Deep rock thermosetting fluid coupling test device and test method

Abstract

The invention discloses a deep rock thermosetting fluid coupling test device and a deep rock thermosetting fluid coupling test method. A confining pressure loading structure applies confining pressure to a rock sample on the periphery; different fluid pressure and temperature effects borne by deep rocks in the geothermal exploitation process can be simulated by adjusting the pressure and temperature of the first fluid in the test space and / or the second fluid in the accommodating cavity; the axial loading mechanism applies an axial force to the top construction of the rock sample through the axial loading plate, so that the axial pressure borne by the deep rock in the geothermal exploitation process can be simulated. Meanwhile, the rock sample is designed to comprise a plurality of ring sheet layers which are distributed in the radial direction and are tightly combined, and a temperature sensor and a damage state sensor are respectively embedded at the joints of the ring sheet layers, so that temperature and crack condition data of different radial areas of the rock sample can be obtained in real time; therefore, the mechanical behavior of the rock in the geothermal exploitation process can be more comprehensively and accurately simulated, and accurate and comprehensive test parameters can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of deep rock mechanics testing, and in particular to a deep rock thermal-solid-fluid coupling testing device and a testing method. Background Art

[0002] The thermal-fluid-solid coupling behavior of deep rocks is one of the key issues affecting underground energy development and deep space utilization. Taking geothermal energy development as an example, in the process of geothermal energy development, the multi-field physical coupling caused by cold liquid injection and hot liquid extraction has a significant impact on the rock. Specifically, the rapid temperature changes caused by cold liquid injection and hot liquid extraction will cause thermal expansion or contraction of the rock and generate thermal stress, thereby inducing microcracks or expanding existing cracks, which in turn affects the mechanical properties of the rock such as permeability, and affects the flow path and heat exchange efficiency of the hot fluid. At the same time, changes in fluid pressure will change the underground pore pressure, resulting in changes in the permeability and pore structure of the rock, which may cause compaction or collapse of the rock. Under the combined effect of these factors, the mechanical stability of the rock and the life of the geothermal well may be significantly affected.

[0003] Generally speaking, the induction or expansion of cracks is affected not only by the intrinsic properties of rocks (such as mineral composition and structure), but also by the combined effects of external stress, temperature change and fluid pressure. Therefore, if we can accurately simulate and measure the crack initiation and expansion behavior of deep rocks under different temperatures, fluid pressures and external pressures, it will be of great significance to improve the efficiency of geothermal energy extraction and predict the development trend of cracks.

[0004] At present, the research on the thermal-solid-fluid coupling behavior of deep rocks mainly relies on laboratory experiments and numerical simulations. However, the existing simulation tests still have shortcomings. The reason is that the existing simulation tests do not comprehensively consider the influence of different temperatures, fluid pressures and external pressure coupling on the initiation and propagation behavior of rock cracks. At the same time, when simulating the influence of temperature on the initiation and propagation behavior of rock cracks, the existing simulation tests do not consider the influence of the radial transfer velocity of temperature on the crack initiation and propagation behavior of rocks with the same or different characteristics. Therefore, it is difficult to simulate the mechanical behavior of rocks in the geothermal mining process and obtain accurate and comprehensive test parameters, which has weak guiding significance for improving the efficiency of geothermal energy mining and predicting the development trend of cracks. Summary of the invention

[0005] The main purpose of the present invention is to propose a deep rock thermal-solid-fluid coupling test device and test method, aiming to accurately and comprehensively simulate the mechanical behavior of rocks in the geothermal mining process and obtain accurate and comprehensive test parameters.

