A water pressure thermotherapy coupled true triaxial loading and panoramic real-time CT scanning device

Abstract

This invention provides a hydraulic pressure-thermal bath coupled true triaxial loading and panoramic real-time CT scanning device, belonging to the fields of rock mechanics, oil and gas field development, and tight sandstone gas extraction. It overcomes the problem in existing rock mechanics experimental devices where true triaxial loading, hydraulic loading, thermal bath environment control, and internal structure observation are difficult to achieve in a single space. The device includes an X-ray scanning system, a forward and backward precession loading system, a temperature-controlled liquid circulation system, and a multi-functional pipeline system with signal linkage, forming a multi-field loading control system. This multi-field loading control system is configured to: monitor the rate of change of loading force, hydraulic pressure, and temperature in each loading direction in real time, and dynamically adjust the frequency or scanning mode of the CT scan based on the monitored parameter change rates.

Description

Technical Field

[0001] This invention relates to the fields of rock mechanics, oil and gas field development and tight sandstone gas extraction, and specifically to a hydraulic thermocoupled true triaxial loading and panoramic real-time CT scanning device. Background Technology

[0002] Tight sandstone gas, as a highly efficient and clean unconventional natural gas resource, has enormous development potential. Although my country has abundant geological reserves of tight sandstone gas, the reservoirs generally have complex geological characteristics such as low porosity, low permeability, and strong heterogeneity. During development, it faces prominent bottlenecks such as "gas cannot be extracted" and "water lock effect." Existing technologies are unable to effectively construct efficient gas flow channels, resulting in low single-well production and recovery rates less than one-third of those of conventional natural gas reservoirs, which seriously affects the economic and effective development of the resource.

[0003] In actual mining operations, tight sandstone gas reservoirs are often accompanied by significant intrusion of edge and bottom water, coupled with high reservoir temperatures. Edge and bottom water intrusion under high-temperature conditions easily leads to a sharp decline in gas phase permeability, severely inhibiting gas well productivity. However, under the coupled effects of heat, fluid, and force fields, the damage and failure mechanisms of tight sandstone, the evolution of fractures, and their impact on gas-water seepage remain unclear, and the underlying mechanisms of productivity decline urgently need to be revealed. Currently, conventional rock mechanics testing equipment has relatively limited functionality, with most only capable of one or two of the following: triaxial loading, pore water pressure testing, or heating. There is a lack of comprehensive experimental platforms capable of simultaneously simulating real triaxial stress fields, hydraulic fracturing, high-temperature thermal bath environments, and integrating real-time in-situ CT scanning. Therefore, it is difficult to fully reproduce the entire process of microfracture initiation, propagation, and gas-water cross-scale seepage in tight sandstone under complex geological conditions.

[0004] Furthermore, existing CT scanning systems used in rock mechanics and fracturing experimental setups are mostly based on fixed structures or single X-ray source rotational scanning, and the scanning process is usually independent of loading control. During multi-physics coupled loading processes such as true triaxial stress, fluid injection, and thermal baths, traditional CT scanning methods are prone to imaging blind spots and artifacts due to factors such as spatial obstruction of loading components, dynamic changes in stress paths, and fluid disturbances, making it difficult to achieve continuous, panoramic, and high-precision real-time observation of the dynamic process of fracture evolution.

[0005] On the other hand, current hydraulic fracturing experiments mostly rely on single fluid injection to induce fracture propagation, with limited control over the fracture initiation location and propagation direction. Although some equipment introduces mechanical cutting or pre-fabricated fractures, the mechanical disturbance and fluid loading are often separated in time and space, failing to achieve synergistic loading on the same interface. Therefore, it cannot effectively simulate the downhole "hydraulic-mechanical" coupled fracture creation process, restricting the systematic study of the directional fracture initiation and propagation laws. Overall, existing experimental devices have functional limitations in simulating real reservoir conditions. Most can only realize some functions of true triaxial loading, hydraulic loading, temperature control, or internal structure observation. There is still a lack of a multi-field coupled comprehensive experimental system that can integrate true triaxial loading, hydraulic fracturing, high-temperature heat bath, and real-time CT scanning in the same experimental space. This makes it difficult to systematically, continuously, and accurately capture and analyze the fracture evolution and multi-physics interaction mechanisms.

