Core holder for displacement scan

Abstract

The present application belongs to the technical field of core clamps, and particularly relates to a core clamping device for displacement scanning, which comprises a carbon fiber sleeve, an axial pressure applying mechanism, a clamping mechanism and a liquid discharging mechanism. The axial pressure applying mechanism, the clamping mechanism and the liquid discharging mechanism are located inside the carbon fiber sleeve and coaxially arranged with the carbon fiber sleeve. The clamping mechanism is internally provided with a containing cavity for containing a core. An annular airtight confining pressure cavity for passing in high-pressure liquid is arranged between the clamping mechanism and the carbon fiber sleeve. The liquid discharging mechanism is arranged at the bottom of the clamping mechanism, and the axial pressure applying mechanism is arranged at the top of the clamping mechanism. Through the arrangement of the axial pressure applying mechanism and the annular airtight confining pressure cavity and the establishment of communication between the annular airtight confining pressure cavity and the axial pressure applying mechanism, liquid force sharing is realized, and the confining pressure and the axial pressure are simulated, so that the stress condition of real rock in the formation state can be well restored, and the accuracy of experimental results can be improved.

Description

Technical Field

[0001] This invention belongs to the field of core holder technology, specifically relating to a core holder device for displacement scanning. Background Technology

[0002] In recent years, micron-scale CT scanning technology and nuclear magnetic resonance technology have been gradually applied in the field of oil reservoir physics experiments. Their characteristics of non-destructive testing and quantitative visualization of samples have made them important experimental characterization methods.

[0003] When performing micron-scale CT scans and nuclear magnetic resonance imaging (NMR) tests, core holders are used to hold the core. Existing core holders typically only apply confining pressure to the core to simulate the confining pressure experienced by real rocks. However, real rocks in the formation are subjected to not only confining pressure but also axial pressure. If axial pressure is not applied to the core, the stress state of the core may differ from that of the real formation, thus affecting the experimental results. Although some experimental devices can apply axial pressure to the core, in actual experimental operations, it is necessary to control both axial pressure and confining pressure simultaneously, which is inconvenient. Summary of the Invention

[0004] The purpose of this invention is to provide a core clamping device for displacement scanning, which solves the technical problems of existing core clamps that do not apply axial pressure, resulting in low accuracy of experimental results, and core clamps that apply axial pressure, which require simultaneous control of axial pressure and confining pressure, making operation inconvenient.

[0005] This invention is achieved by adopting the following technical solution: A core clamping device for displacement scanning includes a carbon fiber sleeve, an axial pressure mechanism, a clamping mechanism, and a drainage mechanism. The axial pressure mechanism, clamping mechanism, and drainage mechanism are located inside the carbon fiber sleeve and are coaxially arranged with the carbon fiber sleeve. An upper sealing plate and a lower sealing plate are respectively provided at both ends of the carbon fiber sleeve. The clamping mechanism includes a rubber sleeve, with an upper pressure plate and a lower pressure plate respectively sealed and fixedly connected to both ends of the rubber sleeve. The upper pressure plate and the lower pressure plate are respectively in a sealing sliding fit with the carbon fiber sleeve. The rubber sleeve, the upper pressure plate, and the lower pressure plate cooperate to form a device for accommodating... The core contains a cavity with several inlets on the upper pressure plate communicating with the cavity, and several outlets on the lower pressure plate communicating with the cavity. An annular closed confining pressure cavity for introducing high-pressure liquid is formed between the outer wall of the rubber sleeve and the inner wall of the carbon fiber sleeve. The liquid discharge mechanism is located at the bottom of the clamping mechanism to support the clamping mechanism and to discharge the fluid flowing out of the outlets. The axial pressure applying mechanism is located at the top of the clamping mechanism to introduce displacement fluid into the cavity through the inlets and to apply pressure to the core in conjunction with the annular closed confining pressure cavity.

[0006] Preferably, the drainage mechanism includes a drainage pipe, a support base, and a lower cover covering all drainage ports; the support base is disposed on the lower sealing plate and connected to the bottom of the lower cover; the lower cover and the lower pressure plate cooperate to form a collection cavity; one end of the drainage pipe is connected to the collection cavity through the lower cover, and the other end of the drainage pipe extends through the support base and the lower sealing plate to the outside of the carbon fiber sleeve.

[0007] Preferably, a first sealing ring is provided between the lower cover and the lower pressure plate.

