An intelligent multi-hole section combined dynamic slotted system in a well and a construction method thereof

Abstract

The present application relates to a kind of downhole intelligent porous section and moving dynamic slotted system, belong to coalbed gas extraction field, including shunt cylinder body, the shunt cylinder body one end is equipped with M pump source input port, the other end is equipped with N pump source output port, N > M, each pump source input port is equipped with input monitoring module, each pump source output port is equipped with output monitoring module;It also includes display console, logic module, the display console is configured parameter to logic module, to send command to input monitoring module and output monitoring module, control each pump source input port and pump source output port opening and closing;The output monitoring module is also used to monitor the slotted state of corresponding borehole in real time, and feedback to logic module;The logic module is also used to carry out dynamic evaluation to each borehole fissure development and to each borehole slotted working state, and according to the result, dynamically intelligent control each borehole slotted configuration parameter.It also relates to a kind of construction method.

Description

A Downhole Intelligent Multi-Section Parallel Dynamic Slotting System and its Construction Method Technical Field

[0001] This invention belongs to the field of coalbed methane extraction and relates to an intelligent downhole multi-segment parallel dynamic slotting system and its construction method. Background Technology

[0002] Currently, there are many types of mobile slotting equipment for downholes, but no intelligent slotting equipment has been realized. There is no substantial realization of "fully automatic" intelligent slotting. The existing mobile slotting range is small, and it can generally only be used for single-hole construction. Due to the high water pressure of the slotting pump set, it requires manual operation, which poses certain personnel safety risks. It has not been able to achieve automatic slotting in the absence of supervision or automatic evaluation of slotting effect. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a downhole intelligent multi-segment parallel dynamic slotting system and its construction method.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A downhole intelligent multi-segment parallel dynamic slotting system includes a flow-diverting cylinder. One end of the flow-diverting cylinder has M pump source input ports, and the other end has N pump source output ports, where N>M. Each pump source input port is equipped with an input monitoring module, and each pump source output port is equipped with an output monitoring module. The system also includes a display console and a logic module. The display console configures parameters for the logic module, thereby sending commands to the input and output monitoring modules to control the opening and closing of each pump source input and output port. The output monitoring module is also used to monitor the slotting status of the corresponding borehole in real time and provide feedback to the logic module. The logic module is also used to dynamically evaluate the fracture development and slotting operation status of each borehole, and dynamically and intelligently adjust the slotting configuration parameters of each borehole based on the results.

[0006] Furthermore, the kerf condition of the borehole includes the magnitude of the pump source output flow rate and the magnitude of the pressure.

[0007] Furthermore, the logic module monitors the output pressure curve of the borehole pump source in real time and compares it with the curves of three slotting models to deduce the current slotting development status; the slotting model curves include pressure balance type, pressure oscillation type, and wave type.

[0008] The pressure-balanced type involves a continuous increase in pressure at the cut hole, followed by stabilization in the working area, during which a slit is cut to a predetermined radius, ultimately forming a circular crack.

[0009] The pressure oscillation type is that when the pressure of the cutting fluid in the coal seam reaches a certain level, it forms a state that surrounds the cutting hole. The pressure continues to rise for a period of time. As coal dust is continuously flushed out, the annular crack continues to expand, the cutting pressure decreases, and this oscillation process is repeated.

[0010] The wave pattern refers to the fluctuation of hydraulic pressure in the slit during the transition from a mature slit area to an unslit area. The transformation of multiple slit systems into this wave pattern is characterized by the wave shape of hydraulic pressure in the slit.

[0011] The developmental state of the slotted fissure includes the slotted fissure propagation stage, the slotted fissure propagation delay stage, and the slotted fissure propagation maturity stage.

[0012] Furthermore, the logic module comprehensively analyzes the flow stability at the pump source output port, whether a sudden flow change occurs, and the cumulative cut water volume parameters, and dynamically evaluates them as follows:

[0013] (1) Set the critical value of flow change Δq. Under normal cutting conditions, the flow rate is relatively stable, there is no sudden change in flow rate, and the cumulative cutting water volume has not reached the preset value Q. At this time, the dynamic feedback is normal cutting. When the cumulative cutting water volume reaches the cutting water limit value, the material fracture judgment condition Q, the cutting will automatically stop.