[0006] Therefore, in order to promote the efficient development of tight sandstone gas, it is urgent to develop an experimental device that can simultaneously realize true triaxial stress loading, water pressure injection, thermal bath environment control and real-time in-situ observation of internal structure in a laboratory environment. This device will support the study of the mechanism of reservoir fracture network evolution and gas-water seepage behavior under complex multi-field coupling, and provide key experimental basis and theoretical support for optimizing fracturing technology and improving recovery rate. Summary of the Invention

[0007] The purpose of this invention is to overcome the problem that it is difficult to coordinate true triaxial loading, hydraulic loading, hot bath environment control and internal structure observation in the same space in existing rock mechanics experimental devices. In particular, in view of the shortcomings of existing devices in being unable to conduct real-time and panoramic observation of the evolution process of internal rock fractures under multi-field coupling conditions, this invention proposes a hydraulic hot bath coupled true triaxial loading and panoramic real-time CT scanning device.

[0008] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted:

[0009] A water pressure thermotherapy coupled true triaxial loading and panoramic real-time CT scanning device includes:

[0010] The panoramic in-situ CT shell has a panoramic in-situ CT inner shell located at its center. The panoramic in-situ CT inner shell is made of a high-temperature resistant material that is permeable to X-rays.

[0011] The precession loading system installed in the inner shell of the panoramic in-situ CT scanner includes an upper pressure plate, a lower pressure plate, a left pressure plate, a right pressure plate, a front pressure plate, and a rear pressure plate. The six pressure plates surround each other to form a true triaxial loading space for clamping the sample. Each pressure plate is connected to an independent pressure monitoring device to achieve independent monitoring and control of the loading force in six directions. A flexible sealing structure is provided between the pressure plates to prevent leakage of the temperature-controlled liquid and improve the uniformity of loading.

[0012] The inner shell of the panoramic in-situ CT is filled with a temperature-controlled liquid, which is connected to an external temperature-controlled liquid circulation system through the inlet and outlet of the temperature-controlled liquid to form a constant temperature heat bath environment within the loading space. The temperature-controlled liquid is a high-temperature resistant thermally conductive liquid, and the circulation path of the temperature-controlled liquid is equipped with a heat preservation structure and a temperature control module.

[0013] The X-ray scanning system, housed within the panoramic in-situ CT housing, includes multiple X-ray tubes spaced circumferentially along the inner wall of the housing and a rotating track for the X-ray tubes. The X-ray tubes can rotate 360° around the sample along the rotating track, achieving panoramic real-time CT imaging of the sample. Furthermore, it can perform segmented or continuous scanning at preset time intervals to acquire tomographic imaging data of the sample at different loading stages. During the rotational scanning process, the multiple X-ray tubes emit X-rays sequentially or collaboratively at preset angular intervals to form multi-angle, multi-source superimposed tomographic imaging data.

[0014] The multi-functional pipeline system located at the bottom of the panoramic in-situ CT shell includes a multi-functional pipeline with one end connected to the interior of the panoramic in-situ CT shell via a tower-type structural steel and the other end connected to a fracturing fluid control terminal. The pipeline is equipped with a pressure regulating and flow monitoring device.

[0015] The multifunctional pipe is provided with a fracturing fluid inlet, a main cutting blade and multiple oblique cutting blades at one end extending into the inner shell. The lower pressure plate is provided with a through hole. The multifunctional pipe, the main cutting blade and multiple oblique cutting blades pass through the through hole to perform mechanical disturbance and fluid injection on or near the surface of the sample.

[0016] Preferably, the X-ray scanning system, the precession loading system, the temperature-controlled liquid circulation system, and the multi-functional piping system are signal-linked to form a multi-field loading control system. This multi-field loading control system is configured to: monitor the rate of change of loading force, water pressure, and temperature in each loading direction in real time, and dynamically adjust the CT scan frequency or scanning mode based on the monitored parameter change rates. The multi-field loading control system includes a human-machine interface for real-time display of loading force, water pressure, temperature parameters, and CT scan status. It also includes a remote data acquisition and transmission system for transmitting CT image data and loading process parameters to an external analysis terminal.

