Fracture modeling device, variable fracture plugging simulation evaluation system and evaluation method thereof

Abstract

The application provides a crack simulation device, a variable crack plugging simulation evaluation system and an evaluation method thereof. According to the technical scheme of the application, the sliding positions of the first movable joint plate, the second movable joint plate and the third movable joint plate in the shell are controlled to simultaneously simulate the closing and opening states of three cracks. Therefore, the variable crack plugging simulation evaluation system can simulate the plugging test of multiple cracks in the closing or opening state, the application range of the crack simulation device is improved, and the crack simulation device can be applied to, for example, the plugging evaluation test of the opening and closing type shale crack and the plugging evaluation test of the plugging effect caused by the expansion under the condition of the drilling fluid excitation pressure. Further, the plugging evaluation method of multiple cracks in the closing or opening state, that is, the plugging evaluation method of multiple opening and closing type cracks, can be established, and more powerful indoor evaluation and data support are provided for the efficient plugging of shale oil and gas reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well plugging equipment technology, and in particular to a fracture simulation device, a variable fracture plugging simulation evaluation system and its evaluation method. Background Technology

[0002] Currently, in the laboratory evaluation of fractured formations, the fracture simulation devices in related technologies are typically limited by their structure and can only simulate multiple fixed fractures. Since the width of fixed fractures remains constant, they cannot close or open. This makes them unsuitable for evaluation tests of leakage plugging in open-closed shale fractures, as well as for evaluation tests of the impact of expansion on plugging effectiveness under drilling fluid pressure.

[0003] In other words, the crack simulation devices in the relevant technologies have poor applicability. Summary of the Invention

[0004] To address the problems in the prior art, this application proposes a crack simulation device, a variable crack sealing simulation evaluation system, and an evaluation method thereof, which solves the problem of poor applicability of crack simulation devices.

[0005] The crack simulation device of the present invention includes: a housing having an inlet and an outlet; a first movable crack plate slidably disposed within the housing along a first direction; a second movable crack plate slidably disposed within the housing along the first direction and located above the first movable crack plate; a first elastic telescopic component extending through the second movable crack plate, one end of which is connected to the top wall of the inner cavity of the housing, and the other end of which is connected to the first movable crack plate; and a second elastic telescopic component, one end of which is connected to the second movable crack plate, and the other end of which is connected to the first movable crack plate; wherein a first simulated crack is defined between the first and second movable crack plates, and a second simulated crack is defined between the second movable crack plate and the top wall of the inner cavity; when an upward thrust is applied to the first movable crack plate, the first and second simulated cracks gradually close, at which time the first elastic telescopic component is compressed; when no upward thrust is applied, the first and second simulated cracks gradually open under the action of the restoring force of the first elastic telescopic component.

[0006] In one embodiment, a third movable seam plate is slidably disposed within the housing along a first direction and located above the second movable seam plate; a first elastic telescopic component extends through the third movable seam plate; and a third elastic telescopic component extends through the second movable seam plate, with one end connected to the third movable seam plate and the other end connected to the first movable seam plate; wherein a first simulated crack is defined between the first and second movable seam plates, a third simulated crack is defined between the third and second movable seam plates, and a second simulated crack is defined between the third movable seam plate and the top wall of the inner cavity.

[0007] In one embodiment, a sealing element is provided on the outer periphery of the first movable seam plate, and the first movable seam plate, the sealing element and the bottom of the inner cavity of the housing define a sealing cavity, and an upward thrust can be applied to the first movable seam plate by pressing the sealing cavity.

[0008] In one embodiment, the system further includes a first partition and a second partition, which are spaced apart along a second direction between the first movable seam plate and the bottom wall of the inner cavity of the housing, for dividing the sealed cavity into three non-communicating cavities. Pressing the cavities can apply an upward thrust to the first movable seam plate.

[0009] In one embodiment, the first elastic telescopic component includes a plurality of first compression springs, and / or the second elastic telescopic component includes a plurality of second compression springs, and / or the third elastic telescopic component includes a plurality of third compression springs.

[0010] In one embodiment, the spring constants of the second compression spring and the third compression spring are different.

[0011] In one embodiment, a limiting rod is also included, which is disposed on the inner cavity side wall of the housing to prevent the first movable slotted plate from sliding to a position where the liquid inlet and / or liquid outlet are connected to the sealing cavity.

