A coal mine roadway roof far field-near field cooperative fracturing control method and device

Abstract

The present application relates to the technical field of coal mine roadway pressure control, and discloses a coal mine roadway roof far field-near field cooperative fracturing control method and device. The aspect includes: based on a coal mine roadway, establishing a test model of the coal mine roadway; according to a target rock stratum of the coal mine roadway, determining a test area corresponding to the target rock stratum in the test model, wherein the target rock stratum includes a key layer and / or a sub-key layer of a roof near field, and a key layer and / or a sub-key layer of a roof far field; based on the test model and the test area, determining a borehole fracture development law under different fracturing modes in a hydraulic fracturing process; wherein the fracture development law includes a fracture expansion direction change law and / or a fracture deflection distance change law; based on the borehole fracture development law, determining a fracturing mode for the target rock stratum. The present application solves the problem that the prior art cannot fundamentally solve roadway large deformation and surrounding rock stress concentration.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine roadway pressure control, and in particular to a coal mine roadway roof far-field-near-field coordinated fracturing control method and device. Background Art

[0002] At present, coal mines are mainly mined underground, with the characteristics of large mining depths, high mining intensity, and complex and changeable geological conditions. Shallow buried deep mines or mines with hard roofs face the problem of large areas of roof exposed in the goaf after coal seam mining, and will not collapse in the short term. However, once it collapses, the area and height of the collapse are large, the initial pressure is severe or there is strong periodic pressure, and there are obvious dynamic phenomena during the pressure, causing equipment damage, endangering personal safety and other serious accidents. Due to the influence of mining stress on the working face, almost all mining tunnels have different degrees of dynamic pressure phenomena. In places where the tunnels are severely deformed, the cross-section cannot meet the requirements of pedestrians, traffic and ventilation. The tunnel surrounding rock shows characteristics such as rapid deformation speed, large deformation amount, uncontrollable deformation, and strong impact. Conventional approaches to addressing these types of tunnels include: first, strengthening support and lifting the bottom to ensure normal operation of the tunnels, but this involves significant engineering effort and low safety standards, severely impacting working face safety and normal production; second, increasing the size of the coal pillars and strengthening the support to ensure the normal operation of the dynamic pressure tunnels, but this results in a significant waste of coal resources. In summary, relying solely on conventional methods cannot fundamentally address the problems of large tunnel deformation and surrounding rock stress concentration. Therefore, fundamentally resolving these issues is a pressing technical challenge facing the industry. Summary of the Invention

[0003] The present invention provides a coal mine roadway roof far-field-near-field coordinated fracturing control method and device, which are used to solve the problem that the existing technology cannot fundamentally solve the large deformation of the roadway and the stress concentration of the surrounding rock.

[0004] A first aspect of the present invention provides a coal mine roadway roof far-field-near-field coordinated fracturing control method, comprising:

[0005] Based on the coal mine tunnel, establishing a test model of the coal mine tunnel;

[0006] Determining, according to a target rock layer of the coal mine roadway, a test area corresponding to the target rock layer in the test model, wherein the target rock layer includes a key layer and / or subkey layer in a near field of the roof, and a key layer and / or subkey layer in a far field of the roof;

[0007] Based on the test model and the test area, determining the development law of borehole cracks under different fracturing methods during the hydraulic fracturing process; wherein the crack development law includes a change law of the crack propagation direction and / or a change law of the crack deflection distance;

[0008] Based on the development law of the drilled cracks, a fracturing method for the target rock formation is determined.

[0009] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, the method of determining the development law of borehole cracks under different fracturing modes during the hydraulic fracturing process based on the test model and the test area includes:

[0010] Establish a drilling fracturing model under bidirectional normal stress;

[0011] Based on the drilling fracturing model, the crack development law of the drilling hole with or without grooving is determined.

[0012] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, the method of determining the crack development law of the borehole with or without grooving based on the borehole fracturing model includes:

[0013] Simulating the fracturing process of the borehole in a non-grooved state, and determining the crack development law according to the normal stress difference;

[0014] The fracturing process of the borehole with the groove cut is simulated, and the crack development law is determined according to the groove direction and the normal stress difference.

