N2 foam penetrating true triaxial fracturing simulation test system

Abstract

The invention provides an N2 foam penetrating true triaxial fracturing simulation test system, and belongs to the technical field of pressure simulation, the N2 foam penetrating true triaxial fracturing simulation test system comprises a workbench, the upper end face of the workbench is provided with a groove, a lifting plate is arranged in the groove, the upper end face of the lifting plate is provided with a test block, the lower side of the lifting plate is provided with a lifting mechanism, and the lifting mechanism is connected with the test block. And four moving openings are uniformly formed in the workbench. Through the arrangement of the sliding head, the connecting frame, the side pressing plate, the connecting ring, the connecting rod, the first telescopic cylinder, the buffer mechanism, the second telescopic cylinder, the upper pressing plate, the first pressure sensor and the second pressure sensor, the layer penetrating effect of N2 foam under the complex stress condition is studied, and three-dimensional stress can be truly simulated; high-precision stress loading and real-time crack expansion monitoring are achieved, reliable experimental data and technical support can be provided for efficient development of unconventional oil and gas resources, and the problem that three-dimensional stress is inconvenient to simulate in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fracturing simulation, in particular to a N2 foam interlayer true triaxial fracturing simulation test system. BACKGROUND

[0002] Unconventional oil and gas resources, such as shale gas, coalbed methane, and tight oil, have become an important supplement to energy supply due to their abundant reserves and wide distribution. Unconventional oil and gas resources are usually stored in low-permeability or ultra-low-permeability reservoirs, which are difficult to develop. In order to improve the permeability of these reservoirs and achieve economic and effective development, fracturing technology has become a key means. In actual oil and gas reservoirs, the expansion behavior of fractures is influenced by a variety of factors, including stress field, rock mechanical properties, and fracturing fluid performance. In order to better understand the expansion law of fractures under complex stress conditions, optimize fracturing design and construction parameters, and improve fracturing effect, fracturing simulation experiments are needed. N2 foam fracturing technology has made significant achievements in foam formula optimization, fracturing process improvement, and equipment development. It has been widely used in many oil and gas fields at home and abroad and has achieved good fracturing effect and economic benefits.

[0003] At present, there are some N2 foam fracturing simulation test devices, but these systems mostly have the problems of single function and limited simulation conditions. For example, some systems can only perform simple foam fracturing experiments and cannot simulate the three-dimensional stress state in the actual formation, and the simulation effect of N2 foam interlayer is not good. In addition, it is not convenient to install and disassemble the fracturing pipe in the prior art, which leads to low simulation efficiency. In the prior art, a curing agent is usually used to seal the top end of the fracturing pipe, which takes a long time to cure and is difficult to disassemble the fracturing pipe.

[0004] Therefore, we improve it and propose a N2 foam interlayer true triaxial fracturing simulation test system. SUMMARY

[0005] The purpose of the present application is to solve the problems of not being convenient to simulate the influence of triaxial stress on fracturing, not being convenient to disassemble the fracturing pipe, and not being convenient to seal the top end of the fracturing pipe in the prior art, and a N2 foam interlayer true triaxial fracturing simulation test system is proposed.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The N2 foam interlayer true triaxial fracturing simulation test system is used to improve the above-mentioned problems.

[0008] The present application is as follows:

[0009] The utility model provides a test block is placed to the upper end surface of the lifting plate, and the lower side of lifting plate is equipped with lifting mechanism, four moving openings are evenly equipped with on the workbench, four the sliding joint of moving opening is slidably connected in, the top of sliding head is all fixedly connected with connecting frame, and connecting frame is connected with side pressure plate through buffer mechanism, and the lower side of workbench is equipped with connecting ring, four connecting rods are evenly rotatably connected on the connecting ring, and the top of four connecting rods is rotatably connected with the bottom of sliding head respectively, the lower end surface of workbench is fixedly connected with support, the lower end surface of support is fixedly connected with first telescopic cylinder, and the drive end of first telescopic cylinder is fixedly connected with connecting ring, and the pressure cracking hole is equipped with in the test block, and the pressure cracking pipe is equipped with in the pressure cracking hole, the top of pressure cracking pipe is fixedly connected with the connecting pipe communicated with it, the lower side of workbench is equipped with conveying mechanism, the rear side of workbench is equipped with mounting frame, the plug -in mechanism for installing pressure cracking pipe is equipped in the mounting frame, the lower side of mounting frame is equipped with displacement mechanism, the plugging mechanism is equipped with on the pressure cracking pipe, and the lower end surface of workbench is fixedly connected with rack.

