A core holder capable of applying differential confining pressure and a confining pressure method

Abstract

The present invention discloses a core holder capable of applying differential confining pressure and a confining pressure method, which includes an upper cover plate, a confining pressure sleeve, two pressurizing pistons, a pressurizing device and a holder base. The bottom of the upper cover plate is provided with a confining pressure sleeve, and the bottom of the confining pressure sleeve is provided with a holder base. A confining pressure cavity is formed in the confining pressure sleeve, and the confining pressure cavity and the core sample are separated by the inner wall of the confining pressure sleeve. Two pressurizing pistons are slidably arranged in the confining pressure cavity to divide the confining pressure cavity into a first cavity, a second cavity and a third cavity; by arranging a confining pressure cavity in the confining pressure sleeve and cooperating with two sliding pressurizing pistons, the confining pressure cavity can be divided into three parts, and the three parts of the cavity are respectively connected to the pressurizing device, so that different confining pressures can be applied vertically to the core sample; at the same time, by sliding the pressurizing pistons, the sizes of the three parts of the cavity can be adjusted to further simulate the range of differential confining pressure in the actual situation.

Description

Technical Field

[0001] The present invention relates to the technical field of rock property testing devices, and particularly relates to a core holder capable of applying differential confining pressure and a confining pressure method. Background Art

[0002] A core holder is a commonly used rock property testing device in the field of geotechnical engineering, usually used to apply confining pressure to rocks. In the actual formation, rocks may be subjected to various lateral forces. For example, in the mud-sand interaction area, the pressures generated by mudstone and sandstone on the core are different, resulting in uneven confining pressure of the rock under specific conditions. When the existing core holder works, generally, hydraulic oil is directly wrapped around the rubber sleeve outside the sample to apply confining pressure to the sample. However, this structure can only apply a single confining pressure to the core and cannot truly restore the confining pressure in different in-situ environments, thus leading to errors in experimental tests.

[0003] In view of this, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] In view of the above deficiencies of the existing technology, the purpose of the present invention is to provide a core holder capable of applying differential confining pressure and a confining pressure method, aiming to solve the problem that the existing core holder can only apply a single confining pressure and cannot truly restore the confining pressure in different in-situ environments, thus leading to errors in experimental tests.

[0005] The technical solution adopted by the present invention to solve the technical problems is as follows:

[0006] A core holder capable of applying differential confining pressure, comprising:

[0007] An upper cover plate, provided with a liquid inlet at the top;

[0008] A confining pressure sleeve, disposed at the bottom of the upper cover plate; the inner hole of the confining pressure sleeve is used to place a core sample, and a confining pressure cavity is formed inside the confining pressure sleeve;

[0009] Two pressurizing pistons, slidably disposed in the confining pressure cavity to divide the confining pressure cavity into a first cavity, a second cavity, and a third cavity;

[0010] A pressurizing device, respectively connected to the first cavity, the second cavity, and the third cavity, for adjusting the pressure inside each cavity;

[0011] A holder base, disposed at the bottom of the confining pressure sleeve; the top of the holder base is provided with a liquid outlet.

[0012] According to the above technical means, a confining pressure cavity is arranged inside the confining pressure sleeve, which can provide confining pressure for the core sample. At the same time, in cooperation with two sliding pressure pistons, the confining pressure cavity can be divided into three parts, and the three cavities are respectively connected to the pressure applying device, so that different confining pressures can be applied vertically to the core sample. At the same time, by sliding the pressure pistons, the sizes of the three cavities can be adjusted to further simulate the range of differential confining pressure under real conditions.

[0013] Furthermore, the pressure applying device includes:

[0014] Two hydraulic devices, which are respectively arranged at both ends of the confining pressure sleeve; the two hydraulic devices are respectively connected to the first cavity and the third cavity to inject hydraulic oil into the first cavity and the third cavity.

[0015] A pressure regulating pump, which is arranged outside the confining pressure sleeve; the pressure regulating pump is connected to the second cavity through a pipeline and is used to adjust the pressure inside the second cavity.

