A rock deformation direct measurement device under high temperature and high pressure environment

Abstract

The application belongs to the field of rock mechanics test equipment, and particularly relates to a rock deformation direct measurement device under high temperature and high pressure environment, aiming to solve the technical problem that the prior art cannot directly and accurately measure the axial and radial deformation of rock under high temperature and high pressure. The device comprises a triaxial pressure chamber, an axial deformation direct measurement assembly and a radial deformation direct measurement assembly. The axial and radial deformation direct measurement assemblies are both arranged in the triaxial pressure chamber, and each comprises a sensor for directly measuring the axial and radial deformation of a rock sample, and an independent cooling structure for locally cooling the sensor. The built-in circulating cooling system is used to ensure the stable work of the sensor under high temperature and high pressure environment. The application realizes direct and high-precision measurement of rock deformation, effectively eliminates additional errors such as pad deformation, can accurately obtain key mechanical parameters such as elastic modulus and Poisson's ratio of rock, and meets the test requirements in the field of deep energy development.

Description

Technical Field

[0001] This invention belongs to the field of rock mechanics testing equipment, and specifically relates to a device for directly measuring rock deformation under high temperature and high pressure conditions. Background Technology

[0002] As energy development moves towards deeper and ultra-deeper layers, engineering fields such as shale oil cracking and conversion, and thermal energy extraction from hot dry rocks place stringent demands on rock mechanical property testing. In these scenarios, the rock environment typically features high temperature (up to 300℃) and high pressure (confining pressure up to 300 MPa), and its fracture deformation patterns directly determine the safety and economy of engineering design.

[0003] Current rock mechanics tests mostly employ triaxial presses combined with conventional displacement measurement methods. The core drawback is the inability to directly measure rock deformation under high temperature and high pressure conditions: First, axial deformation measurements generally use the displacement of the loading piston to replace the actual rock deformation. This displacement includes the deformation of the upper and lower pads, the deformation of the contact surface between the pads and the rock, and the elastic deformation of the equipment itself, resulting in measurement results that are 30% to 50% overestimated. Consequently, the calculated rock elastic modulus is underestimated and cannot reflect the true mechanical properties. Second, there is a lack of effective means for radial deformation measurement. Traditional strain gauges are susceptible to corrosion by high temperature and high pressure media and are cumbersome to install. Optical measurements fail in turbid liquid media, making it impossible to accurately obtain key parameters such as Poisson's ratio.

[0004] While existing high-temperature and high-pressure displacement sensing technologies have made breakthroughs—for example, the high-temperature LVDT displacement sensor disclosed in CN110487161A achieves 300℃ environmental adaptation through oil flow cooling, and the high-temperature and high-pressure LVDT sensor proposed in CN109342186A achieves radial measurement at 600℃ through a cooling water jacket—neither of these technologies is integrated with a triaxial pressure chamber design, thus failing to simultaneously meet the direct measurement requirements of axial and radial deformation, and also failing to address the interference problem caused by pad deformation. Therefore, there is an urgent need to develop an integrated testing device to achieve direct and accurate measurement of rock deformation under high temperature and high pressure. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, namely the inability of existing technologies to directly and accurately measure the axial and radial deformation of rocks under high temperature and high pressure, this invention provides a direct rock deformation measurement device under high temperature and high pressure conditions. The device comprises:

[0006] A triaxial pressure chamber is used to contain rock samples and provide a testing environment for the rock samples.

[0007] An axial deformation direct measurement component is disposed in the triaxial pressure chamber. The axial deformation direct measurement component includes at least one axial sensor and a first cooling structure for cooling the axial sensor. The axial sensor is used to directly measure the axial deformation of the rock sample.

[0008] A radial deformation direct measurement assembly is disposed in the triaxial pressure chamber. The radial deformation direct measurement assembly includes at least one radial sensor and a second cooling structure for cooling the radial sensor. The radial sensor is used to directly contact the rock sample and measure the radial deformation of the rock sample.

[0009] Furthermore, the triaxial pressure chamber is provided with an upper pad and a lower pad, and the rock sample is clamped between the upper pad and the lower pad; it also includes an upper chuck and a lower chuck for fixing the upper pad and the lower pad, respectively;

[0010] The axial sensor is configured to measure the relative displacement between the upper chuck and the lower chuck to characterize the axial deformation of the rock sample.

