Artificial heat reservoir construction device and method based on ultra-high-temperature thermal fracture dry hot rock mass

Abstract

The invention discloses an artificial heat reservoir construction device and method based on ultra-high-temperature thermal fracture dry hot rock mass, and belongs to the technical field of enhanced geothermal systems. The artificial heat storage building device comprises an inner-layer pipeline and an outer-layer annular space pipeline which are coaxially nested, and an annular oxidizing agent channel is formed in an annular space area between the outer wall of the inner-layer pipeline and the inner wall of the outer-layer annular space pipeline. A plurality of groups of inner nozzles are formed in the pipe wall of the inner-layer pipeline, a plurality of groups of outer nozzles are formed in the pipe wall of the outer-layer annular space pipeline, and the inner nozzles and the outer nozzles are in butt joint through magnetic attraction; through non-equal-length nozzle layout, magnetic attraction positioning and runner separation technologies, the risk that fuel and an oxidizing agent are mixed in advance and react in a non-designated area is avoided, efficient and controllable injection and thermal cracking regulation and control of the fuel and the oxidizing agent are achieved, and the reservoir transformation efficiency and engineering safety are remarkably improved; the method is suitable for dry hot rock reservoir artificial transformation and enhanced geothermal system development.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of enhanced geothermal systems, and particularly relates to an artificial heat reservoir construction device and method based on super-high-temperature thermal fracture dry hot rock. BACKGROUND

[0002] Under the background of the intensifying contradiction between global energy supply and demand, geothermal energy has become a key development direction due to its sustainability. Dry hot rock is usually a dense rock body (such as volcanic rock, metamorphic rock) with low porosity and low permeability, and has very poor natural permeability, so a heat exchange channel needs to be formed by artificial modification. There are usually the following ways in the traditional artificial modification technology: 1. Hydraulic fracturing: high-pressure water is injected into the rock body to form a fracture network, but there are problems of uncontrollable structure and low heat extraction efficiency; ‌2. Chemical stimulation: acid solution is injected to dissolve minerals (such as feldspar and quartz) to expand the pore, but the concentration needs to be controlled to avoid rock structure damage; a new type of stimulating liquid (such as a compound formula of fluoroboric acid and organic phosphonic acid) can reduce the risk of secondary sedimentation; 3. Combined process: combining hydraulic fracturing and chemical stimulation to optimize the permeability of the fracture; However, the implementation of artificial reservoir modification of enhanced geothermal systems (EGS) relying on hydraulic fracturing or chemical stimulation still faces multiple bottlenecks: on the technical level, there is a lack of precise fracture control technology, resulting in poor connectivity of the underground fracture network; the water-rock reaction mechanism under high temperature and high pressure conditions is complex, affecting the permeability improvement effect; the imbalance of reservoir thermal stress leads to accelerated heat energy decay and instability risk of ultra-deep well drilling engineering; stress sensitivity may cause further decrease of permeability during the production process; environmental risks involve the probability of induced earthquake events, chemical pollution of fracturing fluid and destruction of the integrity of the underground water system, and regional water resource pressure caused by high water consumption; and it causes the sharp contradiction between economic efficiency and energy output ratio in the whole life cycle. SUMMARY

[0003] The application overcomes the shortcomings of the prior art and proposes an artificial heat reservoir construction device and method based on super-high-temperature thermal fracture dry hot rock, which realizes efficient and controllable injection of fuel and oxidizer and thermal-induced fracture control, improves the reservoir modification efficiency and engineering safety, and solves the problems of poor precision of fracture control and low modification efficiency in the current enhanced geothermal system.