[0015] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, after establishing the drilling fracturing model under the action of bidirectional normal stress, the method further includes:

[0016] The crack development law is determined based on the normal stress ratio of the horizontal normal stress to the vertical normal stress.

[0017] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, the grooving includes a transverse grooving or a longitudinal grooving.

[0018] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, the crack development law is determined based on the normal stress ratio of horizontal normal stress to vertical normal stress, including:

[0019] determining the crack development law according to the normal stress ratio and the cutting direction;

[0020] and / or;

[0021] The crack development law is determined according to the normal stress ratio and the pump flow rate.

[0022] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, the crack development law is determined according to the normal stress ratio and the cutting direction, including:

[0023] Under the condition that the normal stress ratio is fixed, the cutting direction is adjusted to determine the crack development law;

[0024] Determining the crack development law based on the normal stress ratio and the pump flow rate includes:

[0025] When the normal stress ratio is fixed, the pump flow rate is adjusted to determine the crack development law.

[0026] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, before determining the test area corresponding to the target rock formation in the test model according to the target rock formation of the coal mine roadway, the method further includes:

[0027] The target rock layer is determined based on historical geological parameters of the coal mine tunnel and / or based on key layer theory.

[0028] According to the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention, after determining the fracturing method for the target rock formation based on the development law of the drilled cracks, the method further includes:

[0029] The fracturing method is dynamically adjusted according to the real-time geological parameters of the target rock formation so that the actual development of the drilled cracks conforms to the crack development law.

[0030] and / or;

[0031] Dynamically adjust the fracturing method according to the design parameters of the drilling hole so that the actual development of the drilling cracks conforms to the crack development law;

[0032] The real-time geological parameters include geological stress, stress difference and / or surrounding rock structure of the surrounding rock; the design parameters include whether there is grooving, grooving angle, drilling spacing, drilling angle and / or drilling depth.

[0033] A second aspect of the present invention provides a coal mine roadway roof far-field-near-field coordinated fracturing control device, which adopts any of the above-mentioned coal mine roadway roof far-field-near-field coordinated fracturing control methods, comprising:

[0034] A test model establishment unit, configured to establish a test model of the coal mine tunnel based on the coal mine tunnel;

[0035] a first determining unit, configured to determine a target rock layer of a coal mine roadway, and to determine a test area corresponding to the target rock layer in the test model, wherein the target rock layer includes a key layer and / or subkey layer in a near field of a roof, and a key layer and / or subkey layer in a far field of a roof;

[0036] A second determining unit is configured to determine, based on the test model and the test area, a borehole crack development law under different fracturing modes during the hydraulic fracturing process; wherein the crack development law includes a crack propagation direction change law and / or a crack deflection distance change law;

[0037] The third determining unit is configured to determine a fracturing method for the target rock formation based on the development law of the drilled cracks.

[0038] The present invention provides a method for controlling the far-field and near-field coordinated fracturing of the coal mine roadway roof. A test model of the coal mine roadway is established based on the coal mine roadway. According to the target rock layer of the coal mine roadway, a test area corresponding to the target rock layer in the test model is determined. The target rock layer includes the key layer and / or subkey layer of the near-field of the roof, and the key layer and / or subkey layer of the far-field of the roof. Therefore, the test area includes the key layer and / or subkey layer of the near-field of the roof and the far-field of the roof, thereby realizing coordinated fracturing of the near-field and far-field of the roof. The test model and the test area are used as test objects to determine the development law of borehole cracks under different fracturing methods during the hydraulic fracturing process. The crack development law includes the change law of the crack extension direction and / or the change law of the crack deflection distance. The borehole crack development law is then used as a guide for the hydraulic fracturing method of the target rock layer, so that the cracks in the target rock layer can develop according to the borehole crack development law, thereby solving the problem that the existing technology cannot fundamentally solve the large deformation of the roadway and the stress concentration of the surrounding rock. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 It is a "masonry beam" structure.

[0041] Figure 2 It is a plan diagram of the "OX" type overburden structure.

[0042] Figure 3 It is a schematic cross-sectional view of the “Г” type overburden structure.

[0043] Figure 4 It is a far-field roof "OX-Г" type fracture structure mechanics model.