[0010] As a preferred technical scheme of the utility model, the lifting mechanism comprises a base frame fixed to the lower end surface of the workbench, two first threaded rods symmetrically and rotatably connected between the base frame and the workbench, lifting blocks threadedly connected to the two first threaded rods, the lifting blocks slidably connected to the side walls of the base frame, lifting rods fixed to the upper end surfaces of the lifting blocks, the top ends of the lifting rods penetrating through the workbench and fixedly connected to the lower end surface of the lifting plate, driven bevel gears fixed to the bottom ends of the first threaded rods and penetrating through the bottom wall of the base frame, two fixed blocks symmetrically and fixed to the lower end surface of the base frame, a rotating rod rotatably connected between the two fixed blocks, two driving bevel gears fixed to the rotating rod and meshingly connected to the driven bevel gears, a first motor fixed to one of the fixed blocks and having a drive end fixedly connected to the shaft end of the rotating rod.

[0011] As a preferred technical scheme of the utility model, the buffer mechanism comprises sliding columns slidably arranged at the two ends of the connecting frame respectively, a circular plate fixed to the inner end of each sliding column and fixedly connected to the side pressure plate, a disc sleeve arranged on the sliding column and fixedly connected to the connecting frame, a spring sleeve arranged on the sliding column and having two ends fixedly connected to the circular plate and the disc respectively, and a limiting plate fixed to the outer end of the sliding column.

[0012] As a preferred technical scheme of the present application, the conveying mechanism comprises a bearing plate fixed in the rack, the upper end surface of the bearing plate is fixedly connected with a storage tank, a high-pressure pump is fixedly connected to the bearing plate, the input end of the high-pressure pump is communicated with the storage tank through a first assembly pipe, the output end of the high-pressure pump is fixedly connected with a second assembly pipe, and the second assembly pipe is fixedly connected with a connecting pipe through a hose.

[0013] As a preferred technical scheme of the present application, the plug-in mechanism comprises a second threaded rod rotatably arranged in the mounting frame, the upper end surface of the mounting frame is fixedly connected with a second motor, the driving end of the second motor is fixedly connected with the top end of the second threaded rod, a moving block is threadedly connected to the second threaded rod, first guide rods are slidably connected to both ends of the moving block, the upper and lower ends of the mounting frame are fixedly connected with the two ends of the first guide rods, respectively, a connecting frame is fixedly connected to the side wall of the moving block close to the fracturing pipe, and the end of the connecting frame away from the moving block is fixedly connected with the fracturing pipe.

[0014] As a preferred technical scheme of the present application, the shifting mechanism comprises two assembly plates fixed to the upper end surface of the workbench at the rear end, a third threaded rod is rotatably connected between the two assembly plates, a third motor is fixedly connected to the outer side wall of the outer assembly plate, the driving end of the third motor is fixedly connected with the shaft end of the third threaded rod, a shifting block is threadedly connected to the third threaded rod, the upper end surface of the shifting block is fixedly connected with the lower end surface of the mounting frame, second guide rods are slidably connected to both ends of the shifting block, and the two ends of the second guide rods are fixedly connected with the assembly plates.

[0015] As a preferred technical scheme of the present application, the plugging mechanism comprises a first connecting sleeve and a second connecting sleeve fixed on the fracturing pipe, a rubber sleeve is fixedly connected between the first connecting sleeve and the second connecting sleeve, an exhaust pipe is fixedly connected to the upper end surface of the first connecting sleeve, a gas release valve is installed on the exhaust pipe, a gas filling pump is connected to the upper end surface of the first connecting sleeve through an air inlet pipe, the gas filling pump is installed on the connecting frame, and an air inlet valve is installed on the air inlet pipe.

[0016] As a preferred technical scheme of the present application, the two supporting arms of the mounting frame are fixedly connected with second telescopic cylinders, the driving end of the second telescopic cylinder penetrates through the supporting arm and is fixedly connected with a connecting plate, the lower end surface of the connecting plate is fixedly connected with a first pressure sensor at both ends, the lower end surface of the first pressure sensor is fixedly connected with an upper pressing plate, the number of the connecting frames is four, the inner side wall top end of the four connecting frames is fixedly connected with a mounting seat, and a second pressure sensor is installed on the mounting seat.

[0017] As a preferred technical scheme of the present application, the number of the side pressing plates is four, and three acoustic emission sensors are installed on each of the four side pressing plates.