[0006] To achieve the above object, the present invention proposes a deep rock thermal-solid-fluid coupling test device, comprising:

[0007] A chamber, wherein a closable test space is defined inside the chamber, and the test space is connected to an external first fluid supply device so that the first fluid supply device can input a first fluid of a predetermined pressure and temperature into the test space;

[0008] A rock sample, which is in the shape of a circular tube with both ends open, and includes multiple radially distributed and tightly combined annular sheets. The rock sample is placed in the test space, and its lower end is supported by the supporting surface of the test space and the joint is sealed;

[0009] A plurality of temperature sensors are buried at the junction of two radially adjacent ring slice layers to detect the temperature of different areas of the rock sample;

[0010] A plurality of damage state sensors are embedded at the joints of two radially adjacent ring slice layers to detect crack conditions of each ring slice layer;

[0011] A plurality of strain gauges are provided on the rock sample and are used to detect at least one of the axial strain, radial strain and hoop strain of the rock sample;

[0012] An axial loading plate, the axial loading plate being placed on the top surface of the rock sample, and the axial loading plate and the top surface of the rock sample being sealed, so that the support surface, the loading plate and the inner periphery of the rock sample together form a closable accommodation cavity, and the accommodation cavity is connected to an external second fluid supply device, so that the second fluid supply device can input a second fluid of a predetermined pressure and temperature into the accommodation cavity;

[0013] An axial loading mechanism, used to apply a predetermined axial pressure to the top surface of the rock sample through an axial loading plate;

[0014] A confining pressure loading structure, used for applying confining pressure to the rock sample at the periphery; and

[0015] The data acquisition system is used to collect and record the data detected by the temperature sensor, damage status sensor, and strain gauge.

[0016] To achieve the above object, the present invention also proposes a deep rock thermal-solid-fluid coupling test method, comprising the following steps:

[0017] S1. Prepare rock samples and arrange temperature sensors, damage state sensors and strain gauges on the rock samples;

[0018] S2. Install the test device and apply confining pressure to the rock sample at the periphery;

[0019] S3. According to the test requirements, the first fluid and the second fluid with a certain pressure and temperature are respectively input into the test space and the containing cavity, and the axial loading mechanism applies axial pressure to the top surface of the rock sample through the axial loading plate;

[0020] S4, adjusting the temperature and pressure of the first fluid and / or the second fluid to simulate the pressure and temperature changes during geothermal energy development;

[0021] S5. Collect and record the data detected by the temperature sensor, damage status sensor, and strain gauge respectively through the data acquisition system.

[0022] The technical solution of the present invention applies confining pressure to the rock sample at the periphery through the confining pressure loading structure, which can simulate the confining pressure effect on the deep rock during geothermal mining; by adjusting the pressure and temperature of the first fluid in the test space and / or the second fluid in the accommodating chamber, the different fluid pressures and temperatures on the deep rock during geothermal mining can be simulated; the axial loading mechanism applies axial force to the top of the rock sample through the axial loading plate, which can simulate the axial pressure on the deep rock during geothermal mining. Therefore, the present invention can simultaneously simulate the coupling effect of different external pressures (including confining pressure and axial pressure), temperature and fluid pressure on deep rock during geothermal mining, so as to comprehensively study the influence of different temperatures, fluid pressures and external pressure coupling effects on rock crack initiation and expansion behavior. At the same time, the technical solution of the present invention designs the circular tubular rock sample with open ends to include multiple layers of radially distributed and tightly combined ring slices, and buries temperature sensors and damage state sensors at the junctions of two radially adjacent ring slices, respectively, so that the temperature and crack condition data of different radial regions of the rock sample can be obtained in real time, thereby obtaining the influence of different temperatures and different temperature transfer speeds on the crack initiation and expansion behavior of rocks with the same or different characteristics. Based on this, the present invention can more comprehensively and accurately simulate the mechanical behavior of rocks in the geothermal mining process and obtain accurate and comprehensive test parameters, which has a high guiding significance for improving the efficiency of geothermal energy mining and predicting the development trend of cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] Figure 2 It is a three-dimensional schematic diagram of the matching state of the confining pressure loading structure and the rock sample of the present invention;

[0025] Figure 3 A top view of the matching state of the confining pressure loading structure and the rock sample of the present invention;

[0026] Figure 4 The schematic diagram of the decomposition of rock samples;

[0027] Figure 5 is a schematic diagram of one of the circumferentially adjacent segments;

[0028] Figure 6 A schematic diagram of another circumferentially adjacent segment. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial...), then the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] In addition, if there are descriptions involving "first" or "second" etc. in the embodiments of the present invention, the descriptions of "first" or "second" etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] On the one hand, the present invention provides a deep rock thermal-solid-fluid coupling test device.

