Device and method for testing press-in hardness of rock in ultra-deep high-temperature and high-pressure environment

Abstract

The invention discloses a rock press-in hardness testing device and method under an ultra-deep layer high-temperature and high-pressure environment, and relates to the technical field of rock mechanical testing, a frame is provided with a sample bin, a to-be-detected rock sample is placed in the bin, and a medium capable of providing confining pressure for the sample can be injected into the sample bin; the heating device can maintain the temperature in the sample bin, a detection head in contact with the sample is placed at the upper end of the sample bin, and a pressurizing device capable of loading axial pressure and confining pressure to the sample is arranged at the lower end of the sample bin; the frame is provided with a static load module for applying a static load to the detection head and a dynamic load module for applying a high-frequency dynamic load to the detection head. The dynamic and static coupling loading of the device is highly similar to the drilling working condition, so that the device can better fit the actual condition of construction, and the engineering guidance value of the experiment is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, specifically to a device and method for testing the indentation hardness of rocks under ultra-deep, high-temperature, and high-pressure environments. Background Technology

[0002] Deep and ultra-deep oil and gas reservoirs have become a key focus of global oil and gas exploration and development. However, deep strata are characterized by their age, great depth, and combination of ultra-high temperature, ultra-high pressure, and complex skeletal structures. The dynamic and static mechanical responses of these strata under high temperature and high pressure conditions due to the superposition of multiple factors still lack a systematic understanding. Rock indentation hardening tests, which involve pressing a rock sample under controlled load with a known geometric indenter and recording the load-displacement curve in real time, and then retrieving key parameters such as elastic modulus and fracture toughness, have been widely used for formation drillability evaluation. However, existing indentation hardening devices generally operate at ambient temperature and pressure and low loading rates, providing only quasi-static data. This makes it difficult to simulate the high temperature, high pressure, and high strain rate environment of ultra-deep drilling, resulting in significant deviations between the obtained rock mechanical properties and actual working conditions.

[0003] Patent CN 113092295 B discloses a rock hardness testing device, including a support frame, a loading mechanism, and a testing mechanism. The loading mechanism includes a dynamic load generator, a fulcrum adjustment block, a lever, and a first displacement sensor. The dynamic load generator is fixed to the support frame, and the fulcrum adjustment block is slidably mounted on the support frame. The first end of the lever is connected to the force-applying part of the dynamic load generator, and the middle part of the lever is slidably engaged with the fulcrum adjustment block. The sliding direction of the fulcrum adjustment block is the same as the length direction of the lever. The fulcrum adjustment block is located between the lever and the support frame. One end of the first displacement sensor is fixed to the support frame, and the other end of the first displacement sensor is fixed to the second end of the lever. The testing mechanism includes a test indenter, a tension / compression sensor, and a temperature control box, with the temperature control box fixed to the support frame.

[0004] However, it still has the following problems: the device cannot implement dynamic and static load loading, does not have microsecond-level impact dynamic load, and the loading situation is relatively simple, so it cannot be closer to the actual drilling conditions. At the same time, when the hard tip is pressed in, it does not have the function of synchronously collecting pressure and displacement. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a device and method for testing the indentation hardness of rocks under ultra-deep, high-temperature and high-pressure environments.

[0006] The technical solution adopted by the present invention to solve its technical problem is: This invention proposes a rock indentation hardness testing device under ultra-deep high temperature and high pressure environment, comprising a frame, characterized in that a sample chamber is provided on the frame, the sample of the rock to be tested is placed in the chamber, the sample chamber can be injected with a medium that provides confining pressure to the sample, and a heating device is also provided to maintain the temperature inside the sample chamber. A detection head that contacts the sample is placed at the upper end of the sample chamber, and a pressurizing device that applies axial pressure and confining pressure to the sample is provided at the lower end of the sample chamber; the frame is provided with a static load module that applies static load to the detection head, and a dynamic load module that applies high-frequency dynamic load to the detection head.