[0012] This invention provides a variable crack sealing simulation and evaluation system, comprising: a vessel for holding sealing slurry; the aforementioned crack simulation device connected to the vessel; a first pressurizing device connected to the sealing cavity of the crack simulation device; and a second pressurizing device connected to the inlet of the crack simulation device and the vessel; wherein the first pressurizing device simulates the opening and closing of multiple cracks by pressurizing or depressurizing the sealing cavity, and the second pressurizing device can positively press the sealing slurry in the vessel into the multiple simulated cracks of the crack simulation device.

[0013] In one embodiment, the outlet of the crack simulation device is connected to the second pressurizing device, and a grout leakage port is provided at the bottom of the outlet. The second pressurizing device can apply reverse pressure to the sealing grout in the crack simulation device through the outlet.

[0014] This invention provides a variable crack sealing evaluation method. The crack sealing evaluation method adopts the above-mentioned variable crack sealing simulation evaluation system and includes the following steps:

[0015] Step 1: Apply pressure to the crack simulation device;

[0016] Step 2: Adjust the pressure to keep the multiple simulated cracks in the crack simulation device at the preset crack width;

[0017] Step 3: Inject sealing grout into multiple simulated cracks to seal them;

[0018] Step 4: Record the volume of slurry lost under different sealing pressures;

[0019] Step 5: Continue to apply pressure to the crack simulation device to gradually close the multiple simulated cracks;

[0020] Step 6: Record the volume of slurry lost under different sealing pressures;

[0021] Step 7: Depressurize the crack simulation device to allow multiple simulated cracks to gradually open;

[0022] Step 8: Record the volume of slurry lost under different sealing pressures.

[0023] In one embodiment, through this embodiment...

[0024] The above-mentioned technical features can be combined in various suitable ways or replaced by equivalent technical features, as long as the purpose of the present invention can be achieved.

[0025] The crack simulation device, variable crack sealing simulation evaluation system, and evaluation method provided by this invention have at least the following advantages compared with the prior art:

[0026] By controlling the sliding positions of the first, second, and third movable fracture plates within the shell, the closing and opening states of three fractures can be simulated simultaneously. This ensures that the variable fracture plugging simulation and evaluation system can simulate plugging tests of multiple fractures in closed or open states, expanding the applicability of the fracture simulation device. For example, it can be applied to plugging evaluation tests of shale fractures under tension and expansion under drilling fluid pressure conditions, thus evaluating the impact of expansion on plugging effectiveness. Furthermore, this ensures the establishment of a plugging evaluation method for multiple fractures in closed or open states—a multi-tension fracture plugging evaluation method—providing stronger indoor evaluation and data support for efficient plugging of shale oil and gas reservoirs. Attached Figure Description

[0027] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0028] Figure 1 A schematic diagram of the crack simulation device according to Embodiment 1 of the present invention is shown;

[0029] Figure 2 Showing Figure 1 A cross-sectional view of the AA plane;

[0030] Figure 3 Showing Figure 1 Diagram showing the connection relationship between the elastic telescopic component and the first movable seam plate;

[0031] Figure 4 ShowingFigure 1 The first movable seam plate in the middle;

[0032] Figure 5 Showing Figure 1 The second movable seam plate in the middle;

[0033] Figure 6 Showing Figure 1 The third movable sealing plate in the middle;

[0034] Figure 7 This shows a schematic diagram of the variable crack plugging simulation and evaluation system according to Embodiment 3 of the present invention;

[0035] Figure 8 A schematic diagram of the structure of the variable crack plugging simulation evaluation system of Embodiment 4 of the present invention is shown.

[0036] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not to scale.

