Deep coal seam anhydrous fracturing yield increasing device and method based on magnetorheological effect

Abstract

The invention discloses a magneto-rheological effect-based deep coal seam waterless fracturing yield increasing device and method.The magneto-rheological effect-based deep coal seam waterless fracturing yield increasing device comprises a fluid magnetization pretreatment tank, a directional fracture forming assembly, a monitoring assembly and a control terminal, and the directional fracture forming assembly comprises a proppant storage tank, a fluid mixing tank, a main pipeline, a plurality of magnetic field generators, a plurality of nozzles and a temporary plugging ball injector; the fluid mixing tank is connected with the fluid magnetization pretreatment tank and the proppant storage tank, the main pipeline comprises a longitudinal section pipeline connected with the fluid mixing tank and a horizontal section pipeline connected with the gas storage tank, the spray head is inserted into the side wall of the horizontal section pipeline, and the magnetic field generator is arranged in the horizontal section pipeline; the monitoring assembly comprises a magneto-dependent sensor and a micro-seismic monitor, the magneto-dependent sensor is arranged on the outer wall of the horizontal casing pipe, and the micro-seismic monitor is arranged in the horizontal casing pipe; the control terminal is electrically connected with the temporary blocking ball injector, the magnetic field generator and the monitoring assembly; in this way, the rock breaking efficiency is improved, water is not needed, a high-diversion complex fracture network system is formed, and it is ensured that fracture expansion is accurate and controllable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unconventional natural gas development, in particular to a deep coal seam waterless fracturing stimulation device and method based on magneto-rheological effect. BACKGROUND

[0002] Deep coal seam gas reservoirs have the characteristics of high ground stress, low permeability and deep burial. The application of traditional hydraulic fracturing technology in such reservoirs faces many challenges. First, hydraulic fracturing consumes a large amount of water, which limits its application in areas lacking water resources. Second, fracturing fluid can cause swelling of reservoir clay minerals and coal powder to block fractures, resulting in a short effective period of fracture network conduction. At the same time, the ground stress fluctuates dynamically with the mining process, and fixed-parameter hydraulic fracturing cannot be adapted in real time, which can easily cause uneven fracture propagation and single main fracture. In addition, existing waterless fracturing technologies such as CO2 fracturing, liquid nitrogen fracturing and sandblasting fracturing, although they solve the problem of water resource dependence, still cannot achieve real-time, active and accurate control of fracture propagation morphology. SUMMARY

[0003] The main purpose of the present application is to provide a deep coal seam waterless fracturing stimulation device and method based on magneto-rheological effect, which aims to solve the above problems.

[0004] To achieve the above purpose, the present application provides a deep coal seam waterless fracturing stimulation device based on magneto-rheological effect, comprising: A fluid magnetization pretreatment tank is used for pre-magnetizing the magneto-rheological fluid to make the magnetic particles in the magneto-rheological fluid uniformly dispersed and directional arranged. A directional fracture creating assembly includes a proppant storage tank, a fluid mixing tank, a main pipeline, a plurality of magnetic field generators, a plurality of nozzles and a temporary plugging ball injector. The proppant storage tank stores magnetic response proppant. The fluid mixing tank is connected with the fluid magnetization pretreatment tank and the proppant storage tank to mix the pre-magnetized magneto-rheological fluid and the magnetic response proppant to obtain a mixed fluid. The main pipeline is arranged in the coal seam and includes a longitudinal section pipeline connected with the fluid mixing tank and a horizontal section pipeline connected with a gas storage tank. A plurality of nozzles are arranged on the side wall of the horizontal section pipeline at intervals. A plurality of magnetic field generators are arranged in the horizontal section pipeline to apply a pulsed magnetic field to the mixed fluid to cause phase change and form a high-energy solid jet which is sprayed into the coal seam through the nozzles to form a main fracture and / or to act on the magnetic response proppant to be sprayed into the coal seam. The temporary plugging ball injector is used to inject temporary plugging balls into the main fracture to form a secondary fracture. The monitoring components include a magnetic sensor and a microseismic monitoring instrument. The magnetic sensor is disposed on the outer wall of the horizontal sleeve for monitoring changes in the magnetic field and acquiring microseismic signals. The microseismic monitoring instrument is disposed inside the horizontal sleeve for monitoring the three-dimensional propagation signal of the main crack. The control terminal is electrically connected to the temporary plugging ball injector, the magnetic field generator, and the monitoring component. It is used to analyze the morphology of the main crack and predict the extension trend of the main crack based on the monitoring results of the monitoring component, and to control the working state of the temporary plugging ball injector or the magnetic field generator based on the analysis and prediction results.