[0007] Preferably, the static load module includes a static load cylinder fixed to a plurality of frames. The static load cylinder is connected to a controller. The upper end of the static load cylinder is connected to a crossbeam, and the lower end of the crossbeam contacts the detection head, providing a continuous downward static load to the detection head. The dynamic load module includes an impact member disposed on the crossbeam. The detection head is connected to an impact head. The crossbeam has a through hole for the impact head to pass through freely. The impact head is used to receive the instantaneous impact load from the impact member.

[0008] Preferably, a pressure sensor is fixedly connected to the lower end of the detection head and arranged along the loading axis. The lower end of the pressure sensor is connected to a pressure mold that contacts the sample.

[0009] Preferably, a displacement sensor is provided on the frame, and a transmission rod is fixed on the detection head. The transmission rod can drive the displacement sensor to move and measure, so as to realize real-time measurement of the displacement of the detection head during the loading process; both the pressure sensor and the displacement sensor are connected to a controller.

[0010] Preferably, the pressurizing device includes an axial pressure cylinder fixed on a frame, the axial pressure cylinder is connected to a controller, an axial pressure rod slides inside the axial pressure cylinder, a bushing is fixedly connected to the frame, the bushing has a through hole for the axial pressure rod to pass through, a top cover is connected to the upper end of the bushing, the top cover has a through hole for the insertion of a detection head, and a sample chamber for containing the confining pressure medium is formed between the axial pressure rod, the bushing and the top cover.

[0011] Preferably, the front end of the axial compression rod is fixed with a sample base, the side of the sample is covered with soft material and placed on the sample base, the upper and lower ends of the sample are in contact with the sample base and the top cover respectively, so that the confining pressure medium wraps the soft material, and the side of the bushing is provided with several interfaces connected to the sample chamber, and the interfaces are connected to the confining pressure system through pipelines.

[0012] Preferably, the heating device includes a resistance heating wire arranged on the inner wall of the sample chamber, the surface of the resistance heating wire is covered with a heat insulation layer, a thermocouple sensor for measuring the sample temperature is installed in the sample chamber, and the thermocouple sensor is connected to a controller.

[0013] A method for testing the indentation hardness of rocks under ultra-deep high temperature and high pressure conditions, employing the aforementioned rock indentation hardness testing device under ultra-deep high temperature and high pressure conditions, is characterized by comprising the following steps: S1: Open the sample chamber, place the sample inside the sample chamber, then close the sample chamber, start the pressurizing device to apply axial pressure to the sample, and the pressurizing device will cause the sample to adhere tightly to the inner surface of the sample chamber. S2: The heating device heats the confining pressure medium in the sample chamber to the preset temperature, and the pressurization device is started to cyclically apply the axial pressure and confining pressure of the sample in sequence until the axial pressure and confining pressure reach the preset test pressure at the same time. S3: After temperature and pressure loading are completed, collect system operation data and record the initial baseline value; S4: The controller controls the static load module to press down steadily, generating a constant axial static load on the sample. The controller controls the dynamic load module to apply an instantaneous impact load, so that the impact load and the static load are superimposed on the upper end face of the sample. The displacement sensor records the displacement data during the loading process, and the pressure sensor synchronously records the axial load signal during the loading process. S5: After loading is complete, disassemble the device in sequence. First, turn off the dynamic load module, and the controller controls the static load module to push up. The pressurization device unloads the axial pressure and confining pressure in sequence according to the gradient until the pressure is zero. Then, turn off the pressurization device, open the sample chamber and take out the sample to complete the entire test process.

[0014] Preferably, in step S3, axial pressure is first applied to the sample, with each loading amount being P1. After the axial pressure is loaded to P1, confining pressure medium is injected into the sample chamber to make the confining pressure of the sample reach P1. The above steps are repeated until the axial pressure and confining pressure reach the experimental preset pressure Pn.