[0014] (2) If the kerf flow rate changes abruptly and the cumulative kerf water volume does not reach the preset value Q, the dynamic feedback is to stop kerfing and check whether there is a large-area water leakage in the water pump pipeline or kerf system.

[0015] (3) When the flow rate in the slot is relatively stable, no sudden flow occurs, and the cumulative slot water volume reaches the preset value Q, the dynamic feedback indicates that the slot cutting is complete.

[0016] (4) When the flow rate of the cut is relatively stable and there is no sudden change in flow rate, and the design water injection volume is not reached, but the adjacent pressure sensor identifies a stable pressure drop and water outlet status, it is considered that the cut has been completed. Stop the water supply to the two adjacent cut system holes, and so on until all other cuts are completed.

[0017] The critical value for flow rate change is related to the slit jet pressure; the relationship between jet pressure and the critical value Δq for flow rate change is as follows:

[0018] When the jet pressure is 0–40 MPa, Δq is 82 L / min;

[0019] When the jet pressure is 40–50 MPa, Δq is 92 L / min;

[0020] When the jet pressure is 5–90 MPa, Δq is 120 L / min;

[0021] When the jet pressure is 90–100 MPa, Δq is 130 L / min;

[0022] The cumulative water volume in the slit does not reach the preset value Q. When determining the slit pressure, the critical flow rate is multiplied by the slit time, plus a 10% margin factor.

[0023] Furthermore, the calculation steps for the parameters of slot water volume, slot water pressure, slot spacing, borehole spacing, rotation speed, and slotting time are as follows:

[0024] A numerical simulation model of the stress field of the borehole surrounding rock was established. The model parameters were set as basic physical parameters, including coal and rock density, bulk modulus, shear modulus, cohesion, internal friction angle, tensile strength, and vertical stress. The values ​​of the basic physical parameters were determined in the laboratory or fixed empirical values.

[0025] By combining numerical simulation with factors influencing ultra-high pressure hydraulic slotting technology, the stress evolution characteristics of coal seams under different jet pressures, slotting spacing, slotting borehole spacing, and slotting methods were analyzed. The optimal set of parameters for slotting water pressure, slotting spacing, and borehole spacing was obtained. The slotting water volume was calculated based on the slotting nozzle diameter, slotting pressure, and slotting time. The rotation speed and slotting time parameters were obtained from ground slotting tests on coal samples.

[0026] Furthermore, the kerf depth calculation and prediction model x is:

[0027]

[0028] Where d0 is the nozzle diameter (m), and P is the pump driving pressure (MPa). w ρ c C represents the density of water and coal. w C c Let P be the propagation velocity of stress waves in water and coal, and let P be the water hammer pressure on the coal body. w The jet of liquid is subjected to a reaction force of P. c μ is the dynamic viscosity coefficient; υ is the kinematic viscosity coefficient of water; σ1, σ2, and σ3 are obtained from coal body tests; σ1 - μ(σ2 + σ3) ≥ σ t The criteria for determining the fracture of materials with extreme limits;

[0029] The relationship between the kerf pressure and the critical slag discharge rate was calculated using dimensional analysis:

[0030]

[0031] P is the dynamic pressure at the nozzle outlet, Pa; a is a comprehensive factor characterizing the shape of coal particles; T0 is the coal drop velocity (t / min).

[0032] Slot spacing: The spacing between slotted boreholes is determined by the permeability coefficient of the coal seam, and the spacing distance is obtained from field investigation or numerical simulation;

[0033] The slotting time parameter was obtained from the ground slotting test of coal samples, and the cycle of each "circle" was less than 25 minutes; the slotting water volume was calculated based on the slotting nozzle diameter, slotting pressure, and slotting time; the rotation speed was determined based on the robustness coefficient and slotting pressure; the robustness coefficient was 0.4, the slotting pressure was 80 MPa, and the drill rod rotation speed was 80 r / min; the robustness coefficient was 0.8, the slotting pressure was 90 MPa, and the drill rod rotation speed was 40 r / min.

