Core holder capable of applying differential confining pressure and confining pressure method

Abstract

The invention discloses a core holder capable of applying differential confining pressure and a confining pressure method.The core holder comprises an upper cover plate, a confining pressure sleeve, two pressurizing pistons, a pressurizing device and a holder base, the confining pressure sleeve is arranged at the bottom of the upper cover plate, the holder base is arranged at the bottom of the confining pressure sleeve, and a confining pressure cavity is formed in the confining pressure sleeve; the confining pressure cavity is separated from the rock core sample through the inner wall of the confining pressure sleeve, and two pressurizing pistons are arranged in the confining pressure cavity in a sliding manner to divide the confining pressure cavity into a first cavity, a second cavity and a third cavity; the confining pressure cavity is formed in the confining pressure sleeve and is matched with the two sliding pressurizing pistons, the confining pressure cavity can be divided into three parts, and the three parts of cavities are connected with the pressurizing device respectively, so that different confining pressures can be applied to a rock core sample in the vertical direction; meanwhile, the sizes of the three cavities can be adjusted through sliding of the pressurizing piston, and the range of differential confining pressure under the real condition is further simulated.

Description

Technical Field

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

[0002] The core holder is a commonly used rock performance testing device in the field of geotechnical engineering, and is usually used to apply confining pressure to the rock. In actual strata, the rock may be subjected to a variety of lateral forces. For example, in the mud-sand interaction zone, mudstone and sandstone exert different pressures on the core, resulting in uneven confining pressure of the rock under specific conditions. When the existing core holder is working, hydraulic oil is generally directly wrapped on 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 under different in-situ environments, which will cause 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-mentioned deficiencies in the prior art, an object of the present invention is to provide a core holder and a confining pressure method that can apply differential confining pressures, aiming to solve the problem that the existing core holder can only apply a single confining pressure and cannot truly restore the confining pressures under different in-situ environments, thus causing errors in experimental tests.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: A core holder capable of applying differential confining pressure, comprising: 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; A pressurizing device, connected to the first cavity, the second cavity and the third cavity respectively, for adjusting the pressure inside each cavity; The clamp base is arranged at the bottom of the confining pressure sleeve; and a liquid outlet is arranged at the top of the clamp base.

[0006] According to the above technical means, a confining pressure cavity is provided in the confining pressure sleeve, which can provide confining pressure for the core sample. At the same time, with the two sliding pressurizing pistons, the confining pressure cavity can be divided into three parts. 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 size of the three parts of the cavity can be adjusted by sliding the pressurizing piston, so as to further simulate the range of differential confining pressure under real conditions.

[0007] Furthermore, 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; 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.

[0008] According to the above technical means, the pressurizing device includes two hydraulic devices and a pressure regulating pump, which can be connected to the first cavity, the second cavity and the third cavity respectively to provide pressure to the corresponding cavity separately, thereby achieving different confining pressures.

[0009] Furthermore, the hydraulic device comprises: A pressurized pipe is slidably disposed in the confining pressure sleeve; the top of the pressurized pipe is connected to the pressurized piston, and the top of the pressurized pipe is provided with an outlet hole; A driving assembly is arranged on the outside of 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.

[0010] According to the above technical means, the driving components are respectively connected to the corresponding pressurized pipes. By starting the driving components, the pressurized pipes can slide in the confining pressure sleeve, thereby driving the pressurized piston to slide inside the confining pressure cavity and adjusting the size of each cavity.

[0011] Furthermore, the driving assembly includes: 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.

[0012] According to the above technical means, the material of the pressurized pipe is a rigid material, so that a pipe lifting tooth can be set on one side thereof, and in conjunction with the driving gear on the lifting motor, the pressurized pipe and the pressurized piston can be driven to slide inside the confining pressure cavity to facilitate the adjustment of the size of each cavity.

[0013] Furthermore, the outer side of the pressurizing piston is wrapped with a rubber sleeve.

[0014] According to the above technical means, the rubber sleeve is made of expandable and compressible material, and is in contact with the inner walls on both sides of the confining pressure cavity. When pressure is applied to each cavity, the rubber sleeve expands from the compressed state to the initial state and is in contact with the inner wall of the confining pressure cavity in real time to ensure its sealing.

[0015] Furthermore, 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.

[0016] According to the above technical means, the confining pressure sleeve and the upper cover plate can be conveniently positioned and fixed by the matching groove, and the stability between the upper cover plate and the confining pressure sleeve can be further increased by matching the first thread with the second thread.

[0017] Furthermore, a sealing groove is provided at the top of the matching groove, a sealing ring is provided in the sealing groove, and the sealing ring abuts against the top wall of the confining pressure sleeve.

