A method for testing rock mass unloading fracture slip after hydraulic sand fracturing

Abstract

The application discloses a kind of rock mass unloading fracture slip test methods after hydraulic sand fracturing, including mainly by injection component, fracture component and fixed component The test device of component is composed, the injection component is used to inject liquid with proppant into fracture component, the fracture component is used to simulate the reaction of rock mass with fracture after injecting liquid, the fixed component not only can realize the support fixation of fracture component and the exertion of load, still include following test steps: S1: test preparation;S2: load exertion;S3: carry out fracturing;S4: pressure relief after fracturing;S5: change the rigidity of fixed component after exertion normal load and repeat fracturing again.Can simulate the process that fracture with proppant appears slip instability when normal load reduces when excavation induced fracture appears after hydraulic sand fracturing by test device, provide test data for the stress-strain change of coal seam when further exploitation in the process of coal resource exploitation after rock stratum hydraulic fracturing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of safety of hydraulic mining of mineral resources, and particularly relates to a method for testing post-hydraulic sand fracturing rock mass unloading fracture slip. BACKGROUND

[0002] As a main means for development and yield increase in the fields of oil and shale gas, hydraulic fracturing technology has been widely applied, and its mechanism is to inject fracturing fluid into rock strata to generate fractures, so as to change the mechanical properties of the rock strata and increase the permeability of the rock strata to improve the yield of oil and shale gas. At present, hydraulic fracturing technology has also been widely applied in the field of coal, such as coalbed methane extraction, hard roof pre-fracturing, coal and rock burst prevention, coal and gas outburst prevention, etc. There are essential differences between coal mining and oil and gas mining. Hydraulic fracturing of oil and gas resources will reform the reservoir, so that after the oil and gas resources are exhausted, the stress of the reservoir will gradually return to a balanced state. However, in the mining of coal resources, after hydraulic fracturing of the coal rock reservoir, further mining will further disturb and depressurize the original rock stress field.

[0003] In the prior art, most of the research on hydraulic fracturing of coal rock is concentrated on pure fluid fracturing, without considering the fracture slip instability of the coal body after excavation unloading under the condition of containing proppant. SUMMARY

[0004] The present application provides a method for testing post-hydraulic sand fracturing rock mass unloading fracture slip, which can simulate the process of fracture slip instability of the fracture with proppant when the normal load decreases after excavation induced fracture appears by using a test device.

[0005] To this end, the technical solution adopted by the present application is as follows: a method for testing post-hydraulic sand fracturing rock mass unloading fracture slip, comprising a test device, the test device comprises an injection assembly, a fracture assembly and a fixing assembly, the injection assembly is used for injecting liquid with proppant into the fracture assembly, the fracture assembly is used for simulating the reaction of the rock mass with fracture after the injection of liquid, and the fixing assembly is used for supporting and fixing the fracture assembly and applying load; the fracture assembly comprises upper and lower fracture plates arranged oppositely, the left ends of the upper and lower fracture plates are provided with notches for injecting sand fracturing fluid, the upper fracture plate can move up and down, and the upper fracture plate is loaded with a normal load from the fixing assembly, the lower fracture plate can move left and right, and the lower fracture plate is loaded with a tangential load from the fixing assembly; the test device further comprises the following test steps:

[0006] S1: test preparation; connect all parts of the test device completely, confirm whether the connection is complete, and then add fracturing fluid and sand in the injection assembly;

[0007] S2: load application; a predetermined normal load is applied to the upper fracture plate and a predetermined tangential load is applied to the lower fracture plate by the fixing assembly;

[0008] S3: fracturing; a sand-carrying fracturing fluid is injected at a predetermined rate from the gap between the upper fracture plate and the lower fracture plate by the injection assembly;

[0009] S4: post-fracturing pressure relief; when the sand-carrying fracturing fluid injection time reaches a predetermined time, the injection is stopped, and when the injected sand-carrying fracturing fluid stops moving between the upper fracture plate and the lower fracture plate, the normal load is reduced by the fixing assembly, and the left-right movement of the lower fracture plate and the up-down movement of the upper fracture plate during the normal load reduction are observed;

[0010] S5: repeated fracturing; the fracturing fluid between the upper fracture plate and the lower fracture plate is cleaned, the test device is restored to the state before fracturing, the rigidity of the fixing assembly for applying the normal load is changed, and then steps S2-S4 are repeated, so that the slip law during the post-fracturing pressure relief of the fracture hydraulic sand fracturing under different normal rigidities can be obtained.