[0034] On the other hand, the present invention provides a method for intelligent multi-segment parallel dynamic slotting construction in downhole wells, comprising the following steps:

[0035] S1: Multiple slotting boreholes are constructed at certain intervals in the area where slotting is required. Multiple slotting systems extend to the top of the boreholes under water pressure and begin to make backward slotting. The slotting interval, the size of the slotting water pressure, and the rotation speed of the slotter are all related to the hardness of the coal body. The drilling depth is determined according to the specific site conditions.

[0036] S2: Start the slotting test and start the slotting operation. Set the slotting water injection volume, slotting water pressure, slotting spacing, rotation speed and slotting time parameters according to the coal seam hardness, ground stress and coal seam permeability parameters to carry out automatic operation.

[0037] S3: After the operation is completed and the machine is shut down, shut down the entire slit cutting system, extend and retract to the borehole opening and exit the borehole. At this time, disassemble the rotating high-pressure water tail and move all equipment to perform the next set of parallel slit cutting.

[0038] Furthermore, 4-6 slotted boreholes with diameters of 94-113mm are drilled within a 30m radius of the area requiring slotting. The spacing between the slotted boreholes needs to be determined based on site conditions. For medium-hardness coal seams, the slotting radius is 1.5-2.0m, and the slot width is 2-6cm. The slotting depth for in-seam boreholes is 10-100m, and the slotting depth for cross-seam boreholes is 10-10m. The maximum working pressure is 100MPa, and the pressure resistance of the complete set of equipment is 150MPa. Secondary protection is provided at all equipment connections.

[0039] Furthermore, the slotting pump sets employ the same model of pump set, either as a single pump or in parallel operation of two pumps.

[0040] Furthermore, pressure and flow sensors are installed in each borehole of the slit system, and synchronous or differentiated slits are set, including parameters such as slit water injection volume, slit water pressure, slit spacing, rotation speed, and slit time.

[0041] The beneficial effects of this invention are as follows: Through the pump source adaptive diverter and corresponding real-time fracture assessment system for slotted boreholes provided by this invention, parallel slotting operations can be achieved for several boreholes using a limited pump source. This enables parallel slotting construction, 24 / 7 uninterrupted slotting construction, and real-time online monitoring of the slots.

[0042] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0044] Figure 1 is a schematic diagram of the structure of the downhole multi-slot parallel dynamic slotting system described in this invention;

[0045] Figure 2 is a flowchart of the working process of the downhole multi-slot parallel dynamic slotting system of the present invention;

[0046] In Figure 3, (a) is a pressure balance type pressure curve, (b) is a pressure oscillation type pressure curve, and (c) is a wave type pressure curve;

[0047] Figures 4-5 are schematic diagrams of the parallel dynamic slotting construction of the downhole multi-hole section described in the invention;

[0048] Figure 6 shows the curve for the reasonable selection of slag discharge pressure in coordination with the slit cutting. Detailed Implementation

[0049] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0050] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0051] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0052] Please refer to Figures 1-5, which illustrate a multi-segment parallel dynamic slotting system and its construction method in underground coalbed methane extraction. This invention provides a multi-segment parallel slotting system and its construction method for slotting operations during underground coalbed methane extraction. Using the pump source adaptive diverter and corresponding real-time assessment system for slotted borehole fractures provided by this invention, parallel slotting operations can be performed on several boreholes with a limited pump source. The key technologies involved in this invention include the following three points: 1) a real-time assessment system for slotted borehole fractures, 2) a pump source adaptive diverter, and 3) a multi-segment parallel slotting construction method. This achieves the beneficial effects of 1) parallel slotting construction, 2) 7×24 uninterrupted slotting construction, and 3) real-time online monitoring of slots.

[0053] The logical relationship of the key technologies is as follows: the pump source adaptive flow divider outputs the pump source pressure at equal pressure. Based on the real-time flow feedback of multiple parallel slotted boreholes, the slotted borehole fracture real-time assessment system evaluates and calculates the degree of fracture development in the slotted boreholes, thereby adjusting the pump source adaptive flow divider to dynamically adjust the individual output port in real time to achieve the effect of synchronous parallel slotting.

[0054] To achieve the goal of 24 / 7 uninterrupted slotting operations, the pump source adaptive splitter can be manually set to close a designated output end. At this time, a new drilling pipeline can be connected, and slotting operations at ports that are not closed will not be affected.

