A coal rock mass fracturing modification testing device and method integrating drilling and fixing

Abstract

The application discloses a coal rock mass fracturing modification testing device and method, and relates to the technical field of coal rock mass fracturing modification testing. The front end of the drilling fracturing pipe column of the device is provided with a drill bit and is internally provided with a fracturing fluid channel; a sealing air bag is arranged outside the pipe column and can be inflated to adhere to the inner wall of the borehole, and an optical fiber sensor jack is arranged on the air bag; the optical fiber sensor and the electrode plate are respectively connected with a sensing demodulator and a resistivity measuring instrument. The method comprises the following steps: drilling the sample under true triaxial pressure and synchronously monitoring the resistivity; inflating the air bag after drilling to seal the borehole; connecting the optical fiber sensor; injecting fracturing fluid to perform fracturing and synchronously monitoring the strain field and the resistivity change. The application realizes the high integration of drilling, hole sealing, fracturing and multi-physical field monitoring, avoids the disturbance of traditional step-by-step operation on the coal rock, can in-situ, synchronously and high-precisely obtain the strain field evolution information of the whole fracturing process and the fracturing fluid migration and fracture connectivity characteristic information, and significantly improves the test fidelity and efficiency.

Description

Technical Field

[0001] This invention relates to the field of coal and rock mass fracturing modification testing technology, specifically to a drilling-solidification-testing integrated coal and rock mass fracturing modification testing device and method. Background Technology

[0002] Hydraulic fracturing technology is a key means of modifying low-permeability coal and rock formations and enhancing fluid seepage capacity. It plays an important role in safe and efficient coal mining, including efficient coalbed methane extraction, weakening hard roofs to prevent rockbursts, regional outburst mitigation and permeability enhancement, and geostress measurement. The underground geological environment of coal mines is complex. Coal and rock masses are typically heterogeneous, low-strength, easily fractured, and have well-developed natural fractures. Furthermore, they are subject to multiple constraints such as high geostress, high gas pressure, and complex hydrogeological conditions, making it difficult to accurately control and repeatedly verify key hydraulic fracturing process parameters in the field. Therefore, conducting indoor physical simulation experiments has become an indispensable approach for in-depth research on the mechanism of coal and rock hydraulic fracturing and for optimizing fracturing processes.

[0003] Traditional methods for testing fracturing modification of coal and rock masses typically separate drilling, pore solidification / sealing, and monitoring: first, an external drilling rig is used to drill holes in a pre-fabricated coal and rock sample; then, a simulated casing is manually inserted and grout is injected for solidification; and only after solidification are sensors deployed for fracturing. This step-by-step operation mode easily disturbs the fragile coal and rock borehole walls, inducing artificial micro-fractures or even causing borehole wall collapse, damaging the original structure and stress state of the coal and rock. The exothermic effect during the solidification process of the grout also makes it difficult to accurately simulate the downhole temperature, humidity, and stress coupling environment, resulting in a significant difference between the cementation strength at the grout-coal interface and the actual strength. This easily leads to leakage channels or "false sealing" phenomena, affecting the effective injection of fracturing fluid and the authenticity of subsequent monitoring data. In addition, the delayed deployment of sensors makes it impossible to capture in real time, in situ, the initial fracturing moment, fracture propagation morphology, and the coupled response process with gas adsorption / desorption, fracturing fluid migration, and seepage behavior of the coal and rock under high-pressure fluid action.

[0004] Therefore, there is an urgent need for an integrated testing device and method that can be highly integrated in the laboratory to realistically simulate the entire process of drilling-solidification / sealing-fracturing, and simultaneously acquire multi-physical field information on coal and rock mass fracturing modification with high precision, so as to improve the fidelity and experimental efficiency of hydraulic fracturing simulation and provide reliable support for field process optimization and theoretical research. Summary of the Invention

[0005] The purpose of this invention is to provide a drilling-solidification / testing integrated testing device and method for coal and rock mass fracturing modification, which can be highly integrated in the laboratory to realistically simulate the entire process of drilling-solidification / sealing-fracturing, and simultaneously and with high precision monitor and acquire multi-physics field information on coal and rock mass fracturing modification.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A drilling and solidification testing device for testing the fracturing and modification of coal and rock masses, comprising:

[0008] The fracturing string is equipped with a rock-breaking and crushing drill bit at its front end, and a fracturing fluid channel is provided between the fracturing string and the rock-breaking and crushing drill bit.

