Coal rock stratum hydraulic slotting and fracturing combined operation device and operation method

Abstract

The invention provides a coal rock stratum hydraulic slotting and fracturing combined operation device and method, and the device comprises a drill bit which is arranged at the front end of the device and is used for drilling through a coal rock stratum to form a deep drill hole; an annular hollow rotating holder is mounted on the periphery of the composite multifunctional pipeline, and a water jet nozzle is mounted on the rotating holder; the two expandable high-pressure water bags are used for sealing a preset area in the deep drill hole in an expanded state, so that a closed space is formed between the two high-pressure water bags; the fracturing water outlet is formed between the two high-pressure water bags; and the multi-way valve is arranged on the composite multifunctional pipeline and used for controlling the flowing path of the high-pressure liquid, and the flowing path comprises any one or more of the two high-pressure water bags, the water jet nozzles and the fracturing water outlets for controlling the high-pressure liquid to flow to the two high-pressure water bags. According to the scheme, hydraulic slotting and fracturing combined operation is achieved, the slotting angle and range are accurately adjusted, the operation process is integrated, and the accuracy and continuity of hydraulic fracturing operation are improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a coal-rock stratum hydraulic fracturing and hydraulic fracture combined operation device and operation method. Background Art

[0002] In the field of coal mining, hydraulic fracturing technology has been widely used in recent years as a key method to improve gas extraction efficiency. However, under complex coal seam geological conditions, the existing hydraulic fracturing technology faces many challenges, which significantly affect its application effect and operation safety.

[0003] First, the geological characteristics of coal seams are complex and changeable, and key factors such as coal quality and ground stress vary significantly between different regions. This inconsistency in geological conditions increases the difficulty of controlling the direction, length and height of crack expansion, which may lead to uneven crack expansion and affect the effect of gas extraction. Especially in areas with complex geological structures, cracks may extend disorderly along weaker strata, and current hydraulic fracturing equipment lacks the ability to accurately adjust the angle and range of hydraulic drilling and cutting, making it difficult to effectively deal with this problem.

[0004] Secondly, in the prior art, hydraulic cutting and hydraulic fracturing are two independent operation stages, and the two have not yet achieved integrated operation. Usually, after the hydraulic cutting is completed, the pipeline or drill pipe needs to be pulled out to replace the equipment before the hydraulic fracturing work can continue. Such an operation process not only increases the complexity and time cost of the construction, but also reduces the work efficiency to a certain extent, and puts higher requirements on the safety of the overall operation. Summary of the invention

[0005] The present invention provides a coal rock stratum hydraulic cutting and fracturing combined operation device and operation method, which are used to solve the defects of the prior art that crack expansion is difficult to control and the operation process is complicated, and can achieve precise adjustment of the cutting angle and range, integrated operation process, and improve the accuracy and continuity of hydraulic fracturing operations.

[0006] The present invention provides a combined hydraulic fracturing and hydraulic fracture operation device for coal and rock formations, comprising: a drill bit, arranged at the front end of the device, for drilling through the coal and rock formations to form a deep borehole; a composite multifunctional pipeline, on the periphery of which is installed an annular hollow rotating platform, on which is installed a water jet nozzle; two expandable high-pressure water bags, for sealing a predetermined area in the deep borehole in an expanded state to form a closed space between the two high-pressure water bags; a hydraulic fracturing outlet, arranged between the two high-pressure water bags; a multi-channel valve, arranged on the composite multifunctional pipeline, for controlling the flow path of the high-pressure liquid, the flow path comprising controlling the high-pressure liquid to flow to any one or more of the two high-pressure water bags, the water jet nozzle, and the hydraulic fracturing outlet.

[0007] According to one embodiment of the present invention, a micro-stepping motor is included; the rotating pan-tilt platform is transmission-coordinated with the micro-stepping motor so as to control the rotation angle and rotation speed of the rotating pan-tilt platform within an angle range of 360° through the micro-stepping motor.

[0008] According to one embodiment of the present invention, a pressure sensor is provided between the two high-pressure water bags to monitor the pressure changes in the closed space in real time during the fracturing process; and / or a flow sensor is provided at the fracturing water outlet to monitor the amount of liquid used in the fracturing process in real time.

[0009] According to one embodiment of the present invention, the composite multifunctional pipeline is equipped with a variable frequency control system, and the variable frequency control system is used to adapt to different liquid output pressure requirements of the hydraulic slotting process and the hydraulic fracturing process by adjusting the output pressure.

[0010] According to one embodiment of the present invention, a plurality of microseismic sensors are included, and the plurality of microseismic sensors are distributed in the plurality of deep boreholes for detecting the location of earthquake sources generated during the fracturing process.

[0011] The present invention also provides a method for combined hydraulic fracturing and hydraulic cutting of coal rock formations, which is used to control the combined hydraulic fracturing and hydraulic cutting device of the coal rock formation in the above-mentioned embodiment, and the operation method includes: sending the operation device into a deep borehole of a predetermined depth; detecting coal rock formation information; determining the direction of the area to be fracturing according to the coal rock formation information; adjusting the angle of the water jet nozzle according to the direction of the area to be fracturing, and performing hydraulic fracturing operations; inflating two high-pressure water bags to seal the inner wall of the deep borehole to form a closed space; injecting high-pressure liquid into the closed space to implement directional hydraulic fracturing.