[0037] Figure label:

[0038] 10. Shell; 11. Inner cavity top wall; 13. Liquid inlet; 14. Liquid outlet; 141. Slurry leakage outlet; 16. First partition; 17. Second partition; 18. Third partition; 20. First movable joint plate; 21. Sealing element; 22. Mounting hole; 30. Second movable joint plate; 40. Second elastic telescopic assembly; 41. Second compression spring; 50. First simulated crack; 60. Second simulated crack; 70. Third movable joint plate; 80. Third elastic telescopic assembly; 81. Third compression spring; 90. First partition; 100. Second partition; 110. Limit Position rod; 120, first elastic telescopic component; 121, first compression spring; 130, third simulated crack; 140, through hole; 1000, crack simulation device; 200, vessel body; 300, first pressurizing device; 301, manual pressurizing pump; 302, first oil outlet line; 303, second oil outlet line; 304, oil return line; 305, first control valve; 306, third control valve; 307, fourth control valve; 400, second pressurizing device; 401, air source; 402, main pipeline; 403, branch pipeline; 404, second control valve. Detailed Implementation

[0039] The invention will now be further described with reference to the accompanying drawings.

[0040] Example 1

[0041] like Figure 1 and Figure 2As shown, the present invention provides a crack simulation device 1000, which includes a housing 10, a first movable crack plate 20, a second movable crack plate 30, a first elastic telescopic component 120, and a second elastic telescopic component 40. The housing 10 is provided with an inlet 13 and an outlet 14. The first movable crack plate 20 is slidably disposed within the housing 10 along a first direction. The second movable crack plate 30 is disposed within the housing 10 along the first direction and located above the first movable crack plate 20. The first elastic telescopic component 120 extends through the second movable crack plate 30, with one end connected to the inner cavity top wall 11 of the housing 10 and the other end connected to the first movable crack plate 20. One end of the second elastic telescopic component 40 is connected to the second movable crack plate 30, and the other end is connected to the first movable crack plate 20. A first simulated crack 50 is defined between the first movable crack plate 20 and the second movable crack plate 30. The crack simulation device 1000 also includes a third movable crack plate 70 and a third elastic telescopic component 80. The third movable seam plate 70 is slidably disposed within the housing 10 along a first direction and located above the second movable seam plate 30. The first elastic telescopic component 120 extends through the third movable seam plate 70. The third elastic telescopic component 80 extends through the second movable seam plate 30, with one end connected to the third movable seam plate 70 and the other end connected to the first movable seam plate 20. A third simulated crack 130 is defined between the third movable seam plate 70 and the second movable seam plate 30, and a second simulated crack 60 is defined between the third movable seam plate 70 and the inner cavity top wall 11. When an upward thrust is applied to the first movable seam plate 20, the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 gradually close, at which point the first elastic telescopic component 120 is compressed. When no thrust is applied, under the action of the restoring force of the first elastic telescopic component 120, the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 gradually open (expand).

[0042] In the above configuration, the sliding positions of the first movable fracture plate 20, the second movable fracture plate 30, and the third movable fracture plate 70 within the housing 10 are controlled to simultaneously simulate the closing and opening states of three fractures. This ensures that the variable fracture plugging simulation evaluation system can simulate plugging tests of multiple fractures in closed or open states, expanding the applicability of the fracture simulation device 1000. For example, it can be applied to plugging evaluation tests of shale fractures under tension and expansion under drilling fluid pressure conditions, thus evaluating the plugging effect. Furthermore, this ensures the establishment of a plugging evaluation method for multiple fractures in closed or open states, i.e., a multi-tension fracture plugging evaluation method, providing stronger indoor evaluation and data support for efficient plugging of shale oil and gas reservoirs.

[0043] Specifically, such as Figures 1 to 3As shown, in one embodiment, a sealing element 21 is provided on the outer periphery of the first movable seam plate 20. The first movable seam plate 20, the sealing element 21 and the bottom of the inner cavity of the housing 10 define a sealing cavity. Pressing the sealing cavity can apply an upward thrust to the first movable seam plate 20.

[0044] Specifically, such as Figure 1 and Figure 2 As shown, in one embodiment, the seal 21 is a sealing strip.

[0045] Specifically, such as Figure 1 As shown, in one embodiment, it also includes a first partition 90 and a second partition 100. The first partition 90 and the second partition 100 are spaced apart along the second direction between the first movable seam plate 20 and the inner cavity bottom wall of the housing 10, for dividing the sealed cavity into three non-communicating cavities. Pressing the cavities can apply an upward thrust to the first movable seam plate 20.

[0046] Specifically, such as Figure 1 As shown, in one embodiment, pressurizing the middle compartment (i.e., the second compartment 17) of the three compartments can simulate three horizontal simulated cracks within the crack simulation device 1000. That is, the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 are horizontal cracks. This facilitates subsequent analysis and evaluation of the sealing effect of the plugging system on the horizontal cracks.