[0009] The sealing airbag includes an inner bladder layer, an outer bladder layer, and an inflation nozzle arranged in layers. There is a closed cavity between the inner bladder layer and the outer bladder layer, and the inflation nozzle is connected to the closed cavity. The inner bladder layer is fitted onto the outer wall of the drilling fracturing string, and several fiber optic sensor sockets are opened on the outer bladder layer.

[0010] Among them, the air inlet is connected to the air pump via the air inlet pipeline. The air pump inflates the closed cavity through the air inlet, which can inflate the sealing airbag. The outer bladder layer is used to fit the inner wall of the borehole.

[0011] The fiber optic sensor is installed in the fiber optic sensor jack and connected to the optical frequency domain distributed sensing demodulator via a fiber optic signal cable.

[0012] Electrode plates are arranged in pairs and connected to a resistivity measuring instrument via a resistance signal cable.

[0013] Furthermore, the outer wall of the drilling and fracturing tubing is provided with several first annular step structures, and the inner wall of the inner bladder layer is provided with several second annular step structures that cooperate with the first annular step structures.

[0014] Furthermore, the outer wall of the drilling fracturing string is provided with a limiting groove along the axial direction, and the inner wall of the inner bladder layer is provided with a limiting protrusion along the axial direction that cooperates with the limiting groove.

[0015] Furthermore, when the sealing airbag is not inflated, the outer diameter of the sealing airbag is smaller than the outer diameter of the rock-breaking and pulverizing drill bit.

[0016] Furthermore, an electrode plate is connected to the rear end of the drilling fracturing string via a bridging wire.

[0017] Furthermore, the rock-breaking and pulverizing drill bit is equipped with a rock-breaking cutter head and a pulverizing cutter head.

[0018] Furthermore, an air-filling channel is opened along the axial direction at the rear end of the drilling fracturing string, with one end of the air-filling channel connected to an air-filling nozzle and the other end of the air-filling channel connected to an air-filling pipeline.

[0019] Furthermore, the rear end of the drilling fracturing string is provided with an assembly part that connects to the shaft of the core drilling machine and / or the fracturing pipeline.

[0020] A method for testing the fracturing modification of coal and rock mass, using the aforementioned integrated drilling, solidification, and testing device for testing the fracturing modification of coal and rock mass, comprises the following steps:

[0021] S1. Connect the rear end of the fracturing string to the shaft of the core drilling machine, align the rock-breaking and crushing drill bit with the center of the coal and rock mass sample surface, and install electrode plates on the opposite side of the coal and rock mass sample. The electrode plates are connected to the resistivity measuring instrument via a resistance signal cable.

[0022] S2. Place the coal and rock mass sample in a true triaxial pressure chamber and apply triaxial confining pressure to the coal and rock mass sample;

[0023] S3. Start the core drilling machine to drill the coal and rock mass sample, and simultaneously start the resistivity measuring instrument to monitor the cracks in the coal and rock mass sample or the borehole collapse in real time.

[0024] S4. After drilling the coal and rock mass sample to the set depth, stop. The air pump is connected to the air nozzle through the air pump pipeline. The air pump inflates the sealed cavity to make the sealing airbag expand to fit the inner wall of the borehole.

[0025] S5. Connect the fiber optic sensor to the optical frequency domain distributed sensor demodulator via a fiber optic signal cable.

[0026] S6. Connect the rear end of the drilled fracturing string to the fracturing pump via fracturing pipeline. The fracturing fluid delivered by the fracturing pump is applied to the coal and rock mass sample via fracturing pipeline and fracturing fluid channel. Simultaneously start the resistivity measuring instrument to monitor the fracturing fluid seepage area in the coal and rock mass sample in real time, and simultaneously start the optical frequency domain distributed sensor demodulator to monitor the three-dimensional morphological distribution of the fractures in the coal and rock mass sample in real time.