[0005] Optionally, the deep coal seam waterless fracturing enhancement device based on magnetorheological effect further includes a safety assurance component, which includes: Multiple pressure relief valves are provided, each corresponding to one of the multiple nozzles, and are located at the end of the nozzle inserted into the horizontal guide tube; and An emergency shut-off valve is installed between the longitudinal section of the pipeline and the fluid mixing tank; The control terminal is electrically connected to the pressure relief valve and the emergency shut-off valve, and is used to control the working status of the pressure relief valve and the emergency shut-off valve.

[0006] Optionally, the fluid magnetization pretreatment tank includes a tank body and an electromagnetic coil. The inner wall of the tank body is provided with a polytetrafluoroethylene anti-corrosion coating, and the magnetic field strength generated by the electromagnetic coil is 0.5T.

[0007] Optionally, the magnetic field generator includes a double-layered housing and an electromagnetic coil. The electromagnetic coil is disposed inside the double-layered housing and is wound with Litz wire, and is insulated and cured using a vacuum impregnation epoxy resin process.

[0008] Optionally, the magnetic field generator is arranged in a ring shape and is sleeved outside the nozzle.

[0009] Optionally, the magnetic sensor is positioned close to the magnetic field generator.

[0010] Optionally, the flow channel of the nozzle is streamlined, and a polycrystalline diamond bushing is provided at the nozzle orifice.

[0011] Optionally, the temporary plugging ball injector includes a ball storage chamber, a drive unit, and a flow regulating valve. The ball storage chamber contains a plurality of temporary plugging balls. The drive unit is driven to move the temporary plugging balls toward the outlet of the ball storage chamber. The flow regulating valve is located at the outlet of the ball storage chamber.

[0012] Optionally, the deep coal seam waterless fracturing production enhancement device based on magnetorheological effect further includes a magnetorheological fluid storage tank and a high-pressure pump. The magnetorheological fluid storage tank is used to contain the magnetorheological fluid, and its inner wall is coated with an epoxy anti-corrosion coating. The magnetorheological fluid storage tank is connected to the fluid magnetization pretreatment tank through the high-pressure pump to input the magnetorheological fluid into the fluid magnetization pretreatment tank.

[0013] This invention also provides a method for enhancing production in deep coal seams using waterless fracturing based on magnetorheological effect, applicable to a device for enhancing production in deep coal seams using waterless fracturing based on magnetorheological effect. The method for enhancing production in deep coal seams using waterless fracturing based on magnetorheological effect includes the following steps: Step S100: The magnetorheological fluid is pre-magnetized using the aforementioned fluid magnetization pretreatment tank; Step S200: The pre-magnetized magnetorheological fluid is transported to the fluid mixing tank, and the magnetically responsive proppant stored in the proppant storage tank is transported to the fluid mixing tank, so that the magnetically responsive proppant and the pre-magnetized magnetorheological fluid are mixed to obtain a mixed fluid; Step S300: The mixed fluid flows into the main pipeline, and when the mixed fluid flows through the nozzle, the magnetic field generator is driven to apply a pulsed magnetic field instantaneously to cause the magnetorheological fluid in the mixed fluid to undergo a phase change and form a high-energy solid jet. The high-energy solid jet is sprayed into the coal seam through the nozzle to form the main fracture. Step S400: Use the magnetic sensor to monitor the magnetic field changes and collect microseismic signals in real time, and use the microseismic monitoring instrument to monitor the three-dimensional expansion signal of the main crack in real time; Step S500: The control terminal analyzes the morphology of the main fracture and predicts its extension trend based on the monitoring results transmitted by the magnetic sensor and the microseismic monitor. When the analysis and prediction result of the control terminal indicates that the main fracture has a single morphology, the control terminal injects a temporary plugging ball into the main fracture to increase the coal seam pressure and act on the natural weak surface or stress shadow area in the coal seam to form a secondary fracture. When the analysis and prediction result of the control terminal indicates that the main fracture extends relatively close to the main fracture, the control terminal generates a non-uniform magnetic field to allow the magnetically responsive proppant flowing into the main pipeline to flow into the tip or branch of the main fracture.

