Device and method for preparing salt rock core by axial pressure

Abstract

The present invention discloses a device for preparing salt rock cores by axial pressure, comprising a bracket, a high-temperature furnace, an axial pressure assembly, and a three-flap mold; an axial pressure piece is provided on the top of the high-temperature furnace, and the lower end of the axial pressure piece is adapted to the central cavity of the three-flap mold; the axial pressure assembly includes a column piston; the axial pressure assembly is connected to an axial pressure servo unit for controlling the column piston to apply axial pressure to the axial pressure piece; the axial pressure assembly is connected to an axial displacement detection unit for detecting the downward displacement of the column piston. The present invention also discloses a method for preparing salt rock cores by axial pressure. The present invention can be used to artificially prepare cores for exploring the mechanical properties of salt rock indoors, thereby achieving the purpose of studying the mechanical properties of salt rock while protecting the natural salt rock strata from damage; at the same time, the device of the present application is easy for one person to operate, and has the advantages of simple principle and convenient operation.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum drilling engineering, and particularly relates to a device and method for preparing salt rock cores by axial pressure. Background Art

[0002] Salt rock has a dense structure, low porosity, and low permeability, resulting in excellent sealing properties. Furthermore, its mechanical properties are stable and it can self-recover from damage. Furthermore, salt rock is readily soluble in water, allowing for the construction of cavities through water-soluble mining. Therefore, salt rock is an ideal medium for underground gas storage. Comprehensive utilization of salt rock can reduce costs and mitigate environmental pollution.

[0003] At present, the theoretical system for the construction of underground salt rock storage and the research on salt rock are still in the development stage. In addition, factors such as excavation and geological structure often cause a certain degree of damage to the salt rock used as a gas storage reservoir, affecting its sealing performance for compressed gas and its engineering mechanical properties.

[0004] Therefore, for the research on salt rock gas storage, in order to further explore the mechanical properties of salt rock under different test conditions, artificial preparation of salt rock cores is imminent. Artificial preparation of salt rock cores can study the mechanical properties of salt rock while protecting the natural salt rock strata from damage.

[0005] Based on the above problems, the present application proposes a device and method for preparing salt rock cores by axial pressure, which are used to artificially prepare salt rock cores. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a device for preparing salt rock cores by axially pressurizing.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A device for preparing salt rock cores by axial pressure application, comprising a support, a high-temperature furnace, an axial pressure application component, and a three-flap mold that can be placed in the high-temperature furnace;

[0009] The high-temperature furnace is arranged at the lower end of the bracket, an axial pressure piece is arranged on the top of the high-temperature furnace, and the lower end of the axial pressure piece is adapted to the central cavity of the three-petal mold; the high-temperature furnace is connected to a temperature controller;

[0010] The axial pressure assembly is arranged at the upper end of the bracket, and the axial pressure assembly includes a column piston; the axial pressure assembly is connected to an axial pressure servo unit for controlling the column piston to apply axial pressure to the axial pressure member; the axial pressure assembly is connected to an axial displacement detection unit for detecting the downward displacement of the column piston;

[0011] The axial pressure servo unit and the axial displacement detection unit are connected to the computer system.

[0012] Preferably, the high-temperature furnace comprises two symmetrical furnace wall parts that can form a cylindrical structure, one side of the two furnace wall parts is hinged, and the other side is connected by a lock;

[0013] After the two furnace walls are closed, a heating cavity for accommodating the three-petal mold is formed inside. The bottom end of the heating cavity is sealed and an axial pressure port is left at the top end.

[0014] Preferably, the furnace wall portion is radially arranged from outside to inside in sequence of an outer wall and thermal insulation cotton that are in contact with each other;

[0015] A plurality of resistance wires are arranged at the middle portion of the radial inner side of the furnace wall, with gaps being left between the resistance wires and the corresponding insulation cottons in the radial direction;

[0016] The resistance wire is connected to a temperature controller.

[0017] Preferably, the axial pressure member includes a disc pad and a pressure column coaxially fixedly arranged at the bottom of the disc pad;

[0018] The disc pad is located above the axial pressure port and can completely cover the axial pressure port;

[0019] The pressure column can pass through the axial pressure port downwards, and the pressure column is adapted to the central cavity of the three-petal mold;

[0020] A temperature sensor for detecting the temperature in the high-temperature furnace is provided on the side wall of the pressurizing column, and the temperature sensor is connected to a temperature controller.