[0055] Furthermore, the real-time assessment system for slotted borehole fractures can provide online reporting of the real-time input and output parameters of the pump source adaptive distributor and issue early warnings of abnormal slotting behavior. This helps improve the safety of slotted borehole construction.

[0056] As shown in Figure 1, taking a 2-input, 6-output configuration as an example, the working logic of the pump source adaptive splitter is as follows: two sets of pump sources are input through the pump source input port. The working status of the pump sources can be controlled by the input monitoring module. The pump sources are input to the splitter cylinder and then output through the pump source output port. The working status of the output port can be controlled by the output monitoring module.

[0057] The input and output monitoring modules are controlled by a logic module, which can be configured both downhole and remotely via a display console and communication module. The entire pump source adaptive shunt and its components are powered by a power supply module.

[0058] As shown in Figure 2, the logic of the real-time fracture assessment system for slotted boreholes is as follows: The initial operating state of the system can be configured with slotting parameters locally via the display console or remotely via the communication module. The logic module, based on the given slotting parameter configuration, controls the input monitoring module to start the pump input according to the design operating conditions. The logic module, based on the given pressure parameter configuration, controls the output monitoring module to start the pump output according to the design operating conditions. During slotting construction, the output monitoring module will monitor the slotting status (flow rate, pressure, and other index data) of each borehole in real time. Based on the monitored data, the real-time fracture assessment system for slotted boreholes will dynamically evaluate the fracture development and the working status of the slotting in each borehole. The evaluation results are fed back to the logic module in real time, and the logic module will dynamically and intelligently adjust the slotting configuration parameters for each borehole. Through the above process, the real-time fracture assessment system for slotted boreholes is realized. Synchronous or differentiated slotting parameters (including slotting water injection volume, slotting water pressure, slotting spacing, rotation speed, and slotting time parameters) can be set for each slotted borehole, with a suitable borehole diameter of 94-113 mm. In multiple sets of slotted boreholes, the hydraulic system (water pressure) can be used to synchronously extend, retract, and rotate. Different settings can be set for the extension, retraction, and rotation speed. To facilitate the discharge of coal dust outside the borehole as the slotting system rotates, the outer contour of the slotting system is spiral.

[0059] Identifying the formation of cracks and grooves is a prerequisite for adjusting cutting parameters and predicting the cutting effect during the cutting process. The main parameters monitored during the cutting process are pump pressure and flow rate. Generally, the development pattern of cracks and grooves can be identified based on the changes in the pressure curve during the cutting process. The cutting curve can be roughly divided into three types, as shown in Figure 3(a)-(c).

[0060] (1) Pressure balance type. The pressure at the slit hole continuously increases and then stabilizes in the working area. A slit is made at a predetermined radius, eventually forming a circular crack. The slit hole shows an ideal initial crack, and new cracks open sequentially as the slit system rotates.

[0061] (2) Pressure oscillation type. When the pressure of the cutting fluid in the coal seam reaches a certain level, due to the softness of the coal seam and the high stress, or the hardness of the coal seam and the high stress, or the hardness of the coal seam, the cutting hole is surrounded, and the pressure continues to rise for a period of time. As coal dust is continuously flushed out, the annular crack continues to expand, the cutting pressure decreases, and this oscillation process is repeated.

[0062] (3) Wave-shaped. This refers to the fluctuation of hydraulic pressure in the slit during the transition from a mature slit area to an unslit area. After multiple slit systems are transformed, the wave-shaped hydraulic pressure is characterized by the wave-shaped pattern of the hydraulic pressure in the slit. The wave-shaped pressure curve can be used as a basis for identifying the generation of multiple cracks.

[0063] The fracture development evaluation system module incorporates three fracture model curves and monitors the pressure curve in real time to infer the current fracture development status. The overall fracture morphology is categorized into three types: balanced, oscillating, and wavy. The overall fracture development status is divided into three stages using the fracture pressure curve: fracture propagation stage, fracture propagation delay stage, and fracture propagation maturity stage. These stages are then evaluated and fed back into the system. The logical relationship is primarily based on borehole dynamic evaluation.