[0047] Specifically, such as Figure 1 As shown, in one embodiment, simultaneously pressurizing the three cavities can simulate three horizontal simulated cracks within the crack simulation device 1000. That is, the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 are horizontal cracks. Compared with the method of pressurizing only the cavity located in the middle, this pressurization method results in more uniform force distribution on the first diaphragm 90 and reduces the likelihood of jamming.

[0048] Specifically, such as Figure 1 and Figure 7 As shown, in one embodiment, pressure is applied to the left-side compartment (i.e., the first compartment 16) and the right-side compartment (i.e., the third compartment 18), creating a pressure difference between the two compartments. This allows for the simulation of three wedge-shaped simulated cracks within the crack simulation device 1000. Specifically, the crack width near the inlet is greater than the crack width near the outlet, forming a wedge-shaped simulated crack. This facilitates subsequent analysis and evaluation of the sealing effect of the plugging system on the wedge-shaped cracks.

[0049] In the above configuration, by adjusting the pressure within the cavities on the left and right sides (the pressure within the first cavity 16 and the third cavity 18), the oblique sliding positions of the first movable seam plate 20, the second movable seam plate 30, and the third movable seam plate 70 within the housing 10 are controlled, thereby simultaneously simulating the closing and opening states of three wedge-shaped cracks. This expands the applicability of the crack simulation device 1000.

[0050] Specifically, such as Figures 1 to 3 As shown, in one embodiment, the first elastic telescopic component 120 includes four first compression springs 121, the second elastic telescopic component 40 includes four second compression springs 41, and the third elastic telescopic component 80 includes four third compression springs 81.

[0051] In the above configuration, the second compression spring 41 and the third compression spring 81 act as flexible transmission components. When the first movable seam plate 20 is pushed upward, the second compression spring 41 and the third compression spring 81 can respectively push the second movable seam plate 30 and the third movable seam plate 70 to slide upward, causing the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 to gradually close. This simulates the closed state of the three cracks. When the cavity is depressurized, the first compression spring 121, under the action of its own restoring force, drives the first movable seam plate 20 to slide downward. At the same time, the second compression spring 41 and the third compression spring 81 respectively drive the second movable seam plate 30 and the third movable seam plate 70 to slide downward, causing the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 to gradually open from closed. This simulates the three cracks from closed to open.

[0052] Specifically, in one embodiment, four first compression springs 121 are arranged in a rectangular shape.

[0053] Specifically, in one embodiment, four third compression springs 81 are arranged in a rectangular shape and are located outside the four first compression springs 121.

[0054] Specifically, in one embodiment, four second compression springs 41 are arranged in a rectangular shape and are located outside the four third compression springs 81.

[0055] Specifically, such as Figure 5 As shown, in one embodiment, the second movable seam plate 30 is provided with a through hole 140 for passing through the first compression spring 121 and the third compression spring 81.

[0056] Specifically, such as Figure 6 As shown, in one embodiment, the third movable seam plate 70 is provided with a through hole 140 for inserting the first compression spring 121.

[0057] Specifically, such as Figure 4As shown, in one embodiment, the first movable seam plate 20 is provided with mounting holes 22 for mounting the first compression spring 121, the third compression spring 81 and the second compression spring 41.

[0058] Specifically, in one embodiment, the elastic coefficients of the second compression spring 41 and the third compression spring 81 are different.

[0059] In the above configuration, the second compression spring 41 and the third compression spring 81 have different elastic coefficients. Therefore, under the same external force, the second compression spring 41 and the third compression spring 81 will undergo different deformations. This allows the widths of the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130 to be set differently. This simulates the closing and opening states of three cracks with different widths, thereby expanding the applicability of the crack simulation device 1000.

[0060] It should be noted that a high-elasticity rubber column can be used to replace the compression spring. The first movable seam plate 20, the second movable seam plate 30, and the third movable seam plate 70 have the same specifications.

[0061] Specifically, in one embodiment, the elastic coefficients of the first compression spring 121, the second compression spring 41, and the third compression spring 81 are all different.