[0012] According to one embodiment of the present invention, the coal rock formation information includes fracturing fracture detection information; in the step of determining the direction of the area to be fracturing based on the coal rock formation information, it includes: using 10kHz-1MHz low-frequency electromagnetic waves to roughly identify the distribution range of coal rock formation fractures; using 1MHz-100MHz medium-frequency electromagnetic waves to detect large-scale fractures of medium depth in coal rock formation fractures; using 100MHz-1GHz high-frequency electromagnetic waves to accurately detect shallow coal rock formation fractures; completing graphical mapping of the overall coal rock formation fractures to guide the positioning of the water jet nozzle.

[0013] According to one embodiment of the present invention, after the step of forming a closed space, the method includes: monitoring the pressure and flow parameters in the closed space in real time; and determining the progress of the hydraulic fracturing process according to the pressure and flow parameters.

[0014] According to one embodiment of the present invention, in the step of injecting high-pressure liquid into the closed space to implement directional hydraulic fracturing, the step includes: adjusting the flow rate of the fracturing pump through a frequency converter according to the pressure and flow parameters; wherein, when the pressure and flow parameters have not reached the preset values, adjusting the fracturing pump to a high-speed and low-torque working state to perform large-flow rapid water injection; after the pressure and flow parameters reach the preset values, adjusting the fracturing pump to a low-speed and high-torque working state to perform the hydraulic fracturing process.

[0015] According to one embodiment of the present invention, microseismic information is continuously detected during the entire operation process, and the location of the earthquake source generated during the hydraulic fracturing process is determined based on the microseismic information.

[0016] The coal-rock stratum hydraulic cutting and fracturing combined operation device and operation method provided by the present invention realizes the flexible adjustment of the angle of the water jet nozzle through the integrated composite multifunctional pipeline and rotating pan-tilt design, ensuring that the direction, length and range of the cutting can be accurately controlled under complex geological conditions; at the same time, two expandable high-pressure water bags are used to form a closed space, so that directional hydraulic fracturing can be carried out in a preset area, effectively solving the problem of disordered crack expansion. In addition, the application of multi-channel valves realizes the rapid switching of high-pressure liquid flow paths, supports the continuous hydraulic cutting and fracturing operations without changing equipment, greatly simplifies the operation process, improves work efficiency and safety, and thus improves the accuracy and continuity of hydraulic fracturing operations as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a system schematic diagram of the coal rock stratum hydraulic cutting and fracturing combined operation device provided by the present invention.

[0019] Figure 2 It is a schematic diagram of the hydraulic fracturing and hydraulic fracturing combined operation principle of the coal rock stratum hydraulic fracturing and hydraulic fracturing combined operation method provided by the present invention.

[0020] Figure 3 It is a schematic diagram of the principle of earthquake source position detection in the coal rock stratum hydraulic cutting and fracturing combined operation method provided by the present invention.

[0021] Figure 4 It is a schematic diagram of the principle of fracture detection in the combined hydraulic fracture and fracturing method of coal rock strata provided by the present invention.

[0022] Figure 5 It is a schematic flow diagram of the combined operation method of hydraulic fracturing and hydraulic fracturing in coal and rock formations provided by the present invention.

[0023] Reference numerals: 10. Composite multifunctional pipeline; 11. Drill bit; 12. Pan-tilt head; 13. Water jet nozzle; 14. High-pressure water bag; 15. Fracturing water outlet; 16. Multi-channel valve; 17. Micro stepping motor; 20. Controller. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0026] Coal mines face challenges brought by high-gas and low-permeability coal seams during mining operations, which makes gas extraction inefficient, prolongs the compliance period, and increases the risk of coal and gas outbursts. To solve these problems, hydraulic fracturing technology is widely used. This technology expands and connects the original fractures in the coal body to form a fracture network, improves the permeability of the coal seam, thereby promoting gas desorption, improving extraction efficiency, and shortening the compliance time. In addition, the high-pressure liquid injected during hydraulic fracturing can increase the water content of the coal seam, reduce the elastic properties of the coal body, change the stress distribution, and reduce the risk of coal and gas outbursts. At the same time, due to the strong adsorption capacity of water molecules on the coal matrix, they can displace and replace the methane molecules originally adsorbed in the pores of the coal body, further increasing the amount of gas extraction. For hard roofs, hydraulic fracturing can weaken its structure by creating cracks to prevent safety accidents caused by sudden collapse.

[0027] As a pre-step of hydraulic fracturing, hydraulic fracturing uses high-pressure water jets to cut the coal body to increase the exposed area of ​​the coal body, improve the desorption and seepage conditions of gas, and adjust the stress distribution inside the coal body to reduce the risk of disasters. Hydraulic fracturing, on the other hand, is to inject high-pressure liquid to open the original cracks and create new cracks after drilling, thereby enhancing the permeability of the coal seam and the fluidity of gas, while also changing the mechanical properties of the coal body and reducing the risk of outbursts.

[0028] On this basis, the present invention provides a coal rock stratum hydraulic cutting and fracturing combined operation device and operation method, which are used to realize the hydraulic cutting and fracturing combined operation, and to achieve precise adjustment of the cutting angle and range, integrated operation process, and improve the accuracy and continuity of hydraulic fracturing operations.