[0011] As a preferred embodiment of the above-mentioned scheme, the fixing assembly comprises a lower pressure bearing plate arranged below the lower fracture plate, an upper pressure bearing plate arranged above the lower pressure bearing plate through support bolts, and a plurality of normal load springs arranged between the upper pressure bearing plate and the upper fracture plate, the upper pressure bearing plate is arranged above the upper fracture plate, and an upper clamping bolt capable of abutting against the right side surface of the upper fracture plate is arranged on the right side of the lower pressure bearing plate, and a tangential load assembly for simulating the tangential load when the lower fracture plate moves to the right is arranged on the right side of the lower pressure bearing plate.

[0012] Further preferably, the tangential load assembly comprises a tangential load spring, one end of the tangential load spring abuts against the right side surface of the lower fracture plate, and the other end of the tangential load spring is sleeved on a guide column between the lower pressure bearing plate and the lower fracture plate, and a distance is left between the guide column and the lower fracture plate.

[0013] Further preferably, the injection assembly comprises a fracturing fluid tank arranged on the ground through a support column, the fracturing fluid tank is provided with a liquid injection pipe, the distal end of the liquid injection pipe is arranged in parallel with the gap, and a plurality of liquid outlet holes for injecting liquid into the gap are arranged on the distal end of the liquid injection pipe, a water pump for driving the liquid to flow is arranged on the liquid injection pipe, a proppant injection pipe for adding proppant into the liquid injection pipe is further arranged on the liquid injection pipe, a proppant adding assembly for adding a predetermined amount of proppant into the liquid in the liquid injection pipe is arranged on the upper end of the proppant injection pipe, and a liquid injection fixing pipe capable of being fixed to the left end of the fixing assembly and used for ensuring that the liquid in the liquid injection pipe is injected into the gap is arranged on the distal end of the liquid injection pipe.

[0014] Further preferably, the proppant addition assembly includes a proppant storage tank, and a proppant screw conveyor is provided at the lower end of the proppant storage tank. One end of the proppant screw conveyor is connected to the lower end of the proppant storage tank, and the other end is connected to the upper end of the proppant injection pipe.

[0015] Further preferably, the right end of the injection fixing tube is provided with a rectangular groove for the upper and lower slit plates to extend into, and the upper slit plate can move up and down within the rectangular groove. A sealing protrusion extending forward and backward is inserted above the left end of the upper slit plate. The upper end of the sealing protrusion is fitted with an upper and lower sealing ring. The upper wall of the rectangular groove is provided with a sealing strip groove for the sealing protrusion to be inserted and can move up and down, and the upper and lower sealing rings are located within the sealing strip groove. The front and rear side walls of the rectangular groove are provided with retaining strips to ensure that the lower slit plate is in close contact with the lower wall of the rectangular groove. The lower end of the retaining strip contacts the upper end of the lower slit plate, and the upper end of the retaining strip is pressed against the upper slit plate by a micro spring.

[0016] In a further preferred embodiment, the top surface of the lower slit plate is provided with protrusions extending to the left and right on both the front and rear sides. The upper end of the protrusion is fitted with left and right sealing rings. The bottom surface of the upper slit plate is provided with sealing grooves corresponding to the positions of the protrusions, and the left and right sealing rings are located in the sealing grooves.

[0017] In a further preferred embodiment, a base plate located within a fixing assembly is disposed below the lower slit plate, and a plurality of rollers extending forward and backward are disposed on the base plate at intervals from left to right.

[0018] The beneficial effects of this invention are: it can simulate the process of slippage and instability of proppant-supported fractures after hydraulic fracturing and sand formation, when the normal load decreases during excavation-induced fracture formation, by using a test device. This provides experimental data on stress-strain changes in coal seams during further mining after hydraulic fracturing of rock strata. Furthermore, in this embodiment, by changing the stiffness of the applied normal load within the fixed component, it is also possible to simulate the slippage of rock strata with different elastic moduli and lithologies during unloading after hydraulic fracturing. Attached Figure Description

[0019] Figure 1 This is a flowchart of the present invention.

[0020] Figure 2 This is a three-dimensional schematic diagram of the experimental device in this invention. Figure 1 .

[0021] Figure 3 This is a three-dimensional schematic diagram of the experimental device in this invention. Figure 2 .

[0022] Figure 4 This is a schematic diagram of the experimental device in this invention.