[0016] According to the above technical means, the pressure applying device includes two hydraulic devices and a pressure regulating pump, which can be respectively connected to the first cavity, the second cavity and the third cavity to separately provide pressure to the corresponding cavity, so as to realize different confining pressures.

[0017] Furthermore, the hydraulic device includes:

[0018] A pressure applying pipeline, which is slidably arranged inside the confining pressure sleeve; the top of the pressure applying pipeline is connected to the pressure piston, and an outlet hole is arranged at the top end of the pressure applying pipeline.

[0019] A driving assembly, which is arranged outside the confining pressure sleeve; the driving assembly is connected to the pressure applying pipeline to drive the pressure applying pipeline and the pressure piston to slide inside the confining pressure cavity.

[0020] According to the above technical means, the driving assembly is respectively connected to the corresponding pressure applying pipeline. By starting the driving assembly, the pressure applying pipeline can slide inside the confining pressure sleeve, so as to drive the pressure piston to slide inside the confining pressure cavity and adjust the sizes of each cavity.

[0021] Furthermore, the driving assembly includes:

[0022] A pipeline lifting gear, which is vertically arranged on one side of the pressure applying pipeline;

[0023] A lifting motor, which is arranged outside the confining pressure sleeve; a driving gear is arranged on the output shaft of the lifting motor, and the driving gear meshes with the pipeline lifting gear.

[0024] According to the above technical means, the material of the pressure pipeline is a rigid material, so that pipeline lifting teeth can be arranged on one side thereof, and in cooperation with the driving gear on the lifting motor, the pressure pipeline and the pressure piston can be driven to slide inside the confining pressure cavity to facilitate the adjustment of the size of each cavity.

[0025] Furthermore, a rubber sleeve is wrapped around the outside of the pressure piston.

[0026] According to the above technical means, the rubber sleeve is made of an expandable and compressible material. By abutting the rubber sleeve against the inner walls on both sides of the confining pressure cavity, when pressure is applied to each cavity, the rubber sleeve unfolds from the compressed state to the initial state and abuts against the inner wall of the confining pressure cavity in real time to ensure its sealing performance.

[0027] Furthermore, a mating groove is provided at the bottom of the upper cover plate. The side wall of the mating groove is provided with a first thread, and the outside of the confining pressure sleeve is provided with a second thread. The first thread and the second thread cooperate to connect the confining pressure sleeve to the upper cover plate.

[0028] According to the above technical means, the confining pressure sleeve and the upper cover plate can be conveniently positioned and fixed through the mating groove. By the cooperation of the first thread and the second thread, the stability between the upper cover plate and the confining pressure sleeve can be further increased.

[0029] Furthermore, a sealing groove is provided at the top of the mating groove, and a sealing ring is arranged in the sealing groove. The sealing ring abuts against the top wall of the confining pressure sleeve.

[0030] According to the above technical means, by providing the sealing groove and the sealing ring, the upper cover plate and the confining pressure sleeve can be hermetically fitted to meet the experimental requirements.

[0031] Furthermore, a third thread is provided on the inner wall of the confining pressure sleeve, and a fourth thread is provided on the outside of the holder base. The third thread and the fourth thread cooperate to connect the holder base to the confining pressure sleeve.

[0032] According to the above technical means, by the cooperation of the third thread and the fourth thread, the holder base and the confining pressure sleeve can be fixed.

[0033] Furthermore, a sealing block is provided at the top of the holder base. The outside of the sealing block is convex in an arc shape, and the sealing block abuts against the inner wall of the confining pressure sleeve.

[0034] According to the above technical means, by providing a sealing block at the top of the holder base and providing a convex arc-shaped surface on the side wall of the sealing block, the sealing block can abut against the inner wall of the confining pressure sleeve to ensure its sealing performance.

