A layered stress loading fracturing experiment device and method

Abstract

The application discloses a layered stress loading fracturing experiment device and method, and belongs to the field of rock mechanics experiment. The layered stress loading fracturing experiment device comprises a first hydraulic module, a first stop surface and a crack monitoring system. The first hydraulic module is configured to output reciprocating motion along a preset direction. The first stop surface is located on the side of the output end of the first hydraulic module and is arranged in a spaced manner with the first hydraulic module to define a stress application space between the output end of the first hydraulic module and the first stop surface. The crack monitoring system mainly comprises a track and a high-speed camera and is used for monitoring the dynamic expansion process of cracks. The first hydraulic module comprises a plurality of hydraulic components, and each hydraulic component is configured to output different pressures towards a rock sample. In application, the rock sample is placed in the stress application space, and each hydraulic component moves towards the rock sample. Under the cooperation of the stop surface, different layers of the rock sample bear different stress sizes. Meanwhile, since each hydraulic component applies different stress values on the rock sample, the rock sample can more truly simulate the changes occurring when the actual stress is suffered in the underground, so that the user can more accurately understand the cracking and expansion of the hydraulic fracture under different layers.

Description

Technical Field

[0001] This invention relates to the field of unconventional reservoir stimulation engineering technology, and in particular to a layered stress loading fracturing experimental apparatus and method. Background Technology

[0002] China possesses abundant unconventional oil and gas reserves. Unconventional oil and gas reservoirs, represented by shale, typically require hydraulic fracturing technology to enhance their recovery. Hydraulic fracturing, also known as hydraulic splitting or hydraulic cracking, refers to using water pressure to fracture rock formations, thereby releasing natural gas or oil resources. This technology injects high-energy fracturing fluid into a reservoir capable of creating numerous new fractures, significantly improving shale oil recovery. Currently, due to a lack of accurate and effective field monitoring methods, the effects of hydraulic fracturing in underground reservoirs cannot be directly observed, leading to a lack of understanding of the extension patterns of hydraulic fractures. Consequently, the design and layout of current hydraulic fracturing well networks exhibit a degree of randomness and uncertainty. Therefore, the indoor true triaxial fracturing physical simulation experimental system can simulate formation conditions, conduct hydraulic fracturing fracture propagation mechanism simulation experiments on natural and artificial rock samples, and monitor the actual physical process of fracture propagation. It can be used to study the influence of factors such as geostress, fracture, joints, and natural fractures on hydraulic fracture propagation. However, due to the strong vertical heterogeneity of shale reservoirs, large differences in interlayer geostress, and complex fracture propagation morphology, conventional hydraulic fracturing experiments are difficult to simulate the interlayer stress differences. Therefore, through layered stress loading physical simulation experiments, the longitudinal propagation law of hydraulic fractures under interlayer stress differences can be effectively studied, providing theoretical guidance for longitudinal fracture propagation in the field.

[0003] Currently, almost all published indoor true triaxial fracturing physical simulation experimental systems apply uniform stress to the entire surface of the rock sample using a monolithic loading plate when loading triaxial stress. However, the method of controlling the dimensions of each layer of the layered rock sample to achieve layered stress loading can only simulate the case where the minimum principal stress in the middle layer is 0 MPa, which differs significantly from the actual stress state underground. To make the stress state of each layer of the layered rock sample more consistent with the actual underground conditions, and to overcome the high cost of modification, it is necessary to improve the loading method without changing the existing system equipment structure, and to achieve differentiated stress loading for each layer of the layered rock sample. Summary of the Invention

[0004] In view of this, it is necessary to provide a layered stress loading fracturing experimental apparatus and method to address the problem that the stress simulated in the prior art does not match the actual stress on the rock.

[0005] According to one aspect of the present invention, a layered stress loading fracturing experimental apparatus is provided, comprising:

[0006] At least one first hydraulic module, the first hydraulic module being configured to output reciprocating motion in a preset direction;

[0007] At least one first stop surface, the first stop surface being located on the output end of the first hydraulic module facing side and spaced apart from the first hydraulic module, so as to define a compression space for placing the rock sample between the output end of the first hydraulic module and the first stop surface;

[0008] The first hydraulic module includes multiple hydraulic components, each of which is configured to output pressure of different magnitudes toward the rock sample. Since each hydraulic component squeezes the rock sample with different forces, the deformation of each layer of the rock sample is different, which is more consistent with the changes that occur when the rock sample is subjected to actual stress underground.

