One-pump multi-purpose true triaxial pulsating fracturing experimental device and method

Abstract

The invention relates to the technical field of coal mine fracturing, and discloses a one-pump multi-purpose true triaxial pulsating fracturing experiment device and method. The transfer valve is provided with a plurality of transfer interfaces, and one transfer interface is connected with the constant-speed constant-pressure pump; the plurality of piston containers are connected with the plurality of transfer interfaces on the transfer valve one by one, one piston container is filled with a dyeing solution, and the other piston containers are filled with hydraulic oil; the true triaxial device comprises a cavity and base plates, a sample containing space used for containing rock samples is defined by the multiple base plates, the fracturing pipe is connected with the piston containers containing dyeing solutions, and the multiple hydraulic loading devices are connected with the multiple piston containers containing hydraulic oil. The overall redundant degree of the experimental device is effectively reduced, the experimental system is simplified, the equipment and maintenance cost is reduced, the fracturing cracks can be colored, the crack condition can be conveniently observed and recorded, and analysis of subsequent experimental results is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine fracturing, and in particular to a true triaxial pulsating fracturing experimental device and method for one-pump-multi-purpose. Background Art

[0002] As a new fracturing technology, pulsating fracturing can use periodic pulse water to act on coal and rock mass, causing fatigue damage to coal and rock mass, effectively reducing the fracture initiation pressure, activating, expanding and connecting the hidden and micro cracks inside coal and rock mass, forming a new fracture network, and gradually being used in the coal mining field. However, when conducting pulsating indoor tests, the existing experimental system is too complicated, and the rock sample fracturing cracks cannot be clearly tracked. Summary of the invention

[0003] The object of the present invention is to provide a true triaxial pulsating fracturing experimental device and method with a single pump for multiple uses, aiming to solve or improve at least one of the above-mentioned technical problems.

[0004] To achieve the above object, the present invention provides the following solution: The present invention provides a true triaxial pulsation fracturing experimental device with one pump for multiple uses, comprising:

[0005] Constant speed and constant pressure pump;

[0006] A transfer valve having a plurality of transfer interfaces, one of which is connected to the constant speed and constant pressure pump;

[0007] A plurality of piston containers are connected one by one with the plurality of transfer interfaces on the transfer valve, wherein a dyeing solution is arranged in one of the piston containers, and hydraulic oil is arranged in the other piston containers;

[0008] A true triaxial device comprises a rectangular cavity and pads respectively arranged on the top surface, bottom surface and four peripheral surfaces of the cavity, wherein the plurality of pads enclose a sample placement space for placing rock samples, a fracturing tube is arranged on the pad located on the top surface of the cavity, and the fracturing tube is connected to the piston container containing a dyeing solution, and hydraulic loading devices are respectively arranged on the pads located on the bottom surface of the cavity and any two perpendicular side walls, and the plurality of hydraulic loading devices are connected to the plurality of piston containers containing hydraulic oil.

[0009] Optionally, the piston container comprises:

[0010] A housing, specifically a sliding chamber, wherein the sliding chamber is provided with a pair of inlets and outlets, and the pair of inlets and outlets are used to connect with the transfer interface and the hydraulic loading device or the fracturing pipe;

[0011] A piston is slidably disposed in the sliding chamber, and the piston is located between a pair of the inlets and outlets;

[0012] The first switch is arranged on the inlet and outlet connected to the transfer interface.

[0013] Optionally, the hydraulic loading device includes:

[0014] A fixed plate, arranged on the backing plate, the end surface of the fixed plate away from the backing plate is provided with a loading cavity, the fixed plate is provided with an injection port connected to the loading cavity, and the injection port is connected to the inlet and outlet of the piston container;

[0015] A loading plate, slidably disposed in the loading cavity;

[0016] A pressure plate is connected to the loading plate, and the pressure plate is used to abut against the rock sample.

[0017] Optionally, the pressing plate is provided with a hole for placing the probe.

[0018] Optionally, a water tank is also included, which is connected to the constant speed and constant pressure pump.

[0019] Optionally, it also includes a vent box connected to one of the transfer interfaces of the transfer valve.

[0020] Optionally, it also includes a pulsation generating device and a control device connected thereto, wherein the pulsation generating device is connected between the piston container having the dyeing solution and the fracturing pipe.

[0021] Optionally, it also includes an acoustic emission data acquisition system, which is connected to a plurality of probes, and the plurality of probes are respectively arranged in the plurality of reserved holes.