[0035] A confining pressure method, based on a core holder capable of applying differential confining pressure as described above, includes:

[0036] Place the core sample into the confining pressure sleeve and seal it through the upper cover plate and the holder base;

[0037] Adjust the positions of the two pressure pistons;

[0038] Apply pressure to the first cavity, the second cavity, and the third cavity;

[0039] Inject liquid into the confining pressure sleeve through the liquid inlet and observe the liquid seepage state inside the core sample to complete the experiment.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] In the present invention, a confining pressure sleeve is provided at the bottom of the upper cover plate, a holder base is provided at the bottom of the confining pressure sleeve, a liquid inlet is provided at the top of the upper cover plate, the liquid inlet is internally connected to the confining pressure sleeve, a confining pressure cavity is provided inside the confining pressure sleeve, the inner hole of the confining pressure sleeve is used to place the core sample, the confining pressure cavity is arranged around the core sample, the confining pressure cavity and the core sample are separated by the inner wall of the confining pressure sleeve, two pressure pistons are slidably arranged inside the confining pressure cavity to divide the confining pressure cavity into a first cavity, a second cavity, and a third cavity, the first cavity, the second cavity, and the third cavity are respectively connected to a pressurizing device to adjust the pressure inside each cavity; by providing a confining pressure cavity inside the confining pressure sleeve and providing two sliding pressure pistons inside the confining pressure cavity, the confining pressure cavity can be divided into three parts, and the three parts of the cavity are respectively connected to the pressurizing device, so that different confining pressures can be applied vertically to the core sample; at the same time, the sizes of the three parts of the cavity can be adjusted by the sliding of the pressure pistons to further simulate the range of differential confining pressure in the actual situation. Description of the Drawings

[0042] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0043] Figure 2 It is a schematic diagram of the structure of the confining pressure sleeve of the present invention.

[0044] Figure 3 It is a schematic diagram of the structure of the pressurizing pipeline of the present invention.

[0045] Figure 4 It is a schematic diagram of the structure of the upper cover plate of the present invention.

[0046] Figure 5 It is a schematic diagram of the structure of the holder base of the present invention.

[0047] Figure 6 It is a flowchart of the confining pressure method of the present invention.

[0048] The numerical markings in the figure are as follows: 1. upper cover plate; 11. liquid inlet; 12. mating groove; 13. first thread; 14. sealing groove; 2. confining pressure sleeve; 21. confining pressure cavity; 211. first cavity; 212. second cavity; 213. third cavity; 22. second thread; 23. third thread; 3. pressurizing piston; 4. holder base; 41. fourth thread; 42. sealing block; 43. liquid outlet; 5. pressurizing device; 51. pressure regulating pump; 52. pressurizing pipeline; 53. pipeline lifting teeth; 54. driving gear; 55. outlet hole. Detailed implementation manners

[0049] To make the objectives, technical solutions and effects of the present invention clearer and more definite, the following further describes the present invention in detail with reference to the accompanying drawings and by way of examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "plurality" is two or more.

[0051] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection" and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0052] In view of the deficiencies of the prior art, this embodiment provides a core holder capable of applying differential confining pressure and a confining pressure method, which can be specifically referred to as follows:

[0053] As shown in the attached Figure 1 and the attached Figure 2As shown in the figure, a core holder capable of applying differential confining pressure includes an upper cover plate 1, a confining pressure sleeve 2, two pressurizing pistons 3, a pressurizing device 5, and a holder base 4. At the bottom of the upper cover plate 1, there is a confining pressure sleeve 2. In the center of the confining pressure sleeve 2, there is an inner hole for placing a core sample. At the top of the upper cover plate 1, there is a liquid inlet 11, which is connected to the inner hole, and the upper cover plate 1 and the confining pressure sleeve 2 are arranged in a sealed manner. At the bottom of the confining pressure sleeve 2, there is also a holder base 4. At the top of the holder base 4, there is a liquid outlet 43 to facilitate the discharge of seepage fluid. At the same time, the holder base 4 and the confining pressure sleeve 2 are arranged in a sealed manner. Inside the confining pressure sleeve 2, there is also a confining pressure cavity 21, which surrounds the inner hole, and the confining pressure cavity 21 and the inner hole are arranged at intervals. Vertically slidably arranged inside the confining pressure cavity 21 is a pressurizing piston 3. The pressurizing piston 3 is sealed and slidable with the two side walls of the confining pressure cavity 21. Thus, through the two pressurizing pistons 3, the confining pressure cavity 21 is divided into a first cavity 211, a second cavity 212, and a third cavity 213, and the first cavity 211, the second cavity 212, and the third cavity 213 are arranged vertically in sequence. Outside the confining pressure sleeve 2, there is also a pressurizing device 5, which is respectively connected to the first cavity 211, the second cavity 212, and the third cavity 213. By starting the pressurizing device 5, the pressures in the first cavity 211, the second cavity 212, and the third cavity 213 can be adjusted, so as to apply different confining pressures to the core sample. And the two pressurizing pistons 3 can slide vertically and can also adjust the range of different confining pressures to simulate the confining pressure in the real state.