[0018] As the preferred technical scheme of the present application, the adapter plate and the upper pressing plate are both provided with a circular hole matched with the second connecting sleeve.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] In the scheme of the present application:

[0021] 1. By setting the sliding head, connecting frame, side pressing plate, connecting ring, connecting rod, first telescopic cylinder, buffer mechanism, second telescopic cylinder, upper pressing plate, first pressure sensor and second pressure sensor, the through-layer effect of N2 foam under complex stress conditions is realized, three-dimensional stress simulation is realized, high-precision stress loading and real-time crack propagation monitoring are realized, reliable experimental data and technical support are provided for efficient development of unconventional oil and gas resources, and the problem of inconvenient simulation of three-dimensional stress in the prior art is solved.

[0022] 2. By setting the plug-in mechanism, displacement mechanism, lifting plate and lifting mechanism, the pressure pipe is automatically inserted into the fracturing hole, the efficiency of simulation test is improved, the use is convenient, the lifting plate can be automatically lifted to facilitate the placement and removal of the test block, and the problem of inconvenient disassembly and assembly of the fracturing pipe in the prior art is solved.

[0023] 3. By setting the plugging mechanism, inflation of the rubber sleeve is realized to inflate the fracturing pipe and the fracturing hole, the fracturing simulation test is ensured, the use of curing agent for plugging is not required, the simulation test is facilitated, the efficiency of simulation test is improved, and the problem of inconvenient plugging of the fracturing pipe and the fracturing hole in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The overall structure schematic diagram provided by the present application is provided;

[0025] Figure 2 The structure schematic diagram of the conveying mechanism provided by the present application is provided;

[0026] Figure 3 The structure schematic diagram of the lateral stress loading provided by the present application is provided;

[0027] Figure 4 The structure schematic diagram of the lifting mechanism provided by the present application is provided;

[0028] Figure 5 The structure schematic diagram of the plug-in mechanism and displacement mechanism provided by the present application is provided;

[0029] Figure 6 The structure schematic diagram of the plugging mechanism provided by the present application is provided;

[0030] Figure 7The side view structure schematic diagram provided by the present application is shown in the figure.

[0031] Figure 8 The top view structure schematic diagram provided by the present application is shown in the figure. Figure 4 The top view structure schematic diagram provided by the present application is shown in the figure.

[0032] Figure 9 The bottom view structure schematic diagram provided by the present application is shown in the figure.

[0033] The figure shows:

[0034] 1, workbench; 2, lifting plate; 3, test block; 4, lifting mechanism; 401, base frame; 402, first threaded rod; 403, lifting block; 404, lifting rod; 405, driven bevel gear; 406, fixed block; 407, rotating rod; 408, driving bevel gear; 409, first motor; 5, moving opening; 6, sliding head; 7, connecting frame; 8, buffer mechanism; 801, sliding column; 802, round sheet; 803, disc; 804, spring; 805, limiting sheet; 9, side pressing plate; 10, connecting ring; 11, connecting rod; 12, support; 13, first telescopic cylinder; 14, fracturing hole; 15, fracturing pipe; 16, connecting pipe; 17, conveying mechanism; 1701, bearing plate; 1702, storage tank; 1703, high-pressure pump; 1704, first assembly pipe; 1705, second assembly pipe; 1706, hose; 18, mounting frame; 19, plug-in mechanism; 1901, second threaded rod; 1902, second motor; 1903, moving block; 1904, first guide rod; 1905, linking frame; 20, displacement mechanism; 2001, assembly plate; 2002, third threaded rod; 2003, third motor; 2004, displacement block; 2005, second guide rod; 21, second telescopic cylinder; 22, linking plate; 23, first pressure sensor; 24, upper pressing plate; 25, plugging mechanism; 2501, first connecting sleeve; 2502, second connecting sleeve; 2503, rubber sleeve; 2504, exhaust pipe; 2505, air release valve; 2506, air inlet pipe; 2507, air pump; 2508, air inlet valve; 26, rack; 27, mounting seat; 28, second pressure sensor; 29, sound emission sensor. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments.