[0015] Preferably, in S4, the acquired data is converted from analog signals to digital signals and input to the integrated data acquisition card, with a sampling rate range of 10kHz–5MHz.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This application sets up a static load module and a dynamic load module. The static load module applies a constant static load to the sample, pressing it down stably. The dynamic load module applies a microsecond-level instantaneous impact load to the sample through an impactor. The dynamic and static load modules transfer the dynamic and static loads to the sample end face through a detection head, realizing the pressing process under dynamic and static coupling. The dynamic and static coupling loading is highly similar to the drilling conditions, which can better fit the actual construction situation and greatly improve the guiding value of the experiment for the project.

[0017] 2. This application sets up an axial pressure cylinder and an interface. The axial pressure cylinder applies an axial static load to the sample, and the interface injects a confining pressure medium to apply a uniform confining pressure to the sample. The axial pressure cylinder and the interface perform cyclic gradient loading pressure, so that the axial pressure and confining pressure of the sample rise alternately. This can reduce the stress superposition caused by the simultaneous increase of axial pressure and confining pressure, or the stress distortion caused by improper matching of axial pressure and confining pressure, and greatly increase the stability. With the heating device in the sample chamber, it can accurately simulate the real high temperature and high pressure environment of deep earth rocks.

[0018] 3. The lower end of the detection head of this application is embedded with a pressure sensor, and a transmission rod that cooperates with the displacement sensor is fixed on the side of the detection head. The synchronous acquisition of pressure and displacement can track the load magnitude and deformation at each moment in real time, accurately capture the changes of rock under complex loads, and facilitate subsequent analysis. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a front sectional view of the present invention; Figure 2 yes Figure 1 A magnified view of part A in the middle; Figure 3 This is a side view of the present invention; Figure 4 is a top view of the present invention; Figure 5 This is a schematic diagram of the detection head of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Frame; 2. Sample chamber; 3. Sample; 4. Impact head; 5. Detection head; 6. Axial compression rod; 7. Bushing; 8. Top cover; 9. Static load cylinder; 10. Crossbeam; 11. Copper sleeve; 12. Pressure sensor; 13. Compression mold; 14. Displacement sensor; 15. Transmission rod; 16. Interface; 17. Guide rod; 18. Drop hammer; 19. Column; 20. Support platform. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] refer to Figure 1-Figure 5As shown, a rock indentation hardness testing device under ultra-deep high temperature and high pressure environment includes a frame 1, a sample chamber 2 on the frame 1, a sample 3 of the rock to be tested placed in the chamber, the sample chamber 2 can be injected with a medium that provides confining pressure to the sample 3, and also includes a heating device that can maintain the temperature inside the sample chamber 2, a detection head 5 in contact with the sample 3 is placed at the upper end of the sample chamber 2, and a pressurizing device that can apply axial pressure and confining pressure to the sample 3 is provided at the lower end of the sample chamber 2; the frame 1 is provided with a static load module that applies static load to the detection head 5, and a dynamic load module that applies high-frequency dynamic load to the detection head 5.

[0023] By injecting a confining pressure medium into sample chamber 2, confining pressure is applied to sample 3. Then, an axial pressure is provided to sample 3 through a pressurizing device. Simultaneously, in conjunction with a heating device in the sample chamber, the actual high-temperature and high-pressure environment of deep-earth rocks can be accurately simulated. A constant static load is applied to the sample through the static load module, and the sample is stably pressed down. The dynamic load module applies a microsecond-level high-frequency instantaneous impact load to the sample through an impact component. The dynamic load module and the static load module transfer the dynamic and static loads to the sample end face through a detection head, realizing the pressing process under dynamic and static coupling. The dynamic and static coupling loading is highly similar to the drilling conditions, which can better fit the actual construction situation and greatly improve the guiding value of the experiment for the project.