[0064] The dynamic evaluation system for borehole slotting status comprehensively analyzes the flow stability at the pump source output port, whether a sudden flow change occurs, and the cumulative slotting water volume parameters, and dynamically evaluates it in three states:

[0065] (1) Under normal cutting conditions, the flow rate is relatively stable and there is no sudden change in flow rate (the critical value of flow rate change is set △q). The cumulative cutting water volume has not reached the preset value (Q). At this time, the dynamic feedback is normal cutting. When the cumulative cutting water volume (Q) is reached, the cutting will automatically stop.

[0066] (2) If the kerf flow rate changes abruptly (set the critical value of flow rate change Δq) and the cumulative kerf water volume does not reach the preset value, the dynamic feedback is to stop kerfing and check whether there is a large-area water leakage in the water pump pipeline or kerf system.

[0067] (3) When the flow rate is relatively stable and no sudden flow occurs (set flow rate change amount △q), and the cumulative flow of water in the slot reaches the preset value (Q), the dynamic feedback is that the slot cutting is completed.

[0068] (4) When the flow rate of the cut is relatively stable and there is no sudden change in flow rate, and the design water injection volume is not reached, but the adjacent pressure sensor identifies a stable pressure drop and water outlet status, it is considered that the cut has been completed. Stop the water supply to the two adjacent cut system holes, and so on until all other cuts are completed.

[0069] The critical value of flow rate change is related to the slit jet pressure; the relationship between jet pressure / MPa and the critical value of outlet flow rate Δq / (L / min) is shown in Table 1:

[0070] Table 1

[0071]

[0072] Preset value for slot water flow (Q): When determining the slot pressure, the critical flow rate is multiplied by the slot time, plus a 10% margin factor.

[0073] The calculation steps for the parameters of slot water volume, slot water pressure, slot spacing, borehole spacing, rotation speed, and slotting time are as follows:

[0074] (1) Numerical simulation method

[0075] Numerical simulation of the stress field of the borehole surrounding rock is used to establish a model (software such as Mohr-Coulomb and FLAC3D can be used). The model parameters need to be set as basic physical parameters such as coal and rock density, bulk modulus, shear modulus, cohesion, internal friction angle, tensile strength, and vertical stress. The selection of basic parameters is generally based on laboratory measurements or fixed empirical values.

[0076] Numerical simulation combined with factors influencing ultra-high pressure hydraulic slotting technology was used to analyze the stress evolution characteristics of coal seams under different parameters such as jet pressure, slotting spacing, slotting borehole spacing, and slotting method. The optimal set of parameters for slotting water pressure, slotting spacing, and borehole spacing was determined. The slotting water volume was calculated based on the slotting nozzle orifice diameter (usually 2.5 mm), slotting pressure, and slotting time (preset value for slotting water volume (Q): when determining the slotting pressure, the critical flow rate multiplied by the slotting time, plus a 10% margin factor). The rotation speed and slotting time parameters were obtained from ground slotting tests on coal samples.

[0077] (2) Empirical Formula Method

[0078] Cut depth:

[0079] d0 is the nozzle diameter, in meters (m). P is the water pump driving pressure, in MPa. ρ w ρ c C represents the density of water and coal. w C c Let P be the propagation velocity of stress waves in water and coal. The coal body is subjected to water hammer pressure P. w The jet of liquid is subjected to a reaction force of P. c μ is the dynamic viscosity coefficient; υ is the kinematic viscosity coefficient of water. σ1, σ2, and σ3 are derived from coal body experiments. σ1 - μ(σ2 + σ3) ≥ σ t The criterion for determining the fracture of a material at its limit value is given. The prediction model for the kerf depth of ultra-high pressure water jet is as follows:

[0080]

[0081] Cutting pressure:

[0082] The relationship between the kerf pressure and the critical slag discharge rate was calculated using dimensional analysis.

[0083]

[0084] P is the dynamic pressure at the nozzle outlet, Pa; a is a comprehensive factor characterizing coal particle shape and other factors; T0 is the coal drop velocity (t / min).

[0085] Slot spacing: The spacing between slotted boreholes is generally determined by the permeability coefficient of the coal seam. The spacing usually needs to be determined by on-site investigation or numerical simulation.