[0011] Furthermore, the first cooling structure includes a cooling upper cover and a cooling lower housing, the cooling upper cover and the cooling lower housing together forming a first circulation cavity for accommodating the axial sensor;

[0012] The axial deformation direct measurement component also includes an axial displacement transmission rod, one end of which is fixed to the upper chuck, and the other end passes through the cooling upper cover and abuts against the sensing end of the axial sensor to transmit the displacement of the upper chuck to the axial sensor.

[0013] A first seal is provided between the axial displacement transmission rod and the cooling upper cover to isolate the first circulation chamber from the internal test environment of the triaxial pressure chamber.

[0014] Furthermore, the axial deformation direct measurement component includes two sets of axial sensors symmetrically arranged about the central axis of the rock sample, and correspondingly provided with two sets of the first cooling structure and two sets of the axial displacement transmission rods;

[0015] Both sets of axial sensors and the corresponding first cooling structure are mounted on the lower chuck;

[0016] Each of the first circulation chambers is connected to the coolant source through an axial sensor coolant inlet pipe and an axial sensor coolant outlet pipe.

[0017] Furthermore, the radial sensor has an encapsulation structure, and the second cooling structure is disposed within the encapsulation structure in a built-in form.

[0018] Furthermore, the packaging structure includes a packaging shell and a packaging inner shell;

[0019] It also includes a sensing rod, which is movably inserted through the encapsulation housing and cooperates with the body of the radial sensor, and a dynamic seal is provided between the sensing rod and the encapsulation housing;

[0020] The encapsulation shell has a coolant inlet and a coolant outlet;

[0021] A plurality of second seals are provided between the outer casing and the inner casing, and the second seals, the outer casing and the inner casing together define a second circulation cavity that serves as the second cooling structure;

[0022] Thermal insulation material is also provided between the inner casing of the package and the body of the radial sensor.

[0023] Furthermore, the radial deformation direct measurement assembly also includes a radial chain on which the radial sensor is mounted to surround the side surface of the rock sample.

[0024] Furthermore, the second cooling structure is connected to a coolant source via a flexible tube, which includes a radial sensor coolant inlet tube and a radial sensor coolant outlet tube, and is capable of bending with the radial deformation of the rock sample.

[0025] Furthermore, it also includes a high-temperature circulation pipe disposed in the triaxial pressure chamber, the high-temperature circulation pipe being used to circulate high-temperature fluid to heat the rock sample.

[0026] Furthermore, the triaxial pressure chamber includes:

[0027] Pressure chamber housing and pressure chamber base;

[0028] An inner pressure chamber shell is disposed within the outer shell of the pressure chamber, and a main sealing element is provided between the inner pressure chamber shell and the outer shell of the pressure chamber;

[0029] An upper connecting cover is provided on the top of the pressure chamber shell;

[0030] The piston is movably inserted into the upper connecting cover;

[0031] The upper and lower insulation layers are respectively disposed at the top and bottom of the interior of the triaxial pressure chamber;

[0032] The third cooling structure is provided on the inner shell of the pressure chamber and is used to locally cool the main seal. The third cooling structure includes a third circulation chamber and a fourth circulation chamber that are interconnected.

[0033] The third cooling structure also has a housing coolant inlet and a housing coolant outlet. The housing coolant inlet is in fluid communication with the third circulation chamber, and the housing coolant outlet is in fluid communication with the fourth circulation chamber, thereby forming a complete coolant circulation path.

[0034] The beneficial effects of this invention are:

[0035] This invention enables direct and high-precision measurement of rock deformation under high temperature and high pressure conditions, fundamentally eliminating the systematic errors of traditional measurement methods. Its axial deformation direct measurement component effectively avoids additional errors introduced by the elastic deformation of the loading piston, pads, and the equipment itself by measuring the relative displacement between the upper and lower chucks that are in direct contact with the rock sample, resulting in more realistic and accurate calculations of the elastic modulus. Simultaneously, its radial deformation direct measurement component solves the problem of traditional techniques being unable to effectively measure radial deformation in high-temperature and high-pressure fluid media by mounting the sensor on a radial chain surrounding the sample, allowing the sensing end to directly contact the rock's side surface. This enables precise acquisition of the key mechanical parameter, Poisson's ratio.