[0027] S7. After fracturing is completed, release the pressure of the packer airbag, remove the drilling fracturing string and packer airbag, and proceed to the next set of tests.

[0028] Furthermore, in S4, the drilling fracturing string is pulled outward to a set height relative to the borehole so that a closed pressure-locking space is formed between the rock-breaking drill bit and the inner end of the borehole.

[0029] Compared with existing technologies, this invention integrates drilling, hole solidification / sealing, fracturing, and multi-physics field monitoring functions, achieving a high degree of integration and full-process simulation of indoor testing for fracturing and modification of coal and rock masses, and achieving the following significant technical effects:

[0030] 1. This invention significantly improves the fidelity and reliability of experimental testing. The continuous drilling, borehole solidification / sealing, and fracturing operations avoid secondary disturbance to the fragile coal and rock borehole walls caused by traditional step-by-step operations, effectively maintaining the original structure and stress state of the coal and rock. The controllable expansion and sealing of the sealing airbag simulates the downhole solidification / sealing environment. Its flexibility and adaptive fitting characteristics reduce the problem of incomplete interface bonding caused by grouting heat release and shrinkage, greatly reducing the risk of "false sealing" and fracturing fluid leakage, ensuring effective pressure buildup and directional injection of fracturing fluid, thus realistically reproducing the boundary conditions of downhole fracturing.

[0031] 2. This invention achieves in-situ, synchronous, and high-precision capture of multi-physics field information throughout the entire fracturing process. Fiber optic sensors are pre-embedded in the containment gasbag and adhere tightly to the borehole wall as it expands. Combined with distributed demodulation technology, this enables real-time, continuous, and three-dimensional monitoring of the strain field evolution of the coal and rock mass from the very beginning of fracturing, accurately capturing the initial fracturing initiation point, the three-dimensional expansion morphology of the fractures, and the dynamic process. The resistivity monitoring system, through electrode plates, achieves synchronous electrical response monitoring of the fracturing fluid seepage range and the fracture network. The integration of multiple sensor types further constructs a coupled monitoring network of strain, seepage, and other multi-physics fields, providing rich, synchronous, and high-resolution data support for a comprehensive understanding of the fracturing mechanism.

[0032] 3. This invention significantly optimizes the experimental process and efficiency. The integrated design of drilling, borehole solidification / sealing, fracturing, and monitoring simplifies equipment conversion and sample handling, avoiding the loss of time windows caused by delayed sensor deployment. The device has a compact structure and seamless operation, completing the entire process from drilling to fracturing monitoring in a single test, significantly shortening the test cycle and enhancing repeatability and comparability. This facilitates rapid, batch comparative tests under different geological conditions and process parameters, strongly supporting the optimization of fracturing processes and the verification of theoretical models.

[0033] In summary, the integrated drilling and solidification testing device and method provided by this invention achieves high-fidelity, high-efficiency, and high-information physical simulation of the hydraulic fracturing process in coal mines under laboratory conditions, providing a powerful and innovative experimental means and a reliable data foundation for in-depth research on the fracturing and modification mechanism of coal and rock masses and optimization of on-site construction technology. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the integrated drilling and testing device for coal and rock fracturing modification according to an embodiment of the present invention;

[0035] Figure 2 This is a perspective view of the drilling and fracturing tubing string and rock-breaking and crushing drill bit according to an embodiment of the present invention;

[0036] Figure 3 This is a half-sectional view of the drilling and fracturing string and the rock-breaking and crushing drill bit according to an embodiment of the present invention.

[0037] Figure 4 This is a half-sectional view of the sealing airbag according to an embodiment of the present invention;

[0038] in,

[0039] 1. Drilling fracturing string; 11. Limiting slot; 12. Inflation channel; 13. Assembly section; 2. Sealing airbag; 21. Sealed cavity; 22. Inflation nozzle; 23. Fiber optic sensor socket; 24. Limiting protrusion; 3. Electrode plate; 4. Fiber optic signal cable; 5. Resistance signal cable; 6. Bridging wire; 7. Resistivity meter; 8. Optical frequency domain distributed sensor demodulator; 9. Rock breaking and crushing drill bit; 91. Rock breaking cutter head; 92. Crushing cutter head. Detailed Implementation

[0040] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Certain embodiments of the invention will be described more fully below with reference to the accompanying drawings, and some, but not all, of these embodiments will be shown. In fact, various embodiments of the invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to enable the invention to meet applicable legal requirements.