[0033] In the embodiment of the present invention, Figure 1-6 As shown, the deep rock thermal-solid-fluid coupling test device includes a cabin 1, a rock sample 2, multiple temperature sensors 3, multiple damage state sensors 4, multiple strain gauges, an axial loading plate 11, an axial loading mechanism 100, a confining pressure loading structure 5 and a data acquisition system (not shown).

[0034] The cabin 1 defines a closable test space 10 inside, and the test space 10 is connected to the external first fluid supply device 200, so that the first fluid supply device 200 can input the first fluid of predetermined pressure and temperature into the test space 10. The cabin 1 can be made of glass, acrylic or engineering plastics with relatively high strength, and the whole can be a cubic box structure, and the test space 10 is formed inside. During the test, the test space 10 should be in a closed state to avoid fluid leakage. The rock sample 2 is in the shape of a circular tube with open ends, including multiple radially distributed and tightly combined annular layers 21. The rock sample 2 is placed in the test space 10, and its lower end is supported by the supporting surface of the test space 10 and the joint is sealed. A plurality of temperature sensors 3 are buried at the joints of the two radially adjacent annular layers 21, and are used to detect the temperature of different areas of the rock sample 2. A plurality of damage state sensors 4 are buried at the joints of the two radially adjacent annular layers 21, and are used to detect the crack conditions of each annular layer 21. A plurality of strain gauges are provided on the rock sample 2 for detecting at least one of the axial strain, radial strain and circumferential strain of the rock sample 2. The axial loading plate 11 is placed on the top surface of the rock sample 2, and the axial loading plate 11 is sealed with the top surface of the rock sample 2, so that the support surface, the axial loading plate 11 and the inner periphery of the rock sample 2 form a closable accommodating chamber 20, and the accommodating chamber 20 is connected to the external second fluid supply device 300, so that the second fluid supply device 300 can input a second fluid of a predetermined pressure and temperature into the accommodating chamber 20; the axial loading mechanism 100 is used to apply a predetermined axial pressure to the top surface of the rock sample 2 through the axial loading plate 11. The confining pressure loading structure 5 is used to apply confining pressure to the rock sample 2 at the periphery to simulate the confining pressure that the rock is subjected to during geothermal mining. The data acquisition system is used to collect and record the data detected by the temperature sensor 3, the damage state sensor 4, and the strain gauge.

[0035] The technical solution of the present invention applies confining pressure to the rock sample 2 at the periphery through the confining pressure loading structure 5, which can simulate the confining pressure effect on the deep rock during geothermal mining; by adjusting the pressure and temperature of the first fluid in the test space 10 and / or the second fluid in the accommodating chamber 20, the different fluid pressures and temperatures on the deep rock during geothermal mining can be simulated; the axial loading mechanism 100 applies axial force to the top of the rock sample 2 through the axial loading plate 11, which can simulate the axial pressure on the deep rock during geothermal mining. Therefore, the present invention can simultaneously simulate the coupling effect of different external pressures (including confining pressure and axial pressure), temperature and fluid pressure on the deep rock during geothermal mining, so as to comprehensively study the influence of different temperatures, fluid pressures and external pressure coupling effects on the initiation and expansion behavior of rock cracks. At the same time, the technical solution of the present invention designs the circular tubular rock sample 2 with open ends to include multiple layers of radially distributed and tightly combined annular sheets 21, and the temperature sensors 3 and damage state sensors 4 are respectively buried at the joints of the two radially adjacent annular sheets 21, so that the temperature and crack condition data of different radial regions of the rock sample 2 can be obtained in real time, so as to obtain the influence of different temperatures and different temperature transfer speeds on the crack initiation and expansion behavior of rocks with the same or different characteristics. Based on this, the present invention can more comprehensively and accurately simulate the mechanical behavior of rocks in the geothermal mining process and obtain accurate and comprehensive test parameters for subsequent research and analysis, which has a high guiding significance for improving the efficiency of geothermal energy mining and predicting the development trend of cracks. As for how to analyze specifically, the existing technology can be used, and it will not be repeated here. This experiment is mainly to obtain accurate and comprehensive test data.