[0029] Combine the following Figure 1 The specific implementation of the coal rock stratum hydraulic fracture and fracturing combined operation device of the present invention is described.

[0030] The present invention provides a combined hydraulic cutting and fracturing device for coal and rock formations, comprising: a drill bit 11, arranged at the front end of the device, used to drill through the coal and rock formations to form a deep borehole; a composite multifunctional pipeline 10, on the periphery of which is mounted an annular hollow rotating platform 12, on which is mounted a water jet nozzle 13; two expandable high-pressure water bags 14, used to seal a predetermined area in the deep borehole in an expanded state, so as to form a closed space between the two high-pressure water bags 14; a fracturing water outlet 15, arranged between the two high-pressure water bags 14; and a multi-channel valve 16, arranged on the composite multifunctional pipeline 10, used to control the flow path of the high-pressure liquid, the flow path including controlling the high-pressure liquid to flow to any one or more of the two high-pressure water bags 14, the water jet nozzle 13, and the fracturing water outlet 15. The device realizes the integrated operation of hydraulic cutting and fracturing, improves the accuracy and continuity of hydraulic fracturing operation by precisely controlling the cutting angle and range, and using the high-pressure water bags 14 to form a closed space for directional fracturing.

[0031] Specifically, the drill bit 11 is located at the front end of the device and is responsible for drilling through the coal and rock layers to form a deep borehole, providing the necessary channels for subsequent hydraulic cutting and fracturing operations. The composite multifunctional pipeline 10 is the key path for transporting high-pressure liquids in the entire system. An annular hollow rotating platform 12 is installed on its periphery, which can accurately adjust the angle. A water jet nozzle 13 is installed on the rotating platform 12 for performing hydraulic cutting operations. The working mode selected by the controller 20 (i.e., hydraulic cutting mode or hydraulic fracturing mode) can flexibly control the angle and direction of the water jet nozzle 13 to meet the operating requirements under different geological conditions.

[0032] The high-pressure water bag 14 is located inside the deep borehole and can seal a predetermined area in an expanded state. By creating a closed space between the two water bags, it is ensured that when directional hydraulic fracturing is implemented, the pressure only acts on the expected target area, which not only improves the accuracy of fracturing, but also reduces unnecessary impacts on the surrounding rock mass. The fracturing outlet 15 is set at a position between the two high-pressure water bags 14. When the multi-way valve 16 is switched to the fracturing mode, high-pressure liquid is injected into the closed interval. As the amount of water increases, the pressure in the closed interval gradually rises, prompting the cylindrical space formed by the water jet or the fan-shaped / circular space formed by the hydraulic slit to preferentially produce cracks, thereby achieving the effect of directional fracturing.

[0033] The multi-way valve 16 is responsible for managing the flow path of the high-pressure liquid. According to different operation stages, the liquid can be accurately directed to any one or more targets among the water jet nozzle 13, the two high-pressure water bags 14 or the fracturing outlet 15. For example, in the hydraulic fracturing stage, the multi-way valve 16 will direct the liquid to the water jet nozzle 13; while in the hydraulic fracturing stage, the high-pressure water bag 14 will be expanded first, and then the liquid will be directed to the fracturing outlet 15.

[0034] In actual application, first, after the frontmost drill bit 11 enters the coal and rock layer, the operator will select the specific location where hydraulic cutting and fracturing will be performed. Then, the angle of the directional water jet nozzle 13 installed on the rotating pan-tilt table 12 is adjusted through the controller 20 to perform precise water jet cutting or hydraulic cutting operations.

[0035] After completing the water jet cutting or hydraulic slitting, the multi-way valve 16 will control the high-pressure liquid to flow into the two expandable high-pressure water bags 14 located in the deep borehole, causing them to expand and fit tightly against the inner wall of the coal and rock layer, thereby sealing the predetermined area and forming a closed space between the two high-pressure water bags 14. Then, the multi-way valve 16 switches to the fracturing mode and controls the fracturing outlet 15 to start injecting high-pressure liquid into the closed space. As the liquid fills the entire closed area and continues to inject water, the pressure gradually rises, and cracks are preferentially generated inside the cylindrical space formed by the water jet or the fan-shaped / circular space formed by the hydraulic slitting, achieving the goal of directional fracturing.

[0036] Once the fracturing process is completed, the multi-way valve 16 will stop supplying fluid to the fracturing outlet 15 in turn and release the pressure in the two high-pressure water bags 14 to shrink them. At this time, the composite multifunctional pipeline 10 can move outward to a new designated position and prepare to repeat the above process to ensure operation continuity and efficiency.

[0037] According to the present invention, a coal-rock stratum hydraulic cutting and fracturing combined operation device includes a micro-stepping motor 17; a rotating platform 12 is in transmission cooperation with the micro-stepping motor 17, so as to control the rotation angle and rotation speed of the rotating platform 12 within an angle range of 360° through the micro-stepping motor 17. Specifically, the micro-stepping motor 17 can provide precise angular displacement control and stable speed regulation, ensuring that the water jet nozzle 13 can be accurately positioned in a predetermined direction and speed. In this way, when performing hydraulic cutting operations, the operator can set specific rotation parameters through the controller 20, so that the rotating platform 12 drives the water jet nozzle 13 to accurately point to the target position, thereby achieving efficient cutting of specific areas in complex geological structures.