[0004] The application is realized by the following technical solutions: The artificial hot reservoir construction device based on super-high temperature thermal cracking dry hot rock mass comprises coaxially nested inner layer pipes and outer layer annular gap pipes, and an annular oxidant channel is formed between the outer wall of the inner layer pipes and the inner wall of the outer layer annular gap pipes; the inner layer pipes are used for conveying fuel to the dry hot rock mass; a plurality of groups of inner injection ports are arranged on the pipe wall of the inner layer pipes in an axial direction, a plurality of groups of outer injection ports are arranged on the pipe wall of the outer layer annular gap pipes in an axial direction, two adjacent groups of outer injection ports are connected through strip-shaped magnetic attraction bosses arranged in the axial direction of the outer layer annular gap pipes, the inner injection ports are butted through magnetic attraction with the outer injection ports, the number of the outer injection ports is greater than that of the inner injection ports, and the inner layer pipes are connected with a driving mechanism to drive the inner layer pipes to move back and forth in the axial direction of the outer layer annular gap pipes.

[0005] Further, the inner layer pipes are connected with kerosene pipes, and the outer layer annular gap pipes are connected with oxygen pipes.

[0006] Further, each group of inner injection ports comprises a plurality of inner layer pipe injection ports, and the plurality of inner layer pipe injection ports are uniformly arranged in the circumferential direction of the inner layer pipes; the axis of the inner layer pipe injection port is perpendicular to the axis of the inner layer pipe.

[0007] Further, an inner layer pipe end magnetic attraction boss is arranged at the outer port of the inner layer pipe injection port; and a displacement sensor is arranged in the inner layer pipe end magnetic attraction boss.

[0008] Further, each group of outer injection ports comprises a plurality of outer layer pipe injection ports, and the plurality of outer layer pipe injection ports are uniformly arranged in the circumferential direction of the outer layer annular gap pipes; the inner layer pipe injection port is butted through magnetic attraction with the corresponding outer layer pipe injection port.

[0009] Further, the axis of the outer layer pipe injection port is perpendicular to the axis of the outer layer annular gap pipe, and the length of the outer layer pipe injection port is less than that of the inner layer pipe injection port.

[0010] Further, the inner port of the outer layer pipe injection port is located inside the outer layer annular gap pipe, and the outer port of the outer layer pipe injection port is flush with the outer wall of the outer layer annular gap pipe; the inner port of the outer layer pipe injection port is made of a permanent magnet magnetically matched with the inner layer pipe end magnetic attraction boss, and the outer port of the inner layer pipe end magnetic attraction boss is butted through magnetic attraction with the inner port of the outer layer pipe injection port.

[0011] Further, the strip-shaped magnetic attraction boss is arranged between two adjacent outer layer pipe injection ports in the same column; and the width of the strip-shaped magnetic attraction boss is equal to the outer diameter of the inner layer pipe end magnetic attraction boss.

[0012] The artificial hot reservoir construction method based on super-high temperature thermal cracking dry hot rock mass adopts the artificial hot reservoir construction device based on super-high temperature thermal cracking dry hot rock mass, and comprises the following steps: S1, the artificial hot reservoir construction device is placed in the horizontal well located in the target area dry hot rock layer, in the initial state, the outer nozzle and the inner nozzle are coaxially aligned by magnetic attraction; S2, the fuel is quantitatively transported into the dry hot rock layer through the inner layer pipeline, after the fuel diffuses in the dry hot rock layer and forms a continuous fuel belt, the inner layer pipeline is driven to displace along the axial direction by the driving mechanism, and the inner nozzle is synchronously closed; S3, the excess oxidant is injected through the outer annular gap pipeline, the excess oxidant enters the dry hot rock layer from the outer nozzle through the annular oxidant channel, and the heat release oxidation reaction occurs between the fuel and the excess oxidant; the accumulated thermal stress of the rock matrix is generated due to the difference in the thermal expansion coefficient, and the network fracture of the rock mass is induced to expand.

[0013] Further, after step S1, high-purity helium is introduced through the annular gap between the outer annular gap pipeline and the inner layer pipeline, the high-purity helium is sprayed into the wellbore of the horizontal well through the outer nozzle which is not connected with the inner nozzle, a stable laminar flow is formed, and residual active gas and liquid impurities in the wellbore are removed.