[0044] Figure 5is a borehole hydraulic fracturing model; among them, (a) the angle between the mid-cut direction and the minimum normal stress is zero; (b) the angle between the mid-cut direction and the minimum normal stress is 22.5°; (c) the angle between the mid-cut direction and the minimum normal stress is 45°.

[0045] Figure 6 This is one of the flow diagrams of the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention.

[0046] Figure 7 This is the second flow chart of the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention.

[0047] Figure 8 It is a structural schematic diagram of the coal mine tunnel roof far-field-near-field coordinated fracturing control device provided by the present invention.

[0048] Figure 9 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0050] It should be noted that the serial numbers assigned to the objects described in the present invention, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning.

[0051] The following combination Figures 1 to 9 The coal mine roadway roof far-field-near-field collaborative fracturing control method and device of the present invention are described. The coal mine roadway roof far-field-near-field collaborative fracturing control method can be applied to electronic equipment or servers. The electronic equipment may include a computer. The server may include an independent server, a cluster server or a cloud server, etc. The coal mine roadway roof far-field-near-field collaborative fracturing control method and the coal mine roadway roof far-field-near-field collaborative fracturing control device that can be applied to the coal mine roadway roof far-field-near-field collaborative fracturing control device set in an electronic device can be implemented by software, hardware or a combination of the two. The coal mine roadway roof far-field-near-field collaborative fracturing control method is described below by taking the execution subject of the coal mine roadway roof far-field-near-field collaborative fracturing control method as an electronic device as an example.

[0052] To facilitate understanding of the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the embodiments of the present invention, the coal mine roadway roof far-field-near-field coordinated fracturing control method provided by the present invention will be described in detail below through the following exemplary embodiments. It is understood that the following exemplary embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0053] like Figure 6 As shown, a specific embodiment of the first aspect of the present invention provides a coal mine roadway roof far-field-near-field coordinated fracturing control method, comprising:

[0054] S100, establishing a test model of a coal mine tunnel based on the coal mine tunnel;

[0055] S200, determining a test area corresponding to the target rock layer in the test model according to the target rock layer of the coal mine roadway, wherein the target rock layer includes a key layer and / or subkey layer in the near field of the roof, and a key layer and / or subkey layer in the far field of the roof;

[0056] S300, based on the test model and the test area, determining the development law of borehole cracks under different fracturing methods during the hydraulic fracturing process; wherein the crack development law includes a change law of the crack propagation direction and / or a change law of the crack deflection distance;

[0057] S400: Determine a fracturing method for the target rock formation based on the development law of the drilled cracks.

[0058] In this embodiment, a test model of a coal mine tunnel is established based on the coal mine tunnel; according to the target rock layer of the coal mine tunnel, a test area corresponding to the target rock layer in the test model is determined, and the target rock layer includes the key layer and / or sub-key layer in the near field of the roof, and the key layer and / or sub-key layer in the far field of the roof. Therefore, the test area includes the key layer and / or sub-key layer in the near field of the roof and the far field of the roof, thereby realizing the coordinated fracturing of the near field and the far field of the roof. The test model and the test area are used as test objects to determine the development law of borehole cracks under different fracturing methods during the hydraulic fracturing process; wherein, the crack development law includes the change law of crack extension direction and / or the change law of crack deflection distance; and then the borehole crack development law is used as a guide for the hydraulic fracturing method of the target rock layer, so that the cracks in the target rock layer can develop according to the borehole crack development law, thereby solving the problem that the existing technology cannot fundamentally solve the large deformation of the tunnel and the stress concentration of the surrounding rock.

[0059] It should be noted that the key layer theory adopted in the present invention is explained as follows:

[0060] like Figures 1 to 4As shown in the figure, using the key layer theory, combined with the activity law of the overlying rock strata during the mining process of the working face and the formation process of the lateral "masonry beam" structure, as shown in the figure, Figure 1 As shown in the figure, the mechanism of large deformation of peripheral tunnels and advance tunnels was studied, the root cause of strong mine pressure in the working face was analyzed, and a method of using near-field fracturing to unload the end cantilever beam and far-field unloading to deal with the hard and difficult-to-collapse old roof was proposed, namely the "OX-Г" type overburden structure, to solve the rock control problem in the "far-near" field area.