[0018] According to the above technical means, by providing a sealing groove and a sealing ring, the upper cover plate and the confining pressure sleeve can be sealed and matched to meet the experimental requirements.

[0019] Furthermore, 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 cooperates with the fourth thread to connect the clamp base with the confining pressure sleeve.

[0020] According to the above technical means, the clamp base and the confining pressure sleeve can be fixed by cooperating with the third thread and the fourth thread.

[0021] Furthermore, a sealing block is provided on the top of the clamp base, the outer portion of the sealing block is arc-shaped and convex, and the sealing block abuts against the inner wall of the confining pressure sleeve.

[0022] According to the above technical means, by providing a sealing block on the top of the clamp base and providing a convex arc surface on the side wall of the sealing block, the sealing block can be abutted against the inner wall of the confining pressure sleeve, thereby ensuring its sealing performance.

[0023] A confining pressure method, based on a core holder capable of applying differential confining pressure as described above, comprises: 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.

[0024] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, a confining pressure sleeve is provided at the bottom of the upper cover plate, a clamp 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 communicated with the inside of the confining pressure sleeve, a confining pressure cavity is provided in 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, and two pressurizing pistons are slidably provided in 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 the pressurizing device to adjust the pressure inside each cavity; by arranging the confining pressure cavity in the confining pressure sleeve and arranging two sliding pressurizing 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 sliding the pressurizing piston, so as to further simulate the range of differential confining pressure under real conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0026] Figure 2 It is a schematic diagram of the structure of the confining pressure sleeve of the present invention.

[0027] Figure 3 This is a schematic diagram of the pressurized pipeline structure of the present invention.

[0028] Figure 4 It is a schematic diagram of the structure of the upper cover plate of the present invention.

[0029] Figure 5 It is a schematic diagram of the structure of the clamp base of the present invention.

[0030] Figure 6 Flow chart of the confining pressure method of the present invention.

[0031] The numbers in the figure are as follows: 1. upper cover plate; 11. liquid inlet; 12. matching 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. clamp base; 41. fourth thread; 42. sealing block; 43. liquid outlet; 5. pressurizing device; 51. pressure regulating pump; 52. pressurizing pipe; 53. pipe lifting gear; 54. driving gear; 55. outlet hole. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying 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 therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In view of the shortcomings of the prior art, this embodiment provides a core holder and a confining pressure method capable of applying differential confining pressure, which can be specifically referred to as follows: As attached Figure 1 and attached Figure 2As shown, a core clamp capable of applying differential confining pressure comprises an upper cover plate 1, a confining pressure sleeve 2, two pressurizing pistons 3, a pressurizing device 5 and a clamp base 4; a confining pressure sleeve 2 is provided at the bottom of the upper cover plate 1, an inner hole is provided at the center of the confining pressure sleeve 2 for placing core samples, a liquid inlet 11 is provided at the top of the upper cover plate 1, the liquid inlet 11 is connected with the inner hole, and the upper cover plate 1 and the confining pressure sleeve 2 are sealed, a clamp base 4 is also provided at the bottom of the confining pressure sleeve 2, a liquid outlet 43 is provided at the top of the clamp base 4 to facilitate the discharge of seepage fluid, and the clamp base 4 and the confining pressure sleeve 2 are sealed; a confining pressure cavity 21 is also provided inside the confining pressure sleeve 2, the confining pressure cavity 21 is arranged around the inner hole, and the confining pressure cavity 21 is spaced apart from the inner hole, and the interior of the confining pressure cavity 21 is vertically slidably arranged There is a pressurizing piston 3, which is sealed and slides with the two side walls of the confining pressure cavity 21, so that the confining pressure cavity 21 is divided into a first cavity 211, a second cavity 212 and a third cavity 213 through the two pressurizing pistons 3, and the first cavity 211, the second cavity 212 and the third cavity 213 are arranged vertically in sequence; a pressurizing device 5 is also arranged on the outside of the confining pressure sleeve 2, and the pressurizing device 5 is respectively connected to the first cavity 211, the second cavity 212 and the third cavity 213. By starting the pressurizing device 5, the pressure in the first cavity 211, the second cavity 212 and the third cavity 213 can be adjusted, so as to achieve different confining pressures on 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 under the real state.

