Double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system

Abstract

The utility model discloses a double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system which comprises a supporting vibration device and a double-layer circular tube type testing device arranged on the supporting vibration device, the double-layer circular tube type testing device comprises an outer tube and an inner tube which are vertically arranged, the inner tube is coaxially arranged in the outer tube, the outer circle of the inner tube is connected with the inner wall of the outer tube through a plurality of connecting rods, a plurality of water permeable holes are evenly formed in the inner tube, the upper ends and the lower ends of the outer tube and the inner tube are flush, and the upper end of the outer tube is in threaded connection with a top cover. The lower end of the outer pipe is in threaded connection with a bottom cover. The device is scientific in design, simple and compact in structure, comprehensive in function, simple and convenient to operate, convenient to disassemble, recyclable, safe, environment-friendly and higher in test data accuracy.

Description

Technical Field

[0001] This utility model belongs to the field of static crushing technology, specifically relating to a double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system. Background Technology

[0002] Static fracturing (SCA), also known as silent blasting or static cracking technology, is a technique that utilizes the expansion pressure generated by mixing a static fracturing agent with water to cause concrete and stone to crack. It offers advantages such as no explosions, no flying debris, and no pollution, and has been increasingly applied in recent years to improving the permeability of low-permeability coal seams. SCA is a powdery substance primarily composed of calcium oxide, which expands upon contact with water. When CaO reacts with water under closed conditions, it generates enormous expansion pressure. Injecting SCA into boreholes in rock formations triggers a hydration reaction, producing high-temperature gas and expansion pressure that fractures the rock. This expansion pressure creates a highly interconnected network of fractures within the rock.

[0003] In static fracturing technology, the magnitude of the expansion pressure directly affects the fracturing effect, and its accurate measurement is a crucial step in the study of the expansion mechanism. The traditional measurement method is the external tube method, but its drawback is the tendency for blowouts to occur during the static fracturing agent reaction. This is because after the fracturing agent undergoes a hydration reaction, the temperature inside the cylinder rises sharply, increasing the saturated vapor pressure of H2O, exceeding the local atmospheric pressure. According to the ideal gas law pV=nRT, when the pores are compressed and the H2O vapor is superheated, the vapor pressure within the pores rises rapidly, resulting in blowouts.

[0004] Traditional external tube methods can only measure the expansion stress generated by the reaction of the fracturing agent through strain gauges, but cannot simultaneously obtain temperature changes and gas pressure data during the hydration reaction process. In addition, the fracturing agent is often mixed with water and needs to be manually stirred in advance. This not only makes it difficult to ensure that the fracturing agent and water are in sufficient contact, resulting in inconsistent hydration reaction process and unstable stress and pressure, but also the pre-stirring operation is cumbersome, increases the human burden, and poses a huge safety hazard.

[0005] On the other hand, traditional equipment also has shortcomings in terms of practicality and safety. When testing expansion pressure using the traditional external tube method, seamless steel pipes are usually not reusable, and testing methods for sealed pipe openings often lack a pressure relief system, which increases experimental costs, is time-consuming and labor-intensive, and lacks safety barriers.

[0006] After the experiment, the final cleaning stage is crucial. After generating significant expansion pressure, the reacting expanding agent increases in volume and transforms into calcium hydroxide and other substances, filling the entire test tube and making it difficult to remove the residue. Traditional methods often involve chiseling it out with tools or acidifying it with chemical reagents, but the lower end of the test tube is pre-welded and cannot be removed, making cleaning difficult and rendering the test tube unusable.

[0007] Traditional external tube testing methods can only measure the expansion stress generated by the reaction of the expansive agent through strain gauges, but cannot simultaneously obtain data on temperature and gas pressure changes during the hydration reaction process. This has obvious monitoring limitations, and the open tip is prone to blowouts when the expansive agent undergoes a hydration reaction.

[0008] Therefore, in order to address the shortcomings of the existing external tube method for testing expansion pressure, it is necessary to develop a double-layer circular tube-type synchronous temperature-stress-pressure monitoring system for the reaction of the fracturing agent, so as to achieve accurate real-time testing of temperature, stress, and pressure during the hydration and expansion process of the fracturing agent. Utility Model Content

[0009] To solve the above-mentioned technical problems, this utility model provides a double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system that is safe and reliable, has a vibration stirring function, facilitates the cleaning of reaction residues, and provides more accurate test results.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system, including a supporting vibration device and a double-layer circular tube type testing device mounted on the supporting vibration device; the double-layer circular tube type testing device includes a vertically arranged outer tube and an inner tube, the inner tube being coaxially arranged inside the outer tube, the outer circle of the inner tube being connected to the inner wall of the outer tube by several connecting rods, several water-permeable holes being evenly opened on the inner tube, the upper and lower ends of the outer tube and the inner tube being flush, the upper end of the outer tube being threadedly connected to a top cover, and the lower end of the outer tube being threadedly connected to a bottom cover.