[0024] The static load module includes static load cylinders 9 fixed to several frames 1. The static load cylinders 9 are connected to a controller. The upper end of the static load cylinders 9 is connected to a crossbeam 10. The lower end of the crossbeam 10 is in contact with the detection head 5, providing a continuous downward static load to the detection head 5. The dynamic load module includes an impact member set on the crossbeam 10. An impact head 4 is connected to the detection head 5. The crossbeam 10 has a through hole for the impact head 4 to pass through freely. The impact head 4 is used to receive the instantaneous impact load from the impact member.

[0025] The impact component is a drop hammer 18. A guide bracket is fixed on the crossbeam 10. A small crossbeam is fixedly connected to the guide bracket. A guide rod 17 is fixedly connected to the small crossbeam. The drop hammer 18 is slidably sleeved on the guide rod 17. There is a gap between the guide rod 17 and the impact head 4. The mass and height of the drop hammer 18 are adjustable. This can be achieved by replacing drop hammers of different sizes or by fixing weights of different masses on the drop hammers to achieve dynamic load input of different amplitudes. It can also be applied to different experimental objects.

[0026] The impact component is a high-speed hydraulic cylinder, which is detachably connected to the crossbeam 10. The piston rod of the high-speed hydraulic cylinder can impact the impact head 4. The high-speed hydraulic cylinder is connected to a hydraulic station and a controller.

[0027] The static load module is used to apply a controllable constant static load, while the dynamic load module is used to apply a high-frequency instantaneous dynamic load. In the dynamic load section, the drop hammer 18 is guided by the guide rod 17 and can fall freely along the axis at the moment of release. The impact head 4 and the detection head 5 are inserted vertically along the axis to ensure that the impact force can be accurately transmitted to the upper end face of the sample 3. In the static load section, the two static load cylinders 9 set on the left and right are connected to the external high-pressure oil source to realize the downward pressure of the crossbeam 10. A constant axial static load is generated through the synergistic action of the two cylinders.

[0028] A pressure sensor 12 is fixedly connected to the lower end of the detection head 5 and is arranged along the loading axis. The lower end of the pressure sensor 12 is connected to a pressure mold 13 that contacts the sample 3.

[0029] The pressure sensor 12 is an FCL1005 high-temperature resistant piezoelectric load sensor, which has a measurement range of -200 to 1260℃ and a measurement accuracy of ±0.75℃. It is suitable for long-term operation at high temperatures and can record the dynamic and static coupled load applied to the top of the sample 3 in real time. The sensor has a maximum range of 10kN, a sensitivity of 4pC / N, a frequency response bandwidth of over 75kHz, a linearity error of less than ±1%FS, and hysteresis and repeatability errors of less than 1%FS. It is suitable for dynamic mechanical monitoring of high-frequency impact processes.

[0030] The pressure sensor 12 has a through hole in the center, and a slide rod fixed to the detection head 5 is inserted through the through hole. A connecting rod that abuts against the pressure sensor 12 is sleeved on the slide rod. A pressure mold 13 is fixed at the lower end of the connecting rod. The pressure mold 13 is made of high-strength alloy and has good impact resistance and wear resistance.

[0031] The upper end of the detection head 5 is the static load loading end face, which is in contact with the loading components (i.e., the crossbeam 10) of the static load cylinders 9 on both sides. The static load cylinders 9 apply a constant static load to the static load loading end face of the detection head 5 through the crossbeam 10. The detection head 5 transfers the constant static load to the sample 3. The impact head 4 is screwed into the top of the detection head 5 through a screw. The upper end face of the impact head 4 is the dynamic load loading end face, which is used to receive the instantaneous impact load generated by the free fall of the drop hammer 18.

[0032] A displacement sensor 14 is installed on the frame 1, and a transmission rod 15 is fixed on the detection head 5. The transmission rod 15 can drive the displacement sensor 14 to move and measure, so as to realize real-time measurement of the displacement of the detection head 5 during the loading process; both the pressure sensor 12 and the displacement sensor 14 are connected to a controller.