[0021] Preferably, a plurality of buffer springs are provided at the bottom of the disc pad.

[0022] Preferably, the axial pressurizing assembly includes a pressurizing sleeve, a top cover, and a bottom plate for enclosing a pressure chamber;

[0023] The top of the column piston passes through the top cover upwards and is in vertical sliding cooperation with the top cover, and the bottom passes through the bottom plate downwards and is in vertical sliding cooperation with the bottom plate;

[0024] A disc is coaxially fixed on the column piston; the disc is located in the pressure chamber, and a piston sealing ring is provided between the radial outer end of the disc and the inner wall of the pressure chamber;

[0025] The disc and the piston seal ring separate the pressure chamber into an upper chamber and a lower chamber;

[0026] The upper chamber and the lower chamber are connected to the shaft pressure servo unit.

[0027] Preferably, a first pressure sensor is provided at the bottom end of the column piston, and a second pressure sensor is provided at the bottom end of the buffer spring;

[0028] The first pressure sensor and the second pressure sensor are connected to a computer system, which receives the pressure values ​​detected by the first pressure sensor and the second pressure sensor; the computer system calculates the sum of the pressure values ​​detected by all the second pressure sensors, and makes a difference between the pressure value detected by the first pressure sensor and the sum of the pressure values ​​detected by all the second pressure sensors, and records the difference as the axial pressure.

[0029] Preferably, an axial pressure interface is provided on the upper chamber, and an axial pressure circulation port is provided on the lower chamber;

[0030] The shaft pressure servo unit includes a hydraulic oil barrel, a pressure pump, and a reset pump;

[0031] The inlet of the booster pump is connected to the hydraulic oil barrel, and the outlet is connected to the axial pressure interface through a first pipeline; a first valve is provided on the first pipeline;

[0032] A second pipeline is provided between the hydraulic oil barrel and the axial pressure interface, and a second valve is provided on the second pipeline;

[0033] The inlet of the reset pump is connected to the hydraulic oil barrel, and the outlet is connected to the axial pressure circulation port through a third pipeline; a third valve is provided on the third pipeline;

[0034] A fourth pipeline is provided between the hydraulic oil barrel and the axial pressure circulation port, and a fourth valve is provided on the fourth pipeline;

[0035] The pressure pump, the reset pump, the first valve, the second valve, the third valve and the fourth valve are all connected to the computer system.

[0036] Preferably, the axial displacement detection unit includes an axial displacement sensor provided on the column piston;

[0037] The axial displacement sensor is connected to an axial displacement signal processing unit, and the axial displacement signal processing unit is connected to a computer system.

[0038] The present invention also provides a method for preparing salt rock cores by axial pressurization.

[0039] A method for preparing salt rock cores by axial pressure is implemented based on an apparatus for preparing salt rock cores by axial pressure, comprising the following steps:

[0040] Step 1: Obtain geological data of the area where the core is to be prepared, obtain the mineral composition from the geological data, and obtain the mineral composition required for preparing the core in the corresponding area;

[0041] Step 2: Prepare crude salt and corresponding mineral materials according to the mineral composition of the core to be prepared obtained in step 1;

[0042] Step 3: Grind the mineral materials and coarse salt prepared in step 2 into powder using a grinder;

[0043] Step 4: Take out 50g of the powder from step 3 and add it into a three-petal mold. Then, add 5ml of saturated salt water into the three-petal mold.

[0044] Step 5: Place the three-flap mold from step 4 into the open high-temperature furnace, and then close the high-temperature furnace;

[0045] Step 6: Insert the pressure column of the axial pressure member downward through the axial pressure port of the high-temperature furnace into the central cavity of the three-flap mold, so that the bottom end of the pressure column presses on the rock sample in the three-flap mold;

[0046] Step 7: The computer system controls the axial pressure servo system to start, applying axial pressure to the rock sample in the three-petal mold to perform initial compaction on the rock sample;

[0047] Step 8: Remove the axial pressure piece, open the high-temperature furnace, add 10g of coarse salt powder and 2ml of saturated brine to the three-petal mold again, and then close the high-temperature furnace;

[0048] Step 9: Press the pressure column of the axial pressure member onto the rock sample in the three-petal mold again;

[0049] Step 10: Turn on the power switch of the temperature controller, and the room temperature will be displayed on the display of the temperature controller;

[0050] Step 11: The computer system controls the axial pressure servo system to start, the column piston moves downward, and the axial pressure is applied to the rock sample through the axial pressure member. The axial pressure is set to 100 MPa, and the pressure is applied for 30 minutes at room temperature under the axial pressure of 100 MPa.