[0017] Preferably, the X-ray scanning system operates synchronously with the multi-functional pipe front-end cutter during mechanical disturbance and hydraulic loading, to acquire in real time the initiation location, propagation path, and penetration morphology of the fracture under the coupled action of mechanical disturbance and hydraulic pressure. The forward and backward precession loading system is equipped with an electric control unit with an adjustable loading rate to achieve independent control of the loading rate in each direction.

[0018] Preferably, the multi-field loading control system is specifically configured to: automatically increase the CT scanning frequency from 0.01-0.05Hz to 0.1-1Hz, or switch the scanning mode from periodic scanning to continuous rapid scanning when the axial or lateral loading force change rate is not less than 5% / min, or the water pressure change rate is not less than 0.5MPa / min, or the temperature change rate is not less than 2℃ / min, so as to realize dynamic tomographic imaging of the fracture initiation and rapid propagation stages.

[0019] Preferably, the panoramic in-situ CT inner shell is made of a high-temperature resistant material that is permeable to X-rays. The material is selected from one or more of alumina ceramics, silicon nitride ceramics, quartz glass or silicon carbide ceramics, and has a long-term temperature resistance of not less than 300°C, a short-term temperature resistance of not less than 500°C, a compressive strength of not less than 300MPa, and a flexural strength of not less than 200MPa.

[0020] Preferably, the temperature-controlling liquid is one or more of water, silicone oil, ethylene glycol aqueous solution, or high-temperature heat transfer oil; when the test temperature is not higher than 100°C, water or ethylene glycol aqueous solution is used; when the test temperature is higher than 100°C, silicone oil or high-temperature heat transfer oil is used.

[0021] Preferably, the blade angle of the main cutting blade is 30°-60° and the blade length is 5-20mm, used to form an initial fracture or weakening zone on the surface of the sample 27; the preset angle between the plurality of oblique cutting blades and the axis of the main cutting blade or the main loading direction is 15°-60° and the blade thickness is 0.5-2mm, so as to induce the crack to expand along different principal stress directions.

[0022] Preferably, the minimum distance between the tip of the oblique cutting blade and the fracturing fluid inlet is 1-10 mm, and the fracturing fluid inlet is located in front of or laterally adjacent to the blade of the oblique cutting blade, so that the fracturing fluid can preferentially enter the disturbance zone or initial fracture formed by the oblique cutting blade when injected, thereby achieving the synergistic effect of mechanical disturbance and hydraulic loading.

[0023] Preferably, the main cutting blade and the oblique cutting blade are of a replaceable structure to adapt to the loading and fracturing requirements of samples with different strengths, sizes or lithologies.

[0024] Further preferably, it also includes a fracture evolution image analysis software platform, which is used to perform three-dimensional reconstruction, fracture identification, evolution path analysis and seepage channel modeling on the image data acquired by CT scan, and to perform synchronous linkage analysis with the pressure, temperature and flow data during the loading process, so as to generate the temporal-spatial distribution results of fracture evolution under the action of multi-physics fields.

[0025] More preferably, the upper pressure plate, lower pressure plate, left pressure plate, right pressure plate, front pressure plate, and rear pressure plate are made of high-strength alloy steel or stainless steel; the main cutting blade and the oblique cutting blade are made of high-strength alloy steel, tool steel, or cemented carbide.

[0026] Compared with the prior art, the device of the present invention achieves the following significant technical advantages and effects in its structural design:

[0027] (1) Achieve unified construction of multi-field coupled loading conditions:

[0028] This invention integrates true triaxial stress loading, hydraulic loading, and thermal bath environment control into the same experimental device, which can simulate the multi-physics field state of underground reservoirs under laboratory conditions.

[0029] (2) Realize panoramic real-time observation of the fracture evolution process:

[0030] By setting up a multi-X-ray tube rotating scanning structure, the sample can be continuously and CT scanned from all angles during loading, thereby obtaining three-dimensional structural information on the crack initiation, propagation and penetration process.

[0031] (3) Achieving the synergistic effect of mechanical disturbance and hydraulic loading:

[0032] By setting a main cutting blade and an oblique cutting blade structure at the front end of the multifunctional pipe, mechanical disturbance and fluid injection can occur synergistically within the same interface, which is beneficial for experimental research on the crack initiation location and propagation behavior.