[0033] The displacement sensor 14 adopts a high-temperature spring-loaded LVDT displacement sensor. The moving spindle of the displacement sensor contacts the transmission rod 15. At the same time, the displacement sensor is fixed on the top cover 8 through an adjustable structure. Before measurement, the initial contact accuracy is ensured by manual adjustment. The measurement range of the displacement sensor 14 is ±50mm, which is suitable for the measurement needs of high-frequency vibration and small displacement response.

[0034] The adjustable structure uses a self-locking linkage or a bolt and a threaded lifting plate to form an adjustment mechanism, which adjusts the position of the displacement sensor 14 for easy calibration.

[0035] The pressurization device includes an axial pressure cylinder fixed on the frame 1, the axial pressure cylinder is connected to a controller, an axial pressure rod 6 slides inside the axial pressure cylinder, a bushing 7 is fixedly connected to the frame 1, the bushing 7 has a through hole for the axial pressure rod 6 to pass through, the upper end of the bushing 7 is connected to a top cover 8, the top cover 8 has a through hole for the detection head 5 to be inserted, and the axial pressure rod 6, the bushing 7 and the top cover 8 form a sample chamber 2 for containing the confining pressure medium.

[0036] Six columns 19 are fixed on the frame 1. The top of the columns 19 is fixed to the support platform 20 by bolts. The bushing 7 is fixedly installed on the support platform 20.

[0037] The top cover 8 is threadedly connected to the bushing 7. The top cover 8 is a thick-walled cylindrical pressure vessel made of high-temperature and high-pressure resistant alloy steel. The top cover 8 has a through hole for the detection head 5 to pass through and contact the end face of the sample 3. The inner wall of the through hole and the detection head 5 are axially sealed by a perfluoroether FFKMO type sealing ring. The sealing ring can withstand 250MPa hydrostatic pressure.

[0038] The front end of the axial compression rod 6 is fixed with a sample base. The sample 3 is covered with soft material on its side and placed on the sample base. The upper and lower ends of the sample 3 are in contact with the sample base and the top cover 8, respectively, so that the confining pressure medium wraps the soft material. The side of the bushing 7 is provided with several interfaces 16 that are connected to the sample chamber 2. The interfaces 16 are connected to the confining pressure system through pipelines.

[0039] The soft material is copper sleeve 11. After the axial pressure rod 6 pushes the sample 3 and the top cover 8 together, the copper sleeve 11, the sample base and the top cover 8 wrap the sample 3 to prevent the sample from coming into direct contact with the hydraulic oil.

[0040] The interface 16, located in the middle, is connected to the confining pressure system through a high-temperature and high-pressure hydraulic pipeline. It is used to inject the confining pressure medium into the sample chamber 2 and establish a uniform radial hydrostatic pressure in the cavity.

[0041] The confining pressure system is generally a high-temperature hydraulic station.

[0042] The axial compression rod 6 can push the sample base upward to send the sample 3 into the designated position in the sample chamber 2 and apply an axial static load to the end face of the sample 3. At the same time, the confining pressure medium is injected into the sample chamber 2 through the interface 16 to establish and maintain a uniform radial (hydrostatic) confining pressure in the sample chamber 2, so as to achieve a triaxial confining pressure condition of up to 250MPa, accurately simulating the real high pressure environment of deep earth rocks.

[0043] The heating device includes a resistance heating wire arranged on the inner wall of the sample chamber 2, the surface of which is covered with a heat insulation layer. A thermocouple sensor for measuring the temperature of the sample 3 is installed in the sample chamber 2, and the thermocouple sensor is connected to a controller.

[0044] The inner wall of sample chamber 2 generally refers to the inner wall of bushing 7.

[0045] Temperature measurement uses a K-type armored thermocouple sensor, which is installed on the inner wall of sample chamber 2 and close to sample 3 to obtain the true temperature.