[0061] like Figure 1 and Figure 3 As shown in the figure, the old roof strata are often fractured into regular blocks, which squeeze and interlock with each other to form a "masonry beam" structure, and form three key blocks A, B, and C laterally in the goaf. In most cases, the immediate roof and the old roof strata are located above the coal body in this order. When the immediate roof is thick enough, the rotation angle of key block B reaches a certain angle before it contacts the gangue, compacts, and stabilizes. A stress concentration zone will accordingly appear at the compaction point.

[0062] In cases of thin direct roof or hard, thick roof with direct overburden, the high thickness of the rock strata fractured at once places a heavy load on block B, making it prone to slippage and instability, triggering severe pressure and significantly impacting the roadway below. Hydraulic fracturing the roof within a certain range outside the retained coal pillar can significantly reduce the length of block B, eliminating the cantilever beam structure beneath block B and creating a spatially similar "OX-G" overburden structure. After pre-fracture, block C loses lateral restraint and collapses first, forming a cushion layer. Block B later rotates and sinks, interlocking with C at the fracture surface to form a stable, quasi-articulated structure. By optimizing the length of the overburden block, stress concentration is reduced and the given deformation of the roof is lowered, effectively alleviating deformation of the surrounding rock of the retained roadway.

[0063] like Figure 3 and Figure 4 As shown, below rock block B =The height of the collapse zone mainly forms a cantilever beam structure, which belongs to the near-field hydraulic fracturing control range of the roadway roof; rock block B and its upper part are the fracture zone range, which mainly forms a masonry beam structure, which belongs to the far-field hydraulic fracturing control range of the roadway roof. For the dynamic pressure roadway, the mechanism of hydraulic top cutting and pressure relief to retain the roadway can be summarized as follows: (1) Through hydraulic fracturing, the integrity of the rock mass is destroyed, the continuous transmission of the breaking stress is interrupted, and a "quasi-fracture surface" is formed; (2) the dynamic pressure caused by the transfer mining is transferred, and the stress concentration area is transferred from the vicinity of the mining roadway to the deep rock mass near the end of the "fracture surface", mobilizing the bearing capacity of the deep surrounding rock of the roof; (3) The "quasi-fracture surface" helps the timely and sufficient collapse of the roof and shortens the "lateral masonry beam".

[0064] After the working face is mined and hydraulic fracturing is not performed to relieve pressure, the roof forms a stable masonry beam structure. The force requirements for maintaining structural stability are:

[0065] Formula (1).

[0066] In formula (1): F p It is the supporting force of coal body; F G The supporting force of gangue; F C is the mining stress; F Z It is the deadweight of the rock above the structure.

[0067] After artificial hydraulic cutting, the goaf side " F "Type suspended roof structure part falls into the goaf along the top cutting line and generates a new roof fracture line, which reduces the " F The length of the "-shaped suspended roof structure cuts off the stress transfer path between the roadway roof and the overburden in the goaf; on the other hand, new fault lines are generated, causing the suspended roof structure to undergo large sliding deformation along the fault lines, which can release large stress when high superimposed support pressure acts; at the same time, the cut-off roof can better fill the goaf, thereby changing the stress transfer and distribution ratio between the goaf and the coal pillar, improving the stress state of the coal pillar, and reducing roadway deformation.

[0068] like Figure 4 As shown in the figure, due to the hydraulic fracturing pressure relief effect, the fracture line between rock block B and rock block C moves inward to the edge of the coal pillar, the length of rock block B is reduced from L to X, and rock block B evolves from a triangular structure to a trapezoidal structure. Figure 4 The shaded area in the middle is the reduced range after the rock block B is unloaded, from which the coal support force can be calculated:

[0069] Formula (2).

[0070] In formula (2), F’ p It is the supporting force of the coal body after pressure relief; F’ C is the mining stress after pressure relief; F’ Z is the deadweight of the rock above the structure after pressure relief; S ABED for Figure 4 The area of ​​the middle trapezoid ABED; S ABC for Figure 4 The area of ​​triangle ABC.

[0071] Combined with formula (1), the reduction value of the supporting force of the coal body after the far-field high-level hydraulic unloading can be obtained as:

[0072] Formula (3).