[0038] like Figure 2 As shown, when a linear water jet operation is required, the pan-tilt platform 12 stops at a specified position, and the controller 20 supplies liquid to the water jet nozzle 13 in a pulsed manner through the multi-way valve 16. High-pressure water will continuously act on the coal and rock layers with intermittent impacts, gradually forming a cylindrical space. Subsequent fracturing operations will begin to generate cracks from the inside of this cylindrical space, ensuring the directionality and controllability of crack expansion.

[0039] For the needs of sector-shaped or circular hydraulic cutting, the pan-tilt 12 rotates repeatedly within the specified angle range according to the program set by the controller 20. For example, if a 30° sector-shaped cutting is required, the pan-tilt will reciprocate within a 30° range; and for a 360° circular cutting, the pan-tilt will rotate continuously within the entire circumference. This process can accurately create a cutting space of a specific angle and shape in the coal and rock formation, preparing for the subsequent preferential generation of cracks from these areas.

[0040] In the hydraulic cutting process, it is preferred that the size and depth of the formed cutting space can be reversely calculated by monitoring the amount of coal slime flowing out from around the pipeline, so as to ensure that the hydraulic impact operation is stopped in time after reaching the predetermined space.

[0041] According to a coal-rock hydraulic fracturing and fracturing combined operation device of the present invention, a pressure sensor is arranged between two high-pressure water bags 14, which is used to monitor the pressure changes in the closed space in real time during the fracturing process; and / or, a flow sensor is arranged at the fracturing outlet 15, which is used to monitor the amount of liquid used in the fracturing process in real time. Specifically, the pressure sensor can timely feedback the pressure conditions in the closed interval, so that the operator can adjust the injection volume and injection speed according to the actual pressure, and prevent unexpected crack expansion or equipment damage caused by excessive pressure. At the same time, the flow sensor accurately records the total amount of liquid used in the fracturing process, which not only helps to optimize the efficiency of liquid use, but also provides accurate data support for subsequent analysis to ensure that the fracturing effect meets expectations. By combining the data of these two sensors, the controller 20 can achieve fine control of the fracturing process, improve the operation accuracy, and ensure the safety and controllability of the entire process.

[0042] According to a coal-rock hydraulic cutting and fracturing combined operation device of the present invention, the composite multifunctional pipeline 10 is equipped with a variable frequency control system, which is used to adapt to the different liquid output pressure requirements of the hydraulic cutting process and the hydraulic fracturing process by adjusting the output pressure. Specifically, the system can dynamically adjust the output pressure and flow rate to meet the specific requirements of different operation stages. In the hydraulic cutting process, it is necessary to form a concentrated and powerful water jet to achieve precise cutting, so the variable frequency control system will provide a higher output pressure; while in the hydraulic fracturing process, it is necessary to quickly fill the closed space to establish the initial pressure, and then maintain a stable high pressure state to effectively expand the cracks. This flexibility of the variable frequency control system ensures high efficiency and accuracy in both operation modes.

[0043] Preferably, the frequency conversion control system adopts a frequency converter + frequency conversion motor + water outlet switching scheme to accurately output the corresponding pressure according to the needs of hydraulic fracturing and hydraulic slitting at different stages. When the hydraulic slitting mode is selected, the flow rate of the fracturing pump is adjusted by the frequency converter, and a damper is added to the water jet nozzle 13 to form high pressure for hydraulic slitting. The frequency converter controls the motor to maintain high torque to form a stable high-pressure water jet. When the hydraulic fracturing mode is selected, the flow rate of the fracturing pump is adjusted by the frequency converter, and a large flow rate of rapid water injection is performed before the pressure is established to quickly fill the enclosed space. After the water injection is completed, the low-speed high-torque mode is started to perform stable and efficient fracturing operations to ensure the quality and effect of crack expansion.

[0044] Furthermore, when the coal-rock layer is fractured, the weak stress plane near the hydraulic fracture will shear and slide, generating microseismic elastic waves. A combined hydraulic fracturing and fracturing device for coal-rock layer according to the present invention includes a plurality of microseismic sensors, which are distributed in a plurality of deep boreholes and are used to detect the location of the earthquake source generated during the fracturing process.

[0045] like Figure 3 As shown, multiple microseismic sensors are strategically placed in different deep boreholes to form a three-dimensional monitoring network. These sensors can capture microseismic events caused by fracturing activities and record the corresponding characteristic parameters such as elastic wave arrival time, amplitude and frequency. By cross-analyzing the data received by different sensors, the location of the microseismic occurrence and its propagation path can be accurately located. This multi-point monitoring method not only improves the positioning accuracy, but also helps to understand the direction and pattern of crack expansion, providing key data support for optimizing fracturing design. In addition, based on the collected microseismic information, the controller 20 can adjust the fracturing parameters such as water injection volume, pressure and flow rate in real time to adapt to changes in underground structures and ensure the safety and effectiveness of the fracturing process.

[0046] Preferably, three or four deep boreholes may be arranged in the area where the fracturing construction is to be carried out. If three deep boreholes are used, the three deep boreholes are arranged in an equilateral triangle, and if four deep boreholes are used, the four deep boreholes are arranged in a square. After the drilling is completed, the drill pipe is pulled out, and the fracturing composite pipeline is then inserted into the borehole.