[0009] Optionally, the layered stress loading fracturing experimental apparatus further includes:

[0010] A second hydraulic module is configured to output reciprocating motion along a first direction;

[0011] The second stop surface is located on the side facing the output end of the second hydraulic module and is spaced apart from the second hydraulic module; the second stop surface and the output end of the second hydraulic module are respectively located on both sides of the extrusion space;

[0012] There are two first hydraulic modules, which output reciprocating motion along the second direction and the third direction respectively; the first direction, the second direction and the third direction are perpendicular to each other.

[0013] Optionally, the layered stress loading fracturing experimental apparatus further includes:

[0014] A camera assembly for capturing images of the rock sample;

[0015] The shell has an L-shaped space inside, the corner of which is the compression space. The side wall of the shell has a window that connects the compression space and the outer space of the shell. The window is equipped with a transparent plate, and the inner side of the transparent plate is equipped with a protective film to prevent the rock sample from scratching the transparent plate when deforming.

[0016] The camera component includes:

[0017] A guide rail, one end of which is connected to the outer wall of the housing;

[0018] A base, which is movably mounted on the guide rail, and a robotic arm is provided on the base;

[0019] A high-speed camera, mounted on the robotic arm, is used to capture images of the rock sample through the transparent plate. A base on a guide rail drives the robotic arm to move along the rail, while the robotic arm can rotate freely to adjust the angle and height of the high-speed camera, facilitating the capture of images of rock sample deformation through the transparent plate.

[0020] Optionally, each of the hydraulic components includes:

[0021] A sleeve extends in a direction perpendicular to the first stop surface; an opening is formed at one end of the sleeve facing the first stop surface; a hydraulic pipe for connecting to a hydraulic pump is connected to the sleeve.

[0022] A slider, which is movably mounted inside the sleeve;

[0023] A hydraulic rod, one end of which is connected to the slider, and the other end of which extends through the opening and is connected to a pressing mechanism.

[0024] Optionally, the multiple hydraulic pipes are connected in series with the hydraulic pump, and the multiple hydraulic pipes are connected to the same hydraulic pump. Each hydraulic pipe is equipped with a valve, so that the user can control the amount of liquid in each sleeve by opening and closing the valve of each branch, thereby controlling the pressure transmitted by the slider in each sleeve to the extrusion mechanism. Alternatively,

[0025] The hydraulic pipes are connected in parallel to the hydraulic pump, with each hydraulic pipe connected to one hydraulic pump. Each branch uses a hydraulic pump to control the amount of liquid in each sleeve, thereby controlling the pressure transmitted from the slider in each sleeve to the extrusion mechanism.

[0026] Optionally, the second hydraulic module includes:

[0027] A fixing frame, wherein the fixing frame is spaced apart from the first stop surface;

[0028] The first hydraulic cylinder has one end connected to the fixed frame and the other end extending toward the first stop surface;

[0029] A clamp is connected to the other end of the first hydraulic cylinder.

[0030] A first extrusion block is assembled on the fixture;

[0031] A first pad is disposed on the side of the first extrusion block opposite to the clamp; the first pad is detachably connected to the first extrusion block; the first pad is made of an elastic material. Specifically, an I-shaped groove is formed between the first extrusion block and the first pad, and an I-shaped pin is inserted into the I-shaped groove.

[0032] Optionally, the extrusion mechanism includes:

[0033] The second extrusion block is connected to the hydraulic rod on one side and has a protruding structure on the other side. The protruding structure is an arc-shaped protrusion that decreases from the middle to both ends.

[0034] The second pad has a recessed structure that conforms to the shape of the protruding structure; the recessed structure is connected to the protruding structure; the second pad is made of an elastic material.

[0035] The side of the second pad that is away from the recessed structure is set as a plane, a curved surface, or a stepped surface; the corner of the stepped surface is set as a right angle or a rounded corner.

[0036] Optionally, the second extrusion block includes a first sub-block and a second sub-block spaced apart; an expansion mechanism is provided between the first sub-block and the second sub-block; the expansion mechanism includes:

[0037] An expansion fork, two expansion forks are staggered, one end of each expansion fork is slidably connected to the first sub-block or the second sub-block; the other end of one expansion fork is connected to a fixed sleeve, and the other end of the other expansion fork is connected to a movable sleeve;

[0038] A drive motor is connected to the fixed sleeve, and a screw is connected to the output end of the drive motor. The screw passes through the fixed sleeve and is threadedly connected to the movable sleeve.