[0011] The top cover is connected to a pressure gauge, a water injection pipe, and a pressure relief valve. The lower end of the water injection pipe is located in the center of the inner pipe, and a water injection valve is installed on the water injection pipe.

[0012] A wireless temperature sensor is installed on the inner wall of the outer tube, and a strain gauge is bonded to the outer circumference of the outer tube. The strain gauge is connected to the strain gauge via a wire. The temperature acquisition instrument receives the wireless signal emitted by the wireless temperature sensor. The temperature acquisition instrument is connected to the radio frequency reader via a wire. Both the strain gauge and the temperature acquisition instrument are connected to the computer via wires.

[0013] The vibration support device includes a bracket with four vertical tie rods fixed on it. The lower ends of the four vertical tie rods are fixed with a lower plate by a lower nut, and the upper ends of the four vertical tie rods are fixed with an upper ring plate by an upper nut. A columnar vibrator is bolted to the lower plate. The upper end of the columnar vibrator has a groove. The inner diameter of the upper ring plate is larger than the outer diameter of the outer tube. A double-layer circular tube test device is coaxially arranged in the upper ring plate. The bottom cover of the lower end of the outer tube extends into the groove of the columnar vibrator. A lower high-elasticity silicone rubber ring is provided between the outer circle of the outer tube and the inner circle of the groove. An upper high-elasticity silicone rubber ring is provided on the inner circle of the upper ring plate that contacts the outer circle of the outer tube.

[0014] Compared with existing technologies, the above technical solution has the following technical advantages:

[0015] This invention utilizes a single system to achieve precise real-time testing of temperature, expansion stress, and gas pressure within the circular tube during the reaction of the fracturing agent and water. The design of the top and bottom covers, threaded to the outer tube, ensures a tight seal while effectively preventing blowouts and facilitating post-experiment cleaning, enabling the reuse of the double-layer circular tube testing device. The design of a pressure gauge monitors pressure changes during testing, improving data accuracy. A pressure relief valve releases pressure after testing to ensure safety. A columnar vibrator positioned below the outer tube effectively promotes uniform mixing of the fracturing agent and water, improving reaction efficiency and avoiding the drawbacks of premature stirring. Upper and lower high-elasticity silicone rubber rings buffer the columnar vibrator's vibration on the double-layer circular tube testing device and the internal mixing of the fracturing agent and water, preventing vibration transmission to the supporting vibration device and ensuring its stability. This utility model features an upper ring plate, which provides central positioning for the double-layer circular tube testing device. It also facilitates disassembly of the double-layer circular tube testing device after the experiment for reagent cleaning, allowing the circular tube to be directly removed for reagent cleaning.

[0016] In summary, this utility model is scientifically designed, has a simple and compact structure, comprehensive functions, is easy to operate, convenient to disassemble, recyclable, safe and environmentally friendly, and provides higher accuracy in test data. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0018] Figure 2 This is a top view of the upper ring plate in this utility model.

[0019] Figure 3 This is a schematic diagram of the top cover and bottom cover of this utility model.

[0020] Figure 4 This is a planar development view of the inner tube in this utility model.

[0021] The labels in the attached figures are as follows: 1-Lower nut; 2-Bracket; 3-Water injection pipe; 4-Vertical tie rod; 5-Connecting rod; 6-Water permeable hole; 7-Inner tube; 8-Upper ring plate; 9-Upper high-elasticity silicone rubber ring; 10-Pressure gauge; 11-Water injection valve; 12-Pressure relief valve; 13-Top cover; 14-Wireless temperature sensor; 15-Outer tube; 16-Strain gauge; 17-Columnar vibrator; 18-Lower plate; 19-Strain gauge; 20-Temperature acquisition instrument; 21-RF reader; 22-Computer; 23-Upper nut; 24-Bottom cover. Detailed Implementation

[0022] like Figures 1-4 As shown, the double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system of this utility model includes a vertically arranged outer tube 15 and an inner tube 7. The inner tube 7 is coaxially arranged inside the outer tube 15. The outer circle of the inner tube 7 is connected to the inner wall of the outer tube 15 through several connecting rods 5. Several water-permeable holes 6 are evenly opened on the inner tube 7. The upper and lower ends of the outer tube 15 and the inner tube 7 are flush. The upper end of the outer tube 15 is threaded with a top cover 13, and the lower end of the outer tube 15 is threaded with a bottom cover 24.