[0036] It can be understood that the damage state sensor 4 is a damage state sensor based on piezoelectric ceramics, which belongs to the prior art and is well known to technicians in this field. When the structure is damaged (such as cracks, fatigue, impact, etc.), stress waves or vibrations will be generated. The piezoelectric ceramic piece of the damage state sensor 4 will generate charge signals after sensing these stress waves or vibrations. These charge signals are collected through its electrodes and transmitted to the signal processing circuit through wires. The processing unit analyzes the data, and then analyzes the damage condition of the rock through feature extraction, pattern recognition and other methods, thereby obtaining the induction or expansion of cracks in the corresponding area of ​​the rock sample 2 in real time.

[0037] It is understandable that the first fluid and the second fluid can be liquid fluids with good fluidity such as water or oil. In some embodiments, the first fluid is oil and the second fluid is water.

[0038] The bottom of the axial loading plate or the cabin 1 is provided with a second fluid inlet (not marked) and a second fluid outlet (not marked) connected to the accommodating chamber 20, the second fluid inlet is connected to the input end (not marked) of the second fluid supply device 300, and the second fluid outlet is connected to the return end (not marked) of the second fluid supply device 300, thereby forming a second fluid circuit. By adjusting the temperature, pressure and speed of the second fluid in and out of the accommodating chamber 20, the cold liquid injection and hot liquid extraction process of the geothermal well in the geothermal mining process can be simulated. The second fluid supply device 300 is a prior art, such as including components such as an oil tank, a pressure pump, a pipeline and a valve (if necessary), and its specific structure and working principle are not described in detail here.

[0039] The cabin 1 has a first fluid inlet 12 and a first fluid outlet 13, which are respectively connected to the output end (not indicated) and the return end (not indicated) of the first fluid supply device 200, and form a first fluid loop. By adjusting the temperature, pressure and speed of the first fluid entering and exiting the test space 10, different fluid pressures and temperatures around the geothermal well can be simulated. The first fluid supply device 200 is a prior art, such as a water tank, a pressure pump, a pipeline and a valve (if necessary), and its specific structure and working principle are not described in detail here.

[0040] In some embodiments of the present invention, the confining pressure loading structure 5 has various implementations, for example, it can be rock and soil filling the gap between the inner wall of the test space 10 and the rock sample 2. Alternatively, it can be implemented as follows: Figure 1-3 In the embodiment shown, in this embodiment, the confining pressure loading structure 5 includes a sleeve 51 which is sleeved on the rock sample 2 and in close contact with the outer peripheral surface of the rock sample 2, and an adjustment wire 52 which is bounded on the outer periphery of the sleeve 51. The adjustment wire 52 is made of a relatively high-strength metal material. By adjusting the tightening force of the adjustment wire 52 on the sleeve 51, the confining pressure applied by the sleeve 51 to the rock sample 2 can be adjusted.

[0041] It should be noted that before applying the confining pressure, the different confining pressures corresponding to the tightening degree of the adjustment line 52 need to be calibrated to facilitate the loading operation of the confining pressure. Specifically, a calibration sleeve (not shown) of the same shape and size is prepared in advance, and a stress sensor (not shown) is attached to the inside of the calibration sleeve and the outside of the rock sample 2, and then different confining pressure values ​​are obtained by changing the tightening degree of the adjustment line 52. Finally, mark the adjustment line 52, and record the confining pressure value generated by the corresponding marked point. During the test, the corresponding tightening degree of the adjustment line 52 can be adjusted according to the confining pressure value to be applied.

[0042] It is understandable that the material of the pipe sleeve 51 can be a relatively strong metal, plastic or carbon fiber, etc. Metal is preferred to ensure that the outer periphery of the rock sample 2 is subjected to uniform force during the test.