[0047] Regarding the detection of crack positions, it is preferred to arrange a microseismic sensor every 100 meters in the fracturing composite pipeline.

[0048] Among them, if the method of three deep boreholes is adopted, a coordinate system model is first constructed, and three microseismic sensors at the same borehole depth in the measured area are a group of detection units. In the spatial coordinate system, the spatial coordinate positions of the three sensors are marked, and the time difference of the arrival of the transverse wave and the longitudinal wave received by each sensor is recorded, and then the distance from the source to each sensor is obtained. A sphere is made with the spatial coordinate points of the three sensors as the origin and the distance measured from each sensor to the source as the radius. The intersection of the plane where the spatial coordinate points of the three sensors are located and the three spheres corresponding to the three sensors is the source position. All microseismic sensors use high-precision crystal oscillators, and the clock signals are provided by the controller 20 to ensure clock synchronization.

[0049] If the earthquake source location is determined by four sensors, a positioning method based on arrival time difference can be used.

[0050] For example, first record the time when the seismic waves reach the four sensors, set as t1, t2, t3, and t4 respectively, and at the same time estimate the propagation speed v of the seismic waves in the medium. This speed is related to the elastic properties of the medium and can be obtained based on geological survey data or empirical values.

[0051] Then, let the coordinates of the earthquake source be (x, y, z), and the coordinates of the four sensors be (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4). According to the distance formula d=v*(t-t0) (t0 is the time when the earthquake occurred), and the distance formula between two points in space d i = , we can get the following four equations: = v*(t 1 - t 0 ) = v*(t 2 - t 0 ) = v*(t 3 - t 0 ) = v*(t 4 - t 0 ) Subtract the above equations from each other and eliminate t0 to obtain three equations containing only x, y, and z. Then use numerical methods (such as the Newton-Raphson method or the least squares method) to solve the system of equations consisting of these three equations to finally obtain the source location (x, y, z).

[0052] The existing hydraulic fracturing technology scheme does not detect the earthquake source and fracture gap of hydraulic fracturing in coal rock formations, and mainly relies on the borehole peek method, but this method is limited by the depth and number of boreholes and is difficult to fully reflect the fracturing effect. The present invention also provides a coal rock formation hydraulic fracturing and fracturing combined operation method, which is used to control the coal rock formation hydraulic fracturing and fracturing combined operation device of the above embodiment.

[0053] The coal-rock stratum hydraulic fracture and fracturing combined operation method provided by the present invention is described below. The coal-rock stratum hydraulic fracture and fracturing combined operation method described below and the coal-rock stratum hydraulic fracture and fracturing combined operation device described above can be referred to each other.

[0054] Figure 5 FIG. 1 is a flow chart of the combined hydraulic fracturing and hydraulic cutting method for coal rock formations provided by the present invention. Figure 5 As shown, the method includes the following: Step 110, send the working device into a deep borehole of a predetermined depth. Specifically, first, it is necessary to determine the target area according to the geological exploration data, and pre-form one or more deep boreholes reaching the target depth by means of drilling equipment. Subsequently, the working device integrating the drill bit 11, the composite multifunctional pipeline 10, the rotating pan-tilt head 12, the high-pressure water bag 14 and other components is accurately sent into the deep borehole of the predetermined depth using a conveying system.

[0055] Step 120: Detect coal and rock strata information. Specifically, after the operating device is in place, the built-in or externally connected detection instrument is started to collect information on key parameters such as coal and rock strata structure, density, and water content. In addition, microseismic sensors can also be used to monitor the activity of coal and rock strata in their natural state to provide a reference for the next step of analysis.

[0056] Step 130: Determine the direction of the area to be fractured based on the coal-rock formation information. Specifically, by combining engineering experience and numerical simulation tools, analyze the stress distribution and possible weak surfaces of the coal-rock formation to determine the most effective hydraulic fracturing and fracture direction.

[0057] Step 140, adjust the angle of the water jet nozzle 13 according to the direction of the area to be fracturing, and perform the hydraulic slitting operation. Specifically, the angle of the water jet nozzle 13 installed on the rotating pan 12 is adjusted by the controller 20 to point to the pre-selected fracturing direction. Then, start the high-pressure pump and supply liquid to the water jet nozzle 13 through the multi-way valve 16 to generate a high-intensity water jet to cut the coal and rock layers to form an initial slit.

[0058] Step 150: Inflate the two high-pressure water bags 14 to seal the inner wall of the deep borehole and form a closed space. Specifically, after the hydraulic fracturing is completed, the controller 20 injects high-pressure liquid into the two high-pressure water bags 14 in the deep borehole through the multi-way valve 16 to expand the two high-pressure water bags 14 and tightly fit the inner wall of the coal layer, thereby creating a completely closed space between the two water bags. This closed space provides the necessary pressure environment for directional fracturing.

[0059] Step 160: Inject high-pressure liquid into the enclosed space to perform directional hydraulic fracturing. Specifically, once the enclosed space is established, the multi-way valve 16 will switch to the fracturing mode and start injecting high-pressure liquid into the enclosed space. As the liquid fills the entire enclosed area and continues to inject water, the internal pressure gradually rises, causing cracks to preferentially form in the cylindrical space formed by the water jet or the fan-shaped / circular space formed by the hydraulic slit.