[0039] According to another aspect of the present invention, a layered stress loading fracturing test method is provided, applicable to any of the above-mentioned layered stress loading fracturing test apparatus, the layered stress loading fracturing test method comprising:

[0040] S1: Prepare the rock sample into a cube of a predetermined size;

[0041] S2: Place the rock sample inside the compression space;

[0042] S3: The first hydraulic module is activated according to the settings, and the multiple hydraulic components output different pressures to different layers of the rock sample.

[0043] Optionally, the process of shaping the rock sample into a cube of a predetermined size includes:

[0044] Cutting rocks larger than a preset size into multiple rock samples smaller than the preset size; and,

[0045] Multiple rock samples smaller than the preset size are bonded together using cement and shaped into a cube of the preset size.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] In this layered stress loading fracturing experimental device, a rock sample is placed in the compression space, and the output end of the first hydraulic module moves towards the rock sample. With the cooperation of the stop surface, the rock sample is compressed and deformed. At the same time, because each hydraulic component compresses the rock sample with a different force, the deformation of each layer of the rock sample is different, which better reflects the changes that occur when the rock sample is subjected to actual stress underground, so as to more accurately understand the properties of the rock sample.

[0048] Furthermore, due to the guide rails installed on the outside of the housing, the base on the guide rails drives the robotic arm to move along the guide rails. At the same time, the robotic arm can rotate freely to adjust the angle and height of the high-speed camera, facilitating the high-speed camera to capture images of rock sample deformation through the transparent plate. The images captured by the high-speed camera can be stored in the storage unit inside the high-speed camera or uploaded to a cloud server for users to view. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic structural diagram of a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0051] Figure 2 This is a schematic cross-sectional view of a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the hydraulic components in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0053] Figure 4 This is a schematic diagram of the first hydraulic module in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0054] Figure 5 This is a schematic diagram of the first hydraulic module in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0055] Figure 6 This is a schematic partial structural diagram of the hydraulic components in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0056] Figure 7 This is a schematic partial structural diagram of the hydraulic components in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0057] Figure 8 This is a schematic partial structural diagram of the hydraulic components in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0058] Figure 9 This is a schematic partial structural diagram of the hydraulic components in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0059] Figure 10 This is a schematic partial structural diagram of the hydraulic components in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention;

[0060] Figure 11 yes Figure 10 A schematic enlarged view of part A in the middle;

[0061] Figure 12 This is a schematic structural diagram of the expansion mechanism in a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention.

[0062] In the figure: First hydraulic module 100; Hydraulic component 110; Sleeve 111; Slider 112; Hydraulic rod 113; Valve 114; Second extrusion block 115; First sub-block 1151; Second sub-block 1152; Expansion fork 1153; Drive motor 1154; Fixed sleeve 1155; Moving sleeve 1156; Screw 1157; Second pad 116; Plane 1161; Curved surface 1162; Stepped surface 1163; Right angle 11631; Rounded corner 11632; Pressure regulating knob 117; Housing 200; First stop surface 210; Second stop surface 220; Window 230; Transparent plate 240; Second hydraulic module 300; Fixture 310; First hydraulic cylinder 320; Clamp 330; First extrusion block 340; First pad block 350; Hydraulic press 360; I-beam pin 370; Camera assembly 400; Guide rail 410; Base 420; High-speed camera 430; Robotic arm 440; Hydraulic pump 500. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0064] Figure 1 This is a schematic structural diagram of a layered stress loading fracturing experimental apparatus according to an embodiment of the present invention, as shown below. Figure 1 As shown, and see also Figures 1 to 12This invention provides a layered stress loading fracturing experimental apparatus, including at least one first hydraulic module 100 and at least one first stop surface 210. The first hydraulic module 100 is configured to output reciprocating motion in a preset direction. The first stop surface 210 is located on the output end facing side of the first hydraulic module 100 and is spaced apart from the first hydraulic module 100 to define a compression space for placing a rock sample between the output end of the first hydraulic module 100 and the first stop surface 210. The first hydraulic module 100 includes multiple hydraulic components 110, each configured to output pressure of different magnitudes toward the rock sample. Because the first hydraulic module 100 includes multiple hydraulic components 110, and each hydraulic component 110 outputs pressure of different magnitudes toward the rock sample during application, the pressure on different layers of the rock sample is different, which is more consistent with the actual stress state of the rock sample underground. During application, the rock sample is placed in the compression space, the output end of the first hydraulic module 100 moves toward the rock sample, and the rock sample is compressed and deformed with the cooperation of the stop surface. Meanwhile, since each hydraulic component 110 squeezes the rock sample with different forces, the deformation of each layer of the rock sample is different, which is more consistent with the changes that occur when the rock sample is subjected to actual stress underground, so as to more accurately understand the properties of the rock sample.