[0014] The beneficial effects generated by the present application relative to the prior art are: 1, the present application avoids the risk of early mixing and reaction of fuel and oxidant in non-designated areas through non-equal-length nozzle layout, magnetic positioning and flow channel separation technology, realizes efficient and controllable injection of fuel and oxidant and heat-induced cracking regulation, and significantly improves reservoir reconstruction efficiency and engineering safety.

[0015] 2, based on the three-dimensional geological model of the reservoir, kerosene is injected through the inner layer pipeline to form a continuous fuel belt around the pipeline; and excess oxygen is injected through the outer annular gap at high pressure to trigger the self-sustaining oxidation reaction of kerosene in the high-temperature rock layer (T≥80℃); the local thermal stress field (peak temperature≥500℃) is induced by the heat release of the reaction, and the network fracture of the rock matrix is realized through the difference in the thermal expansion coefficient; not only breaks through the limitations of traditional hydraulic fracturing, but also has extremely high economic efficiency compared with it, provides a new method for enhanced geothermal system development, and can realize artificial cracking of deeper strata, increase the permeability, and realize the volume reconstruction of the target reservoir.

[0016] 3, the present application can realize efficient heat cracking, and the reservoir permeability is improved by 2-3 orders of magnitude through the heat-force coupling cracking mechanism; through the flow channel physical isolation and excess oxygen supply strategy (oxygen-fuel ratio≥1.5), complete combustion is ensured, and the safety is higher, and the present application is compatible with ultra-deep well working conditions and supports modular rapid deployment. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a layout schematic diagram of the artificial hot reservoir construction device of the present application; Figure 2 is a structure schematic diagram of the inner layer pipeline of the present application; Figure 3 is the schematic diagram of the outer annular gap pipe structure of the present application; Figure 4 is the overall schematic diagram of the cooperation of the outer annular gap pipe and the inner pipe; Figure 5 is the cross-sectional view of the cooperation of the outer annular gap pipe and the inner pipe; Figure 6 is the cross-sectional view of the coaxial alignment of the injection port of the inner pipe with the injection port of the outer pipe in the stage of injecting kerosene; Figure 7 is the cross-sectional view of the mechanical blocking of the injection port of the inner pipe in the stage of axial displacement of the inner pipe; Figure 8 is the schematic diagram of the fracture network formed in Example 1; Figure 9 is the schematic diagram of the fracture network formed in Example 2: wherein 1 is the inner pipe, 2 is the outer annular gap pipe, 4 is the injection port of the inner pipe, 5 is the injection port of the outer pipe, 6 is the strip-shaped magnetic attraction boss, 7 is the magnetic attraction boss at the end of the inner pipe, and 8 is the horizontal well. DETAILED DESCRIPTION

[0018] In order to make the technical problems to be solved by the present application, the technical solutions and beneficial effects more clearly understood, the present application will be further described in detail in conjunction with the embodiments and the drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. The technical solutions of the present application will be described in detail below in conjunction with the embodiments and the drawings, but the protection scope is not limited by this. Example 1

[0019] Referring to Figures 1 to 7 , the present embodiment proposes an artificial thermal reservoir construction device based on ultra-high temperature thermal cracking dry hot rock, which comprises a coaxially nested inner pipe 1 and an outer annular gap pipe 2. The annular space between the outer wall of the inner pipe 1 and the inner wall of the outer annular gap pipe 2 forms an annular oxidizing agent channel. The inner pipe 1 is connected with a kerosene pipe, and the outer annular gap pipe 2 is connected with an oxygen pipe. The inner pipe 1 is used for directional delivery of kerosene (C 12 H 26 ), and the outer annular gap pipe 2 is used for high-pressure injection of oxygen (O2).