[0086] The slotting time parameter was obtained from ground slotting tests on coal samples, with each "circular" cycle taking less than 25 minutes. The slotting water volume was calculated based on the slotting nozzle orifice diameter (usually 2.5 mm), slotting pressure, and slotting time. Rotation speed was determined primarily based on the robustness coefficient and slotting pressure. Generally, with a robustness coefficient around 0.4, a slotting pressure of 80 MPa, and a drill rod rotation speed of 80 r / min; with a robustness coefficient around 0.8, a slotting pressure of 90 MPa, and a drill rod rotation speed of 40 r / min.

[0087] Based on current experimental experience:

[0088] For coal seams with a firmness coefficient of around 0.4, under a cutting pressure of 80 MPa, the average coal drop rate is 0.145 t / min at a drill rod rotation speed of 40 r / min, 0.130 t / min at 60 r / min, and 0.104 t / min at 80 r / min. It can be seen that, with a constant coal seam firmness coefficient and cutting pressure, the lower the drill rod rotation speed, the greater the coal drop rate. Furthermore, at a drill rod rotation speed of 40 r / min, borehole slag discharge is poor and borehole blockage is severe; at a drill rod rotation speed of 60 r / min, the blockage is somewhat alleviated; and when the drill rod rotation speed increases to 80 r / min, coal slag particles can be discharged from the borehole relatively smoothly.

[0089] For a coal seam with a firmness coefficient of 0.8, at a cutting pressure of 90 MPa, the average coal drop rate is 0.077 t / min at a drill rod speed of 40 r / min, 0.065 t / min at a drill rod speed of 60 r / min, and 0.053 t / min at a drill rod speed of 80 r / min. Due to the relatively high hardness of the coal seam, the amount of coal dropped through the cutting is relatively small, and coal slag particles can be smoothly discharged from the borehole at different speeds.

[0090] For soft coal seams with a low hardness coefficient, a faster drill pipe rotation speed should be selected during the cutting process. Increasing the drill pipe rotation speed reduces the impact of the ultra-high pressure water jet on the coal body, decreasing the amount of coal dropped. Furthermore, the increased rotation speed enhances the auxiliary slag removal capacity of the drill pipe's external thread. Conversely, for hard coal seams with high hardness, where the amount of coal dropped during cutting is smaller and slag particles can be easily discharged from the borehole, a slower drill pipe rotation speed should be selected to increase the efficiency of coal dropping during cutting.

[0091] As shown in Figure 6 of the experimental data, region I is prone to borehole blockage. When the selected pressure is in region I, the amount of coal falling into the borehole is too large, exceeding the critical slag discharge rate, which easily leads to borehole blockage. During the borehole slit cutting process, it is necessary to control the hydraulic slit cutting pressure, adjust the coal falling speed, and increase the drill rod rotation speed to achieve successful slit cutting and slag discharge under these conditions. When the pressure is selected in region II, the amount of coal falling is less than the critical slag discharge rate, achieving the expected slit cutting effect while ensuring smooth discharge of coal slag from the borehole. Therefore, when selecting slit cutting process parameters, the slit cutting pressure in region II should be chosen to ensure the best slit cutting effect in the coal seam and to ensure that the cut coal slag is smoothly discharged to the borehole opening under the combined action of water and the auger drill rod, achieving a better pressure relief and permeability enhancement effect.