[0065] In some embodiments of the present invention, such as Figure 1 , Figure 2 As shown, the layered stress loading fracturing experimental device also includes a second hydraulic module 300 and a second stop surface 220. The second hydraulic module 300 is configured to output reciprocating motion along a first direction. The second stop surface 220 is located on the output end facing side of the second hydraulic module 300 and is spaced apart from the second hydraulic module 300; the second stop surface 220 and the output end of the second hydraulic module 300 are located on opposite sides of the compression space, respectively. There are two first hydraulic modules 100, which output reciprocating motion along a second direction and a third direction, respectively; the first direction, the second direction, and the third direction are perpendicular to each other. The first hydraulic module 100 and the second hydraulic module 300 respectively compress the rock sample in three mutually perpendicular directions, forming a true triaxial layered stress loading fracturing experimental device. The second hydraulic module 300 applies uniform stress to the rock sample in the first direction, while the two first hydraulic modules 100 apply stresses of different magnitudes to the rock sample in the second direction and the third direction, making the stress condition of the rock sample more consistent with the actual stress state experienced by the rock sample when it is underground.

[0066] In some embodiments of the present invention, such as Figure 1 , Figure 2As shown, the layered stress loading fracturing experimental apparatus also includes a camera assembly 400 and a housing 200. The camera assembly 400 is used to capture images of the rock sample. An L-shaped space is formed inside the housing 200, with the corner of the L-shaped space being a compression space. A window 230 is provided on the side wall of the housing 200, connecting the compression space and the outer space of the housing 200. A transparent plate 240 is provided in the window 230, and a protective film is provided on the inner side of the transparent plate 240. Further, the camera assembly 400 includes a guide rail 410, a base 420, and a high-speed camera 430. One end of the guide rail 410 is connected to the outer wall of the housing 200. The base 420 is movably mounted on the guide rail 410, and a robotic arm 440 is mounted on the base 420. The high-speed camera 430 is mounted on the robotic arm 440 and is used to capture images of the rock sample through the transparent plate 240. Because a guide rail 410 is provided outside the housing 200, the base 420 on the guide rail 410 drives the robotic arm 440 to move along the guide rail 410. Simultaneously, the robotic arm 440 can rotate freely to adjust the angle and height of the high-speed camera 430, facilitating the high-speed camera 430 to capture images of rock sample deformation through the transparent plate 240. The images captured by the high-speed camera 430 can be stored in the storage unit within the high-speed camera 430 or uploaded to a cloud server for user viewing. Furthermore, a protective film is affixed to the inside of the transparent plate 240 to prevent the rock sample from scratching the transparent plate 240 during deformation.

[0067] In some embodiments of the present invention, such as Figure 3 As shown, each hydraulic assembly 110 includes a sleeve 111, a slider 112, and a hydraulic rod 113. The sleeve 111 extends in a direction perpendicular to the first stop surface 210; an opening is formed at one end of the sleeve 111 facing the first stop surface 210; a hydraulic pipe for connecting to the hydraulic pump 500 is connected to the sleeve 111. The slider 112 is movably mounted within the sleeve 111. One end of the hydraulic rod 113 is connected to the slider 112, and the other end of the hydraulic rod 113 extends through the opening and is connected to a pressing mechanism. Further, as... Figure 4 As shown, multiple hydraulic pipes are connected in series with the hydraulic pump 500, and multiple hydraulic pipes are connected to the same hydraulic pump 500. Each hydraulic pipe is equipped with a valve 114; or, as shown... Figure 5 As shown, multiple hydraulic pipes are connected to the hydraulic pump 500 in parallel, with each hydraulic pipe connected to one hydraulic pump 500. When the multiple hydraulic pipes are connected to the hydraulic pump 500 in series, the amount of liquid in each sleeve 111 is controlled by opening and closing the valve 114 of each branch, thereby controlling the pressure transmitted by the slider 112 in each sleeve 111 to the extrusion mechanism. When the multiple hydraulic pipes are connected to the hydraulic pump 500 in parallel, each branch is controlled by one hydraulic pump 500, which in turn controls the amount of liquid in each sleeve 111, thereby controlling the pressure transmitted by the slider 112 in each sleeve 111 to the extrusion mechanism.