[0020] The inner layer pipe 1 is provided with a plurality of groups of inner spray ports which are arranged axially and spaced apart, each group of inner spray ports including five inner layer pipe spray ports 4 which are uniformly arranged circumferentially along the inner layer pipe 1; the axis of the inner layer pipe spray port 4 is perpendicular to the axis of the inner layer pipe 1, and the outer end of the inner layer pipe spray port 4 is provided with an inner layer pipe end magnetic attraction boss 7; the inner layer pipe end magnetic attraction boss 7 is provided with a displacement sensor; the length of the inner layer pipe spray port 4 is d2, and the outer diameter of the inner layer pipe end magnetic attraction boss 7 is r1; The outer layer annular gap pipe 2 is provided with a plurality of groups of outer spray ports which are arranged axially and spaced apart, each group of outer spray ports including five outer layer pipe spray ports 5 which are uniformly arranged circumferentially along the outer layer annular gap pipe 2; the number of outer layer pipe spray ports 5 is greater than the number of inner layer pipe spray ports 4, and the inner layer pipe spray port 4 can be docked with the corresponding outer layer pipe spray port 5; the axis of the outer layer pipe spray port 5 is perpendicular to the axis of the outer layer annular gap pipe 2, the length of the outer layer pipe spray port 5 is d1, and d2>d1; in this embodiment, the length-diameter ratio of the inner layer pipe spray port 4 and the outer layer pipe spray port 5 is 2:1-5:1.

[0021] The inner end of the outer layer pipe spray port 5 is located inside the outer layer annular gap pipe 2, and the outer end of the outer layer pipe spray port 5 is flush with the outer wall of the outer layer annular gap pipe 2; the inner end of the outer layer pipe spray port 5 is made of a permanent magnet which is magnetically matched with the inner layer pipe end magnetic attraction boss 7, and the outer diameter of the inner end of the outer layer pipe spray port 5 is r2, r 1= r2; the outer end of the inner layer pipe end magnetic attraction boss 7 can be magnetically attracted and docked with the inner end of the outer layer pipe spray port 5.

[0022] The outer layer annular gap pipe 2 is provided with a strip-shaped magnetic attraction boss 6 along the axis thereof, and each strip-shaped magnetic attraction boss 6 is arranged between two adjacent outer layer pipe spray ports 5 in the same column; the width of the strip-shaped magnetic attraction boss 6 is r3, r 1= r3; the strip-shaped magnetic attraction boss 6 can precisely dock the outer layer pipe spray port 5 with the inner layer pipe end magnetic attraction boss 7 of the inner layer pipe spray port 4 as a magnetic attraction guide channel.

[0023] The inner layer pipe 1 is connected with a driving mechanism, which drives the inner layer pipe 1 to move back and forth along the axis of the outer layer annular gap pipe 2; it should be noted that the driving mechanism is an existing device, and in this embodiment, an electric push rod is used; In use, the artificial heat reservoir construction device is vertically or obliquely implanted into the target depth of hot dry rock layer, the alignment state of the inner pipe jet port 4 and the outer pipe jet port 5 is controlled through the axial displacement of the inner pipe 1, when the inner pipe jet port 4 is connected with the outer pipe jet port 5 through the inner pipe end magnetic attraction boss 7, the kerosene can be quantitatively transported to the hot dry rock layer through the inner pipe 1, then the flow channel is switched, the inner pipe 1 is driven to move along the axial direction through the driving mechanism, when the offset reaches the preset threshold, the inner pipe jet port 4 can be closed through the strip-shaped magnetic attraction boss 6 on the inner wall of the outer annular gap pipe 2, at this time, the excess oxygen can be injected into the hot dry rock through the outer pipe jet port 5 of the outer annular gap pipe 2, and fully reacts with the kerosene to realize the thermal-induced crack strengthening in the hot dry rock. Example 2