[0033] (4) Improve the integrity of parameter control and monitoring during the experimental process:

[0034] By setting up multiple pressure, temperature and flow monitoring devices, real-time monitoring and control of key parameters in the loading process can be achieved, ensuring the stability and repeatability of the experimental process.

[0035] In summary, this invention provides an advanced experimental platform for in-depth exploration of tight sandstone gas extraction and cross-scale seepage mechanisms under complex multi-field coupling conditions in the field of tight sandstone gas development experiments. It has important theoretical and practical significance for developing new technologies for efficient extraction of unconventional oil and gas such as tight sandstone gas. Attached Figure Description

[0036] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0037] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention;

[0038] Figure 2 This is a schematic diagram of the forward and backward precession loading system;

[0039] Figure 3 This is a schematic diagram of the structure of a panoramic in situ CT scan;

[0040] Figure 4 This is a schematic diagram of the internal shell structure of a panoramic in-situ CT scanner;

[0041] Figure 5 This is a schematic diagram of the structure of the front end of a multi-functional pipe;

[0042] The numbers in the diagram represent the following: 1. Panoramic in-situ CT shell; 2. X-ray tube; 3. Panoramic in-situ CT inner shell; 4. First multi-function gauge inside the shell; 5. Temperature-controlled fluid; 6. Upper pressure plate; 7. Right pressure plate; 8. Second multi-function gauge inside the shell; 9. Lower pressure plate; 9-1. Through hole; 10. Forward and backward precession loading system; 11. Left pressure plate; 12. Multi-function pipeline; 13. First flow meter; 14. First pressure gauge; 15. Multi-function pipeline valve; 16. Second flow meter; 17. Second pressure gauge; 18. Fracturing fluid control terminal; 19-1. Lower pressure plate lead wire; 19-2. Lower pressure plate pressure gauge; 20-1. Left pressure plate lead wire. Wire; 20-2. Left pressure plate pressure gauge; 21-1. Upper pressure plate lead wire; 21-2. Upper pressure plate pressure gauge; 22-1. Right pressure plate lead wire; 22-2. Right pressure plate pressure gauge; 23-1. Front pressure plate lead wire; 23-2. Front pressure plate pressure gauge; 24-1. Rear pressure plate lead wire; 24-2. Rear pressure plate pressure gauge; 25. Front pressure plate; 26. Rear pressure plate; 27. Sample; 28. X-ray tube rotating track; 29. ​​Temperature-controlled liquid inlet and outlet; 30. First steel layer; 31. Support layer; 32. Second steel layer; 33. Tower structure steel; 34. Angled cutting blade; 35. Fracturing fluid pipe opening; 36. Main cutting blade. Detailed Implementation

[0043] The following are specific embodiments of the present invention, described in conjunction with the accompanying drawings, to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments. Specific details, such as particular configurations, are provided in the following description merely to aid in a comprehensive understanding of the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0044] This embodiment provides a water pressure thermotherapy coupled true triaxial loading and panoramic real-time CT scanning device, the specific connection structure and implementation method of which are as follows:

[0045] like Figure 1 As shown, a panoramic in-situ CT inner shell 3 is installed at the center of the panoramic in-situ CT outer shell 1. The two are connected by a first steel layer 30, a support layer 31, and a second steel layer 32 (see...). Figure 4 These components are sequentially and tightly integrated to form a stable and robust overall structure. Multiple X-ray tubes 2 are evenly arranged circumferentially on the inner wall of the panoramic in-situ CT shell 3. Each X-ray tube 2 is mounted on an X-ray tube rotation track 28 and can rotate 360° around the panoramic in-situ CT shell 3, enabling real-time CT scanning of the interior of the panoramic in-situ CT shell 3. This multi-X-ray tube rotational scanning structure differs from existing fixed or single-X-ray source scanning methods. It can operate synchronously with the front and rear precession loading system 10 during true triaxial loading and fluid injection, achieving continuous observation of the internal structure of the sample.

[0046] like Figure 1 and Figure 2 As shown, an anterior-posterior precession loading system 10 is installed in the central region of the panoramic in-situ CT inner shell 3. The anterior-posterior precession loading system 10 includes pressure plates in six directions: an upper pressure plate 6, a lower pressure plate 9, a left pressure plate 11, a right pressure plate 7, a front pressure plate 25, and a rear pressure plate 26. Each pressure plate is connected to a corresponding pressure gauge via a corresponding lead wire.