[0022] Optionally, a second switch is provided on the transfer interface.

[0023] The present invention also provides a true triaxial pulsation fracturing test method with one pump for multiple uses, comprising:

[0024] The constant speed and constant pressure pump provides the transfer valve with an accurate and stable constant flow rate or a constant pressure aqueous solution;

[0025] The aqueous solution is diverted by a plurality of transfer interfaces so that it can be supplied to a plurality of piston containers respectively, wherein the piston container containing the dyeing solution is pressurized by the aqueous solution so that the dyeing solution can be pumped into the rock sample through the fracturing pipe, and the piston container containing the hydraulic oil is pressurized by the aqueous solution so that the hydraulic oil can be pumped into the hydraulic loading device, so that the hydraulic loading device pressure-loads the rock sample.

[0026] The present invention discloses the following technical effects:

[0027] 1. The constant speed and constant pressure pump provides accurate and stable constant flow rate or constant pressure aqueous solution, and cooperates with the transfer valve to enable the aqueous solution to be pumped into multiple piston containers respectively, to drive the dyeing solution and hydraulic oil, thereby achieving the effect of one pump for multiple uses, effectively reducing the overall complexity of the experimental device, simplifying the experimental system, and reducing equipment and maintenance costs.

[0028] 2. By setting up a fracturing tube connected to the dyeing solution, during the experiment, the dyeing solution is used as the fracturing fluid in the constant speed and pressure pump to fracture the rock sample, and the fracturing cracks are colored, which is convenient for observing and recording the crack conditions and is conducive to the analysis of subsequent experimental results. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 It is a top view of the cavity of the true triaxial device of the present invention;

[0032] Figure 3 It is a structural schematic diagram of the hydraulic loading device of the present invention;

[0033] Figure 4 It is a front view of the fixing plate of the present invention;

[0034] Figure 5 A schematic structural diagram of a piston container of the present invention.

[0035] In the figure: 1. constant speed and constant pressure pump; 2. transfer valve; 3. piston container; 31. sliding chamber; 32. piston; 33. first switch; 4. true three-axis device; 5. pad; 6. rock sample; 7. fracturing pipe; 8. fixed plate; 9. loading chamber; 10. injection port; 11. loading plate; 12. pressure plate; 13. reserved hole; 14. water tank; 15. vent box; 16. pulsation generating device; 17. control device; 18. acoustic emission data acquisition system; 19. second switch. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Reference Figure 1-Figure 5 The present invention provides a true triaxial pulsation fracturing experimental device with one pump for multiple uses, comprising:

[0039] The constant speed and constant pressure pump 1 is used to provide accurate and stable constant flow rate or constant pressure solution, and monitor the flow rate and pressure in real time. The constant speed and constant pressure pump 1 is a double-cylinder pump, which can realize the working modes of constant flow and constant pressure of pump A, constant flow and constant pressure of pump B, and constant flow and constant pressure of pump AB, and stably output water flow to the transfer valve 2;

[0040] The transfer valve 2 has a plurality of transfer interfaces, one of which is connected to a constant speed and constant pressure pump;

[0041] A plurality of piston containers 3 are connected one by one with a plurality of transfer interfaces on the transfer valve 2, wherein a dyeing solution is arranged in one of the piston containers 3, and hydraulic oil is arranged in the other piston containers 3;

[0042] The true triaxial device 4 comprises a rectangular cavity and pads 5 respectively arranged on the top surface, bottom surface and four peripheral surfaces of the cavity, wherein the plurality of pads 5 enclose a sample placement space for placing a rock sample 6, a fracturing tube 7 is arranged on the pad 5 located on the top surface of the cavity, and the fracturing tube 7 is connected to a piston container 3 containing a dyeing solution, and hydraulic loading devices are respectively arranged on the pads 5 located on the bottom surface of the cavity and any two perpendicular side walls, and the plurality of hydraulic loading devices are connected to the plurality of piston containers 3 containing hydraulic oil.

[0043] The constant speed and constant pressure pump 1 provides an accurate and stable constant flow rate or constant pressure aqueous solution, and cooperates with the transfer valve 2, so that the aqueous solution can be pumped into multiple piston containers 3 respectively, to drive the dyeing solution and the hydraulic oil, thereby achieving a one-pump-multiple-purposes effect, effectively reducing the overall complexity of the experimental device, simplifying the experimental system, and reducing equipment and maintenance costs.