[0051] Step 12: After pressurizing at room temperature for 30 minutes under an axial pressure of 100 MPa, the rock sample is heated in the first stage by controlling the temperature of the high-temperature furnace using a temperature controller. The temperature setting value for the first stage of heating is 60°C. Pressurizing is continued for 1 hour under the conditions of an axial pressure of 100 MPa and a temperature of 60°C.

[0052] Step 13: After pressurizing for 1 hour under the conditions of 100 MPa axial pressure and 60°C temperature, the temperature controller is used to control the high-temperature furnace to continue to increase the temperature and perform the second stage of heating on the rock sample. The temperature setting value of the second stage of heating is 300°C; pressurizing for 1 hour under the conditions of 100 MPa axial pressure and 300°C temperature;

[0053] Step 14: During steps 11 to 13, the computer system records the axial pressure value and the axial displacement value detected by the axial displacement sensor, and draws a relationship curve between the axial pressure and the axial displacement;

[0054] Step 15: After pressurizing for 1 hour under the conditions of axial pressure of 100 MPa and temperature of 300°C, the temperature controller is turned off to stop heating, and the computer system controls the axial pressure servo system to remove the axial pressure;

[0055] Step 16: Open the high-temperature furnace, wait for the temperature inside the furnace to drop to room temperature, and then take out the salt rock core from the three-petal mold.

[0056] The beneficial effects of the present invention are:

[0057] The present invention can be used to artificially prepare rock cores indoors for exploring the mechanical properties of salt rock, thereby achieving the purpose of studying the mechanical properties of salt rock while protecting the natural salt rock strata from damage; at the same time, the device of the present application is easy for one person to operate, and has the advantages of simple principle and easy operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0059] Figure 1 Schematic diagram of the structure of the device for preparing salt rock cores by axial pressure according to the present invention;

[0060] Figure 2 It is a structural schematic diagram of the high temperature furnace of the present invention;

[0061] Figure 3 It is a schematic cross-sectional view of the structure of the three-petal mold in the present invention;

[0062] Figure 4 1. It is a schematic top view of the structure of the three-petal mold in the present invention;

[0063] Figure 5 This is a connection diagram of the axial pressure servo unit in the present invention;

[0064] in:

[0065] 1-Bracket; 2-Computer system; 3-Temperature controller; 4-Axial displacement signal processing unit; 5-Axial pressure servo unit; 501-Hydraulic oil barrel; 502-Pressure pump; 503-Reset pump; 504-First pipeline; 505-First valve; 506-Second pipeline; 507-Second valve; 508-Third pipeline; 509-Third valve; 510-Fourth pipeline; 511-Fourth valve; 6-Axial pressure interface; 7-Axial pressure circulation port; 8-Axial displacement sensor; 9-Top bolt; 10-Buffer spring; 11-Axial pressure 1. Parts; 12. Resistance wire; 13. Insulation cotton; 14. Temperature sensor; 15. Three-flap mold; 16. Electric wire; 17. Handle; 18. Lock buckle; 19. Bolt; 20. Rock sample; 21. Base; 22. Axial pressure assembly; 23. Column piston; 24. Pressure chamber; 25. Top cover; 26. Mold flap; 27. Anti-slip thread; 28. Steel sleeve; 29. ​​Furnace wall; 30. Axial pressure port; 31. Disc pad; 32. Pressure column; 33. Pressure cylinder sleeve; 34. Bottom plate; 35. Disc; 36. Piston seal; 37. Anti-slip sleeve. DETAILED DESCRIPTION

[0066] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0067] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0068] In the present invention, the directions or positional relationships indicated by terms such as "upper", "lower", "bottom", and "top" are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limitations on the present invention.