[0068] In some embodiments of the present invention, such as Figure 1 As shown, the second hydraulic module 300 includes a fixing frame 310, a first hydraulic cylinder 320, a clamp 330, a first pressing block 340, and a first pad block 350. The fixing frame 310 is spaced apart from the first stop surface 210. One end of the first hydraulic cylinder 320 is connected to the fixing frame 310, and the other end extends toward the first stop surface 210. The clamp 330 is connected to the other end of the first hydraulic cylinder 320. The first pressing block 340 is assembled on the clamp 330. The first pad block 350 is disposed on the side of the first pressing block 340 opposite to the clamp 330; the first pad block 350 is made of elastic material. An I-shaped groove is formed between the first pressing block 340 and the first pad block 350, and an I-shaped pin 370 is inserted into the I-shaped groove. A hydraulic press 360 connected to the first hydraulic cylinder 320 is disposed between the fixing frame 310 and the clamp 330. Meanwhile, as... Figure 6 As shown, the extrusion mechanism includes a second extrusion block 115 and a second pad 116. One side of the second extrusion block 115 is connected to a hydraulic rod 113, and the other side has a raised structure, which is an arc-shaped protrusion decreasing in size from the middle to both ends. The second pad 116 has a recessed structure that matches the shape of the raised structure; the recessed structure is connected to the raised structure; the second pad 116 is made of an elastic material. Since both the first pad 350 and the second pad 116 are made of elastic materials (such as oak, rubber, etc.), when extruded simultaneously in three directions, contact between the first pad 350 and the second pad 116 is likely to occur. If the first pad 350 and the second pad 116 are made of hard materials, they are prone to interfering with each other, thus preventing the rock sample from being extruded. Therefore, the first pad 350 and the second pad 116 are made of elastic material, so that both the first pad 350 and the second pad 116 can deform when they come into contact, thus avoiding mutual interference. Simultaneously, the second compression block 115 has a raised structure, and the second pad 116 has a recessed structure that conforms to the shape of the raised structure. This arrangement allows the two ends of the second pad 116 to deform better, enabling the application of load to the rock sample simultaneously in three directions.

[0069] In some embodiments of the present invention, such as Figure 6 As shown, the side of the second pad 116 facing away from the concave structure is set as a plane 1161. This plane can transmit forces to the maximum extent, making it suitable for use when compressing rock samples with thicker bedding. Alternatively, as... Figure 7 As shown, the side of the second pad 116 facing away from the concave structure is set as a curved surface 1162. This curved surface can be milled into an irregular three-dimensional skew by a milling cutter on a plane for use when compressing irregular rock samples. Alternatively, as... Figure 8 , Figure 9As shown, the side of the second pad 116 facing away from the concave structure is set as a stepped surface 1163, and the corners of the stepped surface 1163 are set as right angles 11631 or rounded corners 11632. In application, several stepped surfaces 1163 can be milled out with a milling cutter to suit thinner rock samples with unclear bedding boundaries. When rounded corners 11632 are set at the corners of the stepped surfaces 1163, a second-order continuous curvature is maintained between the stepped surfaces 1163.