[0036] Specifically, the upper cover plate 1 and the confining pressure sleeve 2 can be assembled first, and then the core sample can be placed into the inner hole through the bottom of the confining pressure sleeve 2, and then sealed by the clamp base 4. At this time, the pressure device 5 is respectively connected to the first cavity 211, the second cavity 212 and the third cavity 213, and the ranges of the first cavity 211, the second cavity 212 and the third cavity 213 are adjusted by two pressure pistons 3 to simulate the ranges of different confining pressures under real conditions. After the adjustment, the pressure device 5 can be started to apply pressure to the first cavity 211, the second cavity 212 and the third cavity 213. The pressure acts on the surface of the core sample through the inner wall of the confining pressure cavity 21. Finally, the seepage fluid can be injected through the liquid inlet 11 to make the seepage fluid seep into the core sample under different confining pressures. The seepage fluid flowing out is discharged through the liquid outlet 43, and the simulation experiment can be completed.

[0037] In this embodiment, as shown in the attached Figure 2 As shown, the confining pressure sleeve 2 is divided into two layers, the outer layer of the confining pressure sleeve 2 is 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 a deformable flexible material, such as rubber material, which can be deformed.

[0038] In this embodiment, the inner hole of the confining pressure sleeve 2 is cylindrical, the core sample is also cylindrical, and the diameter of the core sample is the same as the diameter of the inner hole of the confining pressure sleeve 2 .

[0039] In one embodiment of the present application, as shown in the attached Figure 1 As shown, 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 the 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 hydraulic oil is injected into the first cavity 211 and the third cavity 213; the pressure regulating pump 51 is located on the outside of the confining pressure sleeve 2, and the pressure regulating pump 51 is connected to the second cavity 212 through a pipeline, and is used to adjust the pressure inside the second cavity 212.

[0040] Since the outer part of the confining pressure sleeve 2 is made of a material that is not easy to deform, and the inner part 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 toward the core sample to attach the inner wall of the confining pressure sleeve 2 to the surface of the core sample; a hole is opened on the outer side of the confining pressure sleeve 2, and the hole enables the second cavity 212 to be connected to the outside world, and at the same time, the pressure regulating pump 51 is connected to the second cavity 212 through the connecting pipeline. The cavity 212 is connected, that is, one end of the connecting pipe is connected to the pressure regulating pump 51, and the other end is connected to the hole, and is sealed to prevent air leakage; when in use, the positions of the two pressurizing pistons 3 can be adjusted first, and then pressure is injected into the second cavity 212 through the pressure regulating pump 51, 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 conditions inside the core sample under different confining pressures.

[0041] In this embodiment, as shown in the attached Figure 1 and attached Figure 3 As shown, the hydraulic device includes a pressurized pipe 52 and a driving assembly. The pressurized pipe 52 is slidably arranged in the confining pressure sleeve 2. The pressurized pipes 52 of the two hydraulic devices are respectively slidably arranged at the top and bottom of the confining pressure sleeve 2. The pressurized pipe 52 is rigidly connected to the pressurized piston 3, and an outlet hole 55 is arranged at one end of the pressurized pipe 52 close to the pressurized piston 3. The end of the pressurized pipe 52 away from the pressurized piston 3 is connected to an external hydraulic pump; a driving assembly is also arranged on the outside of the confining pressure sleeve 2, and the driving assembly is connected to the pressurized pipe 52 to drive the pressurized pipe 52 and the pressurized piston 3 to slide in the confining pressure cavity 21.

[0042] Specifically, two pressurized pipes 52 are slidably provided at the top and bottom of the confining pressure sleeve 2 and are sealed. The two pressurized pipes 52 located at the same end are arranged symmetrically with each other, and the two pressurized pipes 52 located at the same end are connected to the pressurized piston 3. Two driving components are provided at the top and bottom of the confining pressure sleeve 2, and the four driving components are respectively connected to the corresponding pressurized pipes 52. By starting the driving components, the pressurized pipes 52 can slide in the confining pressure sleeve 2, thereby driving the pressurized piston 3 to slide inside the confining pressure cavity 21 to adjust the size of each cavity.

[0043] Furthermore, the four pressurizing pipes 52 are made of a rigid material, such as steel, so as to facilitate pushing the pressurizing piston 3 to slide and withstand the pulling force of the corresponding cavity internal medium on the pressurizing pipe 52.

[0044] In this embodiment, as shown in the attached Figure 1 and attached Figure 3 As shown, the driving assembly includes a pipe lifting tooth 53 and a lifting motor. The pipe lifting tooth 53 is vertically arranged on one side of the pressurized pipe 52, and the pipe lifting tooth 53 is located on the outside of the confining pressure sleeve 2; the lifting motor is arranged on the outside of the confining pressure sleeve 2, and the output shaft of the lifting motor is provided with a driving gear 54, and the driving gear 54 is meshed with the pipe lifting tooth 53; through the action of the lifting motor, the driving gear 54 can be driven to rotate, thereby driving the pressurized pipe 52 to be lifted and lowered.

