Intelligent control drill rod and blowout prevention hole device for soft coal seam drilling

Abstract

The present application relates to the technical field of soft coal seam drilling, and discloses an intelligent control drill rod and blowout hole device for soft coal seam drilling, which comprises a front-end sensing unit, a relay sensing unit, a hydraulic servo motor, a frequency converter, a shape memory alloy framework, a thermal-responsive polymer expansion gel layer and a control unit. The device can expand to 3 times the original diameter within 2 seconds through thermal triggering, forming a multi-stage labyrinth seal. The control unit is installed with an embedded AI chip to run an LSTM pressure time sequence prediction model, and combines temperature and vibration multi-source data fusion to judge the blowout risk level, solving the problems of lack of real-time gas pressure dynamic monitoring capability of traditional drill rods, reliance on artificial experience to judge blowout risk, and response lag. The single position pressure sensor is easily disturbed by local rock layer mutation, has a high false alarm rate, and cannot distinguish between normal pressure fluctuations and blowout precursors, so the device realizes early blowout warning and actively suppresses blowout accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of soft coal seam drilling, and specifically to an intelligent control drill pipe and a blowout prevention device for soft coal seam drilling. Background Technique

[0002] In China, the reserves of coal seam gas resources are abundant. Improving the recovery rate of coal seam gas has multiple significances such as making up for the shortage of conventional oil and gas resources, reducing greenhouse gas emissions, and promoting coal mine production safety. However, many coal seams have experienced multiple large-scale tectonic movements, resulting in the development of tectonic soft coal, poor gas permeability, low underground extraction concentration, low efficiency, and posing great potential safety hazards to the mine. Problems such as difficult hole formation due to soft and broken coal seams and blockage of gas flow channels due to borehole collapse are prominent, bringing great difficulties to coal seam borehole construction. This is mainly because when drilling in outburst soft coal seams, conventional drilling methods are prone to problems such as blowout and borehole collapse, restricting the drilling efficiency of boreholes. The excessive amount of gas gushing out instantaneously during blowout may lead to gas overlimit, and even more seriously, induced outburst events may occur. Therefore, the gas control plan of "shallow drilling, shallow extraction, and shallow excavation" has to be chosen, resulting in slow construction progress and extended gas control cycles.

[0003] At present, the commonly used blowout prevention technologies during drilling in soft and outburst coal seams are: passive mechanical plugging, pressure monitoring and early warning, gas component analysis, etc. The core problems existing in the existing blowout prevention technologies are the disconnection between monitoring and response, insufficient plugging efficiency, and low intelligent level. Traditional drill pipes lack the ability to dynamically monitor the real-time gas pressure, rely on manual experience to judge the blowout risk, and have a lag in response. Single-position pressure sensors are easily interfered by local rock layer mutations, have a high false alarm rate, and cannot distinguish normal pressure fluctuations from blowout precursors.

[0004] Most of the existing blowout prevention devices are passive mechanical plugging, unable to trigger linkage protection within the golden window period (10 - 30 seconds) at the initial stage of blowout. Blowout is sudden and highly destructive, and it is difficult for the existing technologies to achieve closed-loop control of "perception - early warning - execution". When the drill pipe rotates at high speed, conventional sensors are easily失效 due to vibration, and the plugging structure is difficult to balance sealing performance and drilling efficiency. The existence of these problems makes the current drilling technology difficult to meet the safety drilling requirements of high-gas coal seams. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides an intelligent control drill pipe and a blowout prevention device for soft coal seam drilling, which solve the problems of inaccurate prediction of blowout time and untimely plugging of blowout during the traditional coal seam drilling process and solve the above technical problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an intelligent control drill rod and blowout prevention device for drilling in soft coal seams, comprising a drill rod, wherein the drill rod is connected to a dynamic speed control actuator via a spline coupling, the outer end face of the drill rod is provided with a multi-stage pressure sensing module, and the outer end face of the drill rod is provided with an adaptive sealing device, wherein the adaptive sealing device is located between the multi-stage pressure sensing module and the spline coupling;

[0007] The multi-level pressure sensing module includes a front-end sensing unit and a relay sensing unit. The front-end sensing unit is specifically a MEMS piezoresistive pressure sensor, and the relay sensing unit is specifically a first fiber Bragg grating pressure sensor and a second fiber Bragg grating pressure sensor arranged symmetrically.