[0036] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 ,Figure 7 , Figure 8 and Figure 9 As shown, this embodiment proposes a true triaxial fracturing simulation test system for N2 foam, including a workbench 1. A groove is formed on the upper surface of the workbench 1, and a lifting plate 2 is disposed within the groove. A test block 3 is placed on the upper surface of the lifting plate 2. A lifting mechanism 4 is provided on the lower side of the lifting plate 2. Four movable openings 5 ​​are evenly distributed on the workbench 1, and a slider 6 is slidably connected to each of the four movable openings 5. A connecting frame 7 is fixedly connected to the top of each slider 6. The connecting frame 7 is connected to a side pressure plate 9 through a buffer mechanism 8. A connecting ring 10 is provided on the lower side of the workbench 1. Four connecting rods 11 are rotatably connected to the connecting ring 10. The top ends of the four connecting rods 11 are rotatably connected to the bottom end of the slide head 6. A bracket 12 is fixedly connected to the lower end face of the workbench 1. A first telescopic cylinder 13 is fixedly connected to the lower end face of the bracket 12. The driving end of the first telescopic cylinder 13 is fixedly connected to the connecting ring 10. A fracturing hole 14 is provided on the test block 3. A fracturing tube 15 is provided in the fracturing hole 14. A connecting tube 16 communicating with the top end of the fracturing tube 15 is fixedly connected to it. A conveying mechanism 17 is provided on the lower side of the workbench 1, and a mounting frame 18 is provided on the rear side of the workbench 1. An insertion and removal mechanism 19 for installing the fracturing tube 15 is provided inside the mounting frame 18. A displacement mechanism 20 is provided on the lower side of the mounting frame 18, and a sealing mechanism 25 is provided on the fracturing tube 15. A frame 26 is fixedly connected to the lower end face of the workbench 1. The connecting ring 10 is moved by the first telescopic cylinder 13. The movement of the connecting ring 10 drives the connecting rod 11 to move, and the movement of the connecting rod 11 drives the slide head 6 and the connecting frame 7 to move. The movement, in conjunction with the buffer mechanism 8, causes the side pressure plate 9 to move, thereby applying lateral pressure to the test block 3, improving the accuracy of the simulation test. The conveying mechanism 17 delivers N2 foam to the fracturing tube 15. The insertion and removal mechanism 19 controls the installation and removal of the fracturing tube 15. The shifting mechanism 20 adjusts the position of the mounting frame 18. The sealing mechanism 25 performs sealing and depressurization operations on the fracturing tube 15. In conjunction with the first pressure sensor 23, the second pressure sensor 28, and the acoustic sensor 29, the fracturing process is monitored.

[0037] like Figure 1 , Figure 4 and Figure 8As shown, as a preferred embodiment, based on the above manner, further, the lifting mechanism 4 comprises a chassis 401 fixed at the lower end face of the workbench 1, two first threaded rods 402 are symmetrically and rotatably connected between the chassis 401 and the workbench 1, lifting blocks 403 are threadedly connected on the two first threaded rods 402, the lifting blocks 403 are slidably connected with the side walls of the chassis 401, the upper end faces of the lifting blocks 403 are fixedly connected with lifting rods 404, the top ends of the lifting rods 404 penetrate through the workbench 1 and are fixedly connected with the lower end face of the lifting plate 2, the bottom ends of the first threaded rods 402 penetrate through the bottom wall of the chassis 401 and are fixedly connected with driven bevel gears 405, the lower end face of the chassis 401 is symmetrically and fixedly connected with two fixed blocks 406, a rotating rod 407 is rotatably connected between the two fixed blocks 406, the rotating rod 407 is fixedly connected with two driving bevel gears 408 which are meshingly connected with the driven bevel gears 405, one of the fixed blocks 406 is fixedly connected with a first motor 409, and the driving end of the first motor 409 is fixedly connected with the shaft end of the rotating rod 407; the first motor 409 drives the rotating rod 407 to rotate, the rotation of the rotating rod 407 drives the driving bevel gears 408 to rotate, the rotation of the driving bevel gears 408 drives the driven bevel gears 405 to rotate, so that the two first threaded rods 402 rotate at the same time, the lifting blocks 403 move on the first threaded rods 402, drive the lifting rods 404 and the lifting plate 2 to move up and down, so as to adjust the height of the test block 3, and then the test block 3 is conveniently placed in the side pressing plate 9, and the test block 3 is conveniently placed and taken out.

[0038] As shown in Figure 1 and Figure 7 As a preferred embodiment, based on the above manner, further, the buffer mechanism 8 comprises sliding columns 801 which are respectively and slidably arranged at the two ends of the connecting frame 7, the inner ends of the sliding columns 801 are fixedly connected with circular plates 802, the circular plates 802 are fixedly connected with the side pressing plate 9, disc-shaped plates 803 are sleeved on the sliding columns 801, the disc-shaped plates 803 are fixedly connected with the connecting frame 7, springs 804 are sleeved on the sliding columns 801, the two ends of the springs 804 are respectively fixedly connected with the circular plates 802 and the disc-shaped plates 803, and limiting plates 805 are fixedly connected with the outer ends of the sliding columns 801; when the side pressing plate 9 is subjected to pressure, the side pressing plate 9 pushes the circular plates 802 and the sliding columns 801 to slide in the connecting frame 7, the springs 804 are compressed, a buffering effect is achieved, the impact force on the equipment is reduced, and the limiting plates 805 prevent the sliding columns 801 from sliding out of the connecting frame 7.