[0069] In the present invention, terms such as "connected" and "connection" should be interpreted broadly to mean a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediary. Relevant researchers or technicians in this field may determine the specific meanings of these terms in the present invention based on specific circumstances, and they should not be construed as limitations on the present invention.

[0070] The present invention will be further described below with reference to the accompanying drawings and examples.

[0071] Example 1:

[0072] like Figure 1 As shown, a device for preparing salt rock core by axial pressure includes a support 1, a high-temperature furnace, an axial pressure component 22 and a three-flap mold 15 that can be placed in the high-temperature furnace; wherein the three-flap mold 15 is a prior art, such as Figure 3-4 As shown, it includes a base 21 and a cylindrical steel sleeve 28 fixed to the base 21. The steel sleeve 28 is connected to the base 21 by bolts 19. Three mold petals 26 are provided inside the steel sleeve 28. The inner cavity formed by the three mold petals 26 is the central cavity of the three-petal mold 15. The core is formed in the central cavity of the three-petal mold 15.

[0073] The high-temperature furnace is provided at the lower end of the bracket 1, and an axial pressure member 11 is provided on the top of the high-temperature furnace. The lower end of the axial pressure member 11 is adapted to the central cavity of the three-petal mold 15; the high-temperature furnace is connected to the temperature controller 3;

[0074] The axial pressure assembly 22 is provided at the upper end of the bracket 1 and includes a column piston 23. The axial pressure assembly 22 is connected to an axial pressure servo unit 5 for controlling the column piston 23 to apply axial pressure to the axial pressure member 11. The axial pressure assembly 22 is also connected to an axial displacement detection unit for detecting the downward displacement of the column piston.

[0075] The axial pressure servo unit 5 and the axial displacement detection unit are connected to the computer system.

[0076] Preferably, Figure 2 As shown, the high-temperature furnace includes two symmetrical furnace wall portions 29 that can form a cylindrical structure. One side of the two furnace wall portions 29 is hinged, and the other side is connected by a lock 18. The one side of the two furnace wall portions 29 can be hingedly connected by a hinge, and the lock 18 can be implemented using existing technology, and its specific structure is not repeated here.

[0077] After the two furnace walls 29 are closed, a heating cavity for accommodating the three-petal mold 15 is formed inside. The bottom end of the heating cavity is blocked and an axial pressure opening 30 is left at the top end.

[0078] Specifically, a handle 17 is provided on the outer side of the furnace wall portion 29 .

[0079] Preferably, the furnace wall portion 29 is composed of an outer wall and insulation cotton 13 in sequence from the outside to the inside in radial direction; wherein the outer wall is made of heat-resistant alloy material;

[0080] A plurality of resistance wires 12 are provided in the radially inner middle portion of the furnace wall portion 29. A gap is left radially between the resistance wires 12 and the corresponding insulation cotton 13 to prevent the resistance wires from igniting the insulation cotton during the heating process. The width of the gap is 1 to 2 cm.

[0081] The resistance wire 12 is connected to the temperature controller 3 to realize the control of the power on and off of the resistance wire 12 and the control of the magnitude of the current passed in. Specifically, the resistance wire 12 is electrically connected to the temperature controller through an electric wire 16.

[0082] Preferably, the axial pressure member 11 includes a disc pad 31 and a pressure column 32 coaxially fixedly arranged at the bottom of the disc pad 31;

[0083] The disc pad 31 is located above the axial pressure opening 30 and can completely cover the axial pressure opening 30;

[0084] The pressure column 32 can pass through the axial pressure opening 30 downward, and the pressure column 32 is adapted to the central cavity of the three-flap mold 15 .

[0085] Preferably, a temperature sensor 14 for detecting the temperature in the high-temperature furnace is provided on the side wall of the pressurizing column 32 , and the temperature sensor 14 is connected to the temperature controller 3 .

[0086] Preferably, a plurality of buffer springs 10 are provided at the bottom of the disc pad 31. When the disc pad 31 moves downward under the action of the column piston 23, the buffer spring 10 first contacts the top of the high-temperature furnace. The setting of the buffer spring 10 protects the high-temperature furnace and prevents it from being crushed.