[0008] Preferably, the axial pressure mechanism includes an inlet pipe, a piston cylinder, a piston body, a piston rod, and an upper cover covering all inlets. The upper cover and the upper pressure plate cooperate to form a displacement fluid chamber. The piston cylinder is connected to the annular sealed confining pressure chamber via a connecting hose. The piston body is disposed inside the piston cylinder. One end of the piston rod is connected to the piston body, and the other end of the piston rod is connected to the top of the upper cover. One end of the inlet pipe is connected to the displacement fluid chamber via the upper cover, and the other end of the inlet pipe extends through the upper sealing plate to the outside of the carbon fiber sleeve.

[0009] Preferably, the upper pressure plate has a first interface, and one end of the connecting hose is connected to the annular sealed confining pressure cavity through the first interface.

[0010] Preferably, a sealing partition is provided inside the piston cylinder, and a through hole is provided on the sealing partition; the sealing partition divides the internal space of the piston cylinder into a piston chamber and a buffer chamber, and the piston chamber and the buffer chamber are connected by the through hole; the other end of the connecting hose is connected to the buffer chamber through a second interface on the piston cylinder.

[0011] Preferably, it also includes a liquid guide tube; the lower pressure plate has a liquid inlet, one end of the liquid guide tube is connected to the annular sealed confining cavity through the liquid inlet, and the other end of the liquid guide tube passes through the support base and the lower sealing plate in sequence and extends to the outside of the carbon fiber sleeve.

[0012] Preferably, the ratio of the radial cross-sectional area of ​​the piston body along the receiving cavity to the radial cross-sectional area of ​​the receiving cavity is 1.5 to 3.

[0013] Preferably, a second sealing ring is provided between the upper cover and the upper pressure plate.

[0014] The beneficial technical effects of this invention are as follows: 1) The core clamping device for displacement scanning proposed in this technical solution, by setting up an axial pressure mechanism and an annular sealed confining pressure cavity, and establishing communication between the annular sealed confining pressure cavity and the axial pressure mechanism, realizes hydraulic sharing and simulates confining pressure and axial pressure. It can better restore the stress situation of real rocks in the formation state, which is of great significance for improving the accuracy of experimental results.

[0015] 2) This technical solution, by setting up an upper cover, piston cylinder, and piston body, connects the inner cavity of the piston cylinder with the annular sealed confining pressure chamber, allowing the high-pressure liquid inside the piston cylinder to enter the piston cylinder. The resulting hydraulic force sequentially applies axial pressure to the rock core through the piston body, piston rod, upper cover, and upper pressure plate, thus ensuring that the confining pressure and axial pressure of the rock core originate from the same source. In this way, only the pressure of the high-pressure liquid entering the annular sealed confining pressure chamber needs to be adjusted to simultaneously adjust the confining pressure and axial pressure on the rock core, greatly simplifying the pressure adjustment process in the displacement simulation process. Attached Figure Description

[0016] Figure 1 This is a front cross-sectional view of the core clamping device in this technical solution. Figure 2 This is a front cross-sectional view of the axial pressure mechanism. Figure 3 This is a front sectional view of the drainage mechanism.

[0017] In the picture: 1. Carbon fiber sleeve; 2. Axial pressure mechanism; 2.1. Inlet pipe; 2.2. Piston cylinder; 2.3. Piston body; 2.4. Piston rod; 2.5. Upper cover; 2.6. Displacement fluid chamber; 2.7. Piston cavity; 2.8. Buffer chamber; 2.9. Second interface; 3. Connecting hose; 4. Sealing partition; 5. Through hole; 6. Second sealing ring; 7. Clamping mechanism; 7.1. Rubber sleeve; 7.2. Upper pressure plate; 7.21 7.22. Ring structure; 7.3. Cover plate structure; 7.4. First interface; 7.5. Lower pressure plate; 7.6. Receiving cavity; 7.7. Inlet; 7.8. Outlet; 7.9. Liquid inlet; 8. Liquid guide pipe; 9.0. Drainage mechanism; 9.1. Drainage pipe; 9.2. Support base; 9.3. Lower cover; 9.4. Collection cavity; 10. First sealing ring; 11. Upper sealing plate; 12. Lower sealing plate; 13. Annular sealed confining cavity. Detailed Implementation

[0018] To make the purpose, technical solution and advantages of the invention clearer, the technical solution of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the invention, but not all embodiments.

[0019] Therefore, the following detailed description of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] Example 1 This embodiment discloses a core clamping device for displacement scanning (hereinafter referred to as the core clamping device), which is a basic implementation of this technical solution. It includes a carbon fiber sleeve 1, an axial pressure mechanism 2, a clamping mechanism 7, and a drainage mechanism 9. The axial pressure mechanism 2, the clamping mechanism 7, and the drainage mechanism 9 are located inside the carbon fiber sleeve 1 and are coaxially arranged with it. To improve the performance, an upper sealing plate 11 and a lower sealing plate 12 are respectively provided at both ends of the carbon fiber sleeve 1. The upper sealing plate 11 is detachably connected to the carbon fiber sleeve 1, and the axial pressure mechanism 2 can be removed from the carbon fiber sleeve 1.