[0039] As shown in Figure 1 and Figure 2As shown in the preferred embodiment, on the basis of the above-mentioned mode, further, the conveying mechanism 17 comprises a bearing plate 1701 fixed in the rack 26, the upper end surface of the bearing plate 1701 is fixedly connected with a storage tank 1702, the bearing plate 1701 is fixedly connected with a high-pressure pump 1703, the input end of the high-pressure pump 1703 is communicated with the storage tank 1702 through a first assembly pipe 1704, the output end of the high-pressure pump 1703 is fixedly connected with a second assembly pipe 1705, the second assembly pipe 1705 is fixedly connected with the connecting pipe 16 through a hose 1706; the high-pressure pump 1703 is started, the N2 foam in the storage tank 1702 is sucked in through the first assembly pipe 1704, and then is conveyed to the connecting pipe 16 through the second assembly pipe 1705 and the hose 1706, and then enters the fracturing pipe 15, thereby providing power for fracturing.

[0040] As shown in the preferred embodiment, on the basis of the above-mentioned mode, further, the conveying mechanism 17 comprises a bearing plate 1701 fixed in the rack 26, the upper end surface of the bearing plate 1701 is fixedly connected with a storage tank 1702, the bearing plate 1701 is fixedly connected with a high-pressure pump 1703, the input end of the high-pressure pump 1703 is communicated with the storage tank 1702 through a first assembly pipe 1704, the output end of the high-pressure pump 1703 is fixedly connected with a second assembly pipe 1705, the second assembly pipe 1705 is fixedly connected with the connecting pipe 16 through a hose 1706; the high-pressure pump 1703 is started, the N2 foam in the storage tank 1702 is sucked in through the first assembly pipe 1704, and then is conveyed to the connecting pipe 16 through the second assembly pipe 1705 and the hose 1706, and then enters the fracturing pipe 15, thereby providing power for fracturing. Figure 1 Figure 5 As shown in the preferred embodiment, on the basis of the above-mentioned mode, further, the conveying mechanism 17 comprises a bearing plate 1701 fixed in the rack 26, the upper end surface of the bearing plate 1701 is fixedly connected with a storage tank 1702, the bearing plate 1701 is fixedly connected with a high-pressure pump 1703, the input end of the high-pressure pump 1703 is communicated with the storage tank 1702 through a first assembly pipe 1704, the output end of the high-pressure pump 1703 is fixedly connected with a second assembly pipe 1705, the second assembly pipe 1705 is fixedly connected with the connecting pipe 16 through a hose 1706; the high-pressure pump 1703 is started, the N2 foam in the storage tank 1702 is sucked in through the first assembly pipe 1704, and then is conveyed to the connecting pipe 16 through the second assembly pipe 1705 and the hose 1706, and then enters the fracturing pipe 15, thereby providing power for fracturing.

[0041] As shown in the preferred embodiment, on the basis of the above-mentioned mode, further, the conveying mechanism 17 comprises a bearing plate 1701 fixed in the rack 26, the upper end surface of the bearing plate 1701 is fixedly connected with a storage tank 1702, the bearing plate 1701 is fixedly connected with a high-pressure pump 1703, the input end of the high-pressure pump 1703 is communicated with the storage tank 1702 through a first assembly pipe 1704, the output end of the high-pressure pump 1703 is fixedly connected with a second assembly pipe 1705, the second assembly pipe 1705 is fixedly connected with the connecting pipe 16 through a hose 1706; the high-pressure pump 1703 is started, the N2 foam in the storage tank 1702 is sucked in through the first assembly pipe 1704, and then is conveyed to the connecting pipe 16 through the second assembly pipe 1705 and the hose 1706, and then enters the fracturing pipe 15, thereby providing power for fracturing. Figure 1 Figure 2 Figure 5 ​​​As shown, in a preferred embodiment, based on the above method, the shifting mechanism 20 further includes two assembly plates 2001 fixed to the rear end of the upper surface of the worktable 1. A third threaded rod 2002 is rotatably connected between the two assembly plates 2001. A third motor 2003 is fixedly connected to the outer wall of the outer assembly plate 2001. The driving end of the third motor 2003 is fixedly connected to the shaft end of the third threaded rod 2002. A shifting block 2004 is threadedly connected to the third threaded rod 2002. The upper end surface of the shifting block 2004... The lower end face of the mounting frame 18 is fixedly connected to the displacement block 2004. The two ends of the displacement block 2004 are slidably connected to the second guide rod 2005. The two ends of the second guide rod 2005 are fixedly connected to the assembly plate 2001 respectively. The third motor 2003 drives the third threaded rod 2002 to rotate. The displacement block 2004 moves back and forth on the third threaded rod 2002. The second guide rod 2005 plays a guiding role. The displacement block 2004 drives the mounting frame 18 to move back and forth. By adjusting the position of the mounting frame 18, the fracturing tube 15 can be moved to the upper side of the fracturing hole 14.