[0062] Because the three types of springs have different elastic coefficients and different sensitivities to pressure, the widths of the three simulated cracks generated are different. This facilitates subsequent analysis and evaluation of the sealing effect of the plugging system on multi-scale cracks.

[0063] Specifically, such as Figure 1 and Figure 2 As shown, in one embodiment, a limiting rod 110 is also included. The limiting rod 110 is disposed on the inner cavity sidewall of the housing 10 to prevent the first movable slot plate 20 from sliding to the position where the inlet 13 or outlet 14 communicates with the sealing cavity. This prevents hydraulic oil from entering the first simulated crack 50, the second simulated crack 60, and the third simulated crack 130, thereby ensuring that the variable crack sealing simulation evaluation system can work normally.

[0064] Example 2

[0065] The difference between Example 2 and Example 1 is as follows:

[0066] The crack simulation device 1000 does not include the third movable crack plate 70 and the third elastic telescopic component 80. The crack simulation device 1000 simulates only two cracks, namely the first simulated crack 50 and the second simulated crack 60.

[0067] It should be noted that by controlling the sliding positions of the first movable fracture plate 20 and the second movable fracture plate 30 within the shell 10, the closing and opening states of two fractures can be simulated simultaneously. This ensures that the variable fracture plugging simulation and evaluation system can simulate plugging tests of multiple fractures in closed or open states, thereby establishing a plugging evaluation method for multiple fractures in closed or open states, i.e., a multi-fracture closure-opening type plugging evaluation method, providing stronger indoor evaluation and data support for efficient plugging of shale oil and gas reservoirs.

[0068] Of course, more movable fracture plates and elastic expansion components can be added according to actual conditions, enabling the fracture simulation device 1000 to simulate more fracture closure and opening states. This will allow for the establishment of more evaluation methods for leakage plugging under closed or open fracture states, providing stronger indoor evaluation and data support for efficient leakage plugging in shale oil and gas reservoirs.

[0069] The other structures of Embodiment 2 are the same as those of Embodiment 1, and will not be described again here.

[0070] Example 3

[0071] like Figure 7 As shown, the present invention also provides a variable crack sealing simulation evaluation system, which includes a vessel body 200, a crack simulation device 1000 as described in Embodiment 1 above, a first pressurizing device 300, and a second pressurizing device 400. The vessel body 200 is used to hold the sealing slurry; the crack simulation device 1000 is connected to the vessel body 200; the first pressurizing device 300 is connected to the sealing cavity of the crack simulation device 1000; the second pressurizing device 400 is connected to the inlet of the crack simulation device 1000 and the vessel body 200; the first pressurizing device 300 simulates the opening and closing of multiple cracks by pressurizing or depressurizing the sealing cavity, and the second pressurizing device 400 can positively press the sealing slurry in the vessel body 200 into the multiple simulated cracks of the crack simulation device 1000.

[0072] Specifically, such as Figure 7 As shown, in one embodiment, the outlet 14 of the crack simulation device 1000 is connected to the second pressurizing device 400. A grout leakage port 141 is provided at the bottom of the outlet 14. The second pressurizing device 400 can apply reverse pressure to the sealing grout in the crack simulation device 1000 through the outlet 14.

[0073] Specifically, such as Figure 7 As shown, in one embodiment, the first pressurizing device 300 includes a manual pressurizing pump 301, a first oil outlet line 302 and a second oil outlet line 303, a return oil line 304, a first control valve 305, a third control valve 306 and a fourth control valve 307.

[0074] One end of the first oil outlet line 302 is connected to the oil outlet of the manual pressurizing pump 301, and the other end is connected to the left side of the fracture simulation device 1000 (first compartment 16). One end of the second oil outlet line 303 is connected to the oil outlet of the manual pressurizing pump 301, and the other end is connected to the other end of the right side of the fracture simulation device 1000 (third compartment 18). The three compartments in the fracture simulation device 1000 are not interconnected, which allows for different pressures at both ends of the fracture and different fracture opening degrees. One end of the return oil line 304 is connected to the compartments on both the left and right sides of the fracture simulation device 1000, and the other end is connected to the return port of the manual pressurizing pump 301. A first control valve 305 is installed on the first oil outlet line 302, a third control valve 306 is installed on the second oil outlet line 303, and a fourth control valve 307 is installed on the return oil line 304. The first oil outlet pipeline 302, the second oil outlet pipeline 303, and the return oil pipeline 304 have an intersection point a, and the first oil outlet pipeline 302, the second oil outlet pipeline 303, and the return oil pipeline 304 are connected at the intersection point a.