[0041] In the description of this invention, it should be noted that the terms "inner," "outer," "upper," "lower," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In this embodiment of the invention, a drilling-solidification-testing integrated testing device and method for coal and rock mass fracturing modification is provided. Please refer to [reference needed]. Figures 1 to 4 As shown.

[0043] A drilling and solidification testing device for coal and rock fracturing modification includes a drilling and fracturing string 1, a sealing airbag 2, a fiber optic sensor, an optical frequency domain distributed sensor demodulator 8, an electrode plate 3, and a resistivity meter 7.

[0044] The drilling and fracturing string 1 is made of high-strength alloy steel. A rock-breaking and crushing drill bit 9 is located at the front end of the drilling and fracturing string 1, and a fracturing fluid channel is located between the drilling and fracturing string 1 and the rock-breaking and crushing drill bit 9. The interior of the drilling and fracturing string 1 is a hollow cavity, and a through hole is left between the front and rear ends of the rock-breaking and crushing drill bit 9. The connected hollow cavity and through hole constitute the fracturing fluid channel.

[0045] The sealing airbag 2 includes an inner bladder layer, an outer bladder layer, and an inflation nozzle 22 arranged in layers. The inner and outer bladder layers are made of highly elastic, pressure-resistant rubber, and a closed cavity 21 is formed between the inner and outer bladder layers. The inflation nozzle 22 communicates with the closed cavity. The inner bladder layer is fitted onto the outer wall of the drilling fracturing string 1, and several fiber optic sensor sockets 23 are formed on the outer bladder layer. In this embodiment, there are 40 fiber optic sensor sockets 23, each extending along the axial direction of the drilling fracturing string 1, and the 40 fiber optic sensor sockets 23 are arranged at equal intervals along the circumference. This allows the fiber optic sensors to be uniformly arranged around the perimeter in space. After the fiber optic sensors in the fiber optic sensor sockets 23 are attached to the inner wall of the borehole of the coal and rock mass sample, the fiber optic sensors can collect three-dimensional spatial strain data of the coal and rock mass sample from all directions.

[0046] The air inlet 22 is connected to an air pump via an air inlet pipe. The air pump inflates the sealed cavity 21 through the air inlet, causing the sealing airbag 2 to expand. After the sealing airbag 2 expands, the outer layer of the airbag can adhere to the inner wall of the borehole. The outer layer of the airbag adheres to the inner wall of the borehole to achieve the hole solidification / sealing operation.

[0047] Each fiber optic sensor jack 23 houses a fiber optic sensor, which is connected to the optical frequency domain distributed sensing demodulator 8 via an optical fiber signal cable 4. The fiber optic sensor is an OSI-S series sensing fiber, and the optical frequency domain distributed sensing demodulator 8 is a Luna ODiSI 6100.

[0048] Electrode plate 3 is a 300mm × 300mm copper plate. Electrode plates 3 are arranged in pairs. Electrode plates 3 are connected to resistivity measuring instrument 7 via resistance signal cable 5. The rear end of the drilling fracturing string 1 is connected to an electrode plate 3 via bridging wire 6. The bridging wire 6 is made of silver-plated copper wire to reduce resistance. By connecting an electrode plate 3 to the drilling fracturing string 1 via bridging wire 6, a stable electric field can be generated between the coal and rock mass sample, the drilling fracturing string 1, and the electrode plate 3. This effectively prevents drastic changes in resistance and data distortion caused by the continuous deepening of the drilling fracturing string 1 during drilling, greatly reduces external interference, obtains a stable initial resistance, and improves monitoring accuracy.

[0049] Both the outer side of the sealing airbag 2 and the outer side of the electrode plate 3 are covered with a 0.1 mm thick polytetrafluoroethylene insulating film to prevent the contact voltage from affecting the test results.