[0073] Through the above theoretical analysis, it can be seen that hydraulic drilling and fracturing of the roof far field and the roof approach field can fundamentally reduce the supporting force of the coal body and fundamentally solve the problems of large deformation of the tunnel and stress concentration of the surrounding rock.

[0074] In some embodiments, establishing a test model of the coal mine tunnel based on the coal mine tunnel may include scaling down the coal mine tunnel to establish the test model, wherein the test model has the same surrounding rock structure as the coal mine tunnel.

[0075] In some embodiments, before determining the test area corresponding to the target rock formation in the test model according to the target rock formation of the coal mine roadway, the method further includes:

[0076] The target rock layer is determined based on historical geological parameters of the coal mine tunnel and / or based on key layer theory.

[0077] If fracturing is performed on a coal mine tunnel for the first time, the target rock layer of the coal mine tunnel can be determined based on the key layer theory.

[0078] If it is not the first time to perform fracturing on a coal mine roadway, the target rock layer can be determined based on historical geological parameters; the target rock layer of the coal mine roadway can also be determined based on the key layer theory.

[0079] Specifically, the historical geological parameters include but are not limited to microseismic vibration data. In other words, the target rock layer of the coal mine tunnel can be determined based on the historically collected microseismic vibration data.

[0080] In some embodiments, based on the test model and the test area, determining the development pattern of borehole cracks under different fracturing methods during hydraulic fracturing includes:

[0081] Establish a drilling fracturing model under bidirectional normal stress;

[0082] Based on the drilling fracturing model, the crack development law of the drilling hole with and without groove cutting is determined.

[0083] Furthermore, the fracturing process of a borehole without slotting was simulated, and the crack development pattern was determined based on the normal stress difference. The normal stress difference is the absolute value of the difference between the horizontal normal stress δ2 and the vertical normal stress δ1. Specifically, the borehole was in a normal state, that is, without slots in the borehole. During the fracturing process, the normal stress difference was adjusted, the crack development pattern was recorded, and the normal stress difference and crack development pattern were mapped one-to-one. The results show that the minimum principal stress controls the direction of crack expansion; as the minimum principal stress increases or the normal stress difference decreases, the required fracturing pressure increases accordingly; and as the tensile strength of the rock mass increases, the required fracturing pressure increases accordingly. The minimum principal stress is the smallest normal stress between the horizontal normal stress δ2 and the vertical normal stress δ1.

[0084] Furthermore, the fracturing process of the borehole in the grooved state was simulated, and the crack development law was determined based on the groove direction and the normal stress difference. Among them, the normal stress difference is the absolute value of the difference between the horizontal normal stress δ2 and the vertical normal stress δ1. Specifically, when the borehole is grooved, during the fracturing process, the crack development law is recorded by adjusting the normal stress difference, and the groove direction, normal stress difference and crack development law are matched one by one. The results show that the groove angle has a great influence on the crack propagation path. As the groove angle increases, the crack curvature radius decreases, the curvature increases, and the expansion component along the minimum principal stress direction increases. However, the change in the crack deflection distance is small, the change amplitude is small, and the impact is not obvious. During the construction design process, the appropriate groove angle should be selected according to actual conditions and needs. Among them, the groove angle can refer to the angle between the groove direction and the minimum principal stress.

[0085] like Figure 5 As shown, for example, when horizontal grooving is used (the angle θ between the grooving direction and the minimum principal stress is zero), when the normal stress difference is greater than 6 MPa, the direction of the hydraulic fracturing crack is controlled by the minimum principal stress; when the normal stress difference is reduced, when the normal stress difference is less than 5 MPa, the direction of the hydraulic fracturing crack can be expanded along the grooving direction.

[0086] like Figure 5 As shown in the figure, for example, when using an oblique groove (the angle θ between the groove direction and the minimum principal stress is 22.5°), the hydraulic fracture direction is controlled by the minimum principal stress when the normal stress difference is 7 MPa. When the normal stress difference is reduced to 6 MPa, the hydraulic fracture direction can be extended along the groove direction. This shows that increasing the angle between the groove direction and the minimum principal stress is conducive to the formation of the induced fracture surface.