[0075] When the crack simulation device 1000 is pressurized to simulate crack closure, the fourth control valve 307 on the return oil line 304 is closed, the first control valve 305 on the first oil outlet line 302 and the third control valve 306 on the second oil outlet line 303 are opened, and the manual pressurizing pump 301 is rotated to increase the pressure. After the pressure is increased to the preset pressure P1, the first control valve 305 and the third control valve 306 can be closed at the same time to form a parallel crack. Alternatively, the first control valve 305 can be closed first, the pressure of the manual pressurizing pump 301 can be increased to the preset pressure P2, and then the third control valve 306 can be closed to form a wedge-shaped crack.

[0076] When relieving pressure on the fracture simulation device 1000 to simulate fracture expansion (opening), open the fourth control valve 307 on the return oil line 304. First, open the first control valve 305 to relieve pressure, and the left end of the fracture will expand. Then, close the first control valve 305 and open the third control valve 306, and the right end of the fracture will be relieved and expanded. During the pressure relief process, the first control valve 305 and the third control valve 306 should not be opened at the same time to prevent repeated irregular opening and closing of the two ends of the fracture caused by pressure fluctuations.

[0077] Specifically, such as Figure 7 As shown, in one embodiment, the second pressurization device 400 includes a gas source 401, a main pipeline 402, and a branch pipeline 403. One end of the main pipeline 402 is connected to the gas source 401, and the other end is connected to the outlet 14 of the crack simulation device 1000. One end of the branch pipeline 403 is connected to the vessel body 200, and the other end is connected to the main pipeline 402. A second control valve 404 is installed on both the branch pipeline 403 and the main pipeline 402, located between the outlet 14 and the connection point of the branch pipeline 403 and the main pipeline 402.

[0078] Of course, the structure of the second pressurizing device in this embodiment can be improved according to the actual situation. A piston can be added inside the vessel body 200, with the lower part of the piston containing the sealing slurry. The top of the vessel body 200 is connected to a hydraulic pump through a valve stem. The upper part of the piston inside the vessel body contains hydraulic oil. The hydraulic pump pushes the piston downward to apply high pressure to the sealing slurry. That is, hydraulic pressure is used to replace pneumatic pressure to drive the injection of the sealing slurry.

[0079] It should be noted that using hydraulic pressurization has two advantages: first, hydraulic pressurization is safer than air pressurization; second, the pressure applied by hydraulic pressurization is much higher than that applied by air pressurization.

[0080] Example 4

[0081] The difference between Example 4 and Example 3 is as follows:

[0082] like Figure 8 As shown, the outlet 14 of the crack simulation device 1000 is not connected to the second pressurization device 400. That is, the second pressurization device 400 includes a main pipeline 402, one end of which is connected to the gas source 401 and the other end of which is connected to the vessel body 200. No branch pipelines are set.

[0083] The other structures of Embodiment 4 are the same as those of Embodiment 3, and will not be described again here.

[0084] Example 5

[0085] This invention provides a variable crack sealing evaluation method, which uses the crack simulation device in Example 4, and includes the following steps:

[0086] Step 1: Apply pressure to the crack simulation device;

[0087] Step 2: Adjust the pressure to keep the multiple simulated cracks in the crack simulation device at the preset crack width;

[0088] Specifically, pressure is applied to the diaphragm by a manual pressurizing pump 301, and the first simulated crack 50, the second simulated crack 60 and the third simulated crack 130 are kept at a preset crack width by pressure control.

[0089] Step 3: Inject sealing grout into multiple simulated cracks to seal them;

[0090] Specifically, the plugging slurry is added into the vessel body 200, and the top is connected to the air source 401. The second control valve 404 between the air source 401 and the vessel body 200 is opened, and the second control valve 404 between the air source 401 and the crack simulation device is closed. By controlling the appropriate air source pressure, the plugging slurry quickly enters the three simulated cracks under pressure to achieve sealing.