[0036] This invention, through a sophisticated local cooling and isolation design, ensures the stability and reliability of the measuring sensor under extreme testing environments. The axial sensor is housed within a first circulation chamber with an independent cooling loop and is isolated from the high-temperature zone by a sealed displacement transmission rod. The radial sensor employs an encapsulation structure with an internal cooling circulation chamber and thermal insulation material, forming a self-consistent low-temperature island. These designs maintain the operating temperature of the sensor's core components within a safe range, effectively overcoming the performance degradation or even failure caused by high temperatures, and ensuring the stability and reliability of measurement data throughout the entire testing process (e.g., under conditions of 300°C and 300 MPa).

[0037] The integrated design of this invention enhances the device's integration and ease of operation. By integrating the triaxial pressure chamber, heating system, axial and radial deformation measurement units, and their respective cooling systems into a single, collaborative device, the preparation and operation procedures for experiments are simplified. In particular, the flexible piping for the radial sensor cooling system cleverly adapts to the radial deformation of the rock without interference. This highly integrated solution not only improves experimental efficiency but also provides strong technical support for obtaining complete and accurate rock mechanical parameters in scenarios such as deep-to-ultra-deep energy development. Attached Figure Description

[0038] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1 This is a front view of a direct rock deformation measurement device under high temperature and high pressure environment according to the present invention;

[0040] Figure 2 This is a schematic diagram of the internal structure of a direct rock deformation measurement device under high temperature and high pressure environment according to the present invention.

[0041] Figure 3 This is an internal diagram of the pressure chamber of a direct rock deformation measurement device under high temperature and high pressure environment according to the present invention.

[0042] Figure 4 This is a sample assembly diagram of a direct rock deformation measurement device under high temperature and high pressure environment according to the present invention;

[0043] Figure 5 This is a sample assembly cross-sectional view of a direct rock deformation measurement device under high temperature and high pressure environment according to the present invention;

[0044] Figure 6 This is a cross-sectional view of a radial sensor of a direct rock deformation measurement device under high temperature and high pressure environment according to the present invention;

[0045] Figure 7 This invention relates to a direct measurement device for rock deformation under high temperature and high pressure conditions, showing the stress-strain curve of a triaxial compression test under conditions of 300℃ and 300 MPa. Detailed Implementation

[0046] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] like Figures 1-7 As shown, see details. Figure 1 and Figure 2 The present invention provides a triaxial pressure chamber 100 for containing a rock sample S and providing a test environment for the rock sample S;

[0049] A direct axial deformation measurement component 200 is disposed within the triaxial pressure chamber 100. The direct axial deformation measurement component 200 includes at least one axial sensor 210 and a first cooling structure 220 for cooling the axial sensor 210. The axial sensor 210 is used to directly measure the axial deformation of the rock sample S.

[0050] A radial deformation direct measurement component 300 is disposed within the triaxial pressure chamber 100. The radial deformation direct measurement component 300 includes at least one radial sensor 310 and a second cooling structure 320 for cooling the radial sensor 310. The radial sensor 310 is used to directly contact the rock sample S and measure the radial deformation of the rock sample S.

[0051] Specifically, this embodiment integrates a sensor system for directly measuring rock deformation—namely, an axial deformation direct measurement component 200 and a radial deformation direct measurement component 300—within a triaxial pressure chamber 100 capable of simulating deep geological conditions. The triaxial pressure chamber 100 creates an extreme test environment for the rock sample S, characterized by high temperature (e.g., above 300°C) and high pressure (e.g., confining pressure up to 350 MPa), by applying confining pressure and axial pressure and utilizing a built-in heating system. To ensure the sensors function properly under this environment, the present invention designs independent and efficient first cooling structure 220 and second cooling structure 320, supported by external temperature control and cooling, for the axial sensor 210 and radial sensor 310, respectively. This design allows the sensors to be directly positioned at the measurement location of the rock sample S, capturing its true axial and radial deformation data in real time and accurately, thereby overcoming the measurement inaccuracies caused by the inability to isolate additional errors such as equipment deformation and pad deformation in traditional external measurement methods. Through this integrated design, the device can directly and synchronously obtain the complete stress-strain relationship of rocks under high temperature and high pressure, providing a reliable basis for accurately calculating key mechanical parameters such as elastic modulus and Poisson's ratio.

[0052] As a further explanation of the present invention, the triaxial pressure chamber 100 is provided with an upper pad 115 and a lower pad 125, and the rock sample S is clamped between the upper pad 115 and the lower pad 125.

[0053] It also includes an upper chuck 110 and a lower chuck 120 for fixing the upper pad 115 and the lower pad 125, respectively; the axial sensor 210 is configured to measure the relative displacement between the upper chuck 110 and the lower chuck 120 to characterize the axial deformation of the rock sample S.