[0021] The clamping mechanism 7 includes a rubber sleeve 7.1. An upper pressure plate 7.2 and a lower pressure plate 7.4 are respectively sealed and fixedly connected to both ends of the rubber sleeve 7.1. The upper pressure plate 7.2 and the lower pressure plate 7.4 are respectively in a sealed sliding fit with the carbon fiber sleeve 1. The rubber sleeve 7.1, the upper pressure plate 7.2, and the lower pressure plate 7.4 cooperate to form a receiving cavity 7.5 for accommodating the core. The upper pressure plate 7.2 has several inlets 7.6 communicating with the receiving cavity 7.5, and the lower pressure plate 7.4 has several outlets 7.7 communicating with the receiving cavity 7.5. An annular sealed confining cavity 13 for introducing high-pressure liquid is formed between the outer wall of the rubber sleeve 7.1 and the inner wall of the carbon fiber sleeve 1.

[0022] The draining mechanism 9 is located at the bottom of the clamping mechanism 7 and is used to support the clamping mechanism 7 and to discharge the fluid flowing out of the drain port 7.7.

[0023] The axial pressure mechanism 2 is located on the top of the clamping mechanism 7 and is used to introduce displacement fluid into the receiving cavity 7.5 through the inlet 7.6 and to apply pressure to the core in conjunction with the annular closed confining pressure cavity 13.

[0024] In practical use: After the core is inserted into the rubber sleeve 7.1 and the clamping mechanism 7 is assembled, the axial pressure applying mechanism 2 and the drainage mechanism 9 are installed in place. Then, high-pressure liquid is introduced into the annular sealed confining pressure chamber 13. The high-pressure liquid acts on the rubber sleeve 7.1, thereby transmitting pressure to the sidewalls of the core inside, thus applying confining pressure to the core. Simultaneously, the high-pressure liquid enters the axial pressure applying mechanism 2, causing it to apply axial pressure to the core in the clamping mechanism 7. Further, the axial pressure applying mechanism 2 introduces displacing fluid into the receiving chamber 7.5 through the inlet 7.6. The displacing fluid reaches the upper end of the core inside the rubber sleeve 7.1 through the inlet 7.6, then seeps into the core to the lower end, and finally flows through the outlet 7.7 and is discharged by the drainage mechanism 9. During this process, the entire core clamping device can be scanned using a micron-sized CT scanner or an MRI scanner to determine the distribution of the displacing fluid within the core.

[0025] To facilitate the insertion of the core sample into the rubber sleeve 7.1, the upper pressure plate 7.2 includes a ring structure and a cover plate structure 7.22. The cover plate structure 7.22 is detachably connected to the ring structure, and the ring structure is fixedly connected to the rubber sleeve 7.1. In use, after opening the cover plate structure 7.22, the core sample is inserted into the rubber sleeve 7.1, and then the cover plate structure 7.22 is closed, fixing the cover plate structure 7.22 relative to the ring structure.

[0026] Example 2 This embodiment discloses a core clamping device for displacement scanning (hereinafter referred to as the core clamping device). As a preferred embodiment of this technical solution, it includes a carbon fiber sleeve 1, an axial pressure mechanism 2, a clamping mechanism 7, and a drainage mechanism 9. The axial pressure mechanism 2, the clamping mechanism 7, and the drainage mechanism 9 are located inside the carbon fiber sleeve 1 and are coaxially arranged with the carbon fiber sleeve 1. An upper sealing plate 11 and a lower sealing plate 12 are respectively provided at both ends of the carbon fiber sleeve 1. The clamping mechanism 7 includes a rubber sleeve 7.1, and an upper pressure plate 7.2 and a lower pressure plate 7.4 are respectively sealed and fixedly connected to both ends of the rubber sleeve 7.1. The upper pressure plate 7.2 and the lower pressure plate 7.4 are respectively in a sealing sliding fit with the carbon fiber sleeve 1. The rubber sleeve 7.1 and the upper pressure plate 7.2 are also mentioned. The upper pressure plate 7.2, together with the lower pressure plate 7.4, forms a receiving cavity 7.5 for accommodating the core. The upper pressure plate 7.2 has several inlets 7.6 communicating with the receiving cavity 7.5, and the lower pressure plate 7.4 has several outlets 7.7 communicating with the receiving cavity 7.5. The outer side wall of the rubber sleeve 7.1 and the inner side wall of the carbon fiber sleeve 1 form an annular sealed confining pressure cavity 13 for introducing high-pressure liquid. The liquid discharge mechanism 9 is located at the bottom of the clamping mechanism 7 and is used to support the clamping mechanism 7 and to discharge the fluid flowing out of the outlets 7.7. The axial pressure mechanism 2 is located at the top of the clamping mechanism 7 and is used to introduce displacement fluid into the receiving cavity 7.5 through the inlets 7.6 and to apply pressure to the core in conjunction with the annular sealed confining pressure cavity 13.