[0014] In the technical solution of this invention, pre-magnetizing the magnetorheological fluid enhances its magnetic response activity. A pulsed magnetic field generated by the magnetic generator induces a phase change in the magnetorheological fluid within milliseconds, causing a dramatic increase in viscosity and forming a high-energy solid jet. This jet, ejected at high speed through the nozzle, impacts coal and rock with high kinetic energy, improving rock-breaking efficiency without requiring water. A temporary plugging ball injector injects a temporary plugging ball into the main fracture to form a secondary fracture. The magnetically responsive proppant adheres to the fracture surface under magnetic field adsorption, forming an effective layer that aids in branch expansion. Through the synergistic effect of the temporary plugging ball and the magnetically responsive proppant, active intervention in both "support" and "fracture creation" dimensions is achieved, resulting in a complex fracture network system with high conductivity, significantly improving the long-term conductivity of the fracture network. A "near-field + far-field" three-dimensional monitoring network, constructed by the magnetic sensor and the microseismic monitor, avoids the risk of misjudgment from single monitoring, ensuring precise and controllable fracture expansion. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 A schematic diagram of an embodiment of the deep coal seam waterless fracturing and production enhancement device based on magnetorheological effect provided by the present invention; Figure 2 for Figure 1 A partial structural schematic diagram of a deep coal seam waterless fracturing and production enhancement device based on magnetorheological effect; Figure 3 The flowchart of the deep coal seam waterless fracturing production enhancement method based on magnetorheological effect provided by the present invention.

[0017] Explanation of icon numbers:

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] Deep coalbed methane reservoirs are characterized by high in-situ stress, low permeability, and deep burial, posing numerous challenges to the application of traditional hydraulic fracturing technology in these reservoirs. Firstly, hydraulic fracturing consumes a huge amount of water, limiting its application in water-scarce regions. Secondly, fracturing fluids easily induce expansion of reservoir clay minerals and coal dust clogging of fractures, resulting in a short effective period of fracture network connectivity. Simultaneously, in-situ stress fluctuates dynamically with the mining process, making it impossible for hydraulic fracturing with fixed parameters to adapt in real time, easily leading to uneven fracture propagation and a single main fracture. Furthermore, while existing waterless fracturing technologies such as CO2 fracturing, liquid nitrogen fracturing, and sandblasting fracturing have solved the water resource dependence problem, they still cannot achieve real-time, proactive, and precise control over fracture propagation morphology.

[0023] In view of this, the present invention provides a deep coal seam waterless fracturing and production enhancement device 100 based on magnetorheological effect. Figure 1 and Figure 2 This invention provides an embodiment of a deep coal seam waterless fracturing and production enhancement device 100 based on magnetorheological effect.

[0024] Please seeFigure 1 and Figure 2 The deep coal seam waterless fracturing production enhancement device 100 based on magnetorheological effect includes a fluid magnetization pretreatment tank 1, a directional fracture-forming component, a monitoring component, and a control terminal 10. The fluid magnetization pretreatment tank 1 is used to pre-magnetize the magnetorheological fluid so that the magnetic particles in the magnetorheological fluid are uniformly dispersed and oriented. The directional fracture-forming component includes a proppant storage tank 2, a fluid mixing tank 3, a main pipeline 4, multiple magnetic field generators 5, multiple nozzles 6, and a temporary plugging ball injector 7. The proppant storage tank 2 contains... The fluid mixing tank 3 contains magnetically responsive proppant 500. It is connected to the fluid magnetization pretreatment tank 1 and the proppant storage tank 2 to mix the pre-magnetized magnetorheological fluid and the magnetically responsive proppant 500 to obtain a mixed fluid. The main pipeline 4 is installed within the coal seam 200 and includes a longitudinal section pipeline 41 connected to the fluid mixing tank 3 and a horizontal section pipeline 42 connected to the gas storage tank 300. Multiple nozzles 6 are spaced apart and inserted into the side wall of the horizontal section pipeline 42. Multiple magnetic field generators... The generator 5 is installed inside the horizontal section of the pipe 42 to apply a pulsed magnetic field to the mixed fluid, causing a phase change and forming a high-energy solid jet that is sprayed into the coal seam 200 through the nozzle 6 to form a main fracture 210 and / or to act on the magnetically responsive proppant 500, which is then sprayed into the coal seam 200. The temporary plugging ball injector 7 is used to inject temporary plugging balls into the main fracture 210 to form a secondary fracture 220. The monitoring components include a magnetic sensor 8 and a microseismic monitor 9. The magnetic sensor 8 is installed on the outer wall of the horizontal casing. The system is used to monitor changes in the magnetic field and collect microseismic signals. The microseismic monitoring instrument 9 is located inside the horizontal sleeve and is used to monitor the three-dimensional expansion signal of the main crack 210. The control terminal 10 is electrically connected to the temporary plugging ball injector 7, the magnetic field generator 5, and the monitoring component. It is used to analyze the morphology of the main crack 210 and predict the extension trend of the main crack 210 based on the monitoring results of the monitoring component, and to control the working state of the temporary plugging ball injector 7 or the magnetic field generator 5 based on the analysis and prediction results.