[0054] Specifically, refer to Figure 2 Before the test begins, the rock sample S to be tested is placed on the lower pad 125, and then the upper pad 115 is placed on top of it. The upper pad 115 and the lower pad 125 are typically made of high-strength cemented carbide to ensure minimal deformation under enormous axial pressure. Subsequently, the upper pad 115 and the lower pad 125 are fixed in place using the upper chuck 110 and the lower chuck 120 to form a stable sample loading unit.

[0055] The axial deformation measurement method of this invention differs fundamentally from traditional techniques. Traditional techniques indirectly estimate sample deformation by measuring the stroke of an external loading piston, a method that cannot exclude the elastic deformation of the pad, chuck, and even the entire press force chain. In this embodiment, however, the axial sensor 210 directly measures the relative displacement between the upper chuck 110 and the lower chuck 120, which are located immediately adjacent to both ends of the rock sample S. Since the chuck directly fixes the pad, this relative displacement is precisely equivalent to the axial deformation of the rock sample S itself, thus fundamentally eliminating all additional deformation errors from intermediate links. This setup ensures the authenticity of the measured axial strain data, thereby significantly improving the accuracy of elastic modulus calculation, with the measurement error controlled within 0.5%.

[0056] As a further explanation of the present invention, the first cooling structure 220 includes a cooling upper end cover 221 and a cooling lower housing 222, the cooling upper end cover 221 and the cooling lower housing 222 together forming a first circulation cavity 223 for accommodating the axial sensor 210;

[0057] The axial deformation direct measurement assembly 200 also includes an axial displacement transmission rod 230. One end of the axial displacement transmission rod 230 is fixed to the upper chuck 110, and the other end passes through the cooling upper cover 221 and abuts against the sensing end of the axial sensor 210, so as to transmit the displacement of the upper chuck 110 to the axial sensor 210.

[0058] A first sealing element 231 is provided between the axial displacement transmission rod 230 and the cooling upper end cover 221 to isolate the first circulation chamber 223 from the internal test environment of the triaxial pressure chamber 100.

[0059] Specifically, in order to achieve effective protection of the axial sensor 210, refer to Figure 5This invention designs a localized cooling and isolation structure. The first cooling structure 220 is assembled from a cooling upper cover 221 and a cooling lower shell 222, forming a sealed cavity, namely the first circulation cavity 223, specifically designed to house the axial sensor 210. This cavity is completely isolated from the external high-temperature and high-pressure test environment. To accurately transmit the displacement of the upper chuck 110 to the sensor located in the cooling cavity, an axial displacement transmission rod 230 is provided. This rod can be specifically embodied as a high-temperature resistant and thermally conductive axial high-temperature copper column. One end of the axial displacement transmission rod 230 passes through the upper chuck 110 and is fixed by a fastening nut, allowing the axial displacement transmission rod 230 to move with the upper chuck 110. The other end passes through an opening on the cooling upper cover 221 and contacts the sensing probe of the axial sensor 210. To prevent high-temperature and high-pressure hydraulic oil and other test media from entering the first circulation cavity 223 through the gap between the transmission rod and the upper cover, a high-temperature and high-pressure resistant first sealing element 231, namely a high-temperature and high-pressure sealing ring, is provided between the two. Through this design, the axial sensor 210 is safely placed in a normal-temperature region isolated from the high-temperature and high-pressure environment, while simultaneously receiving displacement signals from the upper chuck 110 without delay or loss. This combination of physical isolation and active cooling is key to ensuring the sensor's long-term stable and high-precision operation under extreme conditions, effectively solving the problem of sensor coil performance degradation under high-temperature environments.

[0060] As a further explanation of the present invention, the axial deformation direct measurement component 200 includes two sets of axial sensors 210 symmetrically arranged about the central axis of the rock sample S, and correspondingly provided with two sets of the first cooling structure 220 and two sets of the axial displacement transmission rods 230;

[0061] Both sets of axial sensors 210 and the corresponding first cooling structure 220 are embedded in the lower chuck 120; each of the first circulation chambers 223 is connected to the coolant source through the axial sensor coolant inlet pipe 224 and the axial sensor coolant outlet 225.