[0023] The top cover 13 is connected to a pressure gauge 10, a water injection pipe 3 and a pressure relief valve 12. The lower end of the water injection pipe 3 is located at the center of the inner pipe 7, and a water injection valve 11 is provided on the water injection pipe 3.

[0024] A wireless temperature sensor 14 is installed on the inner wall of the outer tube 15. A strain gauge 16 is bonded to the outer circle of the outer tube 15. The strain gauge 16 is connected to the strain gauge 19 through a wire. The temperature acquisition device 20 receives the wireless signal emitted by the wireless temperature sensor 14. The temperature acquisition device 20 is connected to the radio frequency reader 21 through a wire. Both the strain gauge 19 and the temperature acquisition device 20 are connected to the computer 22 through wires.

[0025] The vibration support device includes a bracket 2, on which four vertical tie rods 4 are fixedly mounted. The lower ends of the four vertical tie rods 4 are fixedly mounted on a lower plate 18 by a lower nut 1, and the upper ends of the four vertical tie rods 4 are fixedly mounted on an upper ring plate 8 by an upper nut 23. A columnar vibrator 17 is bolted to the lower plate 18. The upper end of the columnar vibrator 17 has a groove. The inner diameter of the upper ring plate 8 is larger than the outer diameter of the outer tube 15. The double-layer circular tube test device is coaxially arranged inside the upper ring plate 8. The bottom cover 24 of the lower end of the outer tube 15 extends into the groove of the columnar vibrator 17. A lower high-elasticity silicone rubber ring is provided between the outer circle of the outer tube 15 and the inner circle of the groove. An upper high-elasticity silicone rubber ring 9 is provided on the inner circle of the upper ring plate 8, which contacts the outer circle of the outer tube 15.

[0026] The working (simulation) method of the double-layer circular tube type temperature-stress-pressure static crushing synchronous simulation system includes the following steps:

[0027] S1. Install the double-layer circular tube test device and load it with the breaking agent;

[0028] S2. Place the double-layer circular tube test device vertically onto the vibration support device;

[0029] S3. Attach strain gauge 16 to the double-layer circular tube test device, connect strain gauge 16 to strain gauge 19, connect temperature acquisition device 20 to radio frequency reader 21, and connect strain gauge 19 and temperature acquisition device 20 to computer 22 at the same time.

[0030] S4. Conduct a synchronous static crushing test involving temperature, stress, and pressure.

[0031] S5. After the test, clean up the reaction residue.

[0032] Step S1 is as follows: Rotate the lower nut 1 to remove the lower plate 18, place the columnar vibrator 17 on the lower plate 18 and fix it with bolts, then reinstall the lower plate 18 to the lower end of the vertical tie rod 4 and fix it with the lower nut 1; fix the wireless temperature sensor 14 at two opposite positions 6cm away from the upper and lower openings on the inner wall of the outer tube 15, fix the wireless temperature sensor 14 with high temperature resistant epoxy resin, then tighten the bottom cover 24, pour the crushing agent into the annular cavity between the outer tube 15 and the inner tube 7 from the upper port of the outer tube 15 to 5cm from the upper port and stop loading, then tighten the top cover 13.

[0033] Step S2 is as follows: Insert the double-layer circular tube test device downwards from the inner hole of the upper ring plate 8 into the four vertical pull rods 4 until the bottom cover 24 at the lower end of the outer tube 15 enters the groove and contacts the columnar vibrator 17, and then stop. At this time, the upper high-elasticity silicone rubber ring 9 and the lower high-elasticity silicone rubber ring are respectively fitted on the upper and lower parts of the outer tube 15.

[0034] Step S3 is as follows: attach a strain gauge 16 to three positions on the outer wall of the outer tube 15 at a distance of 15cm, 30cm and 45cm from the upper port. Then connect the strain gauge 16 to the strain gauge 19 with a wire. Connect the temperature acquisition instrument 20 and the radio frequency reader 21 with a wire. Connect the strain gauge 19 and the temperature acquisition instrument 20 to the computer 22 at the same time and turn on the power to debug the equipment.