[0025] In this invention, pre-magnetizing the magnetorheological fluid enhances its magnetic response activity. A pulsed magnetic field generated by the magnetic generator induces a phase change in the magnetorheological fluid within milliseconds, causing a dramatic increase in viscosity and forming a high-energy solid jet. This jet, ejected at high speed by the nozzle 6, impacts coal and rock with high kinetic energy, improving rock-breaking efficiency without requiring water. A temporary plugging ball is injected into the main fracture 210 via the temporary plugging ball injector 7 to form a secondary fracture 220. The magnetically responsive proppant 500 adheres to the fracture surface under magnetic field adsorption, effectively spreading the proppant and aiding in branch expansion. Through the synergistic effect of the temporary plugging ball and the magnetically responsive proppant 500, active intervention in both "support" and "fracture creation" dimensions is achieved, resulting in a complex fracture network system with high conductivity, significantly improving the long-term conductivity of the fracture network. A near-field + far-field three-dimensional monitoring network, constructed by the magnetic sensor 8 and the microseismic monitor 9, avoids the risk of misjudgment from single monitoring, ensuring precise and controllable fracture expansion.

[0026] It should be noted that, in this invention, the magnetorheological fluid is obtained by compounding carbonyl iron powder that has undergone surface nitriding treatment, high-temperature heat transfer oil, and additives.

[0027] It should also be noted that in this invention, the magnetically responsive proppant 500 has ceramsite as its core and its surface is coated with a magnetic material. Specifically, a nickel-cobalt alloy magnetic layer is coated on its surface using a physical vapor deposition process.

[0028] It should also be noted that in this invention, the temporary plugging ball is made of polyglycolic acid and doped with barium sulfate as a weighting agent to match its density with the fracturing fluid, and the degradation time can be designed according to the material ratio.

[0029] It should also be noted that, in this invention, the horizontal section of the pipeline 42 is located at the position of coal seam 200 in the horizontal section of the deep coal seam 200 with a burial depth of 1200-1500m.

[0030] For further details, please refer to Figure 1 and Figure 2 The deep coal seam waterless fracturing production enhancement device 100 based on magnetorheological effect also includes a safety protection component, which includes multiple pressure relief valves 11 and emergency shut-off valves 12. The multiple pressure relief valves 11 are arranged one-to-one with the multiple nozzles 6 and are located at one end of the nozzle 6 inserted into the horizontal conduit. The emergency shut-off valves 12 are located between the longitudinal section pipeline 41 and the fluid mixing tank 3. The control terminal 10 is electrically connected to the pressure relief valves 11 and the emergency shut-off valves 12 and is used to control the working status of the pressure relief valves 11 and the emergency shut-off valves 12.

[0031] Thus, during the entire operation, the pressure can be finely adjusted through the pressure relief valve 11 to prevent pressure runaway. In the event of an extreme anomaly such as a pipeline rupture or a sudden drop in pressure, the emergency shut-off valve 12 can be triggered instantly to completely cut off the fluid supply within 1 second, ensuring operational safety.

[0032] For further details, please refer to Figure 1 The safety protection component also includes a gas leak alarm 15, which is located on and electrically connected to the control terminal 10. Thus, when a gas concentration exceeding the standard is detected, the gas leak alarm 15 is triggered to alert personnel.

[0033] Specifically, in one embodiment of the present invention, the gas leak alarm 15 is a catalytic combustible gas sensor, the pressure relief valve 11 is a pilot-operated ultra-high pressure solenoid valve, which adopts an all-stainless steel pilot piston, greatly improving the pressure bearing capacity of the solenoid valve. The set pressure can be wirelessly adjusted within the range of 50-75MPa according to ground commands, and the response accuracy is ±0.5MPa. The emergency shut-off valve 12 is a full-bore gate valve, and the valve body material is S32760 stainless steel.