[0044] By setting up a fracturing pipe 7 connected to the dyeing solution, during the experiment, the dyeing solution is used as a fracturing fluid in the constant speed and pressure pump 1 to fractur e the rock sample 6, and the fracturing cracks are colored, which is convenient for observing and recording the crack conditions and is conducive to the analysis of subsequent experimental results.

[0045] By arranging hydraulic loading devices on the backing plates 5 located on the bottom surface of the cavity and any two perpendicular side walls, confining pressure and axial pressure on the rock sample 6 can be achieved.

[0046] The true triaxial device 4 is made of high-strength steel as a whole, which can load and stabilize pressure for a long time. It is suitable for the rock sample 6 with a cube size of 240mm*240mm*240mm. The rock sample 6 is pre-set with a circular hole and the fracturing pipe 7 is inserted to seal the hole.

[0047] In one embodiment of the present invention, the piston container 3 comprises:

[0048] The housing, specifically the sliding chamber 31, is provided with a pair of inlets and outlets, and the pair of inlets and outlets are used to connect with the transfer interface and the hydraulic loading device or the fracturing pipe 7;

[0049] A piston 32 is slidably disposed in the sliding chamber 31, and the piston 32 is located between a pair of inlets and outlets;

[0050] The first switch 33 is arranged on the inlet and outlet connected to the transfer interface.

[0051] The first switch 33 can control the connection state between the piston container 3 and the transfer valve 2. The aqueous solution discharged from the transfer valve 2 enters the sliding cavity 31 to push the piston 32 to move, thereby pushing the hydraulic oil or dyeing solvent on the other side of the piston 32 into the true three-axis device 4.

[0052] Furthermore, a negative pressure method is adopted when the hydraulic oil is reset.

[0053] Furthermore, a cover plate is detachably connected to one end of the shell, and the piston 32 can be manually reset by removing the cover plate.

[0054] In one embodiment of the present invention, the hydraulic loading device comprises:

[0055] The fixing plate 8 is arranged on the backing plate 5. The end surface of the fixing plate 8 away from the backing plate 5 is provided with a loading cavity 9. The fixing plate 8 is provided with an injection port 10 connected with the loading cavity 9. The injection port 10 is connected with the inlet and outlet of the piston container 3.

[0056] A loading plate 11 is slidably disposed in the loading cavity 9;

[0057] The pressing plate 12 is connected to the loading plate 11 , and the pressing plate 12 is used to abut against the rock sample 6 .

[0058] By injecting hydraulic oil into the injection port 10, the hydraulic oil drives the loading plate 11 to slide in the loading cavity 9, thereby driving the pressing plate 12 to load the rock sample 6, and the maximum loading stress can reach 30 MPa.

[0059] In one embodiment of the present invention, a hole 13 for placing the probe is provided on the pressing plate 12 .

[0060] In one embodiment of the present invention, a water tank 14 is further included, which is connected to the constant speed and constant pressure pump 1 .

[0061] In one embodiment of the present invention, a vent box 15 is further included, which is connected to one of the transfer interfaces of the transfer valve 2.

[0062] The vent tank 15 can prevent high-pressure water from being placed in the pipeline for a long time and causing damage.

[0063] In one embodiment of the present invention, a pulsation generating device 16 and a control device 17 connected thereto are further included. The pulsation generating device 16 is connected between the piston container 3 containing the dyeing solution and the fracturing tube 7 .

[0064] The pulsation generating device 16 is used to convert the constant current or constant pressure dyeing solution into pulsation and output it. The control device 17 controls and monitors the pulsating pressure in real time. The control device 17 is a computer, which is controlled by the ACTS module control software. The software can adjust the pulsation frequency and pulsation waveform, and adjust the pulsation amplitude through the amplitude adjustment valve. The pulsation number can be applied in the software and the pulsation pressure can be recorded in real time, so as to achieve the effect of precise real-time control and stable output of pulsation.

[0065] In one embodiment of the present invention, an acoustic emission data acquisition system 18 is further included, which is connected to a plurality of probes, and the plurality of probes are respectively disposed in the plurality of holes 13 .

[0066] The acoustic emission data acquisition system 18 acquires the acoustic emission signals of the rock sample 6 fracture through multiple probes to perform real-time dynamic monitoring of the fracture process of the rock sample 6 .

[0067] In one embodiment of the present invention, a second switch 19 is provided on the transfer interface.