[0062] Specifically, to further improve measurement accuracy and eliminate measurement errors caused by eccentric loading or uneven deformation that may occur in the rock sample S, this embodiment preferably uses two sets of identical axial measurement units. For example... Figure 2 and Figure 5 As shown, the two sets of measuring units are symmetrically arranged along the central axis of the rock sample S. Each set includes an axial sensor 210, a complete first cooling structure 220, and an axial displacement transmission rod 230. Both sets of complete measuring units are cleverly integrated or embedded in a large lower chuck 120, resulting in a compact structure.

[0063] Each independent first circulation chamber 223 is connected to an external coolant circulation system via its respective axial sensor coolant inlet pipe 224 and axial sensor coolant outlet 225. During the test, coolant, such as cooling water or dedicated cooling oil, continuously flows through the two first circulation chambers 223, efficiently removing heat transferred from the high-temperature environment and stabilizing the operating temperature of the sensor core coil below 150°C. Finally, by averaging the readings of the two symmetrically arranged sensors 210, a more reliable and representative average axial deformation value of the rock sample S can be obtained. This symmetrical redundancy design greatly improves the stability and anti-interference capability of the measurement.

[0064] As a further explanation of the present invention, the radial sensor 310 has an encapsulation structure 311, and the second cooling structure 320 is disposed within the encapsulation structure 311 in a built-in form.

[0065] Specifically, for the measurement of radial deformation, since the sensor, acting as a radial extensometer, needs to be in close contact with the side surface of the rock sample S and directly exposed to a high-temperature, high-pressure fluid environment, higher requirements are placed on its protection. Therefore, this invention designs a package structure 311 for the radial sensor 310 that integrates protection, cooling, and sealing. For example... Figure 6 As shown, the encapsulation structure 311 completely encloses the main body of the radial sensor 310, forming a self-contained and robust unit. Its key feature is that the second cooling structure 320, used for active cooling of the sensor, is designed inside the encapsulation structure 311, rather than being externally attached. This built-in cooling design makes the entire radial measurement unit compact and highly efficient, as the cooling medium acts directly on the parts of the sensor that most require cooling. This design concept upgrades a standard sensor into a special sensor capable of withstanding extreme environments, forming the basis for achieving accurate radial measurements within high-temperature and high-pressure chambers. Through this built-in cooling encapsulation, the radial sensor 310 can operate stably in environments up to 300°C and 300 MPa, solving the problems of corrosion and failure inherent in traditional strain gauges and other measurement methods.

[0066] As a further explanation of the present invention, the packaging structure 311 includes a packaging shell 312 and a packaging inner shell 313;

[0067] It also includes a sensing rod 319, which is movably inserted through the encapsulation housing 312 and cooperates with the body 310a of the radial sensor 310, and a dynamic sealing element 319a is provided between the sensing rod 319 and the encapsulation housing 312;

[0068] The outer casing 312 is provided with a coolant inlet 316 and a coolant outlet 317; a plurality of second seals 318 are provided between the outer casing 312 and the inner casing 313, and the second seals 318, the outer casing 312 and the inner casing 313 together define a second circulation chamber 314 as the second cooling structure 320.

[0069] A thermal insulation material 315 is also provided between the inner casing 313 and the main body 310a of the radial sensor 310.

[0070] Specifically, refer to Figure 6 The packaging structure 311 of the radial sensor is described in detail. This structure employs a multi-layered protection design to ensure the safety of the internal sensor body. The outermost layer is a robust packaging shell 312, which directly withstands the high temperature and pressure of the external environment. Inside, there is a packaging inner shell 313. The packaging shell 312 and the packaging inner shell 313 are sealed by multiple second seals 318, which serve as static seals, defining an annular sealed space. This space is the second circulation chamber 314, which serves as the second cooling structure 320. The packaging shell 312 has a coolant inlet 316 and a coolant outlet 317. The coolant circulates within the second circulation chamber 314 through these two ports, forming a surrounding cooling channel that efficiently removes external heat. Inside the packaging inner shell 313, thermal insulation material 315 is also filled, serving as a second thermal barrier to further prevent residual heat from being transferred to the core radial sensor 310 body 310a, which is the main body of the LVDT. To measure rock deformation, a sensing rod 319, serving as an LVDT sensing rod, movably passes through the front end of the encapsulation housing 312. Its outer end directly contacts the rock sample, while its inner end engages with the sensor body 310a to transmit displacement signals. A wear-resistant dynamic seal 319a is provided between the sensing rod 319 and the encapsulation housing 312 to ensure that external high-temperature and high-pressure media do not leak into the encapsulation structure during the reciprocating motion of the sensing rod. This precision encapsulation design, integrating active circulating cooling, passive thermal insulation, and multiple dynamic and static seals, provides ultimate protection for the radial sensor and is the technical guarantee for achieving high-precision direct measurement of radial deformation.