[0023] Figure 5 is a left view. Figure 4

[0024] Figure 6 is a schematic view of the liquid injection fixing tube in the present application.

[0025] Figure 7 is a magnified view of N in Figure 4 DETAILED DESCRIPTION

[0026] The present application is further described below by way of examples and with reference to the accompanying drawings:

[0027] As shown in Figures 1-7 , a hydraulic sand fracturing post rock mass unloading fracture slip test method is based on a hydraulic sand fracturing post rock mass unloading fracture slip test device, wherein the test device mainly consists of an injection assembly A, a fracture assembly B and a fixing assembly C, wherein the injection assembly A is used for injecting liquid with proppant into the fracture assembly B, the fracture assembly B is used for simulating the reaction of the rock mass with fractures after the injection of liquid, and the fixing assembly C is used for realizing the support and fixation of the fracture assembly and the application of load. By loading the normal load on the upper fracture plate and the tangential load on the lower fracture plate, the device will cause the movement of the upper and lower fracture plates when the fracturing fluid seeps, so that the stress condition of the upper and lower fracture plates will change with the movement of the corresponding plate. Therefore, the present application not only has the initial stress field when seeping, but also can simulate the stress change condition in the seeping process, so that the present application can truly simulate the seeping condition of the fracturing fluid with proppant in the fracture.

[0028] The specific structure of the fracture assembly B includes an upper fracture plate 1 and a lower fracture plate 2 oppositely arranged, and a notch for proppant injection is arranged at the left end of the upper fracture plate 1 and the lower fracture plate 2. The upper fracture plate 1 can move up and down, and the normal load from the fixing assembly is loaded on the upper fracture plate 1. The lower fracture plate 2 can move left and right, and the tangential load from the fixing assembly is loaded on the lower fracture plate 2.

[0029] ​​The specific structure of the fixing assembly C includes a lower pressure bearing plate 3 arranged below the lower fracture plate 2, and the lower pressure bearing plate is arranged on the workbench through a support column. An upper pressure bearing plate 4 is arranged above the lower pressure bearing plate 3 through a support bolt 5, and the upper pressure bearing plate 4 is located above the upper fracture plate 1. In order to realize the loading of the normal load on the upper fracture plate, a plurality of normal load springs 6 are arranged between the upper pressure bearing plate 4 and the upper fracture plate 1, and the normal load springs can be arranged in different numbers and different specifications according to the needs. In order to ensure the balanced force of the upper fracture plate, the normal load springs are symmetrically arranged in front and back and left and right. In this embodiment, 18 normal load springs are uniformly arranged between the upper pressure bearing plate 4 and the upper fracture plate 1. In order to prevent the left and right movement of the upper fracture plate, an upper clamping bolt 7 is arranged on the right side of the lower pressure bearing plate 3, which can abut against the right side surface of the upper fracture plate 1.

[0030] At the same time, in order to facilitate the left and right movement of the lower fracture plate and have an initial tangential load, a tangential load assembly is further arranged on the right side of the lower pressure bearing plate 3 for simulating the tangential load when the lower fracture plate 2 moves to the right. The specific structure of the tangential load assembly includes tangential load springs 8, and a plurality of tangential load springs are symmetrically arranged in front and back and up and down between the right side surface of the lower fracture plate and the lower pressure bearing plate. One end of the tangential load spring 8 abuts against the right side surface of the lower fracture plate 2, and the other end of the tangential load spring 8 is sleeved on a guide column 9 located between the lower pressure bearing plate 3 and the lower fracture plate 2. At the same time, in order to ensure that the lower fracture plate can move left and right, a distance is left between the guide column 9 and the lower fracture plate 2. In order to facilitate the change of the distance between the guide column and the lower fracture plate, the guide column is arranged as a lower clamping bolt extending from the right end of the lower pressure bearing plate to the left. In order to realize the compression of the tangential load spring, a nut for adjusting the compression amount of the tangential load spring can also be arranged on the bolt.