[0008] The adaptive plugging device includes a shape memory alloy skeleton and a thermally responsive polymer expandable gel layer. The shape memory alloy skeleton is installed in an annular groove on the outer wall of the drill pipe. The outer surface of the shape memory alloy skeleton is provided with a thermally responsive polymer expandable gel layer, and a phase change medium layer is provided between the two. The phase change medium layer is connected to a PTC heater through a thermally conductive silicone grease layer. The PTC heater is powered by a capacitor energy storage module. The capacitor energy storage module is connected to a microcontroller. The microcontroller is connected to the control unit in the dynamic speed control actuator via a CAN bus.

[0009] As a preferred embodiment of the present invention, the first fiber Bragg grating pressure sensor and the second fiber Bragg grating pressure sensor are connected to the drill rod 1.5m behind the drill bit via a flange. The MEMS piezoresistive pressure sensor is provided in three sets, which are equidistantly embedded in the groove on the outer wall of the drill rod. A wire groove is reserved inside the drill rod, and an RS-485 bus is provided in the wire groove to connect the MEMS piezoresistive pressure sensor and the control unit.

[0010] As a preferred embodiment of the present invention, the first fiber Bragg grating pressure sensor and the second fiber Bragg grating pressure sensor are respectively connected to the control unit via the first fiber and the second fiber.

[0011] As a preferred embodiment of the present invention, the dynamic speed control actuator includes a hydraulic servo motor, which is connected to a frequency converter via a shielded power cable. The frequency converter is connected to a control unit via a Profinet protocol communication line, and the control unit is connected to the hydraulic servo motor via a signal transmission line.

[0012] As a preferred embodiment of the present invention, a blowout preventer is provided between the drill rod and the hydraulic servo motor. The blowout preventer has a three-way pipe structure. The drill rod is threaded through the main pipe of the blowout preventer. One branch pipe is connected upward to the main exhaust pipe, and the other branch pipe is connected downward through the slag discharge hose.

[0013] As a preferred embodiment of the present invention, the adaptive sealing device further includes a temperature sensor and a displacement sensor. The temperature sensor is embedded inside a shape memory alloy skeleton and is electrically connected to the control unit.

[0014] Compared with the prior art, the present invention provides an intelligent control drill rod and blowout prevention device for drilling in soft coal seams, which has the following beneficial effects:

[0015] 1. This invention uses a shape memory alloy skeleton and a thermally responsive polymer expansion gel layer pre-embedded in the outer wall of the drill pipe. Upon thermal triggering, it can expand to three times its original diameter within 2 seconds, forming a multi-level labyrinth seal. The control unit is equipped with an embedded AI chip that runs an LSTM pressure timing prediction model. This model combines temperature and vibration data from multiple sources to determine the blowout risk level, solving the problems of traditional drill pipes lacking real-time dynamic gas pressure monitoring capabilities, relying on manual experience to judge blowout risk, and having a delayed response. Single-position pressure sensors are easily affected by sudden changes in local rock formations, resulting in a high false alarm rate and an inability to distinguish between normal pressure fluctuations and blowout precursors. Existing blowout prevention devices are mostly passive mechanical sealing devices, unable to trigger linkage protection within the golden window period (10-30 seconds) at the initial stage of a blowout, thus failing to achieve early warning of blowouts and actively suppress blowout accidents. This also solves the problem of high manual labor intensity, saving costs and being environmentally friendly.