[0091] Step 4: Record the volume of slurry lost under different sealing pressures;

[0092] Specifically, the gas source pressure was gradually increased, and the volume of leaked slurry under different pressures was recorded to examine the pressure-bearing sealing performance of the sealing layer.

[0093] Step 5: Continue to apply pressure to the crack simulation device to gradually close the multiple simulated cracks;

[0094] Specifically, by operating the first control valve 305, the third control valve 306, and the fourth control valve 307, the pressure in the diaphragm is increased, thereby controlling the proper closure of the three simulated cracks.

[0095] Step 6: Record the volume of slurry lost under different sealing pressures;

[0096] Step 7: Depressurize the crack simulation device to allow multiple simulated cracks to gradually open;

[0097] Pressure is released by operating the first control valve 305, the third control valve 306, and the fourth control valve 307.

[0098] Step 8: Record the volume of slurry lost under different sealing pressures.

[0099] It should be noted that steps three through eight can be repeated to evaluate the impact of simulated crack closure-expansion on the sealing layer and sealing effect.

[0100] Example 6

[0101] This invention provides a variable crack sealing evaluation method, which uses the crack simulation device in Example 3, and includes the following steps:

[0102] Step 1: Apply pressure to the crack simulation device;

[0103] Step 2: Adjust the pressure to keep the multiple simulated cracks in the crack simulation device at the preset crack width;

[0104] Specifically, pressure is applied to the diaphragm by a manual pressurizing pump 301, and the first simulated crack 50, the second simulated crack 60 and the third simulated crack 130 are kept at a preset crack width by pressure control.

[0105] Step 3: Inject sealing grout into multiple simulated cracks to seal them;

[0106] Specifically, the sealing slurry is added into the vessel 200, and the top is connected to the air source 401. The second control valve 404 between the air source 401 and the vessel 200 is opened, and the second control valve 404 between the air source 401 and the crack simulation device is closed. By controlling the appropriate air source pressure, the sealing slurry quickly enters the three simulated cracks under pressure to achieve sealing.

[0107] Step 4: Record the volume of slurry lost under different sealing pressures;

[0108] Specifically, the gas source pressure was gradually increased, and the volume of leaked slurry under different pressures was recorded to examine the pressure-bearing sealing performance of the sealing layer.

[0109] Step 5: Continue to apply pressure to the crack simulation device to gradually close the multiple simulated cracks;

[0110] Step 6: Record the volume of slurry lost under different sealing pressures;

[0111] Step 7: Stop injecting the sealing grout;

[0112] Step 8: Apply reverse pressure to multiple simulated cracks and maintain it for a preset time;

[0113] Step nine: Re-inject sealing grout;

[0114] Step 10: Record the volume of slurry lost under different sealing pressures;

[0115] Specifically, in steps seven to ten, the second control valve 404 between the gas source 401 and the vessel body 200 of the plugging device is closed, and the second control valve 404 between the gas source 401 and the crack simulation device is opened, so that the reverse pressure is appropriately greater than the forward plugging pressure. After maintaining this for a certain period of time (preset time), the second control valve 404 between the gas source 401 and the crack simulation device is closed first, and then the second control valve 404 between the gas source 401 and the vessel body 200 is opened again. The volume of slurry leakage under different pressures is recorded, and the degree of damage to the plugging layer by the reverse pressure is examined.

[0116] Step 11: Depressurize the crack simulation device to allow multiple simulated cracks to gradually open;

[0117] Step 12: Record the volume of slurry lost under different sealing pressures.

[0118] It should be noted that steps three through twelve can be repeated to evaluate the impact of simulated crack closure-expansion on the sealing layer and sealing effect.

[0119] The crack simulation device and variable crack sealing simulation and evaluation system of the present invention have the following characteristics:

[0120] 1. The principle is reliable and the operation is simple. The opening and closing of cracks is achieved by the deformation of the spring, which can better simulate the sealing of variable cracks and is beneficial to the optimization of sealing materials and formulations for pressure-sensitive formations.

[0121] 2. Using springs with different elastic coefficients to create three cracks is more conducive to simulating crack sealing and control in shale formations with heterogeneous bedding and fracture development, thus facilitating evaluation tests of crack sealing for different types of cracks, such as horizontal cracks and wedge cracks, as well as crack widths.