[0047] The upper pressure plate 6 is connected to the upper pressure plate pressure gauge 21-2 via the upper pressure plate lead wire 21-1;

[0048] The lower pressure plate 9 is connected to the lower pressure plate pressure gauge 19-2 via the lower pressure plate lead wire 19-1;

[0049] The left pressure plate 11 is connected to the left pressure plate pressure gauge 20-2 via the left pressure plate lead wire 20-1;

[0050] The right pressure plate 7 is connected to the right pressure plate pressure gauge 22-2 via the right pressure plate lead wire 22-1;

[0051] The front pressure plate 25 is connected to the front pressure plate pressure gauge 23-2 via the front pressure plate lead wire 23-1;

[0052] The rear pressure plate 26 is connected to the rear pressure plate pressure gauge 24-2 via the rear pressure plate lead wire 24-1.

[0053] The pressure plates clamp the specimen 27 together, and the true triaxial stress loading of the specimen 27 is precisely achieved through independent and coordinated loading control in six directions.

[0054] The temperature-controlled liquid 5 fills the internal space of the panoramic in-situ CT inner shell 3. It flows through the outlet 29 and circulates within the panoramic in-situ CT inner shell 3, thereby precisely controlling the temperature inside the shell and achieving the test conditions in a hot bath environment.

[0055] like Figure 1 and Figure 5 As shown, the multi-functional pipeline 12 extends from the bottom of the panoramic in-situ CT outer shell 1 to the inner cavity of the panoramic in-situ CT inner shell 3 via a tower-structure steel 33, directly communicating with the space inside the inner shell. A first flow meter 13, a first pressure gauge 14, a multi-functional pipeline valve 15, a second flow meter 16, and a second pressure gauge 17 are installed on the outside of the multi-functional pipeline 12, and it is ultimately connected to the fracturing fluid control terminal 18. The front end structure of the multi-functional pipeline 12 is as follows... Figure 5 As shown, the device consists of multiple oblique cutting blades 34 and a main cutting blade 36. Fracturing fluid is introduced into the device through the fracturing fluid pipe port 35 to perform real-time hydraulic fracturing loading or other fluid loading experiments on the sample 27, while simultaneously achieving precise mechanical cutting of the sample 27. This front-end structure enables mechanical cutting and fluid injection to be carried out simultaneously in the same action position, which is different from existing experimental devices that only use a single fluid injection method for loading.

[0056] The specific connection and operation steps during the overall implementation process are as follows:

[0057] 1. First, place the sample 27 between the six pressure plates of the front and rear precession loading system 10, and ensure it is stable;

[0058] 2. Connect the pressure plate leads to each pressure gauge, and monitor and control the loading pressure in real time through the external pressure gauges;

[0059] 3. Start the temperature-controlled liquid circulation system so that the temperature-controlled liquid 5 enters the panoramic in-situ CT inner shell 3 through the temperature-controlled liquid inlet outlet 29 to establish a stable heat bath environment;

[0060] 4. The flow rate and pressure of the fracturing fluid in the multi-functional pipeline 12 are controlled by the fracturing fluid control terminal 18. The fracturing fluid is precisely regulated by the multi-functional pipeline valve 15, the first flow meter 13, the second flow meter 16, the first pressure meter 14, and the second pressure meter 17.

[0061] 5. During the test loading process, multiple X-ray tubes 2 rotate on the X-ray tube rotation track 28 to achieve a panoramic real-time CT scan of the sample 27, and the obtained data is transmitted to an external analysis terminal in real time;

[0062] 6. When a fracturing test is required, the sample surface is mechanically cut in real time using the oblique cutting blade 34 and the main cutting blade 36, and then the fracturing fluid is injected into the sample 27 through the fracturing fluid pipe port 35 to complete the test.

[0063] 7. After the fracturing and thermal recovery loading stages are completed, continue to run the temperature control system and the pre- and post-precession loading system 10 for a period of time to continuously observe the stable seepage state after the fracture expands, and perform multiple CT scans to obtain the final evolution results of the fracture morphology.