[0071] As a further explanation of the invention, the radial deformation direct measurement assembly 300 also includes a radial chain 330, on which the radial sensor 310 is mounted to surround the side surface of the rock sample S.

[0072] Specifically, in order to stably fix the specially packaged radial sensor 310 to the side surface of the rock sample S and ensure that its measurement direction is perpendicular to the sample axis, this embodiment uses a radial chain 330. (Refer to...) Figure 3 and Figure 4 The radial chain 330, composed of multiple hinged links, exhibits excellent flexibility, allowing it to tightly wrap around and conform to the side surfaces of cylindrical rock samples S of varying diameters. Encapsulated radial sensors 310 are securely mounted on specific links of the chain. The end of their sensing rods 319 can be designed as blade-shaped probes, perpendicular to the chain and pointing towards the center of the rock sample, enabling point contact measurement. In practical applications, multiple sets of radial sensors 310 are typically arranged symmetrically along the circumference to measure radial deformation in multiple directions and calculate the average value, thereby obtaining more accurate radial strain and achieving a Poisson's ratio measurement accuracy of ±0.005. Using the radial chain 330 as a mounting platform not only facilitates installation and ensures accurate positioning but also accommodates the radial expansion of the rock sample during the experiment, ensuring continuous and stable measurement contact. This installation method solves the problem of difficulty in arranging radial measuring devices within confined, liquid-filled, high-pressure chambers, demonstrating strong practicality.

[0073] As a further explanation of the present invention, the second cooling structure 320 is connected to the coolant source through a flexible tube 321, the flexible tube 321 including a radial sensor coolant inlet tube 321a and a radial sensor coolant outlet tube 321b, and is able to bend with the radial deformation of the rock sample S.

[0074] Specifically, see Figure 3 and Figure 4 To supply coolant to the second cooling structure 320 inside the encapsulated radial sensor 310, connecting pipes are required. Considering that the radial chain 330 and the sensor 310 mounted on it will move outward with the radial expansion of the rock sample S, these connecting pipes must not restrict their free deformation. Therefore, this embodiment specifically uses high-temperature, high-pressure flexible pipes 321 to connect the coolant inlet 316 and outlet 317 on the sensor to the coolant source outside the pressure chamber. The flexible pipe 321 specifically includes a radial sensor coolant inlet pipe 321a and a radial sensor coolant outlet pipe 321b. These pipes are made of high-temperature, high-pressure resistant flexible materials, such as special polymers or metal corrugated pipes, which have sufficient strength to withstand the internal pressure while also possessing good bending performance. When the rock sample S undergoes radial expansion under axial pressure, the radial chain 330 will expand accordingly. These flexible pipes 321 can bend and extend freely, fully adapting to this small displacement, without constraining the natural deformation of the rock or being damaged by stress concentration. This design detail ensures interference-free radial deformation measurement and the reliability of the entire cooling system.

[0075] As a further explanation of the present invention, a high-temperature circulation pipe 400 is also provided in the triaxial pressure chamber 100, the high-temperature circulation pipe 400 being used to circulate high-temperature fluid to heat the rock sample S.

[0076] Specifically, to simulate deep geothermal environments, this device is equipped with an active heating system supported by an external high-temperature circulation module. For example... Figure 2 As shown, a high-temperature circulation pipe 400 is installed inside the triaxial pressure chamber 100, surrounding the assembly area of ​​the rock sample S. This pipe is made of a high-temperature and high-pressure resistant metal material. During the test, high-temperature fluids such as high-temperature heat transfer oil are heated to the target temperature (e.g., 300°C) in an external module and then pumped into the high-temperature circulation pipe 400 for continuous circulation. Through thermal radiation and thermal convection with the pressure-transmitting medium (such as silicone oil) within the chamber, the high-temperature circulation pipe 400 uniformly transfers heat to the rock sample S, thereby achieving precise temperature control and heating of the sample. By adjusting the external high-temperature circulation module, the test temperature can be easily set and stably controlled, allowing temperature fluctuations to be controlled within ±2°C. Compared to external heating of the pressure chamber, this built-in, active circulation heating method has a faster heating rate, more uniform temperature distribution, and more precise control, making it an essential component for realizing high-temperature rock mechanics testing.