[0034] Specifically, the fluid magnetization pretreatment tank 1 includes a tank body and an electromagnetic coil. The inner wall of the tank body is provided with a polytetrafluoroethylene anti-corrosion coating, and the magnetic field strength generated by the electromagnetic coil is 0.5T.

[0035] Specifically, the magnetic field generator 5 includes a double-layered housing and an electromagnetic coil. The electromagnetic coil is located inside the double-layered housing and is wound with Litz wire to reduce eddy current losses at high frequencies. It is also insulated and cured using a vacuum impregnation epoxy resin process to ensure reliability under high temperature and high pressure.

[0036] For details, please refer to Figure 2 In one embodiment of the present invention, the magnetic field generator 5 is arranged in a ring shape and is sleeved on the outside of the nozzle 6.

[0037] For details, please refer to Figure 2 In one embodiment of the present invention, the magnetic sensor 8 is positioned close to the magnetic field generator 5, so that it can both monitor changes in the magnetic field to invert near-wellbore fractures and collect microseismic signals.

[0038] Specifically, in one embodiment of the present invention, the magnetic sensor 8 is an AMR sensor, and the housing is made of C276 Hastelloy alloy.

[0039] Specifically, in one embodiment of the present invention, the flow channel of the nozzle 6 is streamlined to reduce pressure loss, and the nozzle orifice of the nozzle 6 is provided with a polycrystalline diamond bushing to resist the extreme abrasion of the high-energy solid jet.

[0040] Specifically, in one embodiment of the present invention, the body material of the nozzle 6 is a tungsten-nickel-iron high-density alloy, which has both high strength and erosion resistance.

[0041] Specifically, the temporary plugging ball injector 7 includes a ball storage chamber, a drive unit, and a flow regulating valve. The ball storage chamber contains a plurality of temporary plugging balls. The drive unit is driven to move the temporary plugging balls toward the outlet of the ball storage chamber. The flow regulating valve is located at the outlet of the ball storage chamber.

[0042] More specifically, the ball storage chamber is made of 6061 aluminum alloy, and the driving component is a hydraulic cylinder.

[0043] For details, please refer to Figure 1 The deep coal seam waterless fracturing production enhancement device 100 based on magnetorheological effect further includes a magnetorheological fluid storage tank 13 and a high-pressure pump 14. The magnetorheological fluid storage tank 13 is used to contain the magnetorheological fluid, and its inner wall is coated with an epoxy anti-corrosion coating. The magnetorheological fluid storage tank 13 is connected to the fluid magnetization pretreatment tank 1 through the high-pressure pump 14 to input the magnetorheological fluid into the fluid magnetization pretreatment tank 1.

[0044] More specifically, in one embodiment of the present invention, the magnetorheological fluid storage tank 13 is a cylindrical structure made of Q345R low alloy steel; the high-pressure pump 14 is a high-pressure plunger pump with a rated pressure of 50MPa and a flow rate of 20m³ / h, and the pump head is made of AISI431 stainless steel to withstand the abrasiveness of the magnetorheological fluid on the channel, and its inlet is connected to the outlet of the magnetorheological fluid storage tank 13.

[0045] Specifically, in one embodiment of the present invention, the control terminal 10 is a magnetic field control host equipped with a PLC control system, with a fracturing fluid viscosity monitoring screen on the front, and a built-in adaptive fuzzy PID control algorithm, capable of processing multiple sensor signals from downhole and outputting control commands in real time. The control terminal 10 stores a fracture propagation digital twin model and can update the fracture propagation digital twin model through the monitoring results transmitted by the monitoring components.

[0046] Specifically, the proppant storage tank 2 and the fluid mixing tank 3 are sealed together by a compression fitting.

[0047] Specifically, the microseismic monitoring instrument 9 has a cuboid structure, uses a wide-bandwidth, high-sensitivity detector, is fixed to the inner wall of the horizontal section of the pipe 42 by a slip-on sleeve head, and is electrically connected to the control terminal 10 by an optical fiber.