[0070] In some embodiments of the present invention, such as Figures 10 to 12 As shown, the second extrusion block 115 includes a first sub-block 1151 and a second sub-block 1152 spaced apart; an expansion mechanism is provided between the first sub-block 1151 and the second sub-block 1152; the expansion mechanism includes an expansion fork 1153 and a drive motor 1154. The two expansion forks 1153 are staggered, and one end of each expansion fork 1153 is slidably connected to the first sub-block 1151 or the second sub-block 1152; the other end of one expansion fork 1153 is connected to a fixed sleeve 1155, and the other end of the other expansion fork 1153 is connected to a movable sleeve 1156. The drive motor 1154 is connected to the fixed sleeve 1155, and the output end of the drive motor 1154 is connected to a screw 1157, which passes through the fixed sleeve 1155 and is threadedly connected to the movable sleeve 1156. During the extrusion process, the drive motor 1154 can be started, and the drive motor 1154 drives the screw 1157 to rotate, causing the expansion fork 1153 to open, thereby pushing the first sub-block 1151 and the second sub-block 1152 away from each other, further increasing the stress on the second pad 116 connected to the second extrusion block 115, thus increasing the stress applied to the rock sample by the hydraulic assembly 110, so as to adjust the stress applied by each hydraulic assembly 110 according to the rock sample condition.

[0071] Similarly, to achieve the above functions, the inner wall of the other end of the sleeve 111 is formed with an internal thread; the other end of the sleeve 111 is connected to a pressure adjusting knob 117, and the pressure adjusting knob 117 is formed with an external thread that mates with the internal thread. Alternatively, depending on the rock sample conditions, the pressure adjusting knob 117 of the hydraulic component 110 at different strata corresponding to the rock sample can be rotated to adjust the stress applied by each hydraulic component 110 according to the rock sample conditions.

[0072] This invention also provides a layered stress loading fracturing test method, applied to the layered stress loading fracturing test apparatus in any of the above embodiments. The layered stress loading fracturing test method includes:

[0073] S1: Prepare the rock sample into a cube of a predetermined size;

[0074] S2: Place the rock sample in the compression space;

[0075] S3: The first hydraulic module 100 is activated according to the settings, and multiple hydraulic components 110 output different pressures to different layers of the rock sample.

[0076] Specifically, the rock sample is made into a cube of a predetermined size, including cutting a rock larger than the predetermined size into multiple rock samples smaller than the predetermined size; and using cement to bond the multiple rock samples smaller than the predetermined size and shape them into a cube of the predetermined size.

[0077] Working principle: When using this layered stress loading fracturing experimental device, the rock sample is first made into a cube of a preset size. If the rock sample size is larger than the preset size, the rock sample is crushed to a size smaller than or equal to the preset size. If the sample size is smaller than the preset size, cement is applied to the rock sample to bring its size to the preset size. Then, the rock sample is placed in the compression space within the shell 200, and the first hydraulic module 100 and / or the second hydraulic module 300 are activated according to the settings.

[0078] When the first hydraulic module 100 is activated, its output end moves towards the rock sample, and the rock sample is compressed and deformed by the stop surface. Simultaneously, because each hydraulic component 110 compresses the rock sample with a different force, the deformation of each layer of the rock sample varies, better reflecting the changes in actual stress experienced by the rock sample underground, thus providing a more accurate understanding of the rock sample's properties. Furthermore, depending on the condition of different layers of the rock sample, the drive motor 1154 of the hydraulic component 110 in contact with that layer can be activated, or the pressure adjustment knob 117 of the hydraulic component 110 in contact with that layer can be adjusted, achieving the effect of adjusting the stress applied by each hydraulic component 110 according to the rock sample's condition.

[0079] When the second hydraulic module 300 is activated, it applies a uniform stress to the rock sample in the first direction. The two first hydraulic modules 100 apply stresses of different magnitudes to the rock sample in the second and third directions, making the stress state of the rock sample more consistent with the actual stress state experienced by the rock sample when it is underground.

[0080] When the first hydraulic module 100 and / or the second hydraulic module 300 are started, the base 420 on the guide rail 410 drives the robotic arm 440 to move along the guide rail 410. At the same time, the robotic arm 440 can rotate freely to adjust the angle and height of the high-speed camera 430, so that the high-speed camera 430 can capture images of rock sample deformation through the transparent plate 240.