[0043] Furthermore, when the pipe sleeve 51 is made of metal, the present invention also includes an electromagnetic coil 7 that is wound around the outer periphery of the cabin 1 and corresponds to the metal pipe sleeve 51. The electromagnetic coil 7 is connected to a power supply. When the electromagnetic coil 7 is energized, a magnetic field can be generated in the test space 10, so that the metal pipe sleeve 51 generates heat under the action of the magnetic field, and works in coordination with the second fluid to heat the rock sample 2, thereby improving the heating efficiency.

[0044] It can be understood that there are many ways to implement the sealing treatment between the top surface of the rock sample 2 and the axial loading plate 11 and the joint between the lower end of the rock sample 2 and the supporting surface. In a preferred embodiment, a sealing ring (not shown) is provided between the top surface of the rock sample 2 and the axial loading plate and the joint between the lower end of the rock sample 2 and the supporting surface. The sealing ring can cover the entire top surface and bottom surface of the rock sample 2, or partially cover it. The material of the sealing ring can be selected from materials with excellent elasticity and waterproof performance, such as silicone, rubber, polyurethane, etc.

[0045] In some embodiments, waterproof rings may be attached to the top and bottom surfaces of the innermost ring sheet layer 21 and the outermost ring sheet layer 21, respectively, to form an effective seal.

[0046] It can be understood that the strain gauge includes at least one of an axial strain gauge 61, an annular strain gauge (not shown) and a radial strain gauge 62. The axial strain gauge 61 can be axially attached to the inner circumferential wall of the rock sample 2, and the number is one or more. The radial strain gauge 62 can be radially attached to the top surface and / or bottom surface of the rock sample 2, and the number is one or more. The annular strain gauge can be circumferentially attached to the circumferential wall of at least one annular sheet layer 21, and the number can also be one or more. When the axial strain gauge 61, the annular strain gauge and the radial strain gauge 62 are set at the same time, the data obtained is more comprehensive, but the corresponding cost is higher. Strain gauges belong to the prior art and are well known to those skilled in the art, and their specific structure and working principle are not described here.

[0047] In some embodiments of the present invention, radially adjacent ring sheet layers 21 may be tightly combined together by means of a gap or interference fit, or may be tightly combined together by means of waterproof adhesive fixation.

[0048] Each ring sheet layer 21 can be an integrally formed structure, but when the ring sheet layer 21 adopts an integrally formed structure, the close connection between the ring sheet layers 21 and the embedding operation of components such as the temperature sensor 3 and the damage state sensor 4 are relatively complicated and inefficient. Therefore, each ring sheet layer 21 can be formed by connecting at least two adjacent tube sheets 211 and 212 (two pieces are shown in the figure). The two circumferentially adjacent tube sheets 211 and 212 are tightly connected together through a mortise and tenon structure, providing an circumferential constraint force between the two circumferentially adjacent tube sheets 211 and 212 to prevent the relative movement between the two, and a sealing strip 2122 is provided at the connection between the circumferentially adjacent tube sheets 211 and 212 to play a waterproof role.

[0049] Specifically, one of the two opposite sides of the two circumferentially adjacent pipe segments 211, 212 is formed with a trapezoidal tenon 2111 with a large end and a small root, and the other is formed with an open groove 2121 that matches the tenon 2111. When the tenon 2111 and the open groove 2121 of the two circumferentially adjacent pipe segments 211, 212 are radially opposite and clamped, the connection between the two circumferentially adjacent pipe segments 211, 212 is completed. Otherwise, disassembly is achieved, and the operation is very simple.

[0050] In some embodiments of the invention, the ring sheet layer 21 is formed with a first receiving groove (not shown) for accommodating the temperature sensor 3 and its wires. The temperature sensor 3 is placed in the first receiving groove, and its wires are led out of the rock sample 2 along the axial direction of the first receiving groove, and finally electrically connected to the data acquisition system outside the cabin 1. The first receiving groove can be filled with waterproof glue or cement to bury the temperature sensor 3 and its wires in the ring sheet layer 21. Similarly, the ring sheet layer 21 is also formed with a second receiving groove (not shown) for accommodating the damage state sensor 4 and its wires. The damage state sensor 4 is placed in the second receiving groove, and its wires are led out of the rock sample 2 along the axial direction of the second receiving groove, and finally electrically connected to the data acquisition system outside the cabin 1. The second receiving groove is filled with waterproof glue or cement to bury the damage state sensor 4 and its wires in the ring sheet layer 21. Of course, the temperature sensor 3 and the damage state sensor 4 can also be pre-buried in the ring sheet layer 21 when the ring sheet layer 21 is manufactured.