[0087] Preferably, the axial pressurizing assembly 22 includes a pressurizing sleeve 33, a top cover 25, and a bottom plate 34 for enclosing a pressure chamber 24; wherein the pressurizing sleeve 33 and the top cover 25 are detachably connected by a top bolt 9;

[0088] The top of the column piston 23 passes through the top cover 25 upwards and slides with the top cover 25 in the vertical direction, and the bottom passes through the bottom plate 34 downwards and slides with the bottom plate 34 in the vertical direction;

[0089] A disc 35 is coaxially fixed on the column piston 23 ; the disc 35 is located in the pressure chamber 24 , and a piston sealing ring 36 is provided between the radial outer end of the disc 35 and the inner wall of the pressure chamber 24 ;

[0090] The disc 35 and the piston seal 36 separate the pressure chamber 24 into an upper chamber and a lower chamber;

[0091] The upper chamber and the lower chamber are connected to the axial pressure servo unit 5 .

[0092] Preferably, a first pressure sensor is provided at the bottom end of the column piston 23, and a second pressure sensor is provided at the bottom end of the buffer spring 10;

[0093] The first and second pressure sensors are connected to computer system 2, which receives the pressure values ​​detected by the first and second pressure sensors. Computer system 2 calculates the sum of the pressure values ​​detected by all second pressure sensors and takes the difference between the pressure value detected by the first pressure sensor and the sum of the pressure values ​​detected by all second pressure sensors, recording this difference as the axial pressure. Because the weight of the axial pressure member 11 and buffer spring 10 is very small relative to the axial pressure, in this application, computer system 2 ignores the weight of the axial pressure member 11 and buffer spring 10 when recording the axial pressure.

[0094] Preferably, an anti-slip sleeve 37 adapted to the column piston 23 is provided at the bottom end of the bottom plate 34 , and an anti-slip thread 27 is provided on the inner side of the anti-slip sleeve 37 .

[0095] Preferably, an axial pressure interface 6 is provided on the upper chamber, and an axial pressure circulation port 7 is provided on the lower chamber;

[0096] like Figure 5 As shown, the shaft pressure servo unit 5 includes a hydraulic oil barrel 501, a pressure pump 502, and a reset pump 503;

[0097] The inlet of the booster pump 502 is connected to the hydraulic oil barrel 501, and the outlet is connected to the axial pressure interface 6 through a first pipeline 504; a first valve 505 is provided on the first pipeline 504;

[0098] A second pipeline 506 is provided between the hydraulic oil barrel 501 and the axial pressure interface 6, and a second valve 507 is provided on the second pipeline 506;

[0099] The inlet of the reset pump 503 is connected to the hydraulic oil barrel 501, and the outlet is connected to the axial pressure circulation port 7 through a third pipeline 508; a third valve 509 is provided on the third pipeline 508;

[0100] A fourth pipeline 510 is provided between the hydraulic oil barrel 501 and the axial pressure circulation port 7, and a fourth valve 511 is provided on the fourth pipeline 510;

[0101] The pressure pump 502 , the reset pump 503 , the first valve 505 , the second valve 507 , the third valve 509 , and the fourth valve 511 are all connected to the computer system 2 .

[0102] When the column piston 23 moves downward to increase pressure, the first valve 505 and the fourth valve 511 are opened, the third valve 509 and the second valve 507 are closed, and the pressure pump 502 is started. The hydraulic oil in the hydraulic oil barrel 501 is sucked by the pressure pump 502 through the first pipeline 504 into the upper chamber, thereby causing the column piston 23 to move downward. At the same time, the hydraulic oil in the lower chamber flows back to the hydraulic oil barrel 501 through the fourth pipeline 510.

[0103] When the column piston 23 moves upward and resets, the third valve 509 and the second valve 507 are opened, the first valve 505 and the fourth valve 511 are closed, and the reset pump 503 is started. The hydraulic oil in the hydraulic oil barrel 501 is sucked by the reset pump 503 through the third pipeline 508 into the lower chamber, thereby causing the column piston 23 to move upward. At the same time, the hydraulic oil in the upper chamber flows back to the hydraulic oil barrel 501 through the second pipeline 506.

[0104] Preferably, the axial displacement detection unit includes an axial displacement sensor 8 provided on the column piston 23;

[0105] The axial displacement sensor 8 is connected to the axial displacement signal processing unit 4 , and the axial displacement signal processing unit 4 is connected to the computer system 2 .