[0016] 2. This invention significantly reduces the false alarm rate compared to traditional single-point monitoring by using a front-end MEMS sensor and a relay FBG sensor for collaborative verification. The hydraulic servo motor has a response time of less than 0.1 seconds and a speed adjustment range of 50 to 3000 rpm, greatly improving efficiency compared to traditional mechanical speed regulation. The shape memory alloy skeleton maintains sealing strength even at 150℃, and the expanding gel has low porosity, achieving highly efficient and reliable adaptive plugging. The LSTM algorithm provides early warning and, combined with the plugging device, quickly completes sealing, significantly reducing the blowout accident rate. Fully automated control replaces manual inspection and plugging, reducing labor costs and improving operational safety. The separated and recovered coal dust and gas can be directly reused, greatly reducing annual CH4 emissions and minimizing resource waste, meeting the requirements of sustainable development. The sensor and plugging device are temperature resistant to 200℃, vibration resistant, and explosion-proof, suitable for high-gas and high-impact coal seams, improving environmental adaptability. Through modular design, the drill pipe assembly supports rapid downhole replacement, significantly reducing downtime due to malfunctions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the cross-section of the drill pipe sensor portion and the selected area in this invention;

[0019] Figure 3 This is a schematic diagram of the adaptive plugging device of the present invention;

[0020] Figure 4 This is the LSTM time series prediction model in this invention.

[0021] The components include: 1. Drill pipe; 2. Adaptive plugging device; 3. Spline coupling; 4. Hydraulic servo motor; 5. Frequency converter; 6. Control unit; 7. Signal transmission line; 8. Profinet protocol communication line; 9. Shielded power cable; 10. Multi-stage pressure sensing module; 11. MEMS piezoresistive pressure sensor; 12. First fiber Bragg grating pressure sensor; 13. Flange; 14. RS-485 bus; 15. First fiber; 16. Second fiber Bragg grating pressure sensor; 17. Second fiber; 18. Shape memory alloy skeleton; 19. Capacitor energy storage module; 20. Microcontroller; 21. CAN bus; 22. Thermally responsive polymer expansion gel layer; 23. Thermally conductive silicone grease layer; 24. Phase change medium layer; 25. Temperature sensor; 26. Displacement sensor; 27. PTC heater; 28. Hole wall; 29. ​​Blowout preventer sleeve; 30. Main exhaust pipe; 31. Slag discharge hose. Detailed Implementation

[0022] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1 - Figure 3 A smart control drill rod and blowout prevention device for drilling soft coal seams includes a drill rod 1, which is connected to a dynamic speed control actuator via a spline coupling 3. A multi-level pressure sensing module 10 is provided on the outer end face of the drill rod 1, and an adaptive sealing device 2 is provided on the outer end face of the drill rod 1, which is located between the multi-level pressure sensing module 10 and the spline coupling 3.

[0024] The multi-level pressure sensing module 10 includes a front-end sensing unit and a relay sensing unit. The front-end sensing unit is specifically a MEMS piezoresistive pressure sensor 11 (MEMS, Micro-Electro Mechanical Systems), and the relay sensing unit is specifically a first fiber Bragg grating pressure sensor 12 and a second fiber Bragg grating pressure sensor 16 arranged symmetrically.

[0025] The adaptive plugging device 2 includes a shape memory alloy skeleton 18 and a thermally responsive polymer expansion gel layer 22. The thermally responsive polymer expansion gel layer 22 includes an outer flame-retardant polyurethane layer, a middle thermally conductive silicone rubber layer, and an inner temperature-sensitive hydrogel layer. The shape memory alloy skeleton 18 is installed in an annular groove on the outer wall of the drill pipe 1. The thermally responsive polymer expansion gel layer 22 is provided on the outer surface of the shape memory alloy skeleton 18, and a phase change medium layer 24 is provided between the two. The phase change medium layer 24 is connected to the PTC heater 27 through a thermally conductive silicone grease layer 23. The PTC heater 27 is powered by a capacitor energy storage module 19. The capacitor energy storage module 19 is connected to a microcontroller 20. The microcontroller 20 is connected to the control unit 6 in the dynamic speed control actuator through a CAN bus 21 (CAN, Controller Area Network). The control unit 6 is equipped with an embedded AI chip, which is connected to a data acquisition card through a PCIe interface.

