressure vessel, and is used to place multiple stacked rock samples 5. The seepage cavity 201 is coaxially arranged with the sample cavity 8 and surrounds the outside of the sample cavity 8. Multiple conical seepage holes 801 are evenly distributed on the cavity wall of the sample cavity 8, with each conical seepage hole 801 located at the bottom of the corresponding rock sample 5. The designed radius of the sample cavity 8 is... Inside, there is a ring of conical seepage holes 801 spaced 25mm apart from bottom to top, with 14 holes in each ring.

[0050] The seepage cavity 201 is connected to the sample cavity 8 through a conical seepage hole 801; the cross-sectional area of ​​the conical seepage hole 801 decreases from one side of the sample cavity 8 to the other side of the seepage cavity 201; the inner diameter of the sample cavity 8 is d1, and the inner diameter of the seepage cavity 201 is d2, d2 / d1=1.5. When the fluid flows radially from the center of the sample cavity 8 to the seepage cavity 201, the Venturi effect is formed due to the structure of the conical seepage hole 801, which inhibits the backflow of fluid; the seepage water reaches the seepage cavity 201 through the sample cavity 8. The seepage cavity 201 is used for seepage water storage. The seepage cavity 201 is equipped with an inlet 202 and an outlet 301. The inlet 202 is located at the lower part of the first vessel body 2, and the outlet 301 is located at the top of the second vessel body 3. The inlet 202 is located at the lowest point of the vessel body, and the outlet 301 is located at the highest point of the vessel body. This arrangement reduces errors caused by gravity and eliminates interference from sediment retention. A metal sealing gasket 6 is used to seal the seepage cavity 201.

[0051] The water circulation chamber 10 is located above the sample cavity 8 and the seepage cavity 201. The water circulation chamber 10 serves as the water circulation device for the vessel body. The water circulation device has a water circulation chamber inlet 1001 and a water circulation chamber outlet 1002 positioned opposite each other. The water circulation chamber inlet 1001 is located on the side wall of the second vessel body 3, and the water circulation chamber outlet 1002 is located on the side wall of the first vessel body 2. The water circulation chamber 10 greatly assists in the circulation of cooling water within the vessel body, cooling the uniaxial testing machine and preventing the hydraulic oil temperature of the press from becoming too high. The inlet 202 and outlet 301 are not connected to the water circulation chamber 10.

[0052] Four heating rod holes 9 are axially arranged inside the cavity wall of the sample cavity 8, and heating rods are inserted into the heating rod holes 9. The heating rods penetrate the metal wall between the sample cavity 8 and the seepage cavity 201. The heat radiation distance is ≤10mm, which greatly increases the heating rate by 50%. The heat radiation direction is directly facing the side surface of the rock sample 5, and the maximum temperature that the rock sample 5 can achieve is ≥600℃. Since the heating rods are located inside the reactor, and there is also a seepage cavity 201 between them and the outer wall of the reactor, the heat transferred from the heating rods to the outer wall of the reactor is limited during the experiment. The temperature of the outer wall of the reactor is relatively low, which effectively avoids the deterioration of the strength and sealing performance of the reactor body due to temperature rise. Moreover, each heating rod hole 9 is located at the middle position of the conical seepage hole 801 at a 24° interval, and does not contact the conical seepage hole 801. This allows for sufficient heating of the rock sample 5 and less impact on the water inside the seepage cavity 201 and the water circulation cavity 10.

[0053] The rock sample 5 was designed as 6 pieces, each with a height h = 25 mm and a radius. During the experiment, the sample 5 is placed inside the sample cavity 8. The rock sample 5 is interference-fitted with the sample cavity 8. The rock sample 5 is axially fixed and constrained by the sample cavity 8. By fully compressing the rock sample 5, it can expand radially under axial pressure. The interference-fit rock sample 5 automatically generates a high confining pressure loading state, thus achieving the experimental effect.

[0054] An axial pressure head 1 is inserted into the sample cavity 8 from the top and applies axial pressure to the rock sample 5. A seepage channel 101 is provided on the axial pressure head 1. One end of the seepage channel 101 is located on the side wall near the top of the axial pressure head 1, and the other end is located at the center of the bottom of the axial pressure head 1 for water injection during the seepage experiment. A sealing pressure head 11 is connected to the outer wall of the axial pressure head 1, and the axial pressure head 1 and the sealing pressure head 11 are in close contact. The bottom boss of the sealing pressure head 11 is sealed to the upper groove of the vessel body by a graphite packing 12.