[0027] Furthermore, the axial pressure mechanism 2 includes an inlet pipe 2.1, a piston cylinder 2.2, a piston body 2.3, a piston rod 2.4, and an upper cover 2.5 covering all inlets 7.6. The upper cover 2.5 cooperates with the upper pressure plate 7.2 to form a displacement fluid chamber 2.6. The piston cylinder 2.2 is connected to the annular sealed confining pressure chamber 13 via a connecting hose 3. The piston body 2.3 is disposed inside the piston cylinder 2.2. One end of the piston rod 2.4 is connected to the piston body 2.3, and the other end of the piston rod 2.4 is connected to the top of the upper cover 2.5. One end of the inlet pipe 2.1 is connected to the displacement fluid chamber 2.6 via the upper cover 2.5, and the other end of the inlet pipe 2.1 extends through the upper sealing plate 11 to the outside of the carbon fiber sleeve 1.

[0028] In practical use: After the core is inserted into the rubber sleeve 7.1 and the clamping mechanism 7 is assembled, the axial pressure applying mechanism 2 and the drainage mechanism 9 are installed in place. Then, high-pressure liquid is introduced into the annular sealed confining pressure chamber 13. The high-pressure liquid acts on the rubber sleeve 7.1, thereby transmitting pressure to the sidewall of the core inside, thus applying confining pressure to the core. Simultaneously, the high-pressure liquid in the annular sealed confining pressure chamber 13 enters the piston cylinder 2.2, pushing the piston body 2.3 within the piston cylinder 2.2 to move towards the clamping mechanism 7, applying pressure to the upper pressure plate 7.2. The upper pressure plate 7.2 applies pressure to the upper surface of the core, thereby applying axial pressure to the core. Since the annular sealed confining pressure chamber 13 is connected to the internal space of the piston cylinder 2.2, the liquid pressure inside both is equal. Therefore, when the pressure of the high-pressure liquid in the annular sealed confining pressure chamber 13 changes, the pressure on the piston body 2.3 changes synchronously. This simplifies the pressure adjustment process; only the pressure of the high-pressure liquid entering the annular sealed confining pressure chamber 13 needs to be adjusted to synchronously adjust the confining pressure and axial pressure on the core. After pressure adjustment, the displacing fluid is introduced into the displacing fluid chamber 2.6 through the inlet pipe 2.1. The displacing fluid enters the upper end of the core inside the rubber sleeve 7.1 through the inlet port 7.6, then seeps into the core to the lower end, and finally flows through the outlet port 7.7 and is discharged by the drainage mechanism 9. During this process, the entire core clamping device can be scanned using a micron-sized CT scanner or an MRI scanner to determine the distribution of the displacing fluid within the core.

[0029] This technical solution, by setting up an upper cover 2.5, a piston cylinder 2.2, and a piston body 2.3, connects the inner cavity of the piston cylinder 2.2 to the annular sealed confining pressure chamber 13, allowing the high-pressure liquid inside the piston cylinder 2.2 to enter. The resulting hydraulic force sequentially applies axial pressure to the core through the piston body 2.3, piston rod 2.4, upper cover 2.5, and upper pressure plate 7.2. This ensures that the confining pressure and axial pressure of the core originate from the same source. Therefore, only the pressure of the high-pressure liquid entering the annular sealed confining pressure chamber 13 needs to be adjusted to simultaneously regulate the confining pressure and axial pressure on the core, greatly simplifying the pressure adjustment process during displacement simulation. In summary, the core clamping device proposed in this technical solution simulates both confining pressure and axial pressure, effectively reproducing the stress conditions of real rocks in formation, resulting in more accurate experimental results.