[0048] The present invention provides a deep coal seam waterless fracturing enhancement device 100 based on magnetorheological effect. Through magnetorheological jet dynamic rock breaking and intelligent control, it effectively overcomes the inherent defects of traditional hydraulic fracturing, such as water consumption and reservoir damage, and CO2 fracturing, which cannot actively control fractures. In tests simulating deep coal seam 200 conditions, the fracture network complexity formed by this device is more than 45% higher than that of conventional fracturing, and the fracture swept volume increases by more than 60%, which is expected to increase the final recovery rate of a single well by 30-50%. This device achieves 100% waterless operation, completely eliminating waterlock damage and wastewater backflow pollution. Full-process automated control improves operational efficiency by approximately 35%, and safety protection components reduce downhole operation risks by more than 50%, significantly improving the economy, safety, and environmental friendliness of deep coal seam 200 gas development.

[0049] This invention also provides a method for enhancing production in deep coal seams using waterless fracturing based on magnetorheological effects, applicable to the aforementioned device for enhancing production in deep coal seams using waterless fracturing based on magnetorheological effects. Please refer to [link to relevant documentation]. Figure 3 The method for enhancing production in deep coal seams using waterless fracturing based on magnetorheological effects includes the following steps: Step S100: The magnetorheological fluid is pre-magnetized using the fluid magnetization pretreatment tank.

[0050] In this step, magnetorheological fluid is injected into the magnetorheological fluid storage tank, and the tank agitator is activated during this process to ensure uniform mixing of the fluid. The high-pressure pump is then started to pump the magnetorheological fluid from the storage tank to the fluid magnetization pretreatment tank for pre-magnetization treatment. The pre-magnetization magnetic field strength is set to 0.5T, and the pretreatment time is 30 minutes, which allows the magnetic particles to be uniformly dispersed and initially oriented, thereby improving their downhole magnetic response activity.

[0051] It should be noted that before step S100, a sealing test is performed, that is, nitrogen is used to pressurize the deep coal seam waterless fracturing production enhancement device based on magnetorheological effect to 1.2 times the rated working pressure for a pressure holding test, and soapy water is used to check for leaks to ensure that there are no leaks at all connections under high pressure.

[0052] Step S200: The pre-magnetized magnetorheological fluid is transported to the fluid mixing tank, and the magnetically responsive proppant stored in the proppant storage tank is transported to the fluid mixing tank, so that the magnetically responsive proppant and the pre-magnetized magnetorheological fluid are mixed to obtain a mixed fluid.

[0053] Step S300: The mixed fluid flows into the main pipeline, and as the mixed fluid flows through the nozzle, the magnetic field generator is driven to instantaneously apply a pulsed magnetic field (magnetic field line 400 as shown). Figure 2As shown, the magnetorheological fluid in the mixed fluid undergoes a phase change to form a high-energy solid jet, and the high-energy solid jet is sprayed into the coal seam through the nozzle to form the main fracture.

[0054] In this step, the mixed fluid enters the deep coal seam through the main pipeline. When the fluid flows through the nozzle, the magnetic field generator instantaneously applies a high-intensity pulsed magnetic field of 0.5-1.5T with an output frequency of 1-5Hz. At this time, the magnetorheological fluid undergoes a phase change within milliseconds, and its viscosity increases dramatically to form a high-energy solid jet, which is ejected at high speed from the nozzle orifice of the nozzle, impacting the coal and rock with high kinetic energy, thereby more efficiently opening the initial main fracture in the high-stress coal seam.

[0055] Step S400: Use the magnetic sensor to monitor the magnetic field change and collect microseismic signals in real time, and use the microseismic monitoring instrument to monitor the three-dimensional expansion signal of the main crack in real time.

[0056] In this step, magnetic sensors deployed downhole monitor and collect nearby microseismic and magnetic field data in real time. At the same time, a microseismic monitoring instrument fixed to the horizontal inner wall of the casing monitors the three-dimensional propagation signal of far-field cracks with high precision.

[0057] Step S500: The control terminal analyzes the morphology of the main fracture and predicts its extension trend based on the monitoring results transmitted by the magnetic sensor and the microseismic monitor. When the analysis and prediction result of the control terminal indicates that the main fracture has a single morphology, the control terminal injects a temporary plugging ball into the main fracture to increase the coal seam pressure and act on the natural weak surface or stress shadow area in the coal seam to form a secondary fracture. When the analysis and prediction result of the control terminal indicates that the main fracture extends relatively close to the main fracture, the control terminal generates a non-uniform magnetic field to allow the magnetically responsive proppant flowing into the main pipeline to flow into the tip or branch of the main fracture.