[0026] The phase change medium layer itself is made of existing technology, a specially formulated composite shaped phase change material that meets the requirements of fast response and high safety in downhole applications. It is composed of a paraffin base material and 15%–25% by volume boron nitride thermally conductive filler, and is sealed with copper foil (0.1 mm thick) to ensure no leakage under vibration. Its core function is to receive and smoothly release the heat from the PTC heater, achieving intrinsically safe thermal isolation between the electrical system and the actuator.

[0027] The first fiber Bragg grating pressure sensor 12 and the second fiber Bragg grating pressure sensor 16 are connected to the drill rod 1 1.5m behind the drill bit via flange 13. The MEMS piezoresistive pressure sensor 11 is provided in 3 sets, which are equidistantly embedded in the groove on the outer wall of the drill rod 1. The drill rod 1 has a reserved wire groove inside, and an RS-485 bus 14 is set in the wire groove to connect the MEMS piezoresistive pressure sensor 11 and the control unit 6. The MEMS piezoresistive pressure sensor 11 has an accuracy of ±0.1%FS and a pressure resistance of 20MPa. The MEMS piezoresistive pressure sensor 11 is embedded in the drill rod 1 20cm behind the drill bit. The drill rod 1 has a standard sensor interface reserved through modular design.

[0028] Three sets of MEMS piezoresistive pressure sensors 11 are equidistantly embedded in the grooves on the outer wall of the drill pipe 1, encapsulated with high-temperature resistant epoxy resin, and secured with threaded fasteners. The drill pipe 1 has a pre-reserved wire slot, supports an RS-485 bus with a baud rate of 115200bps, and a bit error rate of... The RS-485 bus 14, placed in the cable tray, connects the MEMS piezoresistive pressure sensor 11 and the control unit 6 to transmit data, and the anti-interference shielding layer is grounded.

[0029] The first fiber Bragg grating pressure sensor 12 and the second fiber Bragg grating pressure sensor 16 are connected to the control unit 6 via the first fiber 15 and the second fiber 17, respectively. The first fiber Bragg grating pressure sensor 12 and the second fiber Bragg grating pressure sensor 16 have a wavelength demodulation accuracy of ±1pm and a temperature resistance of 150℃. The first fiber Bragg grating pressure sensor 12 and the second fiber Bragg grating pressure sensor 16 are connected to the drill rod 1 1.5m behind the drill bit via the flange 13.

[0030] The dynamic speed control actuator includes a hydraulic servo motor 4, which is connected to a frequency converter 5 via a shielded power cable 9. The frequency converter 5 is connected to a control unit 6 via a Profinet protocol communication line 8. The control unit 6 is connected to the hydraulic servo motor 4 via a signal transmission line 7, which includes an RS-485 bus 14 (RS-485 is an industry standard serial communication protocol), a first optical fiber 15, a second optical fiber 17, and a CAN bus 21.

[0031] A blowout preventer 29 is provided between the drill rod 1 and the hydraulic servo motor 4. The blowout preventer 29 has a three-way pipe structure. The drill rod 1 is sleeved inside the main pipe of the blowout preventer 29. One end of the main pipe is fixed to the borehole wall 28. One branch pipe is connected upward to the main exhaust pipe 30, and the other branch pipe is connected downward through the slag discharge hose 31.

[0032] The adaptive blocking device 2 also includes a temperature sensor 25 and a displacement sensor 26. The temperature sensor 25 is embedded inside the shape memory alloy skeleton 18 and is electrically connected to the control unit 6.