[0077] As a further explanation of the present invention, the triaxial pressure chamber 100 includes: a pressure chamber housing 103 and a pressure chamber base 107;

[0078] An inner pressure chamber shell 104 is disposed within the outer shell 103 of the pressure chamber, and a main sealing element is provided between the inner pressure chamber shell 104 and the outer shell 103 of the pressure chamber;

[0079] An upper connecting cover 101 is provided on the top of the pressure chamber housing 103; a piston 102 is movably inserted into the upper connecting cover 101;

[0080] The upper heat insulation layer 105 and the lower heat insulation layer 106 are respectively disposed at the top and bottom of the interior of the triaxial pressure chamber 100; the third cooling structure is opened on the inner shell 104 of the pressure chamber for local cooling of the main sealing element, and the third cooling structure includes a third circulation chamber 1041 and a fourth circulation chamber 1042 that are interconnected.

[0081] The third cooling structure also has a shell coolant inlet 1043 and a shell coolant outlet 1044. The shell coolant inlet 1043 is in fluid communication with the third circulation chamber 1041, and the shell coolant outlet 1044 is in fluid communication with the fourth circulation chamber 1042, thereby forming a complete coolant circulation path.

[0082] Specifically, refer to Figure 1 and Figure 2The main structure of the triaxial pressure chamber 100 of the present invention includes a thick-walled pressure chamber outer shell 103 and a stable pressure chamber base 107, which together constitute a pressure vessel. For better thermal management and sealing, a double-shell design is adopted, i.e., an inner pressure chamber shell 104 is also provided inside the outer shell 103. Multiple sets of high-temperature and high-pressure sealing rings, serving as the main sealing elements, are provided at key locations between the inner and outer shells to ensure the chamber's airtightness. The top of the pressure chamber is closed by an upper connecting cover 101. The loading piston 102 can move through the upper connecting cover 101 to apply axial pressure to the sample. A retaining ring, a high-temperature and high-pressure sealing ring, and a guide band are provided to ensure stable and sealed movement of the piston under high temperature and high pressure. To reduce heat loss to the upper and lower ends of the pressure chamber, an upper heat insulation layer 105 and a lower heat insulation layer 106 are respectively provided at the top and bottom of the chamber.

[0083] Because the main seal is prone to aging and failure under prolonged high temperature and pressure, this invention incorporates a third cooling structure on the inner shell 104 of the pressure chamber. This structure includes two interconnected circulation chambers 1041 and 1042, which surround the main seal area. Coolant circulates within these chambers through the shell coolant inlet 1043 and outlet 1044, providing localized forced cooling to the main seal. This design significantly extends the service life of critical seals, improves the overall reliability and safety of the device, and ensures long-term stable operation during high-temperature and high-pressure tests.

[0084] In summary, this invention, through integrated design, places the axial and radial deformation direct measurement components with independent cooling systems inside a triaxial pressure chamber, while also providing cooling protection for key components of the pressure chamber itself. This successfully solves the technical challenge of accurately obtaining the true mechanical parameters of rocks under high temperature and high pressure environments. Figure 7 The comparison curves shown indicate that the stress-strain curve obtained using the device of this invention exhibits less fluctuation, and its slope, i.e., the elastic modulus, more closely matches the actual characteristics of the rock. Furthermore, it provides reliable radial deformation data, thereby accurately calculating Poisson's ratio. This device provides an advanced and reliable experimental platform for rock mechanics research in fields such as deep-to-ultra-deep oil and gas extraction and hot dry rock development, increasing experimental efficiency by more than 40% compared to traditional methods.