[0054] Specifically, the upper cover plate 1 and the confining pressure sleeve 2 can be assembled first, and then the core sample is placed into the inner hole through the bottom of the confining pressure sleeve 2, and then sealed by the holder base 4. At this time, the pressurizing device 5 is respectively connected to the first cavity 211, the second cavity 212, and the third cavity 213. The ranges of the first cavity 211, the second cavity 212, and the third cavity 213 are adjusted through the two pressurizing pistons 3 to simulate the ranges of different confining pressures in the real situation. After the adjustment is completed, the pressurizing device 5 can be started to apply pressure to the first cavity 211, the second cavity 212, and the third cavity 213. This pressure acts on the surface of the core sample through the inner wall of the confining pressure cavity 21. Finally, seepage fluid can be injected through the liquid inlet 11, so that the seepage fluid seeps into the core sample under different confining pressures, and the outflowing seepage fluid is discharged through the liquid outlet 43, and then the simulation experiment can be completed.

[0055] In this embodiment, as shown in the attached Figure 2 figure, the confining pressure sleeve 2 is divided into two layers, the outer layer of the confining pressure sleeve 2 is made of a rigid material that is not easily deformed, such as carbon fiber material or steel, etc.; the inner layer of the confining pressure sleeve 2 is made of a deformable flexible material, such as rubber material, which can deform.

[0056] In this embodiment, the inner hole of the confining pressure sleeve 2 is cylindrical, and the core sample is also cylindrical, and the diameter of the core sample is the same as the inner hole diameter of the confining pressure sleeve 2.

[0057] In one embodiment of the present application, as shown in the attached Figure 1 figure, the pressurizing device 5 includes two hydraulic devices and a pressure regulating pump 51; the two hydraulic devices are respectively arranged at the top and bottom of the confining pressure sleeve 2, and the two hydraulic devices are respectively connected to the first cavity 211 and the third cavity 213, and inject hydraulic oil into the first cavity 211 and the third cavity 213; the pressure regulating pump 51 is located outside the confining pressure sleeve 2, and the pressure regulating pump 51 is connected to the second cavity 212 through a pipeline for adjusting the pressure inside the second cavity 212.

[0058] Since the outside of the confining pressure sleeve 2 is made of a material that is not easily deformed, while the inside of the confining pressure sleeve 2 is made of a deformable material, when the two hydraulic devices inject hydraulic oil into the first cavity 211 and the third cavity 213 through the pipeline and apply a certain pressure, the hydraulic oil will squeeze the inner wall of the confining pressure sleeve 2 to squeeze the core sample, so as to attach the inner wall of the confining pressure sleeve 2 to the surface of the core sample; a hole is provided on the outside of the confining pressure sleeve 2, and this hole makes the second cavity 212 communicate with the outside world. At the same time, the pressure regulating pump 51 is connected to the second cavity 212 through a connecting pipeline, that is, one end of the connecting pipeline is connected to the pressure regulating pump 51, and the other end is connected to the hole and sealed to prevent air leakage; during use, the positions of the two pressurizing pistons 3 can be adjusted first, and then the pressure regulating pump 51 is used to inject pressure into the second cavity 212, and at the same time the two hydraulic devices respectively inject hydraulic oil into the first cavity 211 and the third cavity 213 and apply a certain pressure, so as to synchronously apply different pressures to the core sample to achieve the effect of differential confining pressure, so as to simulate the seepage situation inside the core sample under different confining pressures.