[0035] Step S4 is as follows: After debugging and checking the pressure gauge 10 to ensure that the pressure gauge 10 is correct, open the water injection valve 11. Clean water is injected into the inner tube 7 through the water injection pipe 3. The water injection speed is controlled by the water injection valve 11. When the pre-calculated water injection time is reached, the water injection valve 11 is closed. The water in the inner tube 7 reacts with the breaking agent through the water permeable hole 6. The breaking agent slowly expands inside the outer tube 15. Turn on the columnar vibrator 17 switch and slowly adjust the vibration frequency to drive the entire double-layer circular tube test device to vibrate, promoting the uniform and rapid mixing of the breaking agent and water. During the reaction process, observe and record the reading of the pressure gauge 10. The strain gauge 19 and the wireless temperature sensor 14 monitor the data and transmit it to the strain gauge 19 and the temperature acquisition instrument 20, respectively.

[0036] Step S5 is as follows: After the test is completed, wait for the temperature of the outer tube 15 to drop to a safe range before slowly opening the pressure relief valve 12. After the internal pressure of the outer tube 15 is relieved, remove the strain gauge 16, then pull the upper ring plate 8 upwards from the entire double-layer circular tube test device, and finally open the top cover 13 and the bottom cover 24 to clean up the residue after the reaction.

[0037] In step S4, temperature and pressure data are directly acquired through temperature acquisition instrument 20 and pressure gauge 10, respectively, while the expansion stress data acquired by strain gauge 16 needs to be converted and calculated. The conversion of the micro-strain readings acquired by strain gauge 19 into expansion stress is calculated using the following formula:

[0038]

[0039] In the formula: P r The static expansion pressure of the crack initiator is MPa. E s The elastic modulus of the steel pipe is 2.06 × 10⁻⁶ for the outer pipe 15. 5 MPa; K 1 The outer diameter of the outer tube is 15 mm; K 2 Where is the inner diameter of the steel pipe, in mm; Let be the strain in the circumferential direction of the steel pipe, in μm; v Let be Poisson's ratio, taken as 0.3.

[0040] It should be emphasized that the wireless temperature sensor 14, strain gauge 16, columnar vibrator 17, strain meter 19, temperature acquisition device 20, radio frequency reader 21, and computer 22 in this utility model were all purchased commercially, and their working principles and structures will not be described in detail. The signal transmission and automatic control between the components do not involve new computer programs.

[0041] The above embodiments are only used to illustrate and not limit the technical solutions of this utility model. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the utility model without departing from the spirit and scope of the utility model. Any modifications or partial substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A double round pipe temperature-stress-pressure static fracturing synchronous simulation system, characterized in that: The utility model provides a double-layered pipe type test device, which comprises a support vibration device and a double-layered pipe type test device arranged on the support vibration device.

2. The dual-wall pipe temperature-stress-pressure static fracturing synchronous simulation system according to claim 1, characterized in that: The top cover is connected with a pressure gauge, a water injection pipe and a pressure relief valve.

3. The double-wall pipe temperature-stress-pressure static fracturing synchronous simulation system according to claim 1 or 2, characterized in that: The outer wall of the outer pipe is provided with a wireless temperature sensor, and the outer circle of the outer pipe is bonded with a strain gauge.

4. The dual-wall pipe temperature-stress-pressure static fracturing synchronous simulation system according to claim 3, characterized in that: The strain gauge is connected with a strain meter through a wire. The temperature acquisition instrument receives wireless signals emitted by the wireless temperature sensor. The temperature acquisition instrument and the radio frequency reader are connected through a wire. The strain meter and the temperature acquisition instrument are simultaneously connected to a computer through a wire. The support vibration device comprises a support, four vertical pull rods fixedly arranged on the support, a lower flat plate fixedly arranged on the lower ends of the four vertical pull rods through lower nuts, an upper ring plate fixedly arranged on the upper ends of the four vertical pull rods through upper nuts, a columnar vibrator connected to the lower flat plate through bolts, a groove arranged on the upper end of the columnar vibrator, and an inner hole of the upper ring plate having a diameter greater than the outer diameter of the outer pipe. The double-layered pipe type test device is coaxially arranged in the upper ring plate. The bottom cover at the lower end of the outer pipe is inserted into the groove of the columnar vibrator. A lower high elasticity silicone rubber ring is arranged between the outer circle of the outer pipe and the inner circle of the groove. An upper high elasticity silicone rubber ring is arranged on the inner circle of the upper ring plate and in contact with the outer circle of the outer pipe.

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