[0050] The outer wall of the drilling fracturing string 1 is provided with several first annular step structures, and the inner wall of the inner bladder layer is provided with several second annular step structures. The second annular step structures cooperate with the first annular step structures. By cooperating with the first annular step structures, the axial displacement of the sealing airbag 2 relative to the drilling fracturing string 1 is restricted when the sealing airbag 2 is not inflated.

[0051] A limiting groove 11 is formed along the axial direction on the outer wall of the drilling fracturing string 1, and a limiting protrusion 24 is formed along the axial direction on the inner wall of the inner bladder layer. The limiting protrusion 24 cooperates with the limiting groove 11. By cooperating with the limiting groove 11, the displacement of the sealing airbag 2 relative to the drilling fracturing string 1 in the circumferential direction is restricted when the sealing airbag 2 is not inflated.

[0052] When the core drill drives the rock-breaking drill bit 9 to drill into the coal and rock sample via the drilling and fracturing string 1, avoid rotating the drilling and fracturing string 1 relative to the sealing airbag 2, which would cause wear of the inner bladder layer of the sealing airbag 2.

[0053] When the sealing airbag 2 is not inflated, its outer diameter is smaller than that of the rock-breaking drill bit 9. Thus, when the rock-breaking drill bit 9 drills into the coal and rock sample, the sealing airbag 2 does not contact the borehole wall, preventing wear on the outer layer of the sealing airbag 2.

[0054] The rock-breaking and crushing drill bit 9 is equipped with two rock-breaking cutter heads 91 and two crushing cutter heads 92. The rock-breaking cutter heads 91 are used to cut the coal and rock mass sample to form a borehole, and the crushing cutter heads 92 are used to crush the coal and rock chips cut by the rock-breaking cutter heads 91.

[0055] An air inlet channel 12 is opened along the axial direction at the rear end of the drilling fracturing string 1. One end of the air inlet channel 12 is connected to the air inlet nozzle 22, and the other end of the air inlet channel 12 is connected to the air inlet pipeline.

[0056] An assembly section 13 is provided at the rear end of the drilling and fracturing string 1. The assembly section 13 is connected to the shaft of the core drilling machine and / or the fracturing pipeline. In this embodiment, the assembly section 13 is provided with a threaded hole, which is connected to the shaft of the core drilling machine, or connected to the fracturing pipeline through a union with a built-in one-way valve.

[0057] A method for testing the fracturing modification of coal and rock mass, using the integrated drilling, solidification, and testing device for testing the fracturing modification of coal and rock mass described in this embodiment, includes the following steps:

[0058] S1. Connect the assembly part 13 at the rear end of the fracturing string 1 to the shaft of the core drilling machine, so that the rock breaking and crushing drill bit 9 is aligned with the center position of the coal and rock mass sample surface. Install electrode plates 3 on the opposite side of the coal and rock mass sample. The electrode plates 3 are connected to the resistivity measuring instrument 7 via the resistance signal cable 5. One electrode plate 3 is connected to the rear end of the fracturing string 1 via the bridging wire 6.

[0059] S2. Place a 300mm×300mm×300mm coal-rock mass sample in a true triaxial pressure chamber and apply triaxial confining pressure (σ) to the coal-rock mass sample. H =12MPa, σ h =8MPa, σ v=10MPa), to simulate the underground stress environment of coal and rock masses.

[0060] S3. Start the core drilling machine to drill the coal and rock mass sample. The drilling speed of the core drilling machine is 200 rpm. Simultaneously start the resistivity measuring instrument 7. The resistivity measuring instrument 7 collects data at a frequency of 1 time / second. By monitoring the sudden change in the resistivity of the coal and rock mass sample (for example, the rate of change exceeds 5%), the instrument monitors the cracks or borehole collapse of the coal and rock mass sample in real time and records the drilling depth-resistivity curve.