[0051] In the embodiment of the present invention, each ring sheet layer 21 is a rock sample layer with the same or different characteristics, which can be cast in a mold, and after molding, necessary grinding can be performed. There are many implementation methods for the selection of each component of the ring sheet layer and the distribution ratio of each component in the prior art, which are well known to those skilled in the art and will not be described in detail here.

[0052] It should be noted that the axial loading mechanism 100 adopts existing technology, such as an existing servo pressure loading device, a hydraulic press, a device cylinder or a hydraulic cylinder, etc., and its pressure rod is connected to the axial loading plate 11. The servo pressure loading device is driven by a servo motor to drive a ball screw to load, unload and maintain pressure in the axial direction. The axial loading mechanism 100 can be electrically connected to a controller provided separately, so that the axial loading mechanism 100 can be set by the controller to apply a predetermined axial force to the rock sample 2 before or during the test.

[0053] After introducing the implementation of the deep rock thermal-solid-fluid coupling test device of the present invention, the implementation of the deep rock thermal-solid-fluid coupling test method of the present invention will be introduced next.

[0054] In an embodiment of the present invention, the deep rock thermal-solid-fluid coupling test method comprises the following steps:

[0055] S1. Prepare a rock sample 2, and arrange a temperature sensor 3, a damage state sensor 4 and a strain gauge on the rock sample 2.

[0056] In the embodiment of the present invention, each ring sheet layer is a rock sample layer with the same or different characteristics, which can be cast in a mold, and after forming, necessary grinding can be performed. There are many implementation methods for the selection of each component of the ring sheet layer and the distribution ratio of each component in the prior art, which are well known to those skilled in the art and will not be described in detail here.

[0057] In some embodiments of the present invention, radially adjacent ring sheet layers 21 may be tightly combined together by means of a gap or interference fit, or may be tightly combined together by means of waterproof adhesive fixation.

[0058] Each ring sheet layer 21 may be an integrally formed structure, but when the ring sheet layers 21 are integrally formed, the close connection between the ring sheet layers 21 and the embedding of components such as the temperature sensor 3 and the damage status sensor 4 are relatively complex and inefficient. Therefore, each ring sheet layer 21 may be composed of at least two sheets (such as Figure 2 , 3 The two adjacent segments 211 and 212 are connected together by a mortise and tenon structure, which provides an annular restraining force to prevent the relative movement between the two adjacent segments 211 and 212, and a sealing strip 2122 is provided at the connection between the adjacent segments 211 and 212 to play a waterproof role.

[0059] The strain gauge includes at least one of an axial strain gauge 61, an annular strain gauge (not shown) and a radial strain gauge 62. The axial strain gauge 61 can be axially attached to the inner circumferential wall of the rock sample 2, and the number is one or more. The radial strain gauge can be radially attached to the top surface and / or bottom surface of the rock sample 2, and the number is one or more. The annular strain gauge can be circumferentially attached to the circumferential wall of at least one annular sheet layer 21, and the number can also be one or more. When the axial strain gauge 61, the annular strain gauge and the radial strain gauge 62 are set at the same time, the acquired data is more comprehensive, but the corresponding cost is higher.

[0060] Specifically, one of the two sides of the two circumferentially adjacent segments 211 and 212 is formed with a trapezoidal tenon 2111 with a large end and a small root, and the other is formed with an open groove 2121 that matches the tenon 2111, so that the tenon 2111 and the open groove 2121 of the two circumferentially adjacent segments 211 and 212 are radially opposite to each other (see Figure 4 ) and after being clamped, the connection between the two circumferentially adjacent pipe segments 211 and 212 is completed. The reverse operation can realize disassembly, and the operation is very simple.