[0042] like Figure 1 and Figure 6 As shown, in a preferred embodiment, based on the above method, the sealing mechanism 25 further includes a first connecting sleeve 2501 and a second connecting sleeve 2502 fixed to the fracturing tube 15. A rubber sleeve 2503 is fixedly connected between the first connecting sleeve 2501 and the second connecting sleeve 2502. An exhaust pipe 2504 is fixedly connected to the upper end face of the first connecting sleeve 2501. A vent valve 2505 is installed on the exhaust pipe 2504. The upper end face of the first connecting sleeve 2501 is connected to the inlet valve via an outlet valve. An air pump 2507 is connected to the air pipe 2506. The air pump 2507 is installed on the connecting frame 1905. An air inlet valve 2508 is installed on the air inlet pipe 2506. The air pump 2507 inflates the rubber sleeve 2503 through the air inlet pipe 2506. The air inlet valve 2508 controls the gas entry. The rubber sleeve 2503 expands and seals the fracturing tube 15. When the vent valve 2505 is opened, the gas in the rubber sleeve 2503 is discharged through the vent pipe 2504. The rubber sleeve 2503 contracts and releases the seal.

[0043] like Figure 1 and Figure 3As shown, as a preferred embodiment, on the basis of the above-mentioned mode, further, the two arms of the mounting frame 18 are fixedly connected with the second telescopic cylinder 21, the driving end of the second telescopic cylinder 21 penetrates the arm and is fixedly connected with the connecting plate 22, the lower end surface of the connecting plate 22 is fixedly connected with the first pressure sensor 23 at both ends, the lower end surface of the first pressure sensor 23 is fixedly connected with the upper pressing plate 24, the number of the connecting frame 7 is four, the inner side wall top of the four connecting frames 7 is fixedly connected with the mounting seat 27, and the second pressure sensor 28 is installed on the mounting seat 27; the second telescopic cylinder 21 drives the upper pressing plate 24 to exert vertical pressure on the test block 3, cooperates with the side pressing plate 9 to act on the test block 3, simulates the true triaxial stress environment, the first pressure sensor 23 monitors the vertical pressure exerted by the upper pressing plate 24 on the test block 3, and the second pressure sensor 28 is installed on the mounting seat 27 and monitors the lateral pressure exerted by the side pressing plate 9 on the test block 3.

[0044] As shown in Figure 1 and Figure 3 As a preferred embodiment, on the basis of the above-mentioned mode, further, the number of the side pressing plate 9 is four, and three acoustic emission sensors 29 are installed on each of the four side pressing plates 9; the acoustic emission sensor 29 is used for monitoring the acoustic emission signals generated in the test block 3 during the fracturing process, and analyzing the fracturing condition.

[0045] As shown in Figure 1 and Figure 6 As a preferred embodiment, on the basis of the above-mentioned mode, further, the connecting plate 22 and the upper pressing plate 24 are both provided with a circular hole matched with the second connecting sleeve 2502; convenient for assembly and use.

[0046] Specifically, in use, the N2 foam through-layer true tri-axial fracturing simulation test system is as follows: the hydraulic block is processed into the size of the test block 3, then the fracturing hole 14 is drilled on the test block 3, the first motor 409 drives the rotating rod 407 to rotate, the rotating rod 407 drives the driving bevel gear 408 to rotate, the driving bevel gear 408 drives the driven bevel gear 405 to rotate, so that the two first threaded rods 402 rotate at the same time, the lifting block 403 moves on the first threaded rod 402, driving the lifting rod 404 and the lifting plate 2 to move upwards, the test block 3 is placed on the lifting plate 2, then the first motor 409 is reversed to make the lifting plate 2 and the test block 3 descend, then the third motor 2003 drives the third threaded rod 2002 to rotate, the displacement block 2004 moves on the third threaded rod 2002 to the position of the side pressing plate 9, the displacement block 2004 drives the mounting frame 18 to move, the fracturing pipe 15 is displaced to above the fracturing hole 14, then the second motor 1902 drives the second threaded rod 1901 to rotate, the moving block 1903 moves downwards on the second threaded rod 1901, so that the connecting frame 1905 and the fracturing pipe 15 move downwards to make the fracturing pipe 15 inserted into the fracturing hole 14, the inflation pump 2507 inflates the rubber sleeve 2503 through the air inlet pipe 2506, the air inlet valve 2508 controls the gas to enter, the rubber sleeve 2503 expands to block the gap between the fracturing pipe 15 and the fracturing hole 14, then the first telescopic cylinder 13 drives the connecting ring 10 to move, the movement of the connecting ring 10 drives the connecting rod 11 to move, the movement of the connecting rod 11 drives the sliding head 6 and the connecting frame 7 to move, so that the side pressing plate 9 applies lateral pressure to the test block 3, the second telescopic cylinder 21 drives the upper pressing plate 24 to apply vertical pressure to the test block 3, a true tri-axial stress environment is simulated, the high-pressure pump 1703 is started, the N2 foam in the storage tank 1702 is sucked in through the first assembly pipe 1704, then is transported to the connecting pipe 16 through the second assembly pipe 1705 and the hose 1706, and then enters the fracturing pipe 15 to provide power for fracturing, the acoustic emission sensor 29 monitors the acoustic emission signals generated in the test block 3 during the fracturing process, and analyzes the fracturing condition.