[0060] Further, according to a coal-rock stratum hydraulic fracturing and hydraulic fracture combined operation method of the present invention, as Figure 4 As shown, the coal formation information preferably includes fracture detection information.

[0061] The step of determining the direction of the area to be fractured according to the coal formation information includes: Step 131: Use 10kHz-1MHz low-frequency electromagnetic waves to roughly identify the distribution range of coal rock fractures. Specifically, use low-frequency electromagnetic waves (10kHz to 1MHz) to scan a large area to identify the existence and general direction of larger-scale fractures in coal rock formations. Low-frequency electromagnetic waves can penetrate deeper formations and are suitable for preliminary assessment of the overall distribution of fractures. By analyzing the intensity and phase changes of the reflected electromagnetic signal, the general outline of the fracture can be drawn to provide guidance for subsequent more detailed detection.

[0062] Step 132, use 1MHz-100MHz medium frequency electromagnetic waves to detect large cracks at medium depth in coal rock formations. Specifically, use medium frequency electromagnetic waves (1MHz to 100MHz) to conduct deeper detection of large cracks in coal rock formations. Compared with low frequency electromagnetic waves, medium frequency electromagnetic waves have higher resolution and can more accurately locate those cracks that extend deeper and have larger widths based on previous rough identification, which helps to screen out key structural features that may affect the fracturing effect.

[0063] Step 133: Use 100MHz-1GHz high-frequency electromagnetic waves to accurately detect shallow cracks in coal and rock formations. Specifically, high-frequency electromagnetic waves (100MHz to 1GHz) are used to accurately detect cracks near the surface of coal and rock formations. High-frequency electromagnetic waves provide extremely high spatial resolution and can capture subtle changes in geological structures, such as tiny cracks or holes.

[0064] Step 134, complete the graphical mapping of the overall coal rock fractures to guide the positioning of the water jet nozzle 13. Specifically, after collecting data from electromagnetic wave detection of different frequencies, a special software tool is used to integrate these data into a detailed map to show the spatial distribution of coal rock fractures. The map not only reflects the location, size and shape of the cracks, but also marks potential stress concentration areas and other important geological features. Based on this graphical mapping result, the operator can formulate the optimal fracturing strategy and accurately adjust the angle and position of the water jet nozzle 13 to ensure that it acts on the most suitable area for cutting and fracturing. In addition, this visualization tool also provides a reference for real-time monitoring of crack expansion during the fracturing process, making the entire operation safer and more controllable.

[0065] According to the above embodiment, by detecting the source position and the fracturing gap, it is possible to analyze in which direction the fracturing should be carried out next. The micro-stepping motor 17 drives the pan-tilt table 12 to rotate, so that the water jet nozzle 13 can accurately point to the expected angle to ensure the effectiveness of the cutting and fracturing operations. In order to enhance the effect of electromagnetic wave detection, in a preferred case, metal salts (such as copper salts, silver salts, etc.) or metal nanoparticles can be added to the fracturing medium, which can reflect high-frequency electromagnetic waves to a certain extent and improve the quality of the detection signal.

[0066] The above-mentioned method of jointly detecting rock fractures with multi-frequency electromagnetic waves makes full use of the characteristics of electromagnetic waves of different frequencies. Specifically, low-frequency electromagnetic waves (10kHz - 1MHz) are suitable for large-area, deep-level preliminary detection due to their strong penetration ability, and determine the approximate area where cracks may exist. Medium-frequency electromagnetic waves (1MHz - 100MHz) strike a balance between penetration depth and resolution. Among them, electromagnetic waves of 10MHz - 50MHz can be used to detect rock fractures of medium depth and map hydraulic fracturing fracture structures; while electromagnetic waves of 50MHz - 100MHz can provide higher resolution at relatively shallow depths, which is suitable for detecting some shallow rock fracturing cracks. High-frequency electromagnetic waves (100MHz - 1GHz) can provide high-resolution images due to their short wavelength and sensitivity to subtle changes in the medium, clearly showing detailed information such as the direction and width of the cracks. Therefore, in coal rock fracturing, high-frequency electromagnetic waves of 200MHz - 500MHz can be used to accurately obtain the specific shape and distribution of shallow rock cracks, providing a basis for fracturing plans; high-frequency electromagnetic waves of 100MHz - 200MHz are used to detect the development of cracks in shallow coal rock formations so as to take corresponding fracturing measures.

[0067] In order to achieve flexible electromagnetic wave frequency switching, a voltage-controlled oscillator (VCO) type electromagnetic wave transceiver is preferably used in the present invention. The frequency output of the voltage-controlled oscillator is determined by the input control voltage, and the relationship between the two is generally expressed as f=f0+kVc, where f0 is the center frequency, k is the voltage control sensitivity, and Vc is the control voltage. By changing the input control voltage, the output frequency can be adjusted. In the phase-locked loop frequency synthesis circuit, the digital signal processor (DSP) generates a variable voltage signal to control the frequency of the VCO. When the frequency needs to be increased, the control voltage is increased; conversely, the frequency can be reduced by reducing the control voltage. The above method ensures that the electromagnetic wave transceiver can quickly and accurately switch to the required detection frequency according to actual needs, thereby improving the detection efficiency and accuracy.