[0030] Example 3 This embodiment discloses a core clamping device for displacement scanning (hereinafter referred to as the core clamping device). As a preferred embodiment of this technical solution, it includes a carbon fiber sleeve 1, an axial pressure mechanism 2, a clamping mechanism 7, and a drainage mechanism 9. The axial pressure mechanism 2, the clamping mechanism 7, and the drainage mechanism 9 are located inside the carbon fiber sleeve 1 and are coaxially arranged with the carbon fiber sleeve 1. An upper sealing plate 11 and a lower sealing plate 12 are respectively provided at both ends of the carbon fiber sleeve 1. The clamping mechanism 7 includes a rubber sleeve 7.1, and an upper pressure plate 7.2 and a lower pressure plate 7.4 are respectively sealed and fixedly connected to both ends of the rubber sleeve 7.1. The upper pressure plate 7.2 and the lower pressure plate 7.4 are respectively in a sealing sliding fit with the carbon fiber sleeve 1. The rubber sleeve 7.1 and the upper pressure plate 7.2 are also mentioned. The upper pressure plate 7.2, together with the lower pressure plate 7.4, forms a receiving cavity 7.5 for accommodating the core. The upper pressure plate 7.2 has several inlets 7.6 communicating with the receiving cavity 7.5, and the lower pressure plate 7.4 has several outlets 7.7 communicating with the receiving cavity 7.5. The outer side wall of the rubber sleeve 7.1 and the inner side wall of the carbon fiber sleeve 1 form an annular sealed confining pressure cavity 13 for introducing high-pressure liquid. The liquid discharge mechanism 9 is located at the bottom of the clamping mechanism 7 and is used to support the clamping mechanism 7 and to discharge the fluid flowing out of the outlets 7.7. The axial pressure mechanism 2 is located at the top of the clamping mechanism 7 and is used to introduce displacement fluid into the receiving cavity 7.5 through the inlets 7.6 and to apply pressure to the core in conjunction with the annular sealed confining pressure cavity 13.

[0031] Furthermore, the axial pressure mechanism 2 includes an inlet pipe 2.1, a piston cylinder 2.2, a piston body 2.3, a piston rod 2.4, and an upper cover 2.5 covering all inlets 7.6. The upper cover 2.5 cooperates with the upper pressure plate 7.2 to form a displacement fluid chamber 2.6. Furthermore, a second sealing ring 6 is provided between the upper cover 2.5 and the upper pressure plate 7.2. The piston cylinder 2.2 is connected to the annular sealed confining pressure chamber 13 through a connecting hose 3. The piston body 2.3 is disposed inside the piston cylinder 2.2. One end of the piston rod 2.4 is connected to the piston body 2.3, and the other end of the piston rod 2.4 is connected to the top of the upper cover 2.5. One end of the inlet pipe 2.1 is connected to the displacement fluid chamber 2.6 through the upper cover 2.5, and the other end of the inlet pipe 2.1 extends through the upper sealing plate 11 to the outside of the carbon fiber sleeve 1.

[0032] Furthermore, to ensure the integration of the core clamping device and make its appearance as simple as possible, the connecting hose 3 is located inside the carbon fiber sleeve 1. Based on this, a first interface 7.3 is provided on the upper pressure plate 7.2, and one end of the connecting hose 3 is connected to the annular sealed confining cavity 13 through the first interface 7.3; a second interface 2.9 is provided on the piston cylinder 2.2, and the other end of the connecting hose 3 is connected to the piston cylinder 2.2 through the second interface 2.9.

[0033] Furthermore, a sealing partition 4 is provided inside the piston cylinder 2.2, and a through hole 5 is provided on the sealing partition 4; the sealing partition 4 divides the internal space of the piston cylinder 2.2 into a piston chamber 2.7 and a buffer chamber 2.8, and the piston chamber 2.7 and the buffer chamber 2.8 are connected by the through hole 5; the other end of the connecting hose 3 is connected to the buffer chamber 2.8 through the second interface 2.9 on the piston cylinder 2.2.