[0046] The resistance heating wire on the inner wall of sample chamber 2 and its surface high-efficiency heat insulation layer rapidly heat up under closed-loop control and stably maintain the temperature conditions required for the test. The maximum operating temperature is 250℃, and the temperature control accuracy is ±0.5℃.

[0047] The heating device, pressurizing device, and confining pressure medium can simulate deep-earth environmental conditions within the sealed sample chamber 2, achieving a heating temperature of up to 250℃ and a triaxial confining pressure of 250MPa. This reproduces the thermal pressure state of the sample 3 under ultra-deep geological conditions. The static and dynamic load modules work together to achieve dynamic indentation hardness testing conditions. At the same time, key test parameters such as the temperature of the sample 3, the load and displacement of the detection head 5 are synchronously acquired through sensors, ensuring the data integrity and accuracy of the experimental process.

[0048] A method for testing the indentation hardness of rocks under ultra-deep high temperature and high pressure conditions, using the aforementioned rock indentation hardness testing device under ultra-deep high temperature and high pressure conditions, includes the following steps: S1: Open the sample chamber 2, place the sample 3 inside the sample chamber, then close the sample chamber 2, start the pressurizing device to apply axial pressure to the sample 3, and the pressurizing device will cause the sample 3 to adhere tightly to the inner surface of the sample chamber 2. S2: The heating device heats the confining pressure medium in the sample chamber 2 to the preset temperature, and starts the pressurization device to perform cyclic gradient loading on the axial pressure and confining pressure of the sample 3 in sequence until the axial pressure and confining pressure reach the preset test pressure at the same time; S3: After temperature and pressure loading are completed, collect system operation data and record the initial baseline value; S4: The controller controls the static load module to press down steadily, generating a constant axial static load on the sample. The controller controls the dynamic load module to apply an instantaneous impact load, so that the impact load and the static load are superimposed on the upper end face of the sample 3. The displacement sensor 14 records the displacement data during the loading process, and the pressure sensor 12 synchronously records the axial load signal during the loading process. S5: After loading is completed, disassemble the device in sequence. First, turn off the dynamic load module. The controller controls the static load module to push up. The pressurization device unloads the axial pressure and confining pressure in sequence according to the gradient until the pressure is zero. Turn off the pressurization device, open the sample chamber 2 and take out the sample 3 to complete the entire test process.

[0049] In S2, axial pressure is first applied to sample 3, with each loading amount being P1. After the axial pressure is loaded to P1, confining pressure medium is injected into sample chamber 2 to make the confining pressure of sample 3 reach P1. The above steps are repeated until the axial pressure and confining pressure reach the experimental preset pressure Pn.

[0050] In S4, the acquired data is converted from analog signals to digital signals and input to the integrated data acquisition card, with a sampling rate range of 10kHz-5MHz.

[0051] First, remove the top cover 8 of the sample chamber, fully retract the axial pressure rod 6 of the axial pressure cylinder, and place the prepared sample 3 on the sample base after covering its sides with a soft copper sleeve. Then, screw the top cover 8 of the sample chamber onto the guide bushing 7 to close the sample chamber 2. At this time, push the axial pressure rod 6 up so that the upper end face of the sample 3 is in close contact with the inner surface of the top cover 8, and establish an initial contact pressure of about 0.1 MPa through the control system.

[0052] During the temperature and pressure loading process, the hydraulic oil in the sample chamber 2 is heated to a preset temperature (e.g., 250°C) using a heating device arranged in the sample chamber 2, and the temperature is maintained stable through closed-loop control. Then, the loading system is started, and cyclic gradient loading is performed sequentially in the axial and radial directions. First, the axial pressure is applied by the axial pressure rod 6, with each loading increment being 5MPa. When the axial pressure is loaded to 5MPa, the axial pressure loading is stopped, and the confining pressure medium is injected into the sample chamber 2 through the interface 16 to make the confining pressure reach 5MPa. The above steps are repeated alternately until the axial pressure and confining pressure simultaneously reach the preset test pressure (e.g., 250MPa).