[0058] In this step, if the main fracture has a uniform morphology, the temporary plugging ball injector injects a batch of temporary plugging balls of a predetermined particle size into the main fracture. These balls, carried by the fluid, migrate to the main fracture inlet and form an effective bridge plug, causing an increase in bottom hole pressure. This forces subsequent energy to be redirected to natural weak surfaces or stress-shadowed areas in the coal and rock, thereby generating new branch fractures, i.e., secondary fractures. Alternatively, if the main fracture extends relatively close together, the current in the coils of each magnetic field generator is controlled to construct a non-uniform magnetic field. This induces the subsequently injected magnetically responsive proppant to form a more effective distribution in specific areas within the main fracture, such as the fracture tip or branches, rather than being randomly distributed, thus greatly optimizing propping efficiency.

[0059] It should be noted that the above steps S400 and S500 can be repeated to achieve a step-by-step expansion of "main seam - branch - secondary branch", continuously enriching and complicating the crack network, and finally forming a complex three-dimensional crack network.

[0060] It should also be noted that during the entire operation, the pressure relief valve can be used to finely adjust the operating pressure to prevent pressure runaway; and once an extreme anomaly such as pipeline rupture or sudden pressure drop is detected, the control terminal will instantly trigger the emergency shut-off valve to completely cut off the fluid supply within 1 second to ensure operational safety.

[0061] In addition, after the fracturing operation is completed, the control terminal shuts down the high-pressure pump and the temporary plugging ball injector, stops the magnetic field output, records the total operation time, waits for the temporary plugging ball to completely degrade, and switches to the drainage state after the gas leak alarm has no alarm signal, starts the coalbed methane gathering and transportation system, and extracts the deep coalbed methane into the gas storage tank.

[0062] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A deep coal seam waterless fracturing stimulation device based on the magneto-rheological effect, characterized in that, The deep coal seam non-aqueous pressure fracturing yield increasing device based on the magneto-rheological effect comprises: a fluid magnetization pretreatment tank for pre-magnetizing the magneto-rheological fluid to make the magnetic particles in the magneto-rheological fluid uniformly dispersed and directional arranged; a directional fracture forming assembly comprising a proppant storage tank, a fluid mixing tank, a main pipeline, a plurality of magnetic field generators, a plurality of nozzles and a temporary plugging ball injector, the proppant storage tank stores magnetic response proppants, the fluid mixing tank is connected with the fluid magnetization pretreatment tank and the proppant storage tank to mix the pre-magnetized magneto-rheological fluid and the magnetic response proppants to obtain a mixed fluid, the main pipeline is arranged in the coal seam and comprises a longitudinal section pipeline connected with the fluid mixing tank and a horizontal section pipeline connected with a gas storage tank, a plurality of nozzles are arranged on the side wall of the horizontal section pipeline at intervals, a plurality of magnetic field generators are arranged in the horizontal section pipeline to apply a pulse magnetic field to the mixed fluid to make the mixed fluid phase change to form a high-energy solid-state jet to be sprayed into the coal seam through the nozzles to form a main fracture and / or the magnetic response proppants to be sprayed into the coal seam, and the temporary plugging ball injector is used to inject temporary plugging balls into the main fracture to form a secondary fracture; a monitoring assembly comprising a magnetic sensor arranged on the outer wall of the horizontal casing to monitor the magnetic field change and collect microseismic signals and a microseismic monitor arranged in the horizontal casing to monitor the three-dimensional expansion signals of the main fracture; and a control terminal electrically connected with the temporary plugging ball injector, the magnetic field generators and the monitoring assembly to analyze the shape of the main fracture and predict the extension trend of the main fracture according to the monitoring results of the monitoring assembly and control the working state of the temporary plugging ball injector or the magnetic field generators according to the analysis and prediction results.

2. The device for deep coal seam hydraulic fracturing stimulation based on magneto-rheological effect according to claim 1, characterized in that, The deep coal seam non-aqueous pressure fracturing yield increasing device based on the magneto-rheological effect further comprises a safety guarantee assembly comprising: a plurality of pressure relief valves arranged one by one corresponding to the nozzles and arranged at one end of the nozzles inserted into the horizontal pipeline; and an emergency cutoff valve arranged between the longitudinal section pipeline and the fluid mixing tank; the control terminal is electrically connected with the pressure relief valves and the emergency cutoff valve to control the working state of the pressure relief valves and the emergency cutoff valve.