[0045] In this embodiment, there are four drive components, 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 clamp base 4 are suspended and fixed by the clamping member (the clamping member is the prior art), and the four drive components can be respectively arranged at the top of the upper cover plate 1 and the bottom of the confining pressure sleeve 2 through the external bracket, and are a certain distance away from the surface of the upper cover plate 1 and the bottom wall of the confining pressure sleeve 2, and the four driving gears 54 are respectively engaged with the four pipeline lifting teeth 53, and by starting the lifting motor, the pressurized pipeline 52 can be driven to move into the confining pressure cavity 21, thereby driving the two pressurized pistons 3 to move; in the process of applying confining pressure, the lifting motor is in a self-locking state, at which time the pipeline lifting teeth 53 of the pressurized pipeline 52 and The driving gear 54 is meshed. Since the lifting motor is in a self-locking state, the driving gear 54 is in a fixed state, and the pressurized pipe 52 is also in a fixed state. After the hydraulic pump injects hydraulic oil into the pressurized pipe 52 and the first cavity 211 and the third cavity 213 and applies a certain pressure, the pressurized pipe 52 will not move under the locking action of the driving gear 54, so that the pressure in the first cavity 211 and the third cavity 213 acts on the outer surface of the core sample to achieve the effect of confining pressure; the pressure inside 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 injects a certain pressure into the second cavity 212, the effect of applying differential confining pressure can be achieved.

[0046] Furthermore, the pressure regulating pump 51 is a prior art and may 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 may also be a pressure regulating water pump or a pressure regulating air pump, etc.

[0047] In this embodiment, the outer side of the pressurizing 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, the inner wall of the confining pressure sleeve 2 is squeezed. Since the inner wall of the confining pressure sleeve 2 is thin, 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 effect between each cavity; the sealing effect of the pressurizing piston 3 and the confining pressure cavity 21 can be achieved through the rubber sleeve, thereby preventing the first cavity 211, the second cavity 212 and the third cavity 213 from being connected to each other.

[0048] In this embodiment, as shown in the attached Figure 4As shown, a matching 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 matching groove 12, and a second thread 22 is provided on the outer side of the confining pressure sleeve 2; when in use, the upper cover plate 1 and the confining pressure sleeve 2 are relatively twisted, and the first thread 13 of the matching groove 12 is matched 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 is matched with the inner hole of the confining pressure sleeve 2.

[0049] In this embodiment, a sealing groove 14 is provided at the top of the matching groove 12. A sealing ring is provided in the sealing groove 14. The sealing ring abuts against the top wall of the confining pressure sleeve 2, thereby achieving the effect of sealing the upper cover plate 1 and the confining pressure sleeve 2.

[0050] In this embodiment, a cylindrical protrusion is provided on the top of the upper cover plate 1, the liquid inlet 11 passes through the cylindrical protrusion, and a strip groove is provided on the outer side of the cylindrical protrusion, which can be used for handholding; the strip groove also facilitates manual rotation of the upper cover plate 1.

[0051] In this embodiment, as shown in the attached Figure 2 and attached Figure 5 As shown, 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 clamp base 4; when in use, the clamp base 4 and the confining pressure sleeve 2 can be relatively twisted to make the third thread 23 and the fourth thread 41 cooperate, so that the clamp base 4 and the confining pressure sleeve 2 are fixed; one end of the core sample is supported by the upper cover plate 1, and the other end is abutted against the clamp base 4.

[0052] Furthermore, a sealing block 42 is provided on the top of the clamp base 4. The exterior of the sealing block 42 is arc-shaped and convex, similar to the outer surface of a drum. In the process of matching the third thread 23 with 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 clamp 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 a sealing effect.

[0053] Furthermore, a liquid outlet 43 is provided on the top of the sealing block 42 , and the liquid outlet 43 penetrates the clamp base 4 . The liquid that seeps into the core sample will enter the liquid outlet 43 and be discharged from the bottom of the clamp base 4 .

[0054] In this embodiment, the clamp base 4 includes a bottom plate, a column and a sealing block 42. The bottom plate is a circular bottom plate to facilitate fixation. The column is coaxially arranged on the bottom plate, the fourth thread 41 is arranged on the outer top of the column, and the sealing block 42 is arranged on the top of the column.