[0068] The present invention also provides a true triaxial pulsation fracturing test method with one pump for multiple uses, comprising:

[0069] The constant speed and constant pressure pump 1 provides the transfer valve 2 with an accurate and stable constant flow rate or a constant pressure aqueous solution;

[0070] The aqueous solution is diverted by multiple transfer interfaces so that it can be supplied to multiple piston containers 3 respectively, wherein the piston container 3 with the dyeing solution is pressurized by the aqueous solution so that the dyeing solution can be pumped into the rock sample 6 through the fracturing pipe 7, and the piston container 3 with the hydraulic oil is pressurized by the aqueous solution so that the hydraulic oil can be pumped into the hydraulic loading device, so that the hydraulic loading device pressure-loads the rock sample 6.

[0071] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0072] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A true triaxial pulsation fracturing test device with one pump for multiple uses, characterized in that: include: Constant speed and constant pressure pump (1); A transfer valve (2) having a plurality of transfer interfaces, one of which is connected to the constant speed and constant pressure pump; A plurality of piston containers (3) are connected one by one to the plurality of transfer interfaces on the transfer valve (2), wherein a dyeing solution is arranged in one of the piston containers (3), and hydraulic oil is arranged in the other piston containers (3); A true triaxial device (4) comprises a rectangular cavity and pads (5) respectively arranged on the top surface, bottom surface and four peripheral surfaces of the cavity, wherein a plurality of pads (5) enclose a sample placement space for placing a rock sample (6), a fracturing tube (7) is arranged on the pad (5) located on the top surface of the cavity, and the fracturing tube (7) is connected to the piston container (3) containing a dyeing solution, and hydraulic loading devices are respectively arranged on the pads (5) located on the bottom surface of the cavity and any two perpendicular side walls, and a plurality of the hydraulic loading devices are connected to a plurality of the piston containers (3) containing hydraulic oil.

2. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 1 is characterized in that: The piston container (3) comprises: A housing, specifically a sliding chamber (31), wherein the sliding chamber (31) is provided with a pair of inlets and outlets, wherein the pair of inlets and outlets are used to connect with the transfer interface and the hydraulic loading device or the fracturing pipe (7); A piston (32) is slidably disposed in the sliding chamber (31), wherein the piston (32) is located between a pair of the inlets and outlets; The first switch (33) is arranged on the inlet and outlet connected to the transfer interface.

3. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 2 is characterized in that: The hydraulic loading device includes: A fixed plate (8) is arranged on the backing plate (5), a loading cavity (9) is arranged on the end surface of the fixed plate (8) away from the backing plate (5), an injection port (10) connected to the loading cavity (9) is opened on the fixed plate (8), and the injection port (10) is connected to the inlet and outlet of the piston container (3); A loading plate (11) slidably disposed in the loading cavity (9); A pressure plate (12) is connected to the loading plate (11), and the pressure plate (12) is used to abut against the rock sample (6).

4. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 3 is characterized in that: The pressing plate (12) is provided with a reserved hole (13) for placing the probe.

5. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 1, characterized in that: It also includes a water tank (14) which is in communication with the constant speed and constant pressure pump (1).

6. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 1, characterized in that: It also includes a vent box (15) which is connected to one of the transfer interfaces of the transfer valve (2).

7. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 1, characterized in that: It also includes a pulsation generating device (16) and a control device (17) connected thereto, wherein the pulsation generating device (16) is connected between the piston container (3) containing the dyeing solution and the fracturing tube (7).

8. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 4, characterized in that: It also includes an acoustic emission data acquisition system (18) connected to a plurality of probes, wherein the plurality of probes are respectively arranged in the plurality of reserved holes (13).

9. The one-pump-multi-purpose true triaxial pulsation fracturing test device according to claim 1, characterized in that: The transfer interface is provided with a second switch (19).

10. A one-pump-multi-purpose true triaxial pulsation fracturing test method, based on the one-pump-multi-purpose true triaxial pulsation fracturing test device according to any one of claims 1 to 9, characterized in that: include: The constant speed and constant pressure pump (1) provides the transfer valve (2) with an accurate and stable constant flow rate or a constant pressure aqueous solution; The aqueous solution is diverted by a plurality of transfer interfaces so that the aqueous solution can be supplied to a plurality of piston containers (3) respectively, wherein the piston container (3) containing the dyeing solution is pressurized by the aqueous solution so that the dyeing solution can be pumped into the rock sample (6) through the fracturing pipe (7), and the piston container (3) containing the hydraulic oil is pressurized by the aqueous solution so that the hydraulic oil can be pumped into the hydraulic loading device, so that the hydraulic loading device performs pressure loading on the rock sample (6).

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