[0047] All the technical features in the embodiment can be freely combined according to actual needs.

[0048] The above embodiment is a preferred implementation of the present application, and the present application can also be implemented in other ways without departing from the concept of the technical solution, and any obvious replacement within the protection scope of the present application.

Claims

1. An N2 foam cross-layer true triaxial fracturing simulation test system, comprising a workbench (1), characterized in that, The upper end face of the workbench (1) is provided with a groove, and the lifting plate (2) is arranged in the groove. The upper end face of the lifting plate (2) is provided with a test block (3). The lower side of the lifting plate (2) is provided with a lifting mechanism (4). Four moving openings (5) are uniformly arranged on the workbench (1). Four sliding heads (6) are slidably connected in the moving openings (5). The top ends of the sliding heads (6) are fixedly connected with connecting frames (7). The connecting frames (7) are connected with side pressure plates (9) through buffer mechanisms (8). The lower side of the workbench (1) is provided with a connecting ring (10). Four connecting rods (11) are rotatably connected to the connecting ring (10). The top ends of the four connecting rods (11) are rotatably connected with the bottom ends of the sliding heads (6). The lower end face of the workbench (1) is fixedly connected with a support (12). The lower end face of the support (12) is fixedly connected with a first telescopic cylinder (13). The driving end of the first telescopic cylinder (13) is fixedly connected with the connecting ring (10). A fracturing hole (14) is arranged on the test block (3). A fracturing pipe (15) is arranged in the fracturing hole (14). The top end of the fracturing pipe (15) is fixedly connected with a connecting pipe (16) in communication with the fracturing pipe (15). The lower side of the workbench (1) is provided with a conveying mechanism (17). The rear side of the workbench (1) is provided with a mounting frame (18). The mounting frame (18) is provided with a plug-in mechanism (19) for mounting the fracturing pipe (15). The lower side of the mounting frame (18) is provided with a displacement mechanism (20). The fracturing pipe (15) is provided with a plugging mechanism (25). The lower end face of the workbench (1) is fixedly connected with a rack (26).

2. The N2 foam cross-layer true triaxial fracturing simulation test system according to claim 1, characterized in that, The lifting mechanism (4) comprises a base frame (401) fixed to the lower end face of the workbench (1). Two first threaded rods (402) are symmetrically and rotatably connected between the base frame (401) and the workbench (1). Two lifting blocks (403) are threadedly connected to the first threaded rods (402). The lifting blocks (403) are slidably connected with the side wall of the base frame (401). The upper end faces of the lifting blocks (403) are fixedly connected with lifting rods (404). The top ends of the lifting rods (404) penetrate the workbench (1) and are fixedly connected with the lower end face of the lifting plate (2). The bottom ends of the first threaded rods (402) penetrate the bottom wall of the base frame (401) and are fixedly connected with driven bevel gears (405). The lower end face of the base frame (401) is symmetrically and fixedly connected with two fixed blocks (406). A rotating rod (407) is rotatably connected between the two fixed blocks (406). The rotating rod (407) is fixedly connected with two driving bevel gears (408) which are meshingly connected with the driven bevel gears (405). One of the fixed blocks (406) is fixedly connected with a first motor (409). The driving end of the first motor (409) is fixedly connected with the shaft end of the rotating rod (407).