[0059] In this embodiment, as shown in the attached Figure 1 and the attached Figure 3 figure, the hydraulic device includes a pressurizing pipeline 52 and a driving component. The pressurizing pipeline 52 is slidably arranged inside the confining pressure sleeve 2. The pressurizing pipelines 52 of the two hydraulic devices are respectively slidably arranged at the top and bottom of the confining pressure sleeve 2. The pressurizing pipeline 52 is rigidly connected to the pressurizing piston 3, and an outlet hole 55 is provided at one end of the pressurizing pipeline 52 close to the pressurizing piston 3. The other end of the pressurizing pipeline 52 away from the pressurizing piston 3 is connected to an external hydraulic pump; a driving component is also arranged outside the confining pressure sleeve 2, and the driving component is connected to the pressurizing pipeline 52 to drive the pressurizing pipeline 52 and the pressurizing piston 3 to slide inside the confining pressure cavity 21.

[0060] Specifically, two pressurizing pipes 52 are slidably arranged at the top and bottom of the confining pressure sleeve 2 and are sealed. The two pressurizing pipes 52 at the same end are symmetrically arranged, and the two pressurizing pipes 52 at the same end are both connected to the pressurizing piston 3. Two driving components are arranged at the top and bottom of the confining pressure sleeve 2, and the four driving components are respectively connected to the corresponding pressurizing pipes 52. By starting the driving components, the pressurizing pipes 52 can be slid within the confining pressure sleeve 2, thereby driving the pressurizing piston 3 to slide within the confining pressure cavity 21 to adjust the sizes of the respective cavities.

[0061] Further, the four pressurizing pipes 52 are made of rigid materials, such as steel, to facilitate the sliding of the pressurizing piston 3 and to withstand the tensile force of the medium inside the corresponding cavity on the pressurizing pipes 52.

[0062] In this embodiment, as shown in Figure 1 and Figure 3 the figure, the driving component includes a pipe lifting gear 53 and a lifting motor. The pipe lifting gear 53 is vertically arranged on one side of the pressurizing pipe 52 and is located outside the confining pressure sleeve 2; the lifting motor is arranged outside the confining pressure sleeve 2, and a driving gear 54 is arranged on the output shaft of the lifting motor. The driving gear 54 meshes with the pipe lifting gear 53; by the action of the lifting motor, the driving gear 54 can be driven to rotate, thereby driving the pressurizing pipe 52 to lift.

[0063] In this embodiment, there are four driving components, with two in a group, and the two groups are respectively arranged at the top and bottom of the confining pressure sleeve 2; in the initial state, the confining pressure sleeve 2, the upper cover plate 1, and the gripper base 4 are suspended and fixed by a clamping member (the clamping member is a prior art), and the four driving components can be respectively arranged on the top of the upper cover plate 1 and the bottom of the confining pressure sleeve 2 through an external bracket, and are at a certain distance from the surface of the upper cover plate 1 and the bottom wall of the confining pressure sleeve 2. The four driving gears 54 are respectively engaged with the four pipe lifting teeth 53. By starting the lifting motor, the pressure application pipe 52 can be driven to move into the confining pressure cavity 21, and then the two pressure application pistons 3 are driven to move; during the application of the confining pressure, the lifting motor is in a self-locking state. At this time, the pipe lifting teeth 53 of the pressure application pipe 52 are engaged with the driving gears 54. Since the lifting motor is in a self-locking state and the driving gears 54 are in a fixed state, the pressure application pipe 52 is also in a fixed state. After the hydraulic pump injects hydraulic oil into the pressure application pipe 52, the first cavity 211, and the third cavity 213 and applies a certain pressure, the pressure application pipe 52 will not move under the locking action of the driving gears 54, so that the pressure in the first cavity 211 and the third cavity 213 acts on the outer surface of the core sample, realizing the function of the confining pressure; the pressure in the second cavity 212 can only be adjusted by the pressure regulating pump 51. By injecting different hydraulic pressures into the first cavity 211 and the third cavity 213, and the pressure regulating pump 51 injecting a certain pressure into the second cavity 212, the function of applying differential confining pressure can be realized.