[0087] like Figure 5As shown in the figure, when using an oblique groove (the angle θ between the groove direction and the minimum principal stress is 45°), the hydraulic fracture can be extended along the groove direction when the normal stress difference is 7 MPa. This shows that when the groove direction deviates significantly from the minimum principal stress, it is easier to form an induced fracture surface in the groove direction.

[0088] It should be noted that the grooves in this embodiment can be either transverse or longitudinal. Preferably, the grooves in this embodiment are longitudinal. A transverse groove refers to a groove formed around the central axis of the borehole and extending along the inner sidewall of the borehole. A longitudinal groove refers to a groove formed along the central axis of the borehole and extending along the inner sidewall of the borehole.

[0089] In some embodiments, after establishing the drilling fracturing model under bidirectional normal stress, the method further includes:

[0090] The crack development law is determined based on the normal stress ratio of horizontal normal stress to vertical normal stress.

[0091] Furthermore, the crack growth pattern was determined based on the normal stress ratio and the groove direction. Specifically, while the normal stress ratio was fixed, the crack growth pattern was recorded by varying the groove direction, and the normal stress ratio, groove direction, and crack growth pattern were mapped one by one. The results showed that the normal stress ratio had a significant impact on the crack propagation path and deflection distance. As the normal stress ratio increased, the crack propagation morphology tended to become more contracted, while as the normal stress ratio increased, the crack deflection distance decreased.

[0092] Furthermore, the crack development patterns were determined based on the normal stress ratio and pump flow rate. By fixing the normal stress ratio and adjusting the pump flow rate, the crack development patterns corresponding to different pump flow rates were recorded. The results showed that as the pump flow rate increased, the crack deflection distance increased significantly.

[0093] For example, under the condition of a normal stress ratio of 1.5, the crack initiates along the longitudinal groove and gradually deflects toward the direction of the maximum principal stress during propagation, forming an S-shaped asymmetric morphology with a relatively simple crack shape. In other words, under the condition of a fixed normal stress ratio, the crack initiates along the longitudinal groove and gradually deflects toward the direction of the maximum principal stress during propagation, forming an S-shaped asymmetric morphology.

[0094] For example, under the condition of a normal stress ratio of 1.5, as the pump flow rate increases, the fracture deflection curve tends to flatten, while the deflection distance increases continuously and rapidly. In other words, under the condition of a fixed normal stress ratio, as the pump flow rate increases, the fracture deflection curve tends to flatten, while the deflection distance increases continuously and rapidly.

[0095] For example, the water injection pump flow rate is 90L / min, and the crack deflection distance is 4.05m. The deflection distance can be greatly increased by significantly increasing the pump flow rate.

[0096] like Figure 7 As shown, in some embodiments, after determining the fracturing method for the target rock formation based on the development law of the drilled cracks, the method further includes:

[0097] S500 , dynamically adjusting the fracturing method according to real-time geological parameters of the target rock formation so that the actual development of the drilled cracks conforms to the crack development law.

[0098] and / or;

[0099] Dynamically adjust the fracturing method according to the design parameters of the drilling hole so that the actual development of the drilling cracks conforms to the crack development law;

[0100] The real-time geological parameters include the geological stress, stress difference and / or surrounding rock structure of the surrounding rock; the design parameters include whether there is a groove, the groove angle, the drilling spacing, the drilling angle and / or the drilling depth.

[0101] In this embodiment, by monitoring the real-time geological parameters of the target rock formation and / or the design parameters of the drilling, the fracturing method can be timely adjusted. For example, the drilling angle, depth, drilling spacing, etc. can be adjusted in time to ensure that the actual development of the drilled cracks conforms to the crack development law.

[0102] Specifically, the specific fracturing method is determined according to the crack development law and the surrounding rock structure of the target rock formation; the fracturing methods include directional fracturing and grid fracturing.

[0103] The directional fracturing method is to carry out directional "cutting" and weakening of the target rock formation, which is mainly used for unloading pressure in coal pillar protection tunnels, unloading pressure in goaf-side tunnels, and unloading pressure in advanced tunnels.