[0106] In this application, when axial pressure is applied to the rock sample 20 in the three-petal mold, the axial pressure servo unit 5 is controlled by the computer system 2, and hydraulic oil is injected into the upper chamber through the axial pressure interface 6. The column piston 23 moves downward under the action of the hydraulic oil, thereby achieving the purpose of applying axial pressure. After the bottom end of the column piston 23 contacts the disc pad 31 of the axial pressure member 11, the computer system 2 records the axial pressure value and the axial displacement value detected by the axial displacement sensor, and draws a curve of the relationship between axial pressure and axial displacement until the axial pressure rises to the set value, after which the axial pressure remains unchanged. When the preparation is completed and the axial pressure needs to be removed, the axial pressure servo system 5 injects hydraulic oil into the axial pressure circulation port 7, and the column piston 23 moves upward, thereby removing the axial pressure.

[0107] Example 2:

[0108] A method for preparing a salt rock core by axial pressure, based on the device for preparing a salt rock core by axial pressure in Example 1, comprises the following steps:

[0109] Step 1: Obtain geological data of the area where the core is to be prepared, obtain the mineral composition from the geological data, and obtain the mineral composition required for preparing the core in the corresponding area;

[0110] Step 2: Prepare crude salt and corresponding mineral materials according to the mineral composition of the core to be prepared obtained in step 1;

[0111] Step 3: Grind the mineral materials and coarse salt prepared in step 2 into powder using a grinder;

[0112] Step 4: Take out 50g of the powder from step 3 and add it into the three-flap mold 15, and then drip 5ml of saturated salt water into the three-flap mold 15;

[0113] Step 5: Place the three-flap mold 15 in step 4 into an open high-temperature furnace, and then close the high-temperature furnace;

[0114] Step 6: Insert the pressure column 32 of the axial pressure member 11 downward through the axial pressure port 30 of the high-temperature furnace into the central cavity of the three-flap mold 15, so that the bottom end of the pressure column 32 presses on the rock sample 20 in the three-flap mold 15;

[0115] Step 7: The computer system 2 controls the axial pressure servo system 5 to start, applying axial pressure to the rock sample in the three-petal mold 15 to perform initial compaction on the rock sample;

[0116] Step 8: Remove the axial pressure member 11, open the high-temperature furnace, add 10g of coarse salt powder and 2ml of saturated brine into the three-flap mold 15 again, and then close the high-temperature furnace;

[0117] Step 9: Press the pressure column 32 of the axial pressure member 11 onto the rock sample in the three-petal mold 15 again;

[0118] Step 10: Turn on the power switch of the temperature controller 3, and the room temperature is displayed on the display screen of the temperature controller 3;

[0119] Step 11: The computer system 2 controls the axial pressure servo system 5 to start, and the column piston 23 moves downward, applying axial pressure to the rock sample 20 through the axial pressure member 11. The axial pressure is set to 100 MPa, and the pressure is applied for 30 minutes at room temperature under the axial pressure of 100 MPa.

[0120] Step 12: After pressurizing at room temperature for 30 minutes under an axial pressure of 100 MPa, the high-temperature furnace is heated using the temperature controller 3 to perform the first stage of heating on the rock sample. The temperature setting value for the first stage of heating is 60°C. Pressurizing is performed at an axial pressure of 100 MPa and a temperature of 60°C for 1 hour.

[0121] Step 13: After pressurizing for 1 hour under the conditions of 100 MPa axial pressure and 60°C temperature, the temperature controller 3 is used to control the high-temperature furnace to continue to increase the temperature and perform the second stage of heating on the rock sample. The temperature setting value of the second stage of heating is 300°C; pressurizing for 1 hour under the conditions of 100 MPa axial pressure and 300°C temperature;

[0122] Step 14: During steps 11 to 13, the computer system 2 records the axial pressure value and the axial displacement value detected by the axial displacement sensor, and draws a relationship curve between the axial pressure and the axial displacement;

[0123] Step 15: After pressurizing for 1 hour under the conditions of axial pressure of 100 MPa and temperature of 300° C., the temperature controller 3 is turned off to stop heating, and the computer system 2 controls the axial pressure servo system 5 to remove the axial pressure;

[0124] Step 16: Open the high-temperature furnace, wait for the temperature inside the furnace to drop to room temperature, and then take out the salt rock core in the three-flap mold 15; specifically, unscrew the bolts 19 on the base 21, remove the steel sleeve 28, and thus take out the salt rock core.