[0053] After temperature and pressure loading are completed, the detection head 5 is installed. The detection head 5 and the impact head 4 are placed into the reserved hole in the crossbeam 10. The top of the detection head 5 is in contact with the sample 3, and the lower end of the crossbeam 10 is in contact with the static load loading end face of the upper end of the detection head 5. Then, the impact head 4 is screwed into the detection head 5 through the thread. The detection head 5 has a through hole inside, and a transmission rod 15 is fixed in the through hole. The transmission rod is in contact with the displacement sensor 14 installed on the outside of the sample chamber top cover 8 to realize displacement measurement during the loading process. The detection head 5 is also fixed with a pressure sensor 12 to synchronously record the axial load signal during the loading process. A high-strength alloy pressure mold 13 is installed at the bottom of the detection head 5, which is in direct contact with the sample 3.

[0054] Before dynamic load loading, the data acquisition system is activated to check the stability and response of the signal channels of displacement sensor 14, pressure sensor 12, and thermocouple sensor in sequence, and the initial baseline value is recorded. Then, the static load cylinders 9 on the left and right sides are retracted, and the preload required for the test is applied to the static load loading end face on the test head 5 through the crossbeam 10. The drop hammer 18 is raised to the preset height and released under the constraint of the guide rod 17, falling freely to impact the dynamic load loading end face on the impact head 4. The impact load and the original static load are superimposed on the upper end face of the sample 3, thereby completing the dynamic-static load composite loading.

[0055] After loading is completed, the device is disassembled in sequence. First, the drop hammer and guide rod 17 are removed, and the static load cylinder 9 is pushed up to release the load on the detection head. Then, the detection head 5 is removed and the impact head 4 is then removed. Next, the axial pressure and confining pressure are unloaded in sequence through the axial pressure rod 6 and the interface 16 at a gradient of no more than 5 MPa each time until the pressure is zero. After the axial pressure rod 6 is completely retracted, the top cover 8 of the sample chamber is removed, the sample 3 is taken out, and the entire test process is completed.

[0056] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A rock indentation hardness testing device under ultra-deep high temperature and high pressure environment, comprising a frame (1), characterized in that, The frame (1) is provided with a sample chamber (2), and the sample (3) of the rock to be tested is placed in the chamber. The sample chamber (2) can be injected with a medium that provides confining pressure to the sample (3). It also includes a heating device that can maintain the temperature inside the sample chamber (2). The upper end of the sample chamber (2) is provided with a detection head (5) that is in contact with the sample (3). The lower end of the sample chamber (2) is provided with a pressurizing device that can apply axial pressure and confining pressure to the sample (3). The frame (1) is provided with a static load module that applies static load to the detection head (5) and a dynamic load module that applies high-frequency dynamic load to the detection head (5). The static load module includes static load cylinders (9) fixed to several frames (1), the static load cylinders (9) are connected to a controller, the upper end of the static load cylinders (9) is connected to a crossbeam (10), the lower end of the crossbeam (10) is in contact with the detection head (5), and provides a continuous downward static load to the detection head (5); the dynamic load module includes an impact member set on the crossbeam (10), the detection head (5) is connected to an impact head (4), the crossbeam (10) has a through hole for the impact head (4) to pass through freely, and the impact head (4) is used to receive the instantaneous impact load from the impact member; The pressurization device includes an axial pressure cylinder fixed on a frame (1), the axial pressure cylinder is connected to a controller, an axial pressure rod (6) slides inside the axial pressure cylinder, a bushing (7) is fixedly connected to the frame (1), the bushing (7) has a through hole for the axial pressure rod (6) to pass through, a top cover (8) is connected to the upper end of the bushing (7), the top cover (8) has a through hole for the detection head (5) to be inserted, and a sample chamber (2) for containing the confining pressure medium is formed between the axial pressure rod (6), the bushing (7) and the top cover (8). The heating device includes a resistance heating wire arranged on the inner wall of the sample chamber (2), the surface of the resistance heating wire is covered with a heat insulation layer, and a thermocouple sensor for measuring the temperature of the sample (3) is installed in the sample chamber (2), and the thermocouple sensor is connected to a controller.