[0104] Grid fracturing creates multi-directional fractures in the target rock formation, forming a network of intersecting natural and artificial fractures, ultimately weakening the rock mass's overall strength. It's primarily used for initial roof caving on a working face, addressing overhanging roof in triangular areas, controlling cyclical pressure on the working face, and fracturing high-lying old roofs in remote areas.

[0105] like Figure 8 As shown, a specific embodiment of the second aspect of the present invention provides a coal mine roadway roof far-field-near-field coordinated fracturing control device. The coal mine roadway roof far-field-near-field coordinated fracturing control device includes a test model establishment unit, a first determination unit, a second determination unit, and a third determination unit.

[0106] Among them, the test model establishment unit is used to establish a test model of the coal mine tunnel based on the coal mine tunnel. The first determination unit is used to determine the target rock layer of the coal mine tunnel and the test area corresponding to the target rock layer in the test model, wherein the target rock layer includes the key layer and / or sub-key layer in the near field of the roof, and the key layer and / or sub-key layer in the far field of the roof. The second determination unit is used to determine the development law of the borehole cracks under different fracturing methods during the hydraulic fracturing process based on the test model and the test area; wherein the crack development law includes the change law of the crack extension direction and / or the change law of the crack deflection distance. The third determination unit is used to determine the fracturing method for the target rock layer based on the borehole crack development law.

[0107] Because the control device of this embodiment has the function of the coal mine roadway roof far-field-near-field coordinated fracturing control method, it has at least the above advantages.

[0108] Furthermore, the second determination unit is used to establish a drilling fracturing model under bidirectional normal stress; and to determine the crack development law of the drilling with or without grooving based on the drilling fracturing model.

[0109] Furthermore, the second determining unit is further configured to determine a crack development law based on a normal stress ratio of horizontal normal stress to vertical normal stress.

[0110] Figure 9 An example of a physical structure diagram of an electronic device is shown below. Figure 9 As shown, the electronic device may include: a processor 810, a communications interface 820, a memory 830, and a communications bus 840, wherein the processor 810, the communications interface 820, and the memory 830 communicate with each other via the communications bus 840. The processor 810 may call logic instructions in the memory 830 to execute a method for controlling far-field and near-field coordinated fracturing of a coal mine roadway roof. The method includes: establishing a test model of the coal mine roadway based on the coal mine roadway; determining a test area corresponding to the target rock formation in the test model based on the target rock formation of the coal mine roadway, wherein the target rock formation includes a key layer and / or subkey layer in the near field of the roof, and a key layer and / or subkey layer in the far field of the roof; determining, based on the test model and the test area, the development pattern of borehole fractures under different fracturing methods during the hydraulic fracturing process; wherein the fracture development pattern includes a change pattern of the fracture propagation direction and / or a change pattern of the fracture deflection; and determining the fracturing method for the target rock formation based on the borehole fracture development pattern.

[0111] In addition, the logic instructions in the memory 830 described above can be implemented in the form of software functional units and sold or used as independent products, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or the part of the prior art that contributes essentially or the part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0112] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to execute the coal mine roadway roof far field-near field collaborative fracturing control method provided by the above-mentioned methods. The method comprises: based on the coal mine roadway, establishing a test model of the coal mine roadway; determining a test area corresponding to a target rock stratum in the test model according to the target rock stratum, wherein the target rock stratum comprises a key layer and / or a sub-key layer of the near field of the roof, and a key layer and / or a sub-key layer of the far field of the roof; determining the development law of the borehole fracture under different fracturing modes in the process of hydraulic fracturing based on the test model and the test area; wherein the development law of the fracture comprises the change law of the fracture propagation direction and / or the change law of the fracture deflection distance; and determining the fracturing mode for the target rock stratum based on the development law of the borehole fracture.

[0113] In yet another aspect, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the coal mine roadway roof far field-near field collaborative fracturing control method provided by the above-mentioned methods. The method comprises: based on the coal mine roadway, establishing a test model of the coal mine roadway; determining a test area corresponding to a target rock stratum in the test model according to the target rock stratum, wherein the target rock stratum comprises a key layer and / or a sub-key layer of the near field of the roof, and a key layer and / or a sub-key layer of the far field of the roof; determining the development law of the borehole fracture under different fracturing modes in the process of hydraulic fracturing based on the test model and the test area; wherein the development law of the fracture comprises the change law of the fracture propagation direction and / or the change law of the fracture deflection distance; and determining the fracturing mode for the target rock stratum based on the development law of the borehole fracture.