3. The N2 foam crossing layer true triaxial fracturing simulation test system according to claim 1, characterized in that, The buffer mechanism (8) includes slide posts (801) respectively slidingly arranged at both ends of the connecting frame (7), the inner ends of the slide posts (801) are fixedly connected with round plates (802), the round plates (802) are fixedly connected with the side pressing plates (9), disc plates (803) are sleeved on the slide posts (801), the disc plates (803) are fixedly connected with the connecting frame (7), springs (804) are sleeved on the slide posts (801), the two ends of the springs (804) are fixedly connected with the round plates (802) and the disc plates (803) respectively, and the outer ends of the slide posts (801) are fixedly connected with limiting plates (805).

4. The N2 foam cross-layer true triaxial fracturing simulation test system according to claim 1, characterized in that, The conveying mechanism (17) includes a bearing plate (1701) fixed in the rack (26), the upper end surface of the bearing plate (1701) is fixedly connected with a storage tank (1702), the bearing plate (1701) is fixedly connected with a high-pressure pump (1703), the input end of the high-pressure pump (1703) is in communication with the storage tank (1702) through a first assembly pipe (1704), the output end of the high-pressure pump (1703) is fixedly connected with a second assembly pipe (1705), and the second assembly pipe (1705) is fixedly connected with the connecting pipe (16) through a hose (1706).

5. The N2 foam cross-layer tri-axial fracturing simulation test system according to claim 1, characterized in that, The plug-pull mechanism (19) includes a second threaded rod (1901) rotatably arranged in the mounting frame (18), the upper end surface of the mounting frame (18) is fixedly connected with a second motor (1902), the driving end of the second motor (1902) is fixedly connected with the top end of the second threaded rod (1901), the second threaded rod (1901) is threadedly connected with a moving block (1903), the two ends of the moving block (1903) are slidingly connected with first guide rods (1904), the two ends of the first guide rods (1904) are fixedly connected with the upper and lower ends of the mounting frame (18) respectively, and the side wall, close to the fracturing pipe (15), of the moving block (1903) is fixedly connected with a connecting frame (1905), and the end, away from the moving block (1903), of the connecting frame (1905) is fixedly connected with the fracturing pipe (15).

6. The N2 foam cross-layer tri-axial fracturing simulation test system according to claim 1, characterized in that, The shifting mechanism (20) includes two assembly plates (2001) fixed on the upper end surface of the rear end of the workbench (1), a third threaded rod (2002) is rotatably connected between the two assembly plates (2001), a third motor (2003) is fixedly connected to the outer side wall of the outer assembly plate (2001), the driving end of the third motor (2003) is fixedly connected with the shaft end of the third threaded rod (2002), the third threaded rod (2002) is threadedly connected with a shifting block (2004), the upper end surface of the shifting block (2004) is fixedly connected with the lower end surface of the mounting frame (18), and the two ends of the shifting block (2004) are slidingly connected with second guide rods (2005), and the two ends of the second guide rods (2005) are fixedly connected with the assembly plates (2001).

7. The N2 foam cross-layer tri-axial fracturing simulation test system according to claim 1, characterized in that, The sealing mechanism (25) comprises a first connecting sleeve (2501) and a second connecting sleeve (2502) fixed on the fracturing pipe (15), a rubber sleeve (2503) is fixedly connected between the first connecting sleeve (2501) and the second connecting sleeve (2502), the upper end surface of the first connecting sleeve (2501) is fixedly connected with an exhaust pipe (2504), the exhaust pipe (2504) is provided with a gas release valve (2505), the upper end surface of the first connecting sleeve (2501) is connected with a gas filling pump (2507) through a gas inlet pipe (2506), the gas filling pump (2507) is installed on the connecting frame (1905), and the gas inlet pipe (2506) is provided with a gas inlet valve (2508).

8. The N2 foam cross-layer tri-axial fracturing simulation test system according to claim 1, characterized in that, The two supporting arms of the mounting frame (18) are fixedly connected with second telescopic cylinders (21), the driving end of the second telescopic cylinder (21) penetrates the supporting arm and is fixedly connected with a connecting plate (22), the lower end surface of the connecting plate (22) is fixedly connected with first pressure sensors (23) at both ends, the lower end surface of the first pressure sensor (23) is fixedly connected with an upper pressing plate (24), the number of the connecting frames (7) is four, the inner side wall top end of the four connecting frames (7) is fixedly connected with mounting seats (27), and the mounting seat (27) is provided with a second pressure sensor (28).

9. The N2 foam cross-layer tri-axial fracturing simulation test system according to claim 1, characterized in that, The number of the side pressing plates (9) is four, and three acoustic emission sensors (29) are installed on each of the four side pressing plates (9).

10. The N2 foam cross-laminated triaxial fracturing simulation test system according to claim 8, characterized in that, The connecting plate (22) and the upper pressing plate (24) are both provided with a circular hole matched with the second connecting sleeve (2502).

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