[0092] Drill 4-6 slotting boreholes with a diameter of 95-113mm within a 30m radius of the area requiring slotting (through or along the seam). The drilling depth is determined based on specific site conditions. The slotting pump unit uses a KFSL100-113 single pump or two pumps in parallel operation (or other pump units, but the same model must be used for single or two pumps (parallel) operation). The slotting drilling system is tested and started after water pressure expansion or contraction. Based on parameters such as coal seam hardness and ground stress, parameters such as water injection volume, water pressure, slot spacing, rotation speed, and slotting time are set for automatic operation. After completion and shutdown, the valve at the borehole opening is closed, and the slotting system is expanded or contracted. At this point, the high-pressure rotating water tail can be disassembled, and all equipment can be moved to begin the next set of parallel slotting. The impact range of one operation is 30-80m (specifically determined by the drilling interval). A schematic diagram is shown in Figure 4-5.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A downhole intelligent multi-segment parallel dynamic slotting system, characterized in that: The system includes a flow-diverting cylinder body, with M pump source input ports at one end and N pump source output ports at the other end, where N>M. Each pump source input port is equipped with an input monitoring module, and each pump source output port is equipped with an output monitoring module. It also includes a display console and a logic module. The display console configures parameters for the logic module, thereby sending commands to the input and output monitoring modules to control the opening and closing of each pump source input and output port. The output monitoring module is also used to monitor the development status of the slot in the corresponding borehole in real time and provide feedback to the logic module. The module is also used to dynamically evaluate the development of fractures in each borehole and the working status of the borehole slits, and dynamically and intelligently adjust the configuration parameters of each borehole slit based on the results; the logic module comprehensively analyzes the flow stability of the pump source output port, whether a flow change occurs, and the slit water injection parameters, and dynamically evaluates the following states: (1) Set the critical value of flow change Δq. Under normal slit development conditions, the flow is relatively stable, no flow change occurs, and the slit water injection has not reached the preset value Q. At this time, the dynamic feedback is normal slit cutting. When the cumulative water injection reaches the preset value Q of the slit water limit and material fracture, the slit cutting will automatically stop; ( 2) If the kerf flow rate changes abruptly and the kerf injection volume does not reach the preset value Q, the dynamic feedback is to stop kerfing and check whether there is a large-area leakage in the water pump pipeline or kerfing system; (3) If the kerf development state has a relatively stable flow rate, no flow rate change occurs, and the kerf injection volume reaches the preset value Q, the dynamic feedback is that the kerfing is completed; (4) If the kerf development state has a relatively stable flow rate, no flow rate change occurs, and the designed injection volume is not reached but the adjacent pressure sensor identifies a stable pressure drop and water outlet state, it is considered that the kerfing has been completed, and the water supply to the two adjacent kerfing system holes is stopped, and so on until all other kerfings are completed; Flow rate change The critical value of the flow rate is related to the jet pressure. The relationship between the critical value Δq of the jet pressure and the flow rate change is as follows: when the jet pressure is 0~40MPa, Δq is 82L / min; when the jet pressure is 40~50MPa, Δq is 92L / min; when the jet pressure is 50~90MPa, Δq is 120L / min; when the jet pressure is 90~100MPa, Δq is 130L / min. The flow rate Q is calculated by multiplying the critical flow rate by the cutting time and adding a 10% margin when the cutting pressure is determined. The prediction model x for the cutting depth is: Where d0 is the nozzle diameter, m; P is the water pump driving pressure, MPa; 、 C represents the density of water and coal. w C c Let P be the propagation velocity of stress waves in water and coal, and let P be the water hammer pressure on the coal body. w The jet of liquid is subjected to a reaction force of P. c , It is the dynamic viscosity coefficient; Let σ1, σ2, and σ3 be the kinematic viscosity coefficients of water, obtained from coal body tests. The criteria for determining the fracture of limit-value materials are established; the relationship between the cutting pressure and the critical slag discharge rate is calculated using dimensional analysis. P is the dynamic pressure at the nozzle outlet, Pa; a is a comprehensive factor characterizing the shape of coal particles; T0 is the coal drop velocity (t / min); slit spacing: the slit drilling interval is determined based on the permeability coefficient of the coal seam, and the interval distance is obtained from field investigation or numerical simulation; the slit time parameter is obtained from the ground slit test of the coal sample, and the cycle of each "circle" is less than 25 minutes; the slit water injection volume is calculated based on the slit nozzle diameter, slit pressure, and slit time; the rotation speed is determined comprehensively based on the firmness coefficient and slit pressure; the firmness coefficient is 0.4, the slit pressure is 80 MPa, and the drill rod rotation speed is 80 r / min; the firmness coefficient is 0.8, the slit pressure is 90 MPa, and the drill rod rotation speed is 40 r / min.

2. The intelligent multi-segment parallel dynamic slotting system for downhole drilling according to claim 1, characterized in that: The development status of the slot in the borehole includes the magnitude of the pump output flow rate and pressure.