[0061] In some embodiments of the invention, the ring sheet layer 21 is formed with a first receiving groove (not shown) for accommodating the temperature sensor 3 and its wires. The temperature sensor 3 is placed in the first receiving groove, and its wires are led out of the rock sample 2 along the axial direction of the first receiving groove, and finally electrically connected to the data acquisition system outside the cabin 1. The first receiving groove is filled with waterproof glue or cement to bury the temperature sensor 3 and its wires in the ring sheet layer 21. Similarly, the ring sheet layer 21 is also formed with a second receiving groove (not shown) for accommodating the damage state sensor 4 and its wires. The damage state sensor 4 is placed in the second receiving groove, and its wires are led out of the rock sample 2 along the axial direction of the second receiving groove, and finally electrically connected to the data acquisition system outside the cabin 1. The second receiving groove is filled with waterproof glue or cement to bury the damage state sensor 4 and its wires in the ring sheet layer 21. Of course, the temperature sensor 3 and the damage state sensor 4 can also be pre-buried in the ring sheet layer 21 when the ring sheet layer 21 is manufactured.

[0062] S2. Install the test device and apply confining pressure to the rock sample 2 on the periphery.

[0063] It should be noted that the specific structure of the test device can be found in the above embodiment and will not be repeated here.

[0064] In some embodiments of the present invention, there are multiple implementations of applying the confining pressure, for example, rock and soil may be filled between the inner wall of the test space 10 and the gap between the rock sample 2. Alternatively, an implementation as shown in the figure may be adopted. In this embodiment, the step of applying the confining pressure includes a process of sleeve 51 being sleeved on the outer peripheral surface of the rock sample 2, and tightening the sleeve 51 to a desired degree at the outer periphery of the sleeve 51 by adjusting the wire 52.

[0065] S3. According to the test requirements, the first fluid and the second fluid of certain pressure and temperature are respectively input into the test space 10 and the accommodating chamber 20, and the axial loading mechanism 100 applies axial pressure to the top surface of the rock sample 2 through the axial loading plate 11.

[0066] It can be understood that there are many ways to implement the sealing treatment between the top surface of the rock sample 2 and the axial loading plate 11 and the joint between the lower end of the rock sample 2 and the supporting surface. In a preferred embodiment, a sealing ring (not shown) can be provided between the top surface of the rock sample 2 and the axial loading plate 11 and the joint between the lower end of the rock sample 2 and the supporting surface. The sealing ring can cover the entire top surface and the bottom surface of the rock sample 2, or can cover part of it. The material of the sealing ring can be selected from materials with excellent elasticity and waterproof performance, such as silicone, rubber, polyurethane, etc.

[0067] S4, adjusting the temperature and pressure of the first fluid and / or the second fluid to simulate the pressure and temperature changes during geothermal energy development;

[0068] When the pipe sleeve 51 is made of metal, the present invention also includes a process of energizing the electromagnetic coil wound around the outer periphery of the cabin 1 to make the metal pipe sleeve 51 generate heat under the action of the magnetic field, thereby working in conjunction with the second fluid to heat the rock sample 2, thereby improving the heating efficiency.

[0069] S5. The data detected by the temperature sensor 3, the damage state sensor 4, and the strain gauge are collected and recorded through the data acquisition system. This is for subsequent research and analysis, and has a high guiding significance for improving the efficiency of geothermal energy extraction and predicting the development trend of cracks. As for how to analyze specifically, existing technologies can be used, and no further description will be given here. This test is mainly to obtain accurate and comprehensive test data.