[0034] Example 4 This embodiment discloses a core clamping device for displacement scanning (hereinafter referred to as the core clamping device). As a preferred embodiment of this technical solution, it includes a carbon fiber sleeve 1, an axial pressure mechanism 2, a clamping mechanism 7, and a drainage mechanism 9. The axial pressure mechanism 2, the clamping mechanism 7, and the drainage mechanism 9 are located inside the carbon fiber sleeve 1 and are coaxially arranged with the carbon fiber sleeve 1. An upper sealing plate 11 and a lower sealing plate 12 are respectively provided at both ends of the carbon fiber sleeve 1. The clamping mechanism 7 includes a rubber sleeve 7.1, and an upper pressure plate 7.2 and a lower pressure plate 7.4 are respectively sealed and fixedly connected to both ends of the rubber sleeve 7.1. The upper pressure plate 7.2 and the lower pressure plate 7.4 are respectively in a sealing sliding fit with the carbon fiber sleeve 1. The rubber sleeve 7.1 and the upper pressure plate 7.2 are also mentioned. The upper pressure plate 7.2, together with the lower pressure plate 7.4, forms a receiving cavity 7.5 for accommodating the core. The upper pressure plate 7.2 has several inlets 7.6 communicating with the receiving cavity 7.5, and the lower pressure plate 7.4 has several outlets 7.7 communicating with the receiving cavity 7.5. The outer side wall of the rubber sleeve 7.1 and the inner side wall of the carbon fiber sleeve 1 form an annular sealed confining pressure cavity 13 for introducing high-pressure liquid. The liquid discharge mechanism 9 is located at the bottom of the clamping mechanism 7 and is used to support the clamping mechanism 7 and to discharge the fluid flowing out of the outlets 7.7. The axial pressure mechanism 2 is located at the top of the clamping mechanism 7 and is used to introduce displacement fluid into the receiving cavity 7.5 through the inlets 7.6 and to apply pressure to the core in conjunction with the annular sealed confining pressure cavity 13.

[0035] Furthermore, the drainage mechanism 9 includes a drainage pipe 9.1, a support base 9.2, and a lower cover 9.3 covering all drainage ports 7.7; the support base 9.2 is disposed on the lower sealing plate 12 and connected to the bottom of the lower cover 9.3; the lower cover 9.3 cooperates with the lower pressure plate 7.4 to form a collection cavity 9.4, and further, a first sealing ring 10 is provided between the lower cover 9.3 and the lower pressure plate 7.4; one end of the drainage pipe 9.1 is connected to the collection cavity 9.4 through the lower cover 9.3, and the other end of the drainage pipe 9.1 extends through the support base 9.2 and the lower sealing plate 12 to the outside of the carbon fiber sleeve 1.

[0036] Furthermore, to ensure the integration of the core clamping device and make its appearance as simple as possible, a liquid guide pipe 8 is also included. A liquid inlet 7.8 is provided on the lower pressure plate 7.4. One end of the liquid guide pipe 8 is connected to the annular sealed confining pressure chamber 13 through the liquid inlet 7.8, and the other end of the liquid guide pipe 8 extends through the support base 9.2 and the lower sealing plate 12 to the outside of the carbon fiber sleeve 1. In this way, high-pressure liquid is introduced into the annular sealed confining pressure chamber 13 through the liquid guide pipe 8.

[0037] Based on the above structure, the displacing fluid enters the upper end of the core inside the rubber sleeve 7.1 through the inlet 7.6, then seeps into the lower end of the core, and is then discharged from the outlet 7.7 into the collection chamber 9.4, and finally discharged through the outlet pipe 9.1. It should be understood that a back pressure valve is connected to the lower end of the outlet pipe 9.1, thereby maintaining a constant internal pressure of the system.

[0038] Example 5 This embodiment discloses a core clamping device for displacement scanning (hereinafter referred to as the core clamping device). As a preferred embodiment of this technical solution, it includes a carbon fiber sleeve 1, an axial pressure mechanism 2, a clamping mechanism 7, and a drainage mechanism 9. The axial pressure mechanism 2, the clamping mechanism 7, and the drainage mechanism 9 are located inside the carbon fiber sleeve 1 and are coaxially arranged with the carbon fiber sleeve 1. An upper sealing plate 11 and a lower sealing plate 12 are respectively provided at both ends of the carbon fiber sleeve 1. The clamping mechanism 7 includes a rubber sleeve 7.1, and an upper pressure plate 7.2 and a lower pressure plate 7.4 are respectively sealed and fixedly connected to both ends of the rubber sleeve 7.1. The upper pressure plate 7.2 and the lower pressure plate 7.4 are respectively in a sealed sliding fit with the carbon fiber sleeve 1. The rubber sleeve 7.1 and the upper pressure plate 7.2 are also mentioned. The upper pressure plate 7.2, together with the lower pressure plate 7.4, forms a receiving cavity 7.5 for accommodating the core. The upper pressure plate 7.2 has several inlets 7.6 communicating with the receiving cavity 7.5, and the lower pressure plate 7.4 has several outlets 7.7 communicating with the receiving cavity 7.5. The outer wall of the rubber sleeve 7.1 and the inner wall of the carbon fiber sleeve 1 form an annular sealed confining pressure cavity 13 for introducing high-pressure liquid. The liquid discharge mechanism 9 is located at the bottom of the clamping mechanism 7 and is used to support the clamping mechanism 7 and to discharge the fluid flowing out of the outlets 7.7. The axial pressure mechanism 2 is located at the top of the clamping mechanism 7 and is used to introduce displacement fluid into the receiving cavity 7.5 through the inlets 7.6 and to apply pressure to the core in conjunction with the annular sealed confining pressure cavity 13.