[0024] Referring to Figure 8 The embodiment provides an artificial heat reservoir construction method based on super-high-temperature thermal fracture hot dry rock, in the embodiment, the target area hot dry rock is granite, the buried depth is 4280 m, and the in-situ temperature is 220 DEG C; the artificial heat reservoir construction device provided in the embodiment 1 is used, and the following steps are included. S1. Composite pipe deployment: Two groups of parallel horizontal wells 8 are deployed, the horizontal section spacing of the horizontal wells 8 is 150 m, the initial permeability is low, and no natural crack connection is detected. A group of artificial heat reservoir construction devices is implanted in the two horizontal wells 8 by using the directional drilling technology, the diameter of the outer annular gap pipe 2 is 219 mm (the wall thickness is 12 mm), the diameter of the inner pipe 1 is 114 mm, and the inner pipe 1 and the outer annular gap pipe 2 are made of high-temperature creep-resistant nickel-based alloy material. The outer annular gap pipe 2 is provided with 30 groups of outer pipe jet ports 5 (d1=8 mm), the inner wall of the inner pipe 1 is provided with 20 groups of inner pipe jet ports 4 (d2=25 mm), and in the initial state, the inner pipe jet port 4 of the inner pipe 1 is coaxially aligned with the corresponding outer pipe jet port 5 through magnetic attraction, and the alignment accuracy is less than or equal to 0.5 mm.

[0025] S2. Inert environment construction: High-purity helium is introduced into the annular gap between the outer annular gap pipe 2 and the inner pipe 1, the high-purity helium is sprayed into the wellbore through the outer pipe jet port 5 which is not connected with the inner pipe jet port 4, the helium introduction time lasts for 10-15 minutes, and the purpose is to form a stable laminar flow, effectively remove active gases such as residual oxygen, water vapor and liquid impurities in the wellbore, and ensure that the oxygen content in the established inert environment is within a safe range, thereby providing a safe and controllable initial condition for the subsequent non-premixed oxidation reaction.

[0026] S3. Fuel permeation control: Based on the crack distribution data of the three-dimensional geological model of the borehole, the kerosene (C12 H 26 During the delivery process, the flow rate of kerosene is controlled below 1 m / s to prevent static electricity generation, and continuous injection is performed until the rock fractures form a continuous fuel zone. Specifically, in this embodiment, kerosene is simultaneously injected into the inner pipes 1 of the two groups of horizontal wells 8, so that the fuel spreads to the area between the two wells; after a period of injection, it is confirmed through tracer monitoring that a continuous fuel zone is formed between the two wells.

[0027] S4. Flow channel switching operation: The inner pipes 1 in the two groups of horizontal wells 8 are driven by the driving mechanism to displace along the axial direction, synchronously closing the fuel passage. The displacement amount is fed back in real time by the displacement sensor embedded in the magnetic attraction boss 7 at the end of the inner pipe, and when the displacement amount reaches ΔL=2r, the inner pipe injection port 4 of the inner pipe 1 is completely covered by the inner wall of the outer annular gap pipe 2, mechanically blocking the kerosene from being injected out. At this time, the inner pipe injection port 4 is in a closed state, and the outer pipe injection port 5 is in an open state; the displacement control accuracy of the displacement sensor reaches ±0.1 mm.

[0028] S5. Oxidation reaction triggering: Excess oxygen is injected into the outer annular gap pipe 2 through the oxygen pipe, and the excess oxygen enters the dry hot rock layer, so that the kerosene at the double-well position simultaneously undergoes a violent oxidation reaction.

[0029] In order to make the kerosene fully react, combined with the chemical equation of kerosene oxidation, the molar ratio of oxygen to kerosene is controlled to be 35:1 to 36:1, and the non-premixed oxidation reaction of kerosene and oxygen is catalyzed by the original temperature (80-200°C) of the dry hot rock layer, the temperature gradient of the thermal stress field is 80-200°C / m, and the action time is ≥30 minutes; the reaction heat release rate is ≥500 kJ / (m 3 ·s).

[0030] Excess oxygen is injected into the outer annular gap pipe 2 through the outer annular gap high-pressure injection, and the kerosene self-sustaining oxidation reaction is triggered in the high-temperature rock layer (T≥80°C): C 12 H 26 +18.5O2→12CO2+13H2O+released heat value≈45 MJ / kg; The reaction heat release induces a local thermal stress field (peak temperature≥500°C), and the rock matrix network is broken through the difference in thermal expansion coefficient.