[0064] 8. Stop the operation of the loading and temperature control system, and gradually unload the precession loading system 10 to avoid sample damage or data distortion due to sudden stress changes;

[0065] 9. Disconnect the fracturing fluid control terminal 18 from the multi-functional pipeline 12, drain the residual fluid, and ensure the system is clean and easy to disassemble;

[0066] 10. Carefully remove specimen 27 and conduct subsequent structural observation, physical property testing or microscopic analysis on its surface and interior. Combine CT scan data to verify the crack distribution and its force-thermal-fluid response characteristics.

[0067] 11. Organize and analyze all monitoring data (such as temperature, pressure, flow rate, strain, scanning images, etc.) during the experiment, reconstruct the three-dimensional crack network model of the sample, and carry out cross-scale crack distribution and seepage behavior modeling;

[0068] 12. Complete the restoration and maintenance of the test system, including cleaning the panoramic in-situ CT shell 3 and multi-functional pipeline 12, checking the operating status of X-ray tube 2, and updating the fluid, to ensure that the system can continue to be used for the next set of tests.

[0069] Based on current research on fracture evolution, fracturing mechanism, and in-situ CT observation technology in materials such as rocks, it is known that under multi-field coupled loading conditions, the initiation and propagation behavior of internal fractures in samples is highly dependent on the initial structural disturbance form, stress path, and fluid intrusion mode.

[0070] Based on the above research conclusions and the structural design of this invention, under the synergistic effect of true triaxial stress, hydraulic loading, and hot bath environment, by introducing a disturbance zone formed by mechanical cutting on or near the surface of the sample, cracks can be effectively guided to preferentially initiate at a predetermined location and extend along a specific principal stress direction or its deflection direction during subsequent loading, thereby reducing the uncertainty of crack initiation and improving the controllability and repeatability of crack propagation path.

[0071] Meanwhile, existing research indicates that the initiation and rapid propagation stages of fractures are typically accompanied by nonlinear changes in loading parameters. Based on this, the present invention links the X-ray scanning system with the precession loading system 10, the hydraulic loading system, and the temperature control system. When significant changes occur in the loading parameters, the scanning frequency or timing is automatically adjusted, enabling continuous tomographic imaging of the fracture initiation and rapid propagation process. This avoids the loss of information on key evolutionary stages due to fixed scanning parameters.

[0072] Furthermore, under the combined loading conditions of a hot bath and water pressure, fluid is more likely to penetrate into the sample along the weakened areas of the structure and the tips of cracks, promoting enhanced crack connectivity. Through the synergistic configuration of cutting disturbance structures, water pressure loading, and the hot bath environment in this invention, the evolution of the internal structure of materials under complex force-heat-fluid coupling conditions can be simulated more realistically.

[0073] Therefore, through the above implementation process, this invention achieves multi-functional integration of hot bath environment control, precise water pressure loading, true triaxial stress independent loading, and panoramic real-time CT scanning. It clearly describes the specific connection methods between each part and the corresponding working process, and can realize the effective combination of true triaxial loading and real-time panoramic CT scanning under the coupled environment of water pressure and hot bath for precise experimental research on changes in the internal structure of materials.

[0074] Those skilled in the art to which this application pertains may modify or supplement the specific embodiments described or use similar methods to replace them, but without departing from the inventive concept of this application or exceeding the scope defined by the appended claims.