[0039] Furthermore, the drainage mechanism 9 includes a drainage pipe 9.1, a support base 9.2, and a lower cover 9.3 covering all drainage ports 7.7; the support base 9.2 is disposed on the lower sealing plate 12 and connected to the bottom of the lower cover 9.3; the lower cover 9.3 cooperates with the lower pressure plate 7.4 to form a collection cavity 9.4, and further, a first sealing ring 10 is provided between the lower cover 9.3 and the lower pressure plate 7.4 to improve the sealing performance between the lower cover 9.3 and the lower pressure plate 7.4; one end of the drainage pipe 9.1 is connected to the collection cavity 9.4 through the lower cover 9.3, and the other end of the drainage pipe 9.1 extends through the support base 9.2 and the lower sealing plate 12 to the outside of the carbon fiber sleeve 1.

[0040] Furthermore, the axial pressure mechanism 2 includes an inlet pipe 2.1, a piston cylinder 2.2, a piston body 2.3, a piston rod 2.4, and an upper cover 2.5 covering all inlets 7.6. The upper cover 2.5 cooperates with the upper pressure plate 7.2 to form a displacement fluid chamber 2.6. Furthermore, a second sealing ring 6 is provided between the upper cover 2.5 and the upper pressure plate 7.2 to improve the sealing performance between the upper cover 2.5 and the upper pressure plate 7.2. The piston cylinder 2.2 is connected to the annular sealed confining pressure chamber 13 through a connecting hose 3. The piston body 2.3 is disposed inside the piston cylinder 2.2. One end of the piston rod 2.4 is connected to the piston body 2.3, and the other end of the piston rod 2.4 is connected to the top of the upper cover 2.5. One end of the inlet pipe 2.1 is connected to the displacement fluid chamber 2.6 through the upper cover 2.5, and the other end of the inlet pipe 2.1 extends through the upper sealing plate 11 to the outside of the carbon fiber sleeve 1. The upper pressure plate 7.2 has a first interface 7.3, and one end of the connecting hose 3 is connected to the annular sealed confining cavity 13 through the first interface 7.3. A sealing partition 4 is provided inside the piston cylinder 2.2, and a through hole 5 is provided on the sealing partition 4; the sealing partition 4 divides the internal space of the piston cylinder 2.2 into a piston cavity 2.7 and a buffer cavity 2.8, which are connected through the through hole 5; the other end of the connecting hose 3 is connected to the buffer cavity 2.8 through a second interface 2.9 on the piston cylinder 2.2.

[0041] Furthermore, it also includes a liquid guide tube 8; the lower pressure plate 7.4 is provided with a liquid inlet 7.8, one end of the liquid guide tube 8 is connected to the annular sealed confining cavity 13 through the liquid inlet 7.8, and the other end of the liquid guide tube 8 extends to the outside of the carbon fiber sleeve 1 through the support base 9.2 and the lower sealing plate 12 in sequence.