[0125] The method of the present application can be used to artificially prepare rock cores indoors for exploring the mechanical properties of salt rock, thereby achieving the purpose of studying the mechanical properties of salt rock while protecting the natural salt rock strata from damage; at the same time, the device of the present application is easy for one person to operate, and has the advantages of simple principle and easy operation.

[0126] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not a limitation of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing salt rock cores by axial pressure, characterized in that: The invention relates to a device for preparing salt rock cores by axial pressure, wherein the device comprises a support, a high-temperature furnace, an axial pressure component and a three-flap mold that can be placed in the high-temperature furnace; The high-temperature furnace is arranged at the lower end of the bracket, an axial pressure piece is arranged on the top of the high-temperature furnace, and the lower end of the axial pressure piece is adapted to the central cavity of the three-petal mold; the high-temperature furnace is connected to a temperature controller; The axial pressure assembly is arranged at the upper end of the bracket, and the axial pressure assembly includes a column piston; the axial pressure assembly is connected to an axial pressure servo unit for controlling the column piston to apply axial pressure to the axial pressure member; the axial pressure assembly is connected to an axial displacement detection unit for detecting the downward displacement of the column piston; The axial pressure servo unit and the axial displacement detection unit are connected to the computer system; The axial pressure member includes a disc pad and a pressure column coaxially fixedly arranged at the bottom of the disc pad; A plurality of buffer springs are provided at the bottom of the disc pad; The axial pressurizing assembly includes a pressurizing sleeve, a top cover, and a bottom plate for enclosing a pressure chamber; the bottom end of the bottom plate is provided with an anti-slip sleeve adapted to the column piston, and the inner side of the anti-slip sleeve is provided with an anti-slip thread; The method comprises the following steps: Step 1: Obtain geological data of the area where the core is to be prepared, obtain the mineral composition from the geological data, and obtain the mineral composition required for preparing the core in the corresponding area; Step 2: Prepare crude salt and corresponding mineral materials according to the mineral composition of the core to be prepared obtained in step 1; Step 3: Grind the mineral materials and coarse salt prepared in step 2 into powder using a grinder; Step 4: Take out 50g of the powder from step 3 and add it into a three-petal mold. Then, add 5ml of saturated salt water into the three-petal mold. Step 5: Place the three-flap mold from step 4 into the open high-temperature furnace, and then close the high-temperature furnace; Step 6: Insert the pressure column of the axial pressure member downward through the axial pressure port of the high-temperature furnace into the central cavity of the three-flap mold, so that the bottom end of the pressure column presses on the rock sample in the three-flap mold; Step 7: The computer system controls the axial pressure servo system to start, applying axial pressure to the rock sample in the three-petal mold to perform initial compaction on the rock sample; Step 8: Remove the axial pressure piece, open the high-temperature furnace, add 10g of coarse salt powder and 2ml of saturated brine to the three-petal mold again, and then close the high-temperature furnace; Step 9: Press the pressure column of the axial pressure member onto the rock sample in the three-petal mold again; Step 10: Turn on the power switch of the temperature controller, and the room temperature will be displayed on the display of the temperature controller; Step 11: The computer system controls the axial pressure servo system to start, the column piston moves downward, and the axial pressure is applied to the rock sample through the axial pressure member. The axial pressure is set to 100 MPa, and the pressure is applied for 30 minutes at room temperature under the axial pressure of 100 MPa. Step 12: After pressurizing at room temperature for 30 minutes under an axial pressure of 100 MPa, the rock sample is heated in the first stage by controlling the temperature of the high-temperature furnace using a temperature controller. The temperature setting value for the first stage of heating is 60°C. Pressurizing is continued for 1 hour under the conditions of an axial pressure of 100 MPa and a temperature of 60°C. Step 13: After pressurizing for 1 hour under the conditions of 100 MPa axial pressure and 60°C temperature, the temperature controller is used to control the high-temperature furnace to continue to increase the temperature and perform the second stage of heating on the rock sample. The temperature setting value of the second stage of heating is 300°C; pressurizing for 1 hour under the conditions of 100 MPa axial pressure and 300°C temperature; Step 14: During steps 11 to 13, the computer system records the axial pressure value and the axial displacement value detected by the axial displacement sensor, and draws a relationship curve between the axial pressure and the axial displacement; Step 15: After pressurizing for 1 hour under the conditions of axial pressure of 100 MPa and temperature of 300°C, the temperature controller is turned off to stop heating, and the computer system controls the axial pressure servo system to remove the axial pressure; Step 16: Open the high-temperature furnace, wait for the temperature inside the furnace to drop to room temperature, and then take out the salt rock core from the three-petal mold.