[0068] Furthermore, according to a combined operation method of hydraulic fracturing and hydraulic fracture in coal rock formations of the present invention, after the step of forming a closed space, the method comprises: Step 151, real-time monitoring of the pressure and flow parameters in the closed interval. Specifically, after the two high-pressure water bags 14 expand to form a closed space, the pressure sensor located in the space and the flow sensor installed at the fracturing outlet 15 are started to monitor the internal pressure and liquid flow of the closed interval in real time. The sensor can provide a high-precision data stream to ensure that the operator can instantly understand the dynamic changes in the closed space. Among them, the pressure data recorded by the pressure sensor reflects the growth of the liquid pressure in the closed interval, while the flow sensor accurately measures the amount and speed of the injected liquid. Through this real-time monitoring, the system can quickly respond to a variety of abnormal situations, such as a sudden increase in pressure or flow fluctuations, thereby ensuring the safety and controllability of the operation.

[0069] Step 152, determine the progress of the hydraulic fracturing process according to the pressure and flow parameters. Specifically, based on the data obtained from the pressure and flow sensors, the controller 20 can evaluate the progress of the hydraulic fracturing process and adjust the operating parameters accordingly to optimize the fracturing effect. For example, when the pressure gradually rises and reaches the preset threshold, this indicates that the crack is effectively expanding; at this time, the stable high-pressure state can be maintained by reducing the injection rate to avoid excessive pressure growth leading to unexpected crack expansion or equipment damage. On the other hand, if the flow data shows that the liquid consumption exceeds expectations, it may mean that an unforeseen leakage path or other problems have occurred, and timely measures need to be taken to correct them. In addition, combined with the source information captured by the microseismic sensor, the direction and range of crack expansion can be more accurately judged, providing a basis for subsequent adjustments to the fracturing strategy. Through continuous analysis of pressure and flow parameters, the entire fracturing process can be more finely controlled to ensure the best fracturing effect and maximize gas extraction efficiency.

[0070] Furthermore, according to a coal-rock stratum hydraulic fracturing and hydraulic fracture combined operation method of the present invention, in the step of injecting high-pressure liquid into a closed space to implement directional hydraulic fracturing, the method comprises: Step 161, according to the pressure and flow parameters, the flow of the fracturing pump is adjusted through the frequency converter. Specifically, before starting water injection, the controller 20 can dynamically adjust the working state of the fracturing pump through the frequency converter according to the pressure and flow parameters monitored in real time. The frequency converter can flexibly change the speed and output torque of the motor, thereby accurately controlling the flow of the fracturing pump. In this way, the system can optimize the water injection process according to actual needs, improve operating efficiency and reduce resource waste.

[0071] Step 162, wherein, when the pressure and flow parameters have not reached the preset values, the fracturing pump is adjusted to a high-speed, low-torque working state to perform large-flow rapid water injection. Specifically, when the pressure and flow parameters have not yet reached the set threshold, the controller 20 adjusts the fracturing pump to a high-speed, low-torque working state to achieve large-flow rapid water injection. This mode can quickly fill the enclosed space in a short time, establish initial pressure, and prepare the necessary conditions for subsequent fracturing operations. The high-speed, low-torque setting enables the pump to operate at a lower load, avoiding the premature generation of excessive pressure and causing unnecessary stress concentration or equipment damage.

[0072] Step 163, after the pressure and flow parameters reach the preset values, adjust the fracturing pump to a low speed and high torque working state to perform the hydraulic fracturing process. Specifically, once the monitored pressure and flow parameters reach the preset values, it indicates that the pressure in the enclosed space is sufficient to support the effective expansion of the cracks. At this time, the controller 20 switches the fracturing pump to a low speed and high torque working state. The low speed ensures a stable liquid supply speed, while the high torque provides sufficient power to maintain the high pressure state so that the cracks expand in a predetermined direction and range. This working mode is not only conducive to maintaining the stability of the pressure, but also effectively prevents unexpected crack expansion or equipment failure caused by excessive pressure fluctuations.

[0073] Furthermore, according to a method for combined hydraulic fracturing and hydraulic cutting of coal rock formations of the present invention, microseismic information is continuously detected during the entire operation process, and the location of the earthquake source generated during the hydraulic fracturing process is determined based on the microseismic information. Specifically, during the entire hydraulic fracturing and hydraulic cutting operation, multiple microseismic sensors arranged in the deep borehole will monitor the microseismic events caused by the fracturing activity in real time. These sensors can capture elastic wave signals generated by phenomena such as crack expansion and stress release. Through precise time marking and high-sensitivity detection capabilities, microseismic sensors can record the occurrence time, amplitude, frequency and propagation path of each microseismic event.

[0074] In order to determine the source location, multi-point positioning technology can be used to comprehensively analyze the data from different sensors. The arrival time difference (Δt) of each microseismic event is used to construct a set of time difference equations in three-dimensional space. Combined with the known sensor location coordinates, mathematical algorithms (such as least squares method or hyperbola positioning method) are used to solve the most likely source location.

[0075] In addition, the dynamic characteristics of fracture expansion can be further understood through spectrum analysis of microseismic events. High-frequency components usually correspond to smaller-scale, shallower fracture activities, while low-frequency components may indicate larger-scale, deeper geological structural changes. Therefore, based on the changing trend of spectral characteristics, operators can evaluate the development of fracture networks and adjust fracturing parameters in time to optimize the operation effect.