[0064] Further, the pressure regulating pump 51 is a prior art and can be a hydraulic oil pump, that is, the hydraulic oil is also injected into the second cavity 212, and the pressure of the hydraulic oil in the second cavity 212 is adjusted by the pressure regulating pump 51; at the same time, the pressure regulating pump 51 can also be a pressure regulating water pump or a pressure regulating air pump, etc.

[0065] In this embodiment, the outer side of the pressure application piston 3 is wrapped with a rubber sleeve, and the rubber sleeve abuts against the inner walls on both sides of the confining pressure cavity 21; in the initial state, the rubber sleeve is in a compressed state. When the pressure in the confining pressure cavity 21 increases, it squeezes the inner wall of the confining pressure sleeve 2. Since the inner wall of the confining pressure sleeve 2 is relatively thin and the deformation is also small, at this time, the rubber sleeve is also in a compressed state and abuts against the inner wall of the confining pressure cavity 21 to ensure the sealing function between each cavity; the sealing function between the pressure application piston 3 and the confining pressure cavity 21 can be realized through the rubber sleeve, thereby preventing the first cavity 211, the second cavity 212, and the third cavity 213 from communicating with each other.

[0066] In this embodiment, as shown in the appendix Figure 4As shown in the figure, a mating groove 12 is provided at the bottom of the upper cover plate 1, a first thread 13 is provided on the side wall of the mating groove 12, and a second thread 22 is provided on the outer side of the confining pressure sleeve 2; during use, the upper cover plate 1 and the confining pressure sleeve 2 are screwed relative to each other, and the first thread 13 in the mating groove 12 cooperates with the second thread 22 on the outer side of the confining pressure sleeve 2, so that the upper cover plate 1 and the confining pressure sleeve 2 are fixed; at the same time, the liquid inlet 11 at the top of the upper cover plate 1 cooperates with the inner hole of the confining pressure sleeve 2.

[0067] In this embodiment, a sealing groove 14 is provided at the top of the mating groove 12, a sealing ring is provided in the sealing groove 14, and the sealing ring abuts against the top wall of the confining pressure sleeve 2, so as to achieve the sealing effect between the upper cover plate 1 and the confining pressure sleeve 2.

[0068] In this embodiment, a cylindrical convex block is provided at the top of the upper cover plate 1, the liquid inlet 11 penetrates through the cylindrical convex block, and a strip-shaped groove is provided on the outer side of the cylindrical convex block for holding by hand; the upper cover plate 1 can be conveniently rotated manually through the strip-shaped groove.

[0069] In this embodiment, as shown in the attached Figure 2 and attached Figure 5 figure, a third thread 23 is provided at the bottom of the inner hole of the confining pressure sleeve 2, and a fourth thread 41 is provided on the outer side of the holder base 4; during use, the holder base 4 and the confining pressure sleeve 2 can be screwed relative to each other, so that the third thread 23 cooperates with the fourth thread 41, and the holder base 4 and the confining pressure sleeve 2 are fixed; one end of the core sample abuts against the upper cover plate 1, and the other end abuts against the holder base 4.

[0070] Furthermore, a sealing block 42 is provided at the top of the holder base 4, and the outer part of the sealing block 42 is in an arc-shaped convex shape, similar to the outer surface of a drum. During the process of the cooperation of the third thread 23 and the fourth thread 41, the sealing block 42 will also move into the inner hole of the confining pressure sleeve 2 and abut against the side wall of the inner hole. As the holder base 4 and the confining pressure sleeve 2 are fixed, the side wall of the sealing block 42 squeezes the inner wall of the confining pressure sleeve 2, thereby achieving the sealing effect.

[0071] Furthermore, a liquid outlet 43 is provided at the top of the sealing block 42, and the liquid outlet 43 penetrates through the holder base 4. The liquid for seepage of the core sample will enter the liquid outlet 43 and be discharged from the bottom of the holder base 4.