Claims

1. A water pressure thermotherapy coupled true triaxial loading and panoramic real-time CT scanning device, characterized in that, include: The panoramic in-situ CT shell (1) has a panoramic in-situ CT inner shell (3) located at its center. The front and rear precession loading system (10) is set in the inner shell (3) of the panoramic in-situ CT. The front and rear precession loading system (10) includes an upper pressure plate (6), a lower pressure plate (9), a left pressure plate (11), a right pressure plate (7), a front pressure plate (25), and a rear pressure plate (26). The six pressure plates surround to form a true triaxial loading space for clamping the sample (27), and each pressure plate is connected to an independent pressure monitoring device to realize independent monitoring and control of the loading force in six directions. The panoramic in-situ CT inner shell (3) is filled with temperature-controlled liquid (5), and is connected to the external temperature-controlled liquid circulation system through the inlet and outlet (29) of the temperature-controlled liquid to form a constant temperature heat bath environment in the loading space; The X-ray scanning system located inside the panoramic in-situ CT housing (1) includes multiple X-ray tubes (2) spaced apart along the circumferential direction of the inner wall of the panoramic in-situ CT housing (1) and an X-ray tube rotation track (28). The X-ray tubes (2) can rotate 360° around the sample (27) along the X-ray tube rotation track to achieve panoramic real-time CT imaging of the sample. The multi-functional pipeline system located at the bottom of the panoramic in-situ CT shell (1) includes a multi-functional pipeline (12) with one end connected to the interior of the panoramic in-situ CT shell (3) via a tower-type structural steel (33) and the other end connected to a fracturing fluid control terminal (18). The pipeline is equipped with a pressure regulating and flow monitoring device. The multifunctional pipe (12) is provided with a fracturing fluid pipe port (35), a main cutting blade (36) and multiple oblique cutting blades (34) at one end of the inner shell. The lower pressure plate (9) is provided with a through hole (9-1). The multifunctional pipe (12), the main cutting blade (36) and multiple oblique cutting blades (34) pass through the through hole (9-1) for mechanical disturbance and fluid injection on or near the surface of the sample (27).

2. The apparatus according to claim 1, characterized in that, The X-ray scanning system, together with the forward and backward precession loading system (10), the temperature-controlled liquid circulation system, and the multi-functional pipeline system, forms a multi-field loading control system. The multi-field loading control system is configured to monitor the rate of change of loading force, water pressure, and temperature in each loading direction in real time, and dynamically adjust the frequency or scanning mode of CT scanning based on the monitored parameter change rates.

3. The apparatus according to claim 2, characterized in that, The multi-field loading control system is specifically configured to automatically increase the CT scanning frequency from 0.01-0.05Hz to 0.1-1Hz, or switch the scanning mode from periodic scanning to continuous rapid scanning, when the axial or lateral loading force change rate is not less than 5% / min, or the water pressure change rate is not less than 0.5MPa / min, or the temperature change rate is not less than 2℃ / min.

4. The apparatus according to claim 2, characterized in that, The panoramic in-situ CT inner shell (3) is made of a high-temperature resistant material that is permeable to X-rays. The material is selected from one or more of alumina ceramics, silicon nitride ceramics, quartz glass or silicon carbide ceramics. Its long-term temperature resistance is not less than 300℃, its short-term temperature resistance is not less than 500℃, its compressive strength is not less than 300MPa, and its bending strength is not less than 200MPa.

5. The apparatus according to claim 2, characterized in that, The temperature control liquid (5) is one or more of water, silicone oil, ethylene glycol aqueous solution or high-temperature heat transfer oil; when the test temperature is not higher than 100℃, water or ethylene glycol aqueous solution is used; when the test temperature is higher than 100℃, silicone oil or high-temperature heat transfer oil is used.

6. The apparatus according to claim 2, characterized in that, The blade angle of the main cutting blade (36) is 30°-60° and the blade length is 5-20mm; the preset included angle between the multiple oblique cutting blades (34) and the axis of the main cutting blade or the main loading direction is 15°-60° and the blade thickness is 0.5-2mm.

7. The apparatus according to claim 6, characterized in that, The minimum distance between the blade tip of the oblique cutting blade (34) and the fracturing fluid pipe opening (35) is 1-10 mm, and the fracturing fluid pipe opening (35) is located in front of or to the side of the blade of the oblique cutting blade (34), so that the fracturing fluid can preferentially enter the disturbance zone formed by the oblique cutting blade when injected.

8. The apparatus according to claim 2, characterized in that, The main cutting blade (36) and the oblique cutting blade (34) are interchangeable.

9. The apparatus according to claim 2, characterized in that, It also includes a software platform for analyzing fracture evolution images, which is used to perform three-dimensional reconstruction, fracture identification, evolution path analysis and seepage channel modeling on image data acquired by CT scans, and to perform synchronous analysis with pressure, temperature and flow data during the loading process.

10. The apparatus according to claim 2, characterized in that, The upper pressure plate (6), lower pressure plate (9), left pressure plate (11), right pressure plate (7), front pressure plate (25) and rear pressure plate (26) are made of high-strength alloy steel or stainless steel; the main cutting blade (36) and oblique cutting blade (34) are made of high-strength alloy steel, tool steel or hard alloy.

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