[0076] The microseismic information monitored in real time can also be used in the feedback controller 20 to guide the frequency converter to adjust the working state of the fracturing pump to ensure that the pressure and flow rate remain within the optimal range. If abnormally strong microseismic activity is detected, indicating that there may be over-fracturing or other potential risks, the system can automatically trigger an alarm and take appropriate protective measures, such as slowing down the injection rate or suspending the operation until it is confirmed to be safe to continue.

[0077] The present invention realizes dynamic monitoring and refined management of the hydraulic fracturing process by continuously detecting microseismic information and accurately determining the source location, thereby enhancing the safety and controllability of the operation and providing data support for subsequent geological analysis.

[0078] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A combined hydraulic fracturing and hydraulic fracturing device for coal and rock formations, characterized in that: include: A drill bit, arranged at the front end of the device, is used to drill through the coal and rock layers to form a deep borehole; A composite multifunctional pipeline, on the periphery of which is mounted an annular hollow rotating platform, on which is mounted a water jet nozzle; two inflatable high-pressure water bags, used to seal a predetermined area in the deep borehole in an inflated state to form a closed space between the two high-pressure water bags; A fracturing water outlet is arranged between the two high-pressure water bags; The multi-channel valve is arranged in the composite multifunctional pipeline and is used to control the flow path of the high-pressure liquid, and the flow path includes controlling the high-pressure liquid to flow to any one or more of the two high-pressure water bags, the water jet nozzle, and the fracturing water outlet.

2. The coal-rock stratum hydraulic fracturing and hydraulic fracturing combined operation device according to claim 1 is characterized in that: Includes micro stepper motors; The rotating platform is matched with the micro-stepping motor in transmission so as to control the rotation angle and rotation speed of the rotating platform within an angle range of 360° through the micro-stepping motor.

3. The coal-rock stratum hydraulic fracturing and hydraulic fracturing combined operation device according to claim 1 is characterized in that: A pressure sensor is provided between the two high-pressure water bags to monitor the pressure change in the closed space in real time during the fracturing process; And / or, a flow sensor is provided at the fracturing water outlet to monitor the amount of liquid used during the fracturing process in real time.

4. The coal-rock stratum hydraulic fracturing and hydraulic fracturing combined operation device according to any one of claims 1 to 3, characterized in that: The composite multifunctional pipeline is equipped with a variable frequency control system, and the variable frequency control system is used to adapt to different liquid output pressure requirements of the hydraulic slotting process and the hydraulic fracturing process by adjusting the output pressure.

5. The coal-rock stratum hydraulic fracturing and hydraulic fracturing combined operation device according to any one of claims 1 to 3, characterized in that: It comprises a plurality of microseismic sensors, which are distributed in a plurality of deep boreholes and are used to detect the location of earthquake sources generated during the fracturing process.

6. A method for combined hydraulic fracturing and hydraulic cutting of coal and rock formations, characterized in that: Used to control the coal-rock stratum hydraulic fracturing and hydraulic fracture combined operation device according to any one of claims 1 to 5, the operation method comprising: Sending the working device into the deep borehole of the predetermined depth; Detect coal strata information; Determine the direction of the area to be fracturing according to the coal and rock formation information; Adjust the angle of the water jet nozzle according to the direction of the area to be fracturing to perform hydraulic cutting operation; Inflating two high-pressure water bags to seal the inner wall of the deep borehole to form a closed space; High-pressure liquid is injected into the closed space to implement directional hydraulic fracturing.

7. The method for combined hydraulic fracturing and hydraulic cutting of coal and rock formations according to claim 6, characterized in that: The coal and rock formation information includes fracture detection information; The step of determining the direction of the area to be fracturing according to the coal and rock formation information includes: The distribution range of coal and rock fractures is roughly identified using 10kHz-1MHz low-frequency electromagnetic waves; Use 1MHz-100MHz medium frequency electromagnetic waves to detect large cracks at medium depths in coal and rock formations; Use 100MHz-1GHz high-frequency electromagnetic waves to accurately detect shallow cracks in coal and rock formations; The graphical mapping of the entire coal and rock stratum fractures is completed to guide the positioning of the water jet nozzle.

8. The method for combined hydraulic fracturing and hydraulic cutting of coal and rock formations according to claim 6, characterized in that: After the step of forming the closed space, the method further comprises: Real-time monitoring of pressure and flow parameters within the closed interval; The progress of the hydraulic fracturing process is determined based on the pressure and flow parameters.

9. The method for combined hydraulic fracturing and hydraulic fracture in coal and rock formations according to claim 8, characterized in that: The step of injecting high-pressure liquid into the closed space to implement directional hydraulic fracturing includes: According to the pressure and flow parameters, adjusting the flow of the fracturing pump through a frequency converter; Among them, when the pressure and flow parameters have not reached the preset values, the fracturing pump is adjusted to a high-speed and low-torque working state to perform large-flow rapid water injection; after the pressure and flow parameters reach the preset values, the fracturing pump is adjusted to a low-speed and high-torque working state to perform the hydraulic fracturing process.

10. The coal-rock stratum hydraulic fracturing and hydraulic fracturing combined operation method according to any one of claims 6 to 9, characterized in that: During the entire operation process, microseismic information is continuously detected, and the location of the earthquake source generated during the hydraulic fracturing process is determined based on the microseismic information.

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