[0031] The specific structure of the injection assembly A includes a fracturing fluid tank 15 arranged on the ground through a support column 14. An injection pipe 16 is arranged on the fracturing fluid tank 15, and the end of the injection pipe 16 is arranged in parallel with the notch and is provided with a plurality of liquid outlet holes for injecting liquid into the notch. In order to facilitate the flow of liquid in the injection pipe 16, a water pump 17 is arranged on the injection pipe 16. In order to realize the addition of the proppant, a proppant injection pipe 18 is further arranged on the injection pipe 16, and a proppant adding assembly for adding a certain amount of proppant into the liquid in the injection pipe is arranged at the upper end of the proppant injection pipe 18. In order to ensure that the liquid in the injection pipe 16 can be accurately injected into the notch, an injection fixing pipe 19 fixed to the left end of the fixing assembly is arranged at the end of the injection pipe 16. Preferably, the upper end of the injection fixing pipe is fixed to the upper pressure bearing plate through a bolt, and the lower end of the injection fixing pipe is fixed to the lower pressure bearing plate through a bolt.

[0032] The support agent adding assembly comprises a support agent storage tank 20, a support agent screw conveyor 21 is arranged at the lower end of the support agent storage tank 20, one end of the support agent screw conveyor 21 is communicated with the lower end of the support agent storage tank 20, and the other end is communicated with the upper end of the support agent injection pipe 18; a fixed amount of support agent is added into a certain amount of liquid by the support agent screw conveyor.

[0033] Since the liquid injection fixing pipe 19 is arranged at the end of the liquid injection pipe, in order to ensure the sealing during liquid injection, a rectangular groove 19a for the upper fracture plate 1 and the lower fracture plate 2 to extend into is arranged at the right end of the liquid injection fixing pipe 19, and the upper fracture plate 1 can move up and down in the rectangular groove 19a. In order to ensure the sealing between the upper end of the upper fracture plate and the rectangular groove during the up-and-down movement of the upper fracture plate, a front-and-back extending sealing protrusion 1a is inserted and arranged above the left end of the upper fracture plate 1, the upper end of the sealing protrusion 1a is sleeved with a circle of upper-and-lower sealing rings, meanwhile, a sealing strip groove 19b for the sealing protrusion 1a to insert and move up and down is arranged on the upper wall of the rectangular groove 19a, and the upper-and-lower sealing rings are always located in the sealing strip groove 19b. In this embodiment, a position-to-protrusion 1c is arranged at the position close to the left end of the upper fracture plate, after installation, the left side surface of the position-to-protrusion just abuts against the right side surface of the liquid injection fixing pipe, so that the upper abutting bolt can be prevented from over-tightening the upper-and-lower sealing rings during installation, so that the upper fracture plate cannot move up and down normally.

[0034] In order to ensure the sealing between the lower end of the lower fracture plate and the rectangular groove, a clamping strip 22 for ensuring the lower fracture plate 2 to tightly contact with the lower wall of the rectangular groove 19a is arranged on the front-and-back side walls of the rectangular groove 19a, the lower end of the clamping strip 22 contacts with the upper end of the lower fracture plate, and the upper end of the clamping strip 22 abuts against the upper fracture plate 1 through a micro spring 23, so that the lower end of the lower fracture plate is always in contact with the lower inner wall of the rectangular groove through the compressed micro spring.

[0035] In order to ensure the sealing between the front-and-back sides of the upper fracture plate and the lower fracture plate, protrusions 2a extending left-and-right are arranged on the front-and-back sides of the top surface of the lower fracture plate 2, meanwhile, sealing grooves 1b are arranged on the bottom surface of the upper fracture plate 1 corresponding to the positions of the protrusions 2a, the upper ends of the protrusions 2a are sleeved with left-and-right sealing rings, and the left-and-right sealing rings are always located in the sealing grooves.

[0036] In the embodiment, the card strip is arranged in a door type, and a small pit is arranged at the position corresponding to the installation position of the micro spring at the upper end of the card strip. Since the lower fissure plate can move to the right, in order to facilitate the fixation of the card strip, a card strip groove for inserting the card strip is vertically arranged on the left and right side walls of the rectangular groove, and any one of the two ends of the card strip is horizontally arranged with an extension section capable of being clamped into the card strip groove. In order to facilitate the processing of the sealing strip groove and the two card strip grooves, a circle of grooves is arranged in the rectangular groove, wherein the sealing strip groove is located on the inner wall of the rectangular groove, and the card strip grooves are located on the front and back inner walls of the rectangular groove. In order to ensure sealing, the card strip grooves and the grooves located on the lower inner wall of the rectangular groove are filled with sealing strips, and the cross section of the sealing strip is circular.

[0037] In order to reduce the friction when the lower fissure plate moves to the right, a bottom plate 24 located in the fixed assembly is arranged below the lower fissure plate 2, and a plurality of front and back extending rollers 24a are arranged on the bottom plate 24 at intervals. The upper end of the roller is in contact with the bottom surface of the lower fissure plate.