[0042] Furthermore, to control the ratio of confining pressure to axial pressure on the core, the ratio of the radial cross-sectional area of ​​the piston body 2.3 along the receiving cavity 7.5 to the radial cross-sectional area of ​​the receiving cavity 7.5 is 1.5 to 3. Under otherwise constant conditions, the larger the area of ​​the piston body 2.3, the greater the axial pressure on the core; conversely, the smaller the area of ​​the piston body 2.3, the smaller the axial pressure on the core. Therefore, the ratio of axial pressure to confining pressure on the core can be controlled by designing the radial cross-sectional area of ​​the piston body 2.3 along the receiving cavity 7.5. When specifically designing the dimensions of the piston body 2.3, it is necessary to determine the dimensions based on the ratio of axial pressure to confining pressure in the formation of the study area. Typically, the ratio of axial pressure to confining pressure in the formation is 1.5 to 3.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A core clamping device for displacement scanning, characterized in that: It includes a carbon fiber sleeve (1), an axial pressure mechanism (2), a clamping mechanism (7) and a draining mechanism (9). The axial pressure mechanism (2), the clamping mechanism (7) and the draining mechanism (9) are located inside the carbon fiber sleeve (1) and are coaxially arranged with the carbon fiber sleeve (1). The two ends of the carbon fiber sleeve (1) are respectively provided with an upper sealing plate (11) and a lower sealing plate (12). The clamping mechanism (7) includes a rubber sleeve (7.1), with an upper pressure plate (7.2) and a lower pressure plate (7.4) respectively sealed and fixedly connected to both ends of the rubber sleeve (7.1). The upper pressure plate (7.2) and the lower pressure plate (7.4) are respectively sealed and slidingly engaged with the carbon fiber sleeve (1). The rubber sleeve (7.1), the upper pressure plate (7.2) and the lower pressure plate (7.4) together form a cavity (7.5) for accommodating the core. The upper pressure plate (7.2) has several inlets (7.6) communicating with the cavity (7.5), and the lower pressure plate (7.4) has several outlets (7.7) communicating with the cavity (7.5). An annular closed confining pressure cavity (13) for introducing high-pressure liquid is formed between the outer wall of the rubber sleeve (7.1) and the inner wall of the carbon fiber sleeve (1). The drainage mechanism (9) is located at the bottom of the clamping mechanism (7) and is used to support the clamping mechanism (7) and to discharge the fluid flowing out of the drain port (7.7); The axial pressure mechanism (2) is located on the top of the clamping mechanism (7) and is used to introduce the displacement fluid into the receiving cavity (7.5) through the inlet (7.6) and to apply pressure to the core in conjunction with the annular closed confining pressure cavity (13). The axial pressure mechanism (2) includes an inlet pipe (2.1), a piston cylinder (2.2), a piston body (2.3), a piston rod (2.4), and an upper cover (2.5) covering all inlets (7.6). The upper cover (2.5) and the upper pressure plate (7.2) cooperate to form a displacement fluid chamber (2.6). The piston cylinder (2.2) is connected to the annular sealed confining pressure chamber (13) through a connecting hose (3). The piston body (2.3) is located inside the piston cylinder (2.2). One end of the piston rod (2.4) is connected to the piston body (2.3), and the other end of the piston rod (2.4) is connected to the top of the upper cover (2.5). One end of the inlet pipe (2.1) is connected to the displacement fluid chamber (2.6) through the upper cover (2.5), and the other end of the inlet pipe (2.1) extends through the upper sealing plate (11) to the outside of the carbon fiber sleeve (1). The piston cylinder (2.2) is provided with a sealing partition (4), and a through hole (5) is provided on the sealing partition (4); the sealing partition (4) divides the internal space of the piston cylinder (2.2) into a piston chamber (2.7) and a buffer chamber (2.8), and the piston chamber (2.7) and the buffer chamber (2.8) are connected by the through hole (5); the other end of the connecting hose (3) is connected to the buffer chamber (2.8) through the second interface (2.9) on the piston cylinder (2.2).

2. The core clamping device for displacement scanning as described in claim 1, characterized in that: The drainage mechanism (9) includes a drainage pipe (9.1), a support base (9.2), and a lower cover (9.3) covering all drainage ports (7.7). The support base (9.2) is mounted on the lower sealing plate (12) and connected to the bottom of the lower cover (9.3). The lower cover (9.3) and the lower pressure plate (7.4) cooperate to form a collection cavity (9.4). One end of the drainage pipe (9.1) is connected to the collection cavity (9.4) through the lower cover (9.3), and the other end of the drainage pipe (9.1) passes through the support base (9.2) and the lower sealing plate (12) in sequence and extends to the outside of the carbon fiber sleeve (1).

3. The core clamping device for displacement scanning as described in claim 2, characterized in that: A first sealing ring (10) is provided between the lower cover (9.3) and the lower pressure plate (7.4).

4. The core clamping device for displacement scanning as described in claim 1, characterized in that: The upper pressure plate (7.2) is provided with a first interface (7.3), and one end of the connecting hose (3) is connected to the annular sealed confining cavity (13) through the first interface (7.3).

5. The core clamping device for displacement scanning as described in claim 1, characterized in that: It also includes a liquid guide tube (8); the lower pressure plate (7.4) is provided with a liquid inlet (7.8), one end of the liquid guide tube (8) is connected to the annular sealed confining cavity (13) through the liquid inlet (7.8), and the other end of the liquid guide tube (8) extends through the support base (9.2) and the lower sealing plate (12) to the outside of the carbon fiber sleeve (1).

6. The core clamping device for displacement scanning as described in claim 1, characterized in that: The ratio of the radial cross-sectional area of ​​the piston body (2.3) along the receiving cavity (7.5) to the radial cross-sectional area of ​​the receiving cavity (7.5) is 1.5 to 3.

7. The core clamping device for displacement scanning as described in claim 1, characterized in that: A second sealing ring (6) is provided between the upper cover (2.5) and the upper pressure plate (7.2).

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