[0072] In this embodiment, the holder base 4 includes a bottom plate, a column body and a sealing block 42. The bottom plate is a circular bottom plate for convenient fixation. The column body is coaxially arranged on the bottom plate. The fourth thread 41 is provided at the outer top of the column body, and the sealing block 42 is provided at the top of the column body.

[0073] As shown in the attached Figure 6As shown in the figure, the present application also provides a confining pressure method, based on the above-mentioned core holder capable of applying differential confining pressure, including the following steps:

[0074] S100. Place the core sample into the confining pressure sleeve and seal it through the upper cover plate and the holder base.

[0075] First, fix the upper cover plate 1 to the confining pressure sleeve 2. The liquid inlet 11 on the upper cover plate 1 is located at the central position. The core sample is cylindrical and can be placed inside the confining pressure sleeve 2. Then, fix the holder base 4 to the confining pressure sleeve 2, so that the core sample is fixed.

[0076] S200. Adjust the positions of the two pressure pistons.

[0077] There is a confining pressure cavity 21 inside the confining pressure sleeve 2. Two pressure pistons 3 are slidably arranged in the confining pressure cavity 21, thus dividing the confining pressure cavity 21 into three cavities. The pressure pistons 3 can slide inside the confining pressure cavity 21 and can also be sealed with the side wall of the confining pressure cavity 21. The pressure pistons 3 can be driven to slide by an external driving component, so as to adjust the size of each cavity and simulate the confining pressure ranges in different situations under real conditions.

[0078] S300. Pressurize the first cavity, the second cavity and the third cavity.

[0079] After adjusting the sizes of each cavity through the pressure pipeline 52 in cooperation with the lifting motor, then inject hydraulic oil or other media into the first cavity 211, the second cavity 212 and the third cavity 213 through the hydraulic device and the pressure regulating pump 51, and apply different pressures or the same pressure to the media inside. It can be specifically set according to the experimental requirements. At the same time, the pressure pistons 3 are locked with the lifting motor through the pressure pipeline 52 and will not move again under the action of the media, so as to ensure the stability of the confining pressure in each cavity.

[0080] S400. Inject liquid into the confining pressure sleeve through the liquid inlet and observe the liquid seepage state inside the core sample to complete the experiment.

[0081] After the confining pressure reaches the preset value, seepage fluid is injected into the inner hole of the confining pressure sleeve 2 through the liquid inlet 11, an external pipeline and an injection pump. Under the action of its confining pressure, the seepage fluid needs to flow through the voids inside the core sample or flow through the outer surface of the core sample. At this time, the internal liquid seepage state of the core sample can be observed through external auxiliary equipment and recorded to complete the experiment. After the experiment is completed, the pressure application pipeline 52 and the pressure application piston 3 can be driven by the lifting motor, and the hydraulic oil can be pumped out through the outlet hole 55 of the pressure application pipeline 52 to restore the initial state and wait for the next experiment.

[0082] In summary, the present application provides a core holder and a confining pressure method capable of applying differential confining pressure, including an upper cover plate 1, a confining pressure sleeve 2, a holder base 4, and two pressure application pistons 3. The upper cover plate 1 is fixed to the top of the confining pressure sleeve 2 through threaded cooperation. The core sample is located in the inner hole of the confining pressure sleeve 2. The holder base 4 is fixed to the bottom of the confining pressure sleeve 2 through threaded cooperation. A confining pressure cavity 21 is provided inside the confining pressure sleeve 2. The two pressure application pistons 3 divide the confining pressure cavity 21 into a first cavity 211, a second cavity 212, and a third cavity 213. Under the action of the lifting motor, the driving gear 54, and the pipeline lifting teeth 53, the pressure application pistons 3 can slide inside the confining pressure cavity 21 to adjust the size of each cavity, so as to adjust the confining pressure area acting on the surface of the core sample by each cavity. Hydraulic pressure, air pressure, etc. can be applied to the first cavity 211, the second cavity 212, and the third cavity 213 through an external hydraulic pump and a pressure regulating pump 51 to reach the confining pressure required for the experiment.