[0038] In order to better observe the movement of the fracturing fluid with proppants, the upper and lower pressure bearing plates are made of transparent materials such as organic glass, and the device is preferably equipped with a high-speed camera. In order to facilitate the recovery of the fracturing fluid, a fracturing groove 3a is arranged in the lower pressure bearing plate, and the upper and lower fissure plates are arranged in the fracturing groove. A collection tank 3b is arranged at the right end of the fracturing groove, and the collection tank is connected with the outside through a collection pipe. A pressure gauge and a flow meter are arranged at the end of the liquid injection pipe, and a strain sensor for detecting stress is arranged between each spring and the fissure plate.

[0039] The specific experimental steps are as follows:

[0040] Step 1: Test preparation, connect all parts of the test device completely, and confirm the complete connection, then add fracturing fluid and sand in the injection assembly. Specifically, add sand of a predetermined particle size in the proppant storage tank, and fill the fracturing fluid tank with the fracturing fluid required for the test.

[0041] Step 2: Load application, apply a predetermined normal load to the upper fissure plate and a predetermined tangential load to the lower fissure plate through the fixed assembly. Specifically, by screwing the supporting bolts, the compression of the normal load spring is realized, so that the normal load on the upper fissure plate reaches a predetermined value, and the normal load is the elastic force of all normal load springs. By changing the distance between the fixed column and the diameter of the lower fissure plate, the compression amount of the tangential load spring is changed, so that the tangential load on the lower fissure plate reaches a predetermined value, and the tangential load is the elastic force of all tangential load springs.

[0042] Step 3: Fracturing, start the water pump and the proppant screw conveyor, and inject the sand fracturing fluid into the space between the upper and lower fissure plates at a predetermined rate.

[0043] Fourth step: pressure relief after fracturing, when the injection time of the sand fracturing fluid reaches the predetermined time, stop injection, i.e. close the water pump and the proppant screw conveyor, when the injected sand fracturing fluid stops moving between the upper and lower fracture plates, by counterclockwise rotating the propping bolt, the normal load applied on the upper fracture plate can be reduced, and at the same time, the left and right movement of the lower fracture plate and the up and down movement of the upper fracture plate during the reduction of the normal load are observed, so as to obtain the left and right movement law of the lower fracture plate under the action of the tangential load and the non-uniform deformation law of the upper fracture plate (i.e. the up and down movement law of the left and right sides of the upper fracture plate).

[0044] Fifth step: repeated fracturing, the sand fracturing fluid between the upper and lower fracture plates is cleaned up, and the test device is restored to the state before fracturing. Then the rigidity of the normal load applied in the fixed assembly is changed, specifically by replacing springs with different elastic coefficients to change the rigidity of the normal load, and then the steps of the second to fourth steps are repeated, so as to obtain the slip law during the unloading after the hydraulic sand fracturing under different normal rigidities.

Claims

1. A method for testing the post-hydraulic fracturing rock mass unloading fracture slip, characterized in that: The test device comprises an injection assembly (A) for injecting sand-carrying fracturing fluid into a fracture assembly (B) for simulating the reaction of rock mass with fractures after injection of liquid, and a fixing assembly (C) for supporting and fixing the fracture assembly and applying load; the fracture assembly (B) comprises upper and lower fracture plates (1) and (2) arranged oppositely, the left ends of the upper and lower fracture plates (1) and (2) are provided with notches for injection of sand-carrying fracturing fluid, the upper fracture plate (1) is movable up and down, and is loaded with a normal load from the fixing assembly, and the lower fracture plate (2) is movable left and right, and is loaded with a tangential load from the fixing assembly. ​ The test device further comprises the following test steps: S1: test preparation; All parts of the test device are connected completely, and the connection is confirmed to be complete, and then fracturing fluid and sand are added in the injection assembly; S2: load application; A predetermined normal load is applied to the upper fracture plate by the fixing assembly, and a predetermined tangential load is applied to the lower fracture plate; S3: fracturing; Sand-carrying fracturing fluid is injected at a predetermined rate from the notch between the upper and lower fracture plates by the injection assembly; S4: pressure relief after fracturing; When the injection time of sand-carrying fracturing fluid reaches a predetermined time, the injection is stopped, when the injected sand-carrying fracturing fluid stops moving between the upper and lower fracture plates, the normal load is reduced by the fixing assembly, and the left and right movement of the lower fracture plate and the up and down movement of the upper fracture plate during the reduction of the normal load are observed; S5: repeated fracturing; The fracturing fluid between the upper and lower fracture plates is cleaned, the test device is restored to the state before fracturing, the rigidity of the normal load applied in the fixing assembly is changed, and steps S2-S4 are repeated, so that the slip law during unloading after hydraulic sand fracturing under different normal rigidities can be obtained.

2. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 1, characterized in that: The fixing assembly (C) comprises a lower pressure bearing plate (3) arranged below the lower fracture plate (2), an upper pressure bearing plate (4) arranged above the lower pressure bearing plate (3) through a support bolt (5), the upper pressure bearing plate (4) is located above the upper fracture plate (1), a plurality of normal load springs (6) are arranged between the upper pressure bearing plate (4) and the upper fracture plate (1), an upper abutting bolt (7) is arranged on the right side of the lower pressure bearing plate (3) and can abut against the right side surface of the upper fracture plate (1), and a tangential load assembly for simulating the tangential load when the lower fracture plate (2) moves to the right is arranged on the right side of the lower pressure bearing plate (3).

3. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 2, characterized in that: The tangential load assembly comprises a tangential load spring (8), one end of the tangential load spring (8) abuts against the right side surface of the lower fracture plate (2), the other end of the tangential load spring (8) is sleeved on a guide column (9) between the lower pressure bearing plate (3) and the lower fracture plate (2), and a distance is left between the guide column (9) and the lower fracture plate (2).

4. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 1, characterized in that: The injection assembly (A) comprises a fracturing fluid tank (15) arranged on the ground by support columns (14), a liquid injection pipe (16) arranged on the fracturing fluid tank (15), the end of the liquid injection pipe (16) being arranged in parallel with the fracture, and a plurality of liquid injection holes arranged on the liquid injection pipe (16) for injecting liquid into the fracture, a water pump (17) arranged on the liquid injection pipe (16) for driving the liquid to flow, a proppant injection pipe (18) arranged on the liquid injection pipe (16) for adding proppant into the liquid injection pipe, a proppant adding assembly arranged at the upper end of the proppant injection pipe (18) for adding proppant into the liquid in the liquid injection pipe, and a liquid injection fixing pipe (19) arranged at the end of the liquid injection pipe (16) and capable of being fixed at the left end of the fixing assembly and ensuring that the liquid in the liquid injection pipe (16) is injected into the fracture.

5. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 4, characterized in that: The proppant adding assembly comprises a proppant storage tank (20), the lower end of the proppant storage tank (20) being provided with a proppant screw conveyor (21), one end of the proppant screw conveyor (21) being in communication with the lower end of the proppant storage tank (20), and the other end being in communication with the upper end of the proppant injection pipe (18).

6. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 4, characterized in that: The right end of the liquid injection fixing pipe (19) is provided with a rectangular groove (19a) for the upper fracture plate (1) and the lower fracture plate (2) to extend into, the upper fracture plate (1) being capable of moving up and down in the rectangular groove (19a), a front and back extending sealing protrusion (1a) being inserted above the left end of the upper fracture plate (1), a circle of upper and lower sealing rings being sleeved on the upper end of the sealing protrusion (1a), the upper wall of the rectangular groove (19a) being provided with a sealing strip groove (19b) for the sealing protrusion (1a) to be inserted into and capable of moving up and down, and the upper and lower sealing rings being located in the sealing strip groove (19b), the front and back side walls of the rectangular groove (19a) being provided with a clamping strip (22) for ensuring that the lower fracture plate (2) is in close contact with the lower wall of the rectangular groove (19a), the lower end of the clamping strip (22) being in contact with the upper end of the lower fracture plate, and the upper end of the clamping strip (22) being abutted against the upper fracture plate (1) by a micro spring (23).

7. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 1, characterized in that: The top surface of the lower fracture plate (2) is provided with left and right extending protrusions (2a) on the front and back sides, the upper end of the protrusions (2a) being sleeved with left and right sealing rings, and the bottom surface of the upper fracture plate (1) being provided with sealing grooves (1b) corresponding to the positions of the protrusions (2a).

8. The method for testing post-hydraulic fracturing rock mass unloading fracture slip according to claim 1, characterized in that: The lower fracture plate (2) is provided below with a bottom plate (24) located in the fixing assembly, and a plurality of front and back extending rolling columns (24a) are arranged on the bottom plate (24) at intervals.

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