[0055] Example 2

[0056] A method for simulating radial extraction of a split-type high-temperature resistant geothermal well, using the split-type high-temperature resistant geothermal well radial extraction simulation test device described in Example 1, includes the following steps:

[0057] Step 1: Rock Sample Processing

[0058] Take dry hot rock cores according to radius Six standard rock samples 5 were prepared with a height h=25mm. Radial cracks (0.1-0.3mm wide) were pre-fabricated on the rock samples 5 to simulate natural fissures.

[0059] Step Two: Equipment Assembly Process

[0060] Install the metal sealing gasket 6 on the groove of the first vessel body 2, fill the rock sample 5 into the sample cavity 8, close the second vessel body 3 so that the boss is inserted into the groove, and tighten the 6 flange bolts 4 (tighten them in a cross-shaped symmetrical order).

[0061] Step 3: Preparation before the experiment

[0062] Water is injected into the inlet 202 until it overflows from the outlet 301 and no more bubbles emerge. Then, the inlet 202 and outlet 301 are closed to ensure that the internal seepage cavity 201 is full of water. The installed vessel is placed on the base 7. Water is pre-filled into the seepage channel 101 of the axial pressure head 1 to reduce experimental errors. The graphite packing 12 is placed in the groove where the vessel body contacts the axial pressure head 1. The axial pressure head 1 and the sealing pressure head 11 are inserted. A heating rod is inserted into the heating rod hole 9. The whole thing is placed on the uniaxial testing machine, with the axial pressure head 1 aligned with the axial pressure and the sealing pressure head 11 aligned with the ring pressure.

[0063] Step 4: Experimental Operation Procedure

[0064] The cooling circulating water is turned on, and the water flows through the water circulation chamber inlet 1001 to the water circulation chamber outlet 1002. The heating rod is turned on to heat the rock sample 5 until the required experimental temperature is reached. The uniaxial testing machine applies axial stress through the axial pressure head 1; simulated geothermal water is injected through the seepage channel 101 and flows out from the outlet 301. The flow rate can be recorded and the permeability coefficient can be calculated to achieve the effect of simulating geothermal extraction experiments.

[0065] (Injection fluid path: Axial head 1 → seepage channel 101 → center of rock sample 5 → radial diffusion → conical seepage hole 801 → seepage cavity 201 → outlet 301)

[0066] Step 5: Disassembly and Sampling after Testing

[0067] After stopping heating, maintain water circulation (≥30 min until the vessel temperature <100℃), stop axial pressure, remove flange bolts 4, open the second vessel 3, and the rock sample 5 can be completely removed for subsequent structural analysis.

[0068] Example 3

[0069] The radial extraction simulation test method for a split-type high-temperature geothermal well described in Example 2, which is verified by reinjection simulation, includes the following steps:

[0070] Repeat the above assembly process and pre-experiment preparation. Reverse-inject cold water from outlet 301, with a pressure gradient of 0→20MPa. Use axial head 1 as the reflux monitoring point and record the flow rate Q. Calculate the reflux rate using the fluorescent tracer concentration formula:

[0071]

[0072] in C in For the injection concentration, C back Concentration at monitoring points;

[0073] It can be seen that when d2 / d1=1.5, the Venturi effect significantly suppresses backflow and improves sealing, and the recharge rate can be precisely controlled by adjusting the reverse pressure difference.

[0074] Reverse path: outlet 301 → seepage cavity 201 → conical hole 801 → fissure in rock sample 5 → axial pressure head 1.

[0075] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A split type high temperature geothermal well radial extraction simulation test device, characterized in that, The utility model provides a pressure vessel, the pressure vessel includes first cauldron body (2), second cauldron body (3) and axial pressure head (1), first cauldron body (2) and second cauldron body (3) combination form the pressure cauldron body that can open and shut, be provided with water circulation cavity (10), seepage cavity (201) and sample cavity (8) in the pressure cauldron body, sample cavity (8) is set along the center axis of pressure cauldron, and sample cavity (8) is used for placing multiple stacked rock samples (5) in, seepage cavity (201) is coaxially arranged with sample cavity (8) and surrounds sample cavity (8) outside, and the cavity wall of sample cavity (8) is evenly provided with multiple circles of conical seepage hole (801), and the position of each circle of conical seepage hole (801) is at the bottom of each rock sample (5) correspondingly, and seepage cavity (201) is communicated with sample cavity (8) through conical seepage hole (801), and the cross section area of conical seepage hole (801) decreases from one side of sample cavity (8) to one side of seepage cavity (201), the inner diameter of sample cavity (8) is d1, the inner diameter of seepage cavity (201) is d2, and d2 / d1=1.5; Seepage cavity (201) is provided with water inlet (202) and water outlet (301), water circulation cavity (10) is located in the upper portion of sample cavity (8) and seepage cavity (201), water inlet (202) and water outlet (301) are not communicated with water circulation cavity (10), the cavity wall of sample cavity (8) is provided with a plurality of heating rod holes (9) in the axial direction, and a heating rod is inserted into the heating rod hole (9), the axial pressure head (1) is inserted into the sample cavity (8) from the top and axially pressurizes the rock sample (5), the axial pressure head (1) is provided with a seepage channel (101), and the outer wall of the axial pressure head (1) is connected with a sealing pressure head (11).

2. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, The contact surface of the first cauldron body (2) and the second cauldron body (3) is provided with an interlocking groove-shoulder structure, a metal sealing gasket (6) is installed in the groove, and the first cauldron body (2) and the second cauldron body (3) form a cylindrical sealed cavity after being fastened and sealed by a plurality of flange bolts (4).

3. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, The water inlet (202) is located at the lower portion of the first cauldron body (2), and the water outlet (301) is arranged at the top of the second cauldron body (3).

4. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, The water circulation cavity (10) is provided with a water circulation cavity inlet (1001) and a water circulation cavity outlet (1002) that are opposite to each other, the water circulation cavity inlet (1001) is arranged on the side wall of the second cauldron body (3), and the water circulation cavity outlet (1002) is arranged on the side wall of the first cauldron body (2).

5. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, Each heating rod hole (9) is located at an interval of 24° from the conical seepage hole (801), and the heating rod penetrates the metal wall between the sample cavity (8) and the seepage cavity (201).

6. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, The internal radius of the sample cavity (8) is R, N rock samples (5) are prefabricated, each rock sample (5) has a height H and a radius r, and the radius r is greater than the internal radius R to achieve an interference fit, so that the rock sample (5) is tightly pressed in the sample cavity (8), the rock sample (5) is axially fixed and constrained by the sample cavity (8), and under the action of axial pressure, the rock sample (5) is radially expanded, and the interference rock sample (5) automatically generates a high confining pressure loading state.

7. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, One end of the seepage channel (101) is located on the side wall near the top of the axial pressure head (1), and the other end of the seepage channel (101) is arranged at the center of the bottom of the axial pressure head (1).

8. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, The boss at the bottom of the sealing pressure head (11) and the groove at the upper part of the kettle body are sealed by the graphite packing (12).

9. The split-type high-temperature geothermal well radial extraction simulation test device according to claim 1, characterized in that, The base (7) is also included, and the first kettle body (2) and the second kettle body (3) after being closed and connected are sleeved into the groove of the base (7).

10. A method for simulating radial extraction in a split high-temperature geothermal well, characterized in that, The device comprises the following steps: Step one: rock sample processing Take dry hot rock core to prepare multiple standard rock samples (5), and pre-prepare radial cracks on the rock samples (5) to simulate natural fractures; Step two: device assembly Insert the rock samples (5) into the sample cavity (8) on one side of the first kettle body (2), and close and fix the second kettle body (3); Step three: preparation before experiment Inject water from the water inlet (202), and after the water continuously overflows from the water outlet (301) without bubbles, close the water inlet (202) and the water outlet (301) to ensure that the internal seepage cavity (201) is full of water; insert the axial pressure head (1) and the sealing pressure head (11), insert the heating rod into the heating rod hole (9), and place the whole on the single-axis testing machine, with the axial pressure head (1) aligned with the axial pressure and the sealing pressure head (11) aligned with the ring pressure; Step four: test operation Open the cooling circulating water, and the water flows through the water circulation cavity (10); turn on the heating rod to heat the rock sample (5) until the required experimental temperature is reached; the single-axis testing machine applies axial stress through the axial pressure head (1); inject simulated geothermal water from the seepage channel (101), and the geothermal water flows out from the water outlet (301); record the flow rate and calculate the permeability coefficient; The fluid path of the injected simulated geothermal water is: axial pressure head (1) → seepage channel (101) → center of rock sample (5) → radial diffusion → conical seepage hole (801) → seepage cavity (201) → water outlet (301); Step five: disassembly and sampling after experiment After stopping heating, maintain water circulation, stop axial pressure, open the second kettle body (3), and completely take out the rock sample (5) for subsequent structure analysis.

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