2. The rock indentation hardness testing device under ultra-deep high temperature and high pressure environment according to claim 1, characterized in that, A pressure sensor (12) is fixedly connected to the lower end of the detection head (5), and is arranged along the loading axis. The lower end of the pressure sensor (12) is connected to a pressure mold (13) that contacts the sample (3).

3. The rock indentation hardness testing device under ultra-deep high temperature and high pressure environment according to claim 2, characterized in that, The frame (1) is equipped with a displacement sensor (14), and the detection head (5) is fixed with a transmission rod (15). The transmission rod (15) can drive the displacement sensor (14) to move and measure, so as to realize the real-time measurement of the displacement of the detection head (5) during the loading process; the pressure sensor (12) and the displacement sensor (14) are both connected to a controller.

4. The rock indentation hardness testing device under ultra-deep high temperature and high pressure environment according to claim 1, characterized in that, The front end of the axial compression rod (6) is fixed with a sample base. The side of the sample (3) is covered with soft material and placed on the sample base. The upper and lower ends of the sample (3) are in contact with the sample base and the top cover (8) respectively, so that the confining pressure medium wraps the soft material. The side of the bushing (7) is provided with several interfaces (16) that are connected to the sample chamber (2). The interfaces (16) are connected to the confining pressure system through pipelines.

5. A method for testing the indentation hardness of rock under ultra-deep high temperature and high pressure conditions, using the rock indentation hardness testing device under ultra-deep high temperature and high pressure conditions as described in claim 3, characterized in that... The following steps are involved: S1: Open the sample chamber (2), place the sample (3) inside the sample chamber, then close the sample chamber (2), start the pressurizing device to apply axial pressure to the sample (3), and the pressurizing device will cause the sample (3) to adhere tightly to the inner surface of the sample chamber (2). S2: The heating device heats the confining pressure medium in the sample chamber (2) to the preset temperature, and starts the pressurization device to perform cyclic gradient loading on the axial pressure and confining pressure of the sample (3) in sequence until the axial pressure and confining pressure reach the preset test pressure at the same time; S3: After temperature and pressure loading are completed, collect system operation data and record the initial baseline value; S4: The controller controls the static load module to press down steadily, generating a constant axial static load on the sample. The controller controls the dynamic load module to apply an instantaneous impact load, so that the impact load and the static load are superimposed on the upper end face of the sample (3). The displacement sensor (14) records the displacement data during the loading process, and the pressure sensor (12) records the axial load signal during the loading process simultaneously. S5: After loading is completed, disassemble the device in sequence. First, turn off the dynamic load module. The controller controls the static load module to push up. The pressurizing device unloads the axial pressure and confining pressure in sequence according to the gradient until the pressure is zero. Turn off the pressurizing device, open the sample chamber (2), take out the sample (3), and complete the entire test process.

6. The method for testing the indentation hardness of rock under ultra-deep high temperature and high pressure environment according to claim 5, characterized in that, In S2, axial pressure is first applied to the sample (3), with a loading amount of P1 each time. After the axial pressure is loaded to P1, confining pressure medium is injected into the sample chamber (2) to make the confining pressure of the sample (3) reach P1. The above steps are repeated until the axial pressure and confining pressure reach the experimental preset pressure P. n .

7. The method for testing the indentation hardness of rock under ultra-deep high temperature and high pressure environment according to claim 5, characterized in that, In S4, the acquired data is converted from analog signals to digital signals and input to the integrated data acquisition card, with a sampling rate range of 10kHz–5MHz.

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