[0061] By monitoring the fractures or borehole collapse of coal and rock mass samples during the drilling process, the actual fracturing conditions of coal and rock mass can be matched. Specifically, before the fracturing operation, coal and rock mass samples with predetermined geological conditions are drilled with predetermined drilling parameters to determine whether fractures are generated and to determine the fracture area when fractures are generated, thereby differentiating the fractures and fracture areas generated by subsequent fracturing operations on the coal and rock mass samples.

[0062] S4. After drilling the coal and rock mass sample to the set depth (160mm), stop and disassemble the core drilling machine. Using an air pump with a pressure gauge, connect the air pump to the air nozzle 22 via the air pump through the air pump pipeline and air pump channel 12. Inflate nitrogen into the sealed cavity 21 through the air pump, causing the sealing airbag 2 to expand and adhere to the inner wall of the borehole. The inflation pressure is stabilized at 2 MPa. The expansion of the sealing airbag 2 to adhere to the inner wall of the borehole achieves the borehole solidification / sealing operation. At the same time, it causes the fiber optic sensor in the fiber optic sensor socket 23 to adhere to the inner wall of the borehole.

[0063] When the inflation pressure of the sealing airbag 2 is low, the drilling fracturing string 1 is pulled outwards by a set height (10mm) relative to the borehole to create a closed pressure-sealed space between the rock-breaking drill bit 9 and the inner end of the borehole. This allows the fracturing fluid to accumulate in the pressure-sealed space and continue to diffuse into the coal and rock mass sample during subsequent fracturing processes, preventing the fracturing fluid from directly penetrating the sidewall of the drilling fracturing string 1 or the space between the sealing airbag 2 and the inner wall of the borehole, thereby avoiding equipment damage or borehole sealing failure.

[0064] S5. Connect the fiber optic sensor to the optical frequency domain distributed sensing demodulator 8 via fiber optic signal cable 4.

[0065] S6. Connect the rear end of the drilling fracturing string 1 to the fracturing pump via fracturing pipeline. The fracturing pump outputs fracturing fluid at a constant flow rate of 30 mL / min. The fracturing fluid delivered by the fracturing pump is used to apply fracturing to the coal and rock mass sample through the fracturing pipeline and fracturing fluid channel. Simultaneously, start the resistivity meter 7, which collects data at a frequency of 1 time / second. By monitoring abrupt changes in the resistivity of the coal and rock mass sample (e.g., a change rate exceeding 5%), record the change in resistivity of the coal and rock mass sample over time and monitor the fracturing fluid seepage area within the coal and rock mass sample in real time. Simultaneously, start the optical frequency domain distributed sensor demodulator 8, which collects strain data at a frequency of 100 Hz to monitor the three-dimensional morphological distribution of fractures in the coal and rock mass sample in real time. The spatial resolution of the fractures reaches 1 mm, which can accurately capture the fracture initiation location (strain concentration point), propagation, and closure path.

[0066] Among them, resistivity data collected by resistivity meter 7 and strain data collected by optical frequency domain distributed sensor demodulator 8 can be mutually verified, further improving the accuracy of monitoring.

[0067] When the pressure of the fracturing fluid delivered by the fracturing pump reaches a peak and then drops sharply, it indicates that the main fracture has formed. Fracturing should be stopped once the fracturing fluid pressure stabilizes. A pressure sensor is installed at the output of the fracturing pump or on the fracturing pipeline to monitor the fracturing fluid pressure.

[0068] S7. After fracturing is completed, release the pressure of the packer 2, remove the drilling fracturing string 1 and the packer 2, and proceed with the next set of tests.