[0085] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0086] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0087] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A device for directly measuring rock deformation under high temperature and high pressure conditions, characterized in that, include: A triaxial pressure chamber (100) is used to contain a rock sample (S) and provide a testing environment for the rock sample (S); An axial deformation direct measurement assembly (200) is disposed within the triaxial pressure chamber (100). The axial deformation direct measurement assembly (200) includes at least one axial sensor (210) and a first cooling structure (220) for cooling the axial sensor (210). The axial sensor (210) is used to directly measure the axial deformation of the rock sample (S). A radial deformation direct measurement assembly (300) is disposed within the triaxial pressure chamber (100). The radial deformation direct measurement assembly (300) includes at least one radial sensor (310) and a second cooling structure (320) for cooling the radial sensor (310). The radial sensor (310) is used to directly contact the rock sample (S) and measure the radial deformation of the rock sample (S). The radial sensor (310) has an encapsulation structure (311), and the second cooling structure (320) is disposed within the encapsulation structure (311) in a built-in form; The packaging structure (311) includes a packaging shell (312) and a packaging inner shell (313). It also includes a sensing rod (319), which is movably inserted through the encapsulation shell (312) and cooperates with the body (310a) of the radial sensor (310), and a dynamic seal (319a) is provided between the sensing rod (319) and the encapsulation shell (312). The encapsulation shell (312) is provided with a coolant inlet (316) and a coolant outlet (317). A plurality of second seals (318) are provided between the outer casing (312) and the inner casing (313), and the second seals (318), the outer casing (312) and the inner casing (313) together define a second circulation chamber (314) as the second cooling structure (320). A thermal insulation material (315) is also provided between the inner casing (313) and the body (310a) of the radial sensor (310).

2. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 1, characterized in that, The triaxial pressure chamber (100) is provided with an upper pad (115) and a lower pad (125), and the rock sample (S) is clamped between the upper pad (115) and the lower pad (125); it also includes an upper chuck (110) and a lower chuck (120) for fixing the upper pad (115) and the lower pad (125) respectively. The axial sensor (210) is configured to measure the relative displacement between the upper chuck (110) and the lower chuck (120) to characterize the axial deformation of the rock sample (S).

3. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 2, characterized in that, The first cooling structure (220) includes a cooling upper cover (221) and a cooling lower housing (222), the cooling upper cover (221) and the cooling lower housing (222) together form a first circulation cavity (223) for accommodating the axial sensor (210). The axial deformation direct measurement assembly (200) also includes an axial displacement transmission rod (230), one end of which is fixed to the upper chuck (110), and the other end passes through the cooling upper cover (221) and abuts against the sensing end of the axial sensor (210) to transmit the displacement of the upper chuck (110) to the axial sensor (210). A first seal (231) is provided between the axial displacement transmission rod (230) and the cooling upper cover (221) to isolate the first circulation chamber (223) from the internal test environment of the triaxial pressure chamber (100).

4. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 3, characterized in that, The axial deformation direct measurement component (200) includes two sets of axial sensors (210) symmetrically arranged about the central axis of the rock sample (S), and correspondingly provided with two sets of the first cooling structure (220) and two sets of the axial displacement transmission rods (230). Both sets of axial sensors (210) and the corresponding first cooling structure (220) are mounted on the lower chuck (120); Each of the first circulation chambers (223) is connected to the coolant source through the axial sensor coolant inlet pipe (224) and the axial sensor coolant outlet (225).

5. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 1, characterized in that, The radial deformation direct measurement assembly (300) also includes a radial chain (330), on which the radial sensor (310) is mounted to surround the side surface of the rock sample (S).

6. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 1, characterized in that, The second cooling structure (320) is connected to a coolant source via a flexible tube (321), which includes a radial sensor coolant inlet tube (321a) and a radial sensor coolant outlet tube (321b) and is capable of bending with the radial deformation of the rock sample (S).

7. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 1, characterized in that, It also includes a high-temperature circulation pipe (400) disposed within the triaxial pressure chamber (100), the high-temperature circulation pipe (400) being used to circulate high-temperature fluid to heat the rock sample (S).

8. The device for directly measuring rock deformation under high temperature and high pressure environment according to claim 1, characterized in that, The triaxial pressure chamber (100) includes: Pressure chamber housing (103) and pressure chamber base (107); An inner pressure chamber shell (104) is disposed inside the outer shell of the pressure chamber (103), and a main seal is provided between the inner pressure chamber shell (104) and the outer shell of the pressure chamber (103); The upper connecting cover (101) is installed on the top of the pressure chamber housing (103); The piston (102) is movably inserted into the upper connecting cover (101); The upper insulation layer (105) and the lower insulation layer (106) are respectively disposed at the top and bottom of the interior of the triaxial pressure chamber (100); The third cooling structure is provided on the inner shell (104) of the pressure chamber and is used to locally cool the main seal. The third cooling structure includes a third circulation chamber (1041) and a fourth circulation chamber (1042) that are interconnected. The third cooling structure also has a shell coolant inlet (1043) and a shell coolant outlet (1044). The shell coolant inlet (1043) is in fluid communication with the third circulation chamber (1041), and the shell coolant outlet (1044) is in fluid communication with the fourth circulation chamber (1042), thereby forming a complete coolant circulation path.

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