[0033] The specific process of this invention is as follows:

[0034] Procedure 1: When the control unit 6 detects an abnormal change in the data transmitted by the MEMS piezoresistive pressure sensor 11, but the data transmitted by the first fiber Bragg grating pressure sensor 12 is normal, it is determined that there is a risk of blowout. The control unit 6 will issue a corresponding command to the frequency converter 5 in the dynamic speed control actuator through the Profinet protocol communication line 8 to reduce the speed of the drill rod to a safe threshold in a short time to prevent blowout accidents. After the data detected by the MEMS piezoresistive pressure sensor 11 returns to normal, the drilling work will resume.

[0035] Process 2: When the control unit 6 detects abnormal changes in the data transmitted by the MEMS piezoresistive pressure sensor 11 and the first fiber Bragg grating pressure sensor 12, it is determined that a blowout has occurred in the borehole. The control unit 6 simultaneously issues corresponding instructions to the frequency converter 5 and the microcontroller 20, and performs the following actions: the drill rod 1 quickly reduces the drilling speed to a safe threshold, the capacitor energy storage module 19 triggers the adaptive sealing device 2 to form a negative pressure drainage channel to guide the gas into the recovery cavity inside the drill rod 1, the thermally responsive polymer expansion gel layer 22 undergoes a phase change at a temperature > 80°C, expands to 3 times its original volume, forms a multi-level labyrinth-like sealing structure, and the micro aerogel fire extinguishing agent spraying module embedded in the drill rod 1 is activated to suppress friction sparks;

[0036] Specifically, the control unit 6 is equipped with an embedded AI chip that runs an LSTM (Long Short-Term Memory) pressure time-series prediction model. This model uses front-end MEMS sensors and relay FBG (Fiber Bragg Grating) sensors to collect real-time borehole pressure, vibration, and temperature data at a sampling rate of 1kHz. The data is then analyzed based on the LSTM time-series prediction model, which has a 6-dimensional input layer and includes the following real-time multi-source borehole data:

[0037] Drilling pressure measured by a MEMS sensor located 20cm behind the drill bit;

[0038] The X-axis vibration acceleration of drill pipe 1;

[0039] The radial Y-axis vibration acceleration of drill pipe 1;

[0040] The radial Z-axis vibration acceleration of drill pipe 1;

[0041] Temperature at the drill bit;

[0042] The mass flow rate of pulverized coal in the borehole is used to output the borehole risk level from 0 to 5. The model is trained using 100,000 sets of historical borehole data, with cross-entropy as the loss function and Adam as the optimizer with a learning rate of 1e-3.

[0043] No action is taken when the risk level is <3. When the risk level is ≥3, a speed reduction command is executed. When the risk level is ≥4, both the speed reduction command and the trigger sealing are executed simultaneously, triggering the discharge of the capacitor energy storage module 19, causing the PTC heater 27 (PTC, Positive Temperature Coefficient) to heat up to 85°C within 0.5 seconds; the shape memory alloy skeleton 18 has an expansion rate ≥300%, and the expansion gel layer 22 undergoes a phase change at 80°C, expanding its volume to 3 times; when the displacement sensor 26 detects an expansion diameter <140mm, the PTC heater 27 will continue to supply energy through the thermally conductive silicone grease layer 23.

[0044] Step 3: The sealing device incorporates a temperature sensor 25 (PT100) and a displacement sensor 26 (LVDT, Linear Variable Displacement Transducer) to provide real-time feedback on the expansion status, temperature, and diameter to the control unit. The temperature sensor 25 is embedded within a shape memory alloy frame, with a temperature range of -50 to 300℃. The displacement sensor 26 has a range of 0 to 200 mm and an accuracy of ±0.1 mm. If the expansion does not reach the set threshold, the PTC heater 27 continuously supplies energy through the thermally conductive silicone grease layer 23, repeating the operation of the drill pipe expansion sealing device in Step 2 to ensure a sealing success rate >99%.