[0114] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0115] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A coal mine roadway roof far-field-near-field coordinated fracturing control method, characterized in that: include: Based on the coal mine tunnel, establishing a test model of the coal mine tunnel; Determining, according to a target rock layer of the coal mine roadway, a test area corresponding to the target rock layer in the test model, wherein the target rock layer includes a key layer and / or subkey layer in a near field of the roof, and a key layer and / or subkey layer in a far field of the roof; Based on the test model and the test area, determining the development law of borehole cracks under different fracturing methods during the hydraulic fracturing process; wherein the crack development law includes a change law of the crack propagation direction and / or a change law of the crack deflection distance; Determining a fracturing method for the target rock formation based on the development law of the drilled cracks; Dynamically adjusting the fracturing method based on real-time geological parameters of the target rock formation so that the actual development of the borehole fractures conforms to the fracture development law, and / or dynamically adjusting the fracturing method based on design parameters of the borehole so that the actual development of the borehole fractures conforms to the fracture development law; The real-time geological parameters include geological stress, stress difference and / or surrounding rock structure of the surrounding rock; the design parameters include whether there is grooving, grooving angle, drilling spacing, drilling angle and / or drilling depth.

2. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 1, characterized in that: Determining, based on the test model and the test area, the development patterns of borehole cracks under different fracturing methods during the hydraulic fracturing process includes: Establish a drilling fracturing model under bidirectional normal stress; Based on the drilling fracturing model, the crack development law of the drilling hole with or without grooving is determined.

3. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 2, characterized in that: The method of determining the crack development law of the borehole with or without a groove cut based on the borehole fracturing model includes: Simulating the fracturing process of the borehole without cutting grooves, and determining the crack development law based on the normal stress difference; The fracturing process of the borehole with a groove is simulated, and the crack development law is determined according to the groove direction and the normal stress difference.

4. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 3, characterized in that: The cutting grooves include transverse cutting grooves or longitudinal cutting grooves.

5. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 4, characterized in that: After establishing the drilling fracturing model under bidirectional normal stress, the method further includes: The crack development law is determined based on the normal stress ratio of the horizontal normal stress to the vertical normal stress.

6. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 5, characterized in that: The determining of the crack development law based on the normal stress ratio of the horizontal normal stress to the vertical normal stress includes: determining the crack development law according to the normal stress ratio and the cutting direction; and / or; The crack development law is determined according to the normal stress ratio and the pump flow rate.

7. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 6, characterized in that: Determining the crack development law according to the normal stress ratio and the grooving direction includes: Under the condition that the normal stress ratio is fixed, the cutting direction is adjusted to determine the crack development law; Determining the crack development law based on the normal stress ratio and the pump flow rate includes: When the normal stress ratio is fixed, the pump flow rate is adjusted to determine the crack development law.

8. The coal mine roadway roof far-field-near-field coordinated fracturing control method according to claim 1, characterized in that: Before determining the test area corresponding to the target rock layer in the test model according to the target rock layer of the coal mine roadway, the method further includes: The target rock layer is determined based on historical geological parameters of the coal mine tunnel and / or based on key layer theory.

9. A coal mine roadway roof far-field-near-field coordinated fracturing control device, using the coal mine roadway roof far-field-near-field coordinated fracturing control method according to any one of claims 1 to 8, characterized in that: include: A test model establishment unit, configured to establish a test model of the coal mine tunnel based on the coal mine tunnel; a first determining unit, configured to determine a target rock layer of a coal mine roadway, and to determine a test area corresponding to the target rock layer in the test model, wherein the target rock layer includes a key layer and / or subkey layer in a near field of a roof, and a key layer and / or subkey layer in a far field of a roof; A second determining unit is configured to determine, based on the test model and the test area, a borehole crack development law under different fracturing modes during the hydraulic fracturing process; wherein the crack development law includes a crack propagation direction change law and / or a crack deflection distance change law; The third determining unit is configured to determine a fracturing method for the target rock formation based on the development law of the drilled cracks.

Images