[0070] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. Deep rock thermal solid-fluid coupling test device, characterized in that: include: A chamber, wherein a closable test space is defined inside the chamber, and the test space is connected to an external first fluid supply device so that the first fluid supply device can input a first fluid of a predetermined pressure and temperature into the test space; A rock sample, which is in the shape of a circular tube with both ends open, and includes multiple radially distributed and tightly combined annular sheets. The rock sample is placed in the test space, and its lower end is supported by the supporting surface of the test space and the joint is sealed; A plurality of temperature sensors are buried at the junction of two radially adjacent ring slice layers to detect the temperature of different areas of the rock sample; A plurality of damage state sensors are embedded at the joints of two radially adjacent ring slice layers to detect crack conditions of each ring slice layer; A plurality of strain gauges are provided on the rock sample and are used to detect at least one of the axial strain, radial strain and hoop strain of the rock sample; An axial loading plate, the axial loading plate being placed on the top surface of the rock sample, and the axial loading plate and the top surface of the rock sample being sealed, so that the support surface, the loading plate and the inner periphery of the rock sample together form a closable accommodation cavity, and the accommodation cavity is connected to an external second fluid supply device, so that the second fluid supply device can input a second fluid of a predetermined pressure and temperature into the accommodation cavity; An axial loading mechanism, used to apply a predetermined axial pressure to the top surface of the rock sample through an axial loading plate; The confining pressure loading structure is used to apply confining pressure to the rock sample at the periphery; as well as The data acquisition system is used to collect and record the data detected by the temperature sensor, damage status sensor, and strain gauge.

2. The deep rock thermal-solid-fluid coupling test device according to claim 1, characterized in that: The confining pressure loading structure comprises a pipe sleeve which is sleeved on the rock sample and in close contact with the outer peripheral surface of the rock sample, and an adjustment line which is bounded on the outer periphery of the pipe sleeve.

3. The deep rock thermal-solid-fluid coupling test device according to claim 2, characterized in that: The invention also comprises an electromagnetic coil which is wound around the outer periphery of the cabin and corresponds to the metal pipe sleeve, and the electromagnetic coil is connected to a power source.

4. The deep rock thermal-solid-fluid coupling test device according to claim 1, characterized in that: The top surface and the bottom surface of the innermost ring sheet layer and the outermost ring sheet layer are respectively provided with waterproof rings.

5. The deep rock thermal-solid-fluid coupling test device according to claim 1, characterized in that: The strain gauge includes at least one of an axial strain gauge, an annular strain gauge and a radial strain gauge. The axial strain gauge is axially attached to the inner circumferential wall of the rock sample; the radial strain gauge is radially attached to the top surface and / or bottom surface of the rock sample; and the annular strain gauge is annularly attached to the circumferential wall of at least one annular sheet layer.

6. The deep rock thermal-solid-fluid coupling test device according to claim 1, characterized in that: The annular sheet layer is formed by connecting at least two adjacent tube sheets. The two annularly adjacent tube sheets are tightly connected together through a mortise and tenon structure, and a sealing strip is provided at the connection.

7. The deep rock thermal-solid-fluid coupling test device according to claim 1, characterized in that: One of the two opposite sides of the two circumferentially adjacent pipe segments is formed with a trapezoidal tenon portion with a large end and a small root, and the other is formed with an open groove matching the tenon portion, and the two are clamped together by the matching of the trapezoidal tenon portion and the open groove.

8. A test method using the deep rock thermal-solid-fluid coupling test device according to any one of claims 1 to 7, characterized in that: Includes steps: S1. Prepare rock samples and arrange temperature sensors, damage state sensors and strain gauges on the rock samples; S2. Install the test device and apply confining pressure to the rock sample at the periphery; S3. According to the test requirements, the first fluid and the second fluid with a certain pressure and temperature are respectively input into the test space and the containing cavity, and the axial loading mechanism applies axial pressure to the top surface of the rock sample through the axial loading plate; S4, adjusting the temperature and pressure of the first fluid and / or the second fluid to simulate the pressure and temperature changes during geothermal energy development; S5. Collect and record the data detected by the temperature sensor, damage status sensor, and strain gauge respectively through the data acquisition system.

9. The test method according to claim 8, characterized in that: The step of applying confining pressure includes putting a sleeve on the outer peripheral surface of the rock sample and tightening the sleeve to a desired degree around the outer periphery of the sleeve by adjusting the wire.

10. The test method according to claim 8, characterized in that: The step S3 also includes a process of energizing the electromagnetic coil wound around the outer periphery of the cabin so that the metal pipe sleeve generates heat under the action of the magnetic field.

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