[0045] Step 4: After the sealing is completed, the drill rod automatically retracts 0.5m, and the adaptive sealing device 2 slowly retracts after 30 minutes. The water and coal slag gushing out of the borehole are discharged through the blowout preventer sleeve 29. The blowout preventer sleeve 29 is a three-way pipe structure. One end of its main pipe is fixed to the borehole wall, and the drill rod 1 is sleeved inside the main pipe. One branch pipe is connected upward to the main exhaust pipe 30, and the other branch pipe is connected downward through the slag discharge hose 31. The water and coal slag gushing out of the borehole are discharged through the slag discharge hose 31, and the gas gushing out of the borehole is discharged through the main exhaust pipe 30 until the monitoring data returns to normal.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An intelligent controllable drill rod and blowout prevention device for drilling in soft coal seams, comprising a drill rod (1), characterized in that: The drill rod (1) is connected to the dynamic speed regulating actuator through the spline coupling (3). The outer end face of the drill rod (1) is provided with a multi-level pressure sensing module (10). The outer end face of the drill rod (1) is provided with an adaptive sealing device (2). The adaptive sealing device (2) is located between the multi-level pressure sensing module (10) and the spline coupling (3). The multi-level pressure sensing module (10) includes a front-end sensing unit and a relay sensing unit. The front-end sensing unit is specifically a MEMS piezoresistive pressure sensor (11), and the relay sensing unit is specifically a first fiber Bragg grating pressure sensor (12) and a second fiber Bragg grating pressure sensor (16) arranged symmetrically. The first fiber Bragg grating pressure sensor (12) and the second fiber Bragg grating pressure sensor (16) are connected to the drill rod (1) 1.5m behind the drill bit via a flange (13). The MEMS piezoresistive pressure sensor (11) is provided in 3 sets, which are equidistantly embedded in the groove on the outer wall of the drill rod (1). The drill rod (1) has a reserved wire groove inside, and an RS-485 bus (14) is provided in the wire groove to connect the MEMS piezoresistive pressure sensor (11) and the control unit (6). The adaptive plugging device (2) includes a shape memory alloy skeleton (18) and a thermally responsive polymer expansion gel layer (22). The shape memory alloy skeleton (18) is installed in an annular groove on the outer wall of the drill pipe (1). The outer surface of the shape memory alloy skeleton (18) is provided with a thermally responsive polymer expansion gel layer (22), and a phase change medium layer (24) is provided between the two. The phase change medium layer (24) is connected to a PTC heater (27) through a thermally conductive silicone grease layer (23). The PTC heater (27) is powered by a capacitor energy storage module (19). The capacitor energy storage module (19) is connected to a microcontroller (20). The microcontroller (20) is connected to a control unit (6) in a dynamic speed control actuator via a CAN bus (21).

2. The intelligent control drill rod and blowout prevention device for drilling in soft coal seams according to claim 1, characterized in that: The first fiber Bragg grating pressure sensor (12) and the second fiber Bragg grating pressure sensor (16) are connected to the control unit (6) through the first fiber (15) and the second fiber (17), respectively.

3. The intelligent control drill rod and blowout prevention device for drilling in soft coal seams according to claim 1, characterized in that: The dynamic speed control actuator includes a hydraulic servo motor (4), which is connected to a frequency converter (5) via a shielded power cable (9). The frequency converter (5) is connected to a control unit (6) via a Profinet protocol communication line (8). The control unit (6) is connected to the hydraulic servo motor (4) via a signal transmission line (7).

4. The intelligent control drill rod and blowout prevention device for drilling in soft coal seams according to claim 1, characterized in that: A blowout preventer (29) is provided between the drill rod (1) and the hydraulic servo motor (4). The blowout preventer (29) has a three-way pipe structure. The drill rod (1) is sleeved inside the main pipe of the blowout preventer (29). One branch pipe is connected upward to the main exhaust pipe (30), and the other branch pipe is connected downward through the slag discharge hose (31).

5. The intelligent control drill rod and blowout prevention device for drilling in soft coal seams according to claim 1, characterized in that: The adaptive blocking device (2) also includes a temperature sensor (25) and a displacement sensor (26), wherein the temperature sensor (25) is embedded inside the shape memory alloy skeleton (18) and electrically connected to the control unit (6).

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