3. The device for deep coal seam hydraulic fracturing stimulation based on magneto-rheological effect according to claim 1, characterized in that, The fluid magnetization pretreatment tank comprises a tank body and an electromagnetic coil, the inner wall of the tank body is provided with a polytetrafluoroethylene anticorrosive coating, and the magnetic field generated by the electromagnetic coil has a strength of 0.5T.

4. The device for deep coal seam hydraulic fracturing stimulation based on magneto-rheological effect according to claim 1, characterized in that, The magnetic field generator comprises a double-layer shell and an electromagnetic coil, the electromagnetic coil is arranged in the double-layer shell, the electromagnetic coil is wound by Litz wire and is subjected to insulation and solidification treatment by a vacuum impregnation epoxy resin process.

5. The device for deep coal seam hydraulic fracturing stimulation based on magneto-rheological effect according to claim 1, characterized in that, The magnetic field generator is arranged in a ring shape and is sleeved outside the nozzle.

6. The device for deep coal seam hydraulic fracturing stimulation based on magneto-rheological effect according to claim 1, characterized in that, The magnetic sensor is arranged close to the magnetic field generator.

7. The device for deep coal seam hydraulic fracturing stimulation based on magneto rheological effect according to claim 1, characterized in that, The flow channel of the nozzle is arranged in a streamline shape, and a polycrystalline diamond bushing is arranged at the nozzle hole of the nozzle.

8. The device for deep coal seam hydraulic fracturing stimulation based on magneto rheological effect according to claim 1, characterized in that, The temporary plugging ball injector comprises a ball storage bin, a driving member and a flow regulating valve, the ball storage bin contains a plurality of temporary plugging balls, the driving member is in driving connection with the temporary plugging balls to drive the temporary plugging balls to move towards the outlet of the ball storage bin, and the flow regulating valve is arranged at the outlet of the ball storage bin.

9. The device for deep coal seam hydraulic fracturing stimulation based on magneto rheological effect according to claim 1, characterized in that, The deep coal seam waterless fracturing yield increasing device based on the magneto-rheological effect further comprises a magneto-rheological fluid storage tank and a high-pressure pump, the magneto-rheological fluid storage tank is used for containing the magneto-rheological fluid, and the inner wall of the magneto-rheological fluid storage tank is coated with an epoxy anticorrosive coating, and the magneto-rheological fluid storage tank is connected with the fluid magnetization pretreatment tank through the high-pressure pump to input the magneto-rheological fluid into the fluid magnetization pretreatment tank.

10. A method for deep coal seam waterless fracturing stimulation based on magneto-rheological effect, suitable for the device for deep coal seam waterless fracturing stimulation based on magneto-rheological effect as claimed in any one of claims 1-9, characterized in that, The deep coal seam waterless fracturing yield increasing method based on the magneto-rheological effect comprises the following steps: Step S100, pre-magnetizing the magneto-rheological fluid by using the fluid magnetization pretreatment tank; Step S200, delivering the pre-magnetized magneto-rheological fluid into the fluid mixing tank, and delivering the magnetic response proppant stored in the proppant storage tank into the fluid mixing tank, so that the magnetic response proppant is mixed with the pre-magnetized magneto-rheological fluid to obtain a mixed fluid; Step S300, flowing the mixed fluid into the main pipeline, and when the mixed fluid flows through the nozzle, driving the magnetic field generator to instantaneously apply a pulse magnetic field to the magneto-rheological fluid in the mixed fluid to form a high-energy solid-state jet, and the high-energy solid-state jet is sprayed into the coal seam through the nozzle to form a main fracture; Step S400, using the magnetic sensor to monitor the magnetic field change and collect the microseismic signal in real time, and using the microseismic monitor to monitor the three-dimensional expansion signal of the main fracture in real time; Step S500, analyzing the morphology of the main fracture and predicting the extension trend of the main fracture by the control terminal according to the monitoring results delivered by the magnetic sensor and the microseismic monitor, and when the analysis and prediction result of the control terminal is that the morphology of the main fracture is single, controlling the temporary plugging ball injector to inject temporary plugging balls into the main fracture to increase the pressure of the coal seam and form secondary fractures on the natural weak surface or stress shadow area in the coal seam, and when the analysis and prediction result of the control terminal is that the morphology of the main fracture is close to the extension, controlling the magnetic field generator to generate a non-uniform magnetic field to make the magnetic response proppant flowing into the main pipeline subsequently flow into the tip or branch of the main fracture.

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