3. The intelligent multi-segment parallel dynamic slotting system for downhole drilling according to claim 1, characterized in that: The logic module monitors the output pressure curve of the borehole pump source in real time and compares it with the curves of three different kerfing models to deduce the current kerfing development status. The kerfing model curves include pressure balance type, pressure oscillation type, and wave type. The pressure balance type is characterized by a continuous increase in the output pressure of the kerfing hole, followed by stabilization in the working area, kerfing at a predetermined radius, and finally forming a circular crack. The pressure oscillation type is characterized by a state where the kerfing fluid pressure in the coal seam reaches a certain level, forming a state that surrounds the kerfing hole. The pressure continues to increase for a period of time, and as coal dust is continuously flushed out, the circular crack continues to expand, and the kerfing pressure decreases. And repeat this oscillation process; the wave pattern is the fluctuation of hydraulic pressure in the slit during the transfer from a mature slit area to an unslit area. After multiple slit systems are transformed and formed, it is characterized as the wave pattern of hydraulic pressure in the slit; the slit development state includes the slit crack expansion period, the slit expansion delay period, and the slit expansion maturity period.

4. The intelligent multi-segment parallel dynamic slotting system for downhole drilling according to claim 1, characterized in that: The calculation steps for the parameters of water injection volume, water pressure, spacing, borehole spacing, rotation speed, and cutting time are as follows: A numerical simulation model of the stress field of the surrounding rock is established. The model parameters are set as basic physical parameters, including coal density, bulk modulus, shear modulus, cohesion, internal friction angle, tensile strength, and vertical stress. The values ​​of these basic physical parameters are determined in the laboratory or fixed empirical values. Using numerical simulation combined with the influencing factors of ultra-high pressure hydraulic cutting technology, the stress evolution characteristics of the coal seam under different jet pressures, cutting spacing, borehole spacing, and cutting methods are analyzed to obtain the optimal set of water pressure, spacing, and borehole spacing parameters. The water injection volume is calculated based on the nozzle diameter, cutting pressure, and cutting time. The rotation speed and slit time parameters were obtained from ground slit tests on coal samples.

5. A method for intelligent multi-segment parallel dynamic slotting construction in downhole wells, characterized in that: The intelligent multi-slot parallel dynamic slotting system for downhole drilling according to any one of claims 1-4 includes the following steps: S1: Multiple slotting boreholes are drilled at certain intervals in the area where slotting is required. Multiple slotting systems extend to the top of the boreholes under water pressure and begin reverse slotting. The slotting spacing, slotting water pressure, and slotter rotation speed are all related to the hardness of the coal seam. The drilling depth is determined according to the specific site conditions. S2: The slotting system is started for commissioning and testing. The slotting operation is automatically performed by setting the slotting water injection volume, slotting water pressure, slotting spacing, rotation speed, and slotting time parameters according to the hardness of the coal seam, the magnitude of the ground stress, and the coal seam permeability parameters. S3: After the operation is completed and the machine is shut down, the entire slotting system is closed, and the system is extended to the borehole opening and withdrawn from the borehole. At this time, the rotating high-pressure water tail is disassembled, and all equipment is moved to perform the next set of parallel slotting.

6. The intelligent multi-segment parallel dynamic slotting construction method for downhole drilling according to claim 5, characterized in that: Drill 4-6 slotted boreholes with a diameter of 94-113mm within a 30m radius of the area requiring slotting; the spacing between slotted boreholes needs to be determined according to site conditions; for medium-hardness coal seams, the slotting radius is 1.5-2.0m and the slot width is 2-6cm; the depth of slotted boreholes along the seam is 10-100m; the maximum working pressure is 100MPa, the pressure resistance of the complete set of equipment is 150MPa, and all equipment connections have secondary protection.

7. The intelligent multi-segment parallel dynamic slotting construction method for downhole drilling according to claim 5, characterized in that: The slotting pump set uses the same model of pump set, either as a single pump or in parallel operation of two pumps.

8. The intelligent multi-slot parallel dynamic slotting construction method for downhole drilling according to claim 5, characterized in that: Pressure and flow sensors are installed in each borehole of the slit system, and synchronous or differentiated slits are set, including parameters such as slit water injection volume, slit water pressure, slit spacing, rotation speed, and slit time.

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