[0031] S6. Thermal cracking reinforcement: The heat released by the oxidation reaction continues to act in the hot dry rock for 30-120 minutes, providing the necessary time for the effective conduction and accumulation of heat energy in the rock mass, causing the accumulation of thermal stress due to the difference in thermal expansion coefficients of the rock matrix, and when the thermal stress value exceeds the tensile strength of the rock by 3-5 MPa, the network of cracks in the rock mass expands, and the crack density increases by 40%-70%; the excess stress of 3-5 MPa is a safety margin to compensate for the uncertainty caused by the heterogeneity of the rock mass and the fluctuation of the in-situ stress field, ensuring the effectiveness and universality of the thermal cracking effect. S7. Circulating cracking: After the thermal cracking is completed, the inner pipe 1 is reset to the initial alignment position, and kerosene is injected again to repeat the above steps to further increase the permeability of the target area. The peak heat flux density released by the oxidation of kerosene reaches 3.2×10 6 W / m 3 The local temperature of the rock mass breaks through 800℃, and the rock starts to crack, and microseismic monitoring shows that the cracks expand from the two wells, and the injection of kerosene and oxygen is repeated to make the oxidation reaction occur repeatedly, and finally the crack bridging is realized through stress interference. Example 3

[0032] Referring to Figure 9 , this embodiment proposes a method for constructing an artificial thermal reservoir based on super-high temperature thermal cracking of hot dry rock. This engineering case is aimed at the development of deep granite thermal reservoirs, and adopts the Enhanced Geothermal System (EGS) technical route. The target reservoir is located at a vertical depth of 4280m, and the in-situ temperature gradient reaches 220℃. The artificial thermal reservoir construction device proposed in Example 1 is used, and the following steps are included: S1. Composite pipe deployment: The well pattern is deployed in a horizontal well-double vertical well combined configuration, with a horizontal section length of 1500m, penetrating through the low permeability granite mass. A group of artificial thermal reservoir construction devices are implanted at the position of the horizontal section. The outer annular pipe 2 has a diameter of 219mm (wall thickness of 12mm), and the inner pipe 1 has a diameter of 114mm. Both the inner pipe 1 and the outer annular pipe 2 are made of high-temperature creep-resistant nickel-based alloy material. The outer annular pipe 2 is configured with 30 groups of outer pipe injection ports 5 (d1=8mm), and the inner pipe wall of the inner pipe 1 is provided with 20 groups of inner pipe injection ports 4 (d2=25mm). In the initial state, the inner pipe injection ports 4 of the inner pipe 1 and the corresponding outer pipe injection ports 5 are kept coaxially aligned by magnetic attraction, with an alignment accuracy of ≤0.5mm.

[0033] Steps S2-S7 are the same as in Example 2.

[0034] This embodiment utilizes a thermo-chemical coupled fracturing mechanism to construct a high-conductivity fracture network between isolated horizontal wells, enabling cross-well spacing engineering stimulation of deep hot dry rock reservoirs. Compared to traditional hydraulic fracturing technology, it offers significantly higher economic efficiency. This technology system, through a control strategy of directional fuel pre-positioning and precise oxidation triggering, overcomes the well spacing limitations of traditional enhanced geothermal systems (EGS), providing a technological paradigm with industrial-scale value for the development of deep, low-permeability hot dry rock. Its unique non-hydraulic fracturing mechanism not only eliminates the risk of fracturing fluid contamination but also achieves synergistic optimization of reservoir stimulation efficiency and engineering safety through dynamic balance control of thermal fracturing and shock waves.

[0035] To provide the public with a thorough understanding of the present invention, specific details have been described in detail in the above preferred embodiments. However, those skilled in the art can fully understand the invention even without these detailed descriptions. Several improvements and modifications can be made without departing from the principles of the invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A device for constructing artificial thermal reservoirs based on ultra-high temperature thermally fractured dry hot rock masses, characterized in that, The system includes an inner pipe (1) and an outer annular pipe (2) that are coaxially nested. The annular region between the outer wall of the inner pipe (1) and the inner wall of the outer annular pipe (2) forms an annular oxidant channel. The inner pipe (1) is used to transport fuel to the dry hot rock mass. Multiple sets of inner nozzles are arranged axially on the pipe wall of the inner pipe (1), and multiple sets of outer nozzles are arranged axially on the pipe wall of the outer annular pipe (2). Adjacent sets of outer nozzles are connected by strip-shaped magnetic suction bosses (6), which are arranged axially along the outer annular pipe (2). The inner nozzles and outer nozzles are magnetically connected. The number of outer nozzles is greater than the number of inner nozzles. The inner pipe (1) is connected to a driving mechanism, which drives the inner pipe (1) to move back and forth along the axial direction of the outer annular pipe (2).

2. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 1, characterized in that, The inner pipe (1) is connected to the kerosene pipe, and the outer annular pipe (2) is connected to the oxygen pipe.

3. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 1, characterized in that, Each group of inner nozzles includes multiple inner pipe nozzles (4), which are evenly arranged around the inner pipe (1); the axis of the inner pipe nozzles (4) is perpendicular to the axis of the inner pipe (1).

4. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 3, characterized in that, An inner pipe end magnetic protrusion (7) is provided at the outer port of the inner pipe injection port (4); a displacement sensor is provided inside the inner pipe end magnetic protrusion (7).

5. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 4, characterized in that, Each group of external nozzles includes multiple outer pipe nozzles (5), which are evenly arranged around the outer annular pipe (2); the inner pipe nozzles (4) are magnetically connected to the corresponding outer pipe nozzles (5).

6. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 5, characterized in that, The axis of the outer pipe nozzle (5) is perpendicular to the axis of the outer annular pipe (2), and the length of the outer pipe nozzle (5) is less than the length of the inner pipe nozzle (4).

7. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 5, characterized in that, The inner port of the outer pipe nozzle (5) is located inside the outer annular pipe (2), and the outer port of the outer pipe nozzle (5) is flush with the outer wall of the outer annular pipe (2). The inner port of the outer pipe nozzle (5) is made of a permanent magnet that is magnetically matched with the magnetic boss (7) at the end of the inner pipe. The outer port of the magnetic boss (7) at the end of the inner pipe is magnetically connected to the inner port of the outer pipe nozzle (5).

8. The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass according to claim 5, characterized in that, The strip-shaped magnetic suction protrusion (6) is set between two adjacent outer pipe injection ports (5) in the same column; the width of the strip-shaped magnetic suction protrusion (6) is equal to the outer diameter of the magnetic suction protrusion (7) at the end of the inner pipe.

9. A method for constructing artificial thermal reservoirs based on ultra-high temperature thermally fractured dry hot rock masses, characterized in that, The artificial thermal reservoir construction device based on ultra-high temperature thermal fractured dry hot rock mass as described in any one of claims 1-8 includes the following steps: S1. Place the artificial thermal reservoir construction device into a horizontal well (8) located in the dry hot rock layer of the target area. In the initial state, the external nozzle and the internal nozzle are kept coaxially aligned by magnetic attraction. S2. Fuel is quantitatively delivered into the dry hot rock layer through the inner pipe (1). After the fuel diffuses in the dry hot rock layer and forms a continuous fuel strip, the inner pipe (1) is moved along the axial direction by the drive mechanism, and the inner nozzle is closed simultaneously. S3. Excess oxidant is injected through the outer annular pipe (2). The excess oxidant enters the dry hot rock layer from the outer nozzle through the annular oxidant channel and reacts with the fuel in an exothermic oxidation reaction. This causes the rock matrix to generate accumulated thermal stress due to the difference in thermal expansion coefficient, which induces the expansion of the network of cracks in the rock mass.

10. The method for constructing artificial thermal reservoirs based on ultra-high temperature thermally fractured dry hot rock masses according to claim 9, characterized in that, After step S1, high-purity helium gas is introduced through the annular gap between the outer annular pipe (2) and the inner pipe (1). The high-purity helium gas is injected into the wellbore of the horizontal well (8) through the outer nozzle that is not connected to the inner nozzle, forming a stable laminar flow and removing the residual active gas and liquid impurities in the wellbore.

Images