[0122] 3. It can conduct reverse pressure displacement tests, which is beneficial for evaluating the destructive effect of reverse displacement on the sealing layer and examining the dense pressure-bearing performance of the sealing layer.

[0123] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., 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, they should not be construed as limitations on this invention.

[0124] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A crack simulation device, characterized in that, include: The casing is equipped with a liquid inlet and a liquid outlet; A first movable seam plate is slidably disposed within the housing along a first direction; The second movable seam plate is slidably disposed within the housing along the first direction and is located above the first movable seam plate; as well as A first elastic telescopic component extends out from the second movable seam plate, with one end connected to the inner cavity top wall of the housing and the other end connected to the first movable seam plate. The first elastic telescopic component includes a plurality of first compression springs. The second elastic telescopic component has one end connected to the second movable seam plate and the other end connected to the first movable seam plate. The second elastic telescopic component includes a plurality of second compression springs. The third movable seam plate is slidably disposed in the housing along the first direction and located above the second movable seam plate, and the first elastic telescopic component passes through the third movable seam plate; as well as A third elastic telescopic component extends from the second movable seam plate, with one end connected to the third movable seam plate and the other end connected to the first movable seam plate. The third elastic telescopic component includes a plurality of third compression springs, and the elastic coefficients of the second compression spring and the third compression spring are different. A first simulated crack is defined between the first movable seam plate and the second movable seam plate, a third simulated crack is defined between the third movable seam plate and the second movable seam plate, and a second simulated crack is defined between the third movable seam plate and the top wall of the inner cavity. When an upward thrust is applied to the first movable seam plate, the first simulated crack and the second simulated crack gradually close, at which time the first elastic telescopic component is compressed. When the upward thrust is not applied, the first simulated crack and the second simulated crack gradually open under the action of the restoring force of the first elastic telescopic component.

2. The crack simulation device according to claim 1, characterized in that, A sealing element is provided on the outer periphery of the first movable seam plate. The first movable seam plate, the sealing element, and the bottom of the inner cavity of the housing define a sealing cavity. The upward thrust can be applied to the first movable seam plate by pressing the sealing cavity.

3. The crack simulation device according to claim 2, characterized in that, It also includes a first partition and a second partition, which are spaced apart along a second direction between the first movable seam plate and the bottom wall of the inner cavity of the housing, for dividing the sealed cavity into three non-communicating cavities. The upward thrust can be applied to the first movable seam plate by pressing the cavities.

4. The crack simulation device according to claim 3, characterized in that, It also includes a limiting rod, which is disposed on the inner cavity side wall of the housing to prevent the first movable seam plate from sliding to the position where the liquid inlet and / or the liquid outlet are connected to the sealing cavity.

5. A variable crack sealing simulation and evaluation system, characterized in that, include: The vessel body is used to hold the sealing slurry; The crack simulation device as described in any one of claims 1 to 4 is connected to the vessel body; The first pressurizing device is connected to the sealed cavity of the crack simulation device; The second pressurizing device is connected to the liquid inlet of the crack simulation device and the vessel body; The first pressurizing device simulates the opening and closing of multiple cracks by pressurizing or depressurizing the sealed cavity, while the second pressurizing device can positively press the plugging slurry in the vessel body into the multiple simulated cracks of the crack simulation device.

6. The variable crack plugging simulation and evaluation system according to claim 5, characterized in that, The outlet of the crack simulation device is connected to the second pressurizing device. A grout leakage port is provided at the bottom of the outlet. The second pressurizing device can apply reverse pressure to the sealing grout in the crack simulation device through the outlet.

7. A variable crack sealing evaluation method, characterized in that, The crack plugging evaluation method uses the variable crack plugging simulation evaluation system as described in claim 5, and includes the following steps: Step 1: Apply pressure to the crack simulation device; Step 2: Adjust the pressure to keep the multiple simulated cracks in the crack simulation device at a preset crack width; Step 3: Inject the sealing grout into the simulated cracks to seal them; Step 4: Record the volume of slurry lost under different sealing pressures; Step 5: Continue to apply pressure to the crack simulation device to gradually close the multiple simulated cracks; Step 6: Record the volume of slurry lost under different sealing pressures; Step 7: Depressurize the crack simulation device to allow the multiple simulated cracks to gradually open; Step 8: Record the volume of slurry lost under different sealing pressures.

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