[0081] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

Claims

1. A layered fracturing experimental apparatus, characterized in that, include: At least one first hydraulic module, the first hydraulic module being configured to output reciprocating motion in a preset direction; At least one first stop surface, the first stop surface being located on the output end of the first hydraulic module facing side and spaced apart from the first hydraulic module, so as to define a compression space for placing the rock sample between the output end of the first hydraulic module and the first stop surface; The first hydraulic module includes multiple hydraulic components, each of which is configured to output pressure of varying magnitude toward the rock sample; Each of the hydraulic components includes a sleeve, a slider, and a hydraulic rod; The sleeve extends in a direction perpendicular to the first stop surface; an opening is formed at one end of the sleeve facing the first stop surface; a hydraulic pipe for connecting to a hydraulic pump is connected to the sleeve; the slider is movably installed inside the sleeve; one end of the hydraulic rod is connected to the slider, and the other end of the hydraulic rod extends out of the opening and is connected to a pressing mechanism. The extrusion mechanism includes a second extrusion block and a second pad block; The second extrusion block is connected to the hydraulic rod on one side and has a protruding structure on the other side. The protruding structure is an arc-shaped protrusion that decreases from the middle to both ends. The second pad has a recessed structure that conforms to the shape of the protruding structure; the recessed structure is connected to the protruding structure; the second pad is made of an elastic material; the side of the second pad facing away from the recessed structure is set as a plane, a curved surface, or a stepped surface; the corner of the stepped surface is set as a right angle or a rounded corner; The second extrusion block includes a first sub-block and a second sub-block spaced apart; an expansion mechanism is provided between the first sub-block and the second sub-block; the expansion mechanism includes an expansion fork, two expansion forks are staggered, one end of each expansion fork is slidably connected to the first sub-block or the second sub-block; the other end of one expansion fork is connected to a fixed sleeve, and the other end of the other expansion fork is connected to a movable sleeve; a drive motor is connected to the fixed sleeve, and the output end of the drive motor is connected to a screw, the screw passing through the fixed sleeve and threadedly connected to the movable sleeve.

2. The layered fracturing experimental apparatus according to claim 1, characterized in that, The layered fracturing experimental apparatus also includes: A second hydraulic module is configured to output reciprocating motion along a first direction; The second stop surface is located on the side facing the output end of the second hydraulic module and is spaced apart from the second hydraulic module; the second stop surface and the output end of the second hydraulic module are respectively located on both sides of the extrusion space; There are two first hydraulic modules, which output reciprocating motion along the second direction and the third direction respectively; the first direction, the second direction and the third direction are perpendicular to each other.

3. The layered fracturing experimental apparatus according to claim 2, characterized in that, The layered fracturing experimental apparatus also includes: A camera assembly for capturing images of the rock sample; The shell has an L-shaped space inside, the corner of which is the extrusion space. A window is provided on the side wall of the shell to connect the extrusion space with the outer space of the shell. The window is provided with a transparent plate, and a protective film is provided on the inner side of the transparent plate. The camera component includes: A guide rail, one end of which is connected to the outer wall of the housing; A base, which is movably mounted on the guide rail, and a robotic arm is provided on the base; A high-speed camera, mounted on the robotic arm, is used to capture images of the rock sample through the transparent plate.

4. The layered fracturing experimental apparatus according to claim 1, characterized in that, Multiple hydraulic pipes are connected in series with the hydraulic pump, and multiple hydraulic pipes are connected to the same hydraulic pump. Each hydraulic pipe is equipped with a valve; or... The hydraulic pipes are connected in parallel to the hydraulic pump, with each hydraulic pipe connected to one hydraulic pump.

5. The layered fracturing experimental apparatus according to claim 2, characterized in that, The second hydraulic module includes: A fixing frame, wherein the fixing frame is spaced apart from the first stop surface; The first hydraulic cylinder has one end connected to the fixed frame and the other end extending toward the first stop surface; A clamp, wherein the clamp is connected to the other end of the first hydraulic cylinder; A first extrusion block is assembled on the fixture; A first pad is disposed on the side of the first extrusion block opposite to the clamp; the first pad is detachably connected to the first extrusion block; the first pad is made of an elastic material.

6. A layered fracturing experimental method, characterized in that, The layered fracturing experimental apparatus according to any one of claims 1 to 5, wherein the layered fracturing experimental method comprises: S1: Prepare the rock sample into a cube of a predetermined size; S2: Place the rock sample within the compression space; S3: The first hydraulic module is activated according to the settings, and the multiple hydraulic components output different pressures to different layers of the rock sample.

7. The layered fracturing experimental method according to claim 6, characterized in that, The process of shaping the rock sample into a cube of a predetermined size includes: Cutting a rock larger than a preset size into multiple rock samples smaller than the preset size; and, Multiple rock samples smaller than the preset size are bonded together using cement and shaped into a cube of the preset size.

Images