[0055] As attached Figure 6As shown, the present application also provides a confining pressure method, based on the above-mentioned core holder capable of applying differential confining pressure, comprising the following steps: S100, placing the core sample into the confining pressure sleeve, and sealing it with the holder base through the upper cover plate; First, fix the upper cover plate 1 and the confining pressure sleeve 2, wherein the liquid inlet 11 on the upper cover plate 1 is located at the center position, and the core sample is cylindrical and can be used to be placed inside the confining pressure sleeve 2, and then fix the clamp base 4 and the confining pressure sleeve 2, so that the core sample is fixed.

[0056] S200, adjusting the positions of the two pressurizing pistons; A confining pressure cavity 21 is arranged inside the confining pressure sleeve 2, and two pressurizing pistons 3 are slidably arranged inside the confining pressure cavity 21, thereby dividing the confining pressure cavity 21 into three cavities, and the pressurizing piston 3 can slide in the confining pressure cavity 21, and the pressurizing piston 3 can also be sealed with the side wall of the confining pressure cavity 21; the pressurizing piston 3 can be driven to slide by an external driving component, and then the size of each cavity can be adjusted to simulate the confining pressure range of different situations under real conditions.

[0057] S300, applying pressure to the first cavity, the second cavity, and the third cavity; After adjusting the size of each cavity through the pressurized pipe 52 and the lifting motor, hydraulic oil or other medium is injected 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 different pressures are applied to the medium inside, or the same pressure can be applied, which can be set specifically according to experimental requirements; at the same time, the pressurized piston 3 is locked with the lifting motor through the pressurized pipe 52, and will not move again under the action of the medium, thereby ensuring the stability of the confining pressure in each cavity.

[0058] S400, injecting liquid into the confining pressure sleeve through the liquid inlet, and observing the liquid seepage state inside the core sample to complete the experiment.

[0059] When the confining pressure reaches the preset value, the seepage fluid is injected into the inner hole of the confining pressure sleeve 2 through the liquid inlet 11, the external pipeline and the injection pump. Under the action of the confining pressure, the seepage fluid needs to flow through the gaps inside the core sample or flow through the outer surface of the core sample. At this time, the liquid seepage state inside the core sample can be observed and recorded through external auxiliary equipment to complete the experiment. After the experiment is completed, the pressurized pipe 52 and the pressurized piston 3 can be driven to move by the lifting motor, and the hydraulic oil can be extracted through the outlet hole 55 of the pressurized pipe 52 to restore the initial state and wait for the next experiment.

[0060] In summary, the present application provides a core holder capable of applying differential confining pressure and a confining pressure method, comprising an upper cover plate 1, a confining pressure sleeve 2, a holder base 4 and two pressurizing pistons 3, wherein the upper cover plate 1 is fixed to the top of the confining pressure sleeve 2 by threaded engagement, 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 by threaded engagement, a confining pressure cavity 21 is provided in the confining pressure sleeve 2, and the two pressurizing pistons 3 divide the confining pressure cavity 21 into a first cavity and a second cavity. The first cavity 211, the second cavity 212 and the third cavity 213 are provided, and the pressurizing piston 3 can slide in the confining pressure cavity 21 under the action of the lifting motor, the driving gear 54 and the pipeline lifting gear 53, and the size of each cavity is adjusted to adjust the confining pressure area of ​​each cavity acting on the surface of the core sample; hydraulic pressure or air pressure can be applied to the first cavity 211, the second cavity 212 and the third cavity 213 through the external hydraulic pump and the pressure regulating pump 51 to achieve the confining pressure required by the experiment.

[0061] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the schemes disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed in this scheme. The description and examples are to be regarded as exemplary only, and the true scope and spirit of the present invention are indicated 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; A pressurizing device, connected to the first cavity, the second cavity and the third cavity respectively, for adjusting the pressure inside each cavity; The clamp base is arranged at the bottom of the confining pressure sleeve; and a liquid outlet is arranged at the top of the clamp base.

2. A core holder capable of applying differential confining pressure according to claim 1, characterized in that: 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; 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 2, characterized in that: 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 the top end of the pressurized pipe is provided with an outlet hole; A driving assembly is arranged on the outside of 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.

4. A core holder capable of applying differential confining pressure according to claim 3, characterized in that: 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.

5. A core holder capable of applying differential confining pressure according to claim 1, characterized in that: The outer side of the pressurizing piston is wrapped with a rubber sleeve.

6. 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.

7. A core holder capable of applying differential confining pressure according to claim 6, 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.

8. 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.

9. A core holder capable of applying differential confining pressure according to claim 8, 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.

10. A confining pressure method, based on a core holder capable of applying differential confining pressure according to any one of claims 1 to 9, 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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