[0083] After considering the specification and practicing the disclosed solutions herein, those skilled in the art will readily conceive of other embodiments of the present invention. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include the common general knowledge or conventional technical means in the technical field not disclosed in this solution. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present invention are pointed out by the claims.

Claims

1. A core holder capable of applying differential confining pressure, characterized in that: include: An upper cover plate, the top of which is provided with a liquid inlet; A confining pressure sleeve is arranged at the bottom of the upper cover plate; the inner hole of the confining pressure sleeve is used to place the core sample, and a confining pressure cavity is opened inside the confining pressure sleeve; Two pressurizing pistons are slidably disposed in the confining pressure cavity to divide the confining pressure cavity into a first cavity, a second cavity and a third cavity; the outer side of the pressurizing piston is wrapped with a rubber sleeve; A pressurizing device, connected to the first cavity, the second cavity and the third cavity respectively, for adjusting the pressure inside each cavity; A clamp base is arranged at the bottom of the confining pressure sleeve; a liquid outlet is arranged at the top of the clamp base; The pressurizing device comprises: Two hydraulic devices are respectively arranged at two ends of the confining pressure sleeve; the two hydraulic devices are respectively connected to the first cavity and the third cavity to inject hydraulic oil into the first cavity and the third cavity; The hydraulic device comprises: A pressurized pipe is slidably disposed in the confining pressure sleeve; the top end of the pressurized pipe is connected to the pressurized piston, and an outlet hole is disposed at the top end of the pressurized pipe; an outlet hole is disposed at one end of the pressurized pipe close to the pressurized piston, and one end of the pressurized pipe away from the pressurized piston is connected to an external hydraulic pump; A driving assembly is arranged outside the confining pressure sleeve; the driving assembly is connected to the pressurizing pipeline to drive the pressurizing pipeline and the pressurizing piston to slide in the confining pressure cavity; The drive assembly comprises: A pipeline lifting tooth is vertically arranged on one side of the pressurized pipeline; The lifting motor is arranged outside the confining pressure sleeve; the output shaft of the lifting motor is provided with a driving gear, and the driving gear is meshed with the pipeline lifting gear.

2. A core holder capable of applying differential confining pressure according to claim 1, characterized in that: The pressurizing device also includes: A pressure regulating pump is arranged outside the confining pressure sleeve; the pressure regulating pump is connected to the second cavity through a pipeline and is used to adjust the pressure in the second cavity.

3. A core holder capable of applying differential confining pressure according to claim 1, characterized in that: A matching groove is provided at the bottom of the upper cover plate, a first thread is provided on the side wall of the matching groove, a second thread is provided on the outer side of the confining pressure sleeve, and the first thread matches with the second thread to connect the confining pressure sleeve to the upper cover plate.

4. A core holder capable of applying differential confining pressure according to claim 3, characterized in that: A sealing groove is arranged at the top of the matching groove, a sealing ring is arranged in the sealing groove, and the sealing ring abuts against the top wall of the confining pressure sleeve.

5. A core holder capable of applying differential confining pressure according to claim 1, characterized in that: The inner wall of the confining pressure sleeve is provided with a third thread, the outer side of the clamp base is provided with a fourth thread, and the third thread matches with the fourth thread to connect the clamp base with the confining pressure sleeve.

6. A core holder capable of applying differential confining pressure according to claim 5, characterized in that: A sealing block is arranged on the top of the clamp base, the outer portion of the sealing block is in an arc-shaped convex shape, and the sealing block abuts against the inner wall of the confining pressure sleeve.

7. A confining pressure method, based on a core holder capable of applying differential confining pressure according to any one of claims 1 to 6, characterized in that: include: Putting the core sample into the confining pressure sleeve and sealing it with the holder base through the upper cover plate; Adjusting the positions of the two pressurizing pistons; Applying pressure to the first cavity, the second cavity, and the third cavity; Liquid is injected into the confining pressure sleeve through the liquid inlet, and the liquid seepage state inside the core sample is observed to complete the experiment.

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