2. The method for preparing salt rock cores by axial pressure according to claim 1, characterized in that: The high-temperature furnace comprises two symmetrical furnace wall parts that can form a cylindrical structure, one side of the two furnace wall parts is hinged, and the other side is connected by a lock; After the two furnace walls are closed, a heating cavity for accommodating the three-petal mold is formed inside. The bottom end of the heating cavity is sealed and an axial pressure port is left at the top end.

3. The method for preparing salt rock cores by axial pressure according to claim 2, characterized in that: The furnace wall portion is composed of an outer wall and thermal insulation cotton in sequence from the outside to the inside along the radial direction; A plurality of resistance wires are arranged at the middle portion of the radial inner side of the furnace wall, with gaps being left between the resistance wires and the corresponding insulation cottons in the radial direction; The resistance wire is connected to a temperature controller.

4. The method for preparing salt rock cores by axial pressure according to claim 3, characterized in that: The disc pad is located above the axial pressure port and can completely cover the axial pressure port; The pressure column can pass through the axial pressure port downwards, and the pressure column is adapted to the central cavity of the three-petal mold; A temperature sensor for detecting the temperature in the high-temperature furnace is provided on the side wall of the pressurizing column, and the temperature sensor is connected to a temperature controller.

5. The method for preparing salt rock cores by axial pressure according to claim 1, characterized in that: The top of the column piston passes through the top cover upwards and is in vertical sliding cooperation with the top cover, and the bottom passes through the bottom plate downwards and is in vertical sliding cooperation with the bottom plate; A disc is coaxially fixed on the column piston; the disc is located in the pressure chamber, and a piston sealing ring is provided between the radial outer end of the disc and the inner wall of the pressure chamber; The disc and the piston seal ring separate the pressure chamber into an upper chamber and a lower chamber; The upper chamber and the lower chamber are connected to the shaft pressure servo unit.

6. The method for preparing salt rock cores by axial pressure according to claim 5, characterized in that: A first pressure sensor is provided at the bottom end of the column piston, and a second pressure sensor is provided at the bottom end of the buffer spring; The first pressure sensor and the second pressure sensor are connected to a computer system, and the computer system receives the pressure values ​​detected by the first pressure sensor and the second pressure sensor; The computer system calculates the sum of the pressure values ​​detected by all the second pressure sensors, and makes a difference between the pressure value detected by the first pressure sensor and the sum of the pressure values ​​detected by all the second pressure sensors, and records the difference as the axial pressure.

7. The method for preparing salt rock cores by axial pressure according to claim 5, characterized in that: An axial pressure interface is provided on the upper chamber, and an axial pressure circulation port is provided on the lower chamber; The shaft pressure servo unit includes a hydraulic oil barrel, a pressure pump, and a reset pump; The inlet of the booster pump is connected to the hydraulic oil barrel, and the outlet is connected to the axial pressure interface through a first pipeline; a first valve is provided on the first pipeline; A second pipeline is provided between the hydraulic oil barrel and the axial pressure interface, and a second valve is provided on the second pipeline; The inlet of the reset pump is connected to the hydraulic oil barrel, and the outlet is connected to the axial pressure circulation port through a third pipeline; a third valve is provided on the third pipeline; A fourth pipeline is provided between the hydraulic oil barrel and the axial pressure circulation port, and a fourth valve is provided on the fourth pipeline; The pressure pump, the reset pump, the first valve, the second valve, the third valve and the fourth valve are all connected to the computer system.

8. The method for preparing salt rock cores by axial pressure according to claim 1, characterized in that: The axial displacement detection unit includes an axial displacement sensor provided on the column piston; The axial displacement sensor is connected to an axial displacement signal processing unit, and the axial displacement signal processing unit is connected to a computer system.

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