[0069] The present invention has been described in detail above with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the integrated drilling and testing device and method for coal and rock fracturing modification of the present invention. Of course, the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drilling-solidification-testing integrated testing device for coal and rock mass fracturing modification, characterized in that, include: The drilling fracturing string has a rock-breaking and crushing drill bit at its front end. Several first annular step structures are set on the outer wall of the drilling fracturing string. A limiting groove is opened along the axial direction on the outer wall of the drilling fracturing string. A fracturing fluid channel is set in the middle of the drilling fracturing string and the rock-breaking and crushing drill bit. The sealing airbag includes an inner bladder layer, an outer bladder layer, and an inflation nozzle arranged in layers. The inner wall of the inner bladder layer is provided with several second annular step structures that cooperate with the first annular step structure. The inner wall of the inner bladder layer is provided with limiting protrusions along the axial direction that cooperate with limiting slots. There is a closed cavity between the inner bladder layer and the outer bladder layer. The inflation nozzle is connected to the closed cavity. The inner bladder layer is sleeved on the outer wall of the drilling fracturing string. Several fiber optic sensor sockets are opened on the outer bladder layer. Among them, the air inlet is connected to the air pump via the air inlet pipeline. The air pump inflates the closed cavity through the air inlet, which can inflate the sealing airbag. The outer bladder layer is used to fit the inner wall of the borehole. The fiber optic sensor is installed in the fiber optic sensor jack and connected to the optical frequency domain distributed sensing demodulator via a fiber optic signal cable. Electrode plates are arranged in pairs and connected to a resistivity measuring instrument via a resistance signal cable.

2. The integrated drilling and testing device for coal and rock fracturing modification according to claim 1, characterized in that, When the sealing airbag is not inflated, the outer diameter of the sealing airbag is smaller than the outer diameter of the rock-breaking and crushing drill bit.

3. The integrated drilling and testing device for coal and rock fracturing modification according to claim 1, characterized in that, An electrode plate is connected to the rear end of the drilling fracturing string via a bridging wire.

4. The integrated drilling and testing device for coal and rock fracturing modification according to claim 1, characterized in that, The rock-breaking and crushing drill bit is equipped with a rock-breaking cutter head and a crushing cutter head.

5. The integrated drilling and testing device for coal and rock fracturing modification according to claim 1, characterized in that, An air-filling channel is opened along the axial direction at the rear end of the drilling fracturing string. One end of the air-filling channel is connected to an air-filling nozzle, and the other end of the air-filling channel is connected to an air-filling pipeline.

6. The integrated drilling and testing device for coal and rock fracturing modification according to claim 1, characterized in that, The rear end of the drilling and fracturing string is provided with an assembly part that connects to the shaft of the core drilling machine and / or the fracturing pipeline.

7. A coal rock mass fracturing modification test method, applying the drilling and cementing integrated coal rock mass fracturing modification test device according to any one of claims 1 to 6, characterized in that, The method steps are as follows: S1. Connect the rear end of the fracturing string to the shaft of the core drilling machine, align the rock-breaking and crushing drill bit with the center of the coal and rock mass sample surface, and install electrode plates on the opposite side of the coal and rock mass sample. The electrode plates are connected to the resistivity measuring instrument via a resistance signal cable. S2. Place the coal and rock mass sample in a true triaxial pressure chamber and apply triaxial confining pressure to the coal and rock mass sample; S3. Start the core drilling machine to drill the coal and rock mass sample, and simultaneously start the resistivity measuring instrument to monitor the cracks in the coal and rock mass sample or the borehole collapse in real time. S4. After drilling the coal and rock mass sample to the set depth, stop. The air pump is connected to the air nozzle through the air pump pipeline. The air pump inflates the sealed cavity to make the sealing airbag expand to fit the inner wall of the borehole. S5. Connect the fiber optic sensor to the optical frequency domain distributed sensor demodulator via a fiber optic signal cable. S6. Connect the rear end of the drilled fracturing string to the fracturing pump via fracturing pipeline. The fracturing fluid delivered by the fracturing pump is applied to the coal and rock mass sample via fracturing pipeline and fracturing fluid channel. Simultaneously start the resistivity measuring instrument to monitor the fracturing fluid seepage area in the coal and rock mass sample in real time, and simultaneously start the optical frequency domain distributed sensor demodulator to monitor the three-dimensional morphological distribution of the fractures in the coal and rock mass sample in real time. S7. After fracturing is completed, release the pressure of the packer airbag, remove the drilling fracturing string and packer airbag, and proceed to the next set of tests.

8. The method for testing the fracturing modification of coal and rock mass according to claim 7, characterized in that, In S4, the drilling fracturing string is pulled outward to a set height relative to the borehole to create a closed pressure-locking space between the rock-breaking drill bit and the inner end of the borehole.

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