Directional drilling multi-layer collaborative pressure relief gas treatment method for bottom drainage roadway of low-permeability coal seam

Abstract

The invention discloses a low-permeability coal seam bottom drainage roadway directional drilling multi-layer collaborative pressure relief gas treatment method, relates to the technical field of mineral disaster prevention and control, and aims to solve the problem that the production safety is affected by low gas treatment efficiency. The method comprises the steps that based on basic parameters of a top plate, a coal seam and a bottom plate of a target area, a priority pressure relief mode is determined from a pressure relief mode library, and the basic parameters comprise coal rock physical property parameters, gas occurrence parameters and stratum characteristic parameters; the pressure relief mode library comprises an independent pressure relief mode of a bottom plate, a coal seam and a top plate, a cooperative pressure relief mode of the bottom plate-coal seam, the coal seam-top plate and the bottom plate-top plate, and a cooperative pressure relief mode of the bottom plate-coal seam-top plate; a drill hole group corresponding to the preferential pressure relief mode is arranged in a bottom drainage roadway arranged on a bottom plate of the working face; and pressure relief operation is executed in the drill hole group according to the preset procedure so as to expand the fracture network, the fracture network is used for conducting gas pressure relief extraction on the target area, and the pressure relief operation comprises slotting operation, fracturing operation and cave forming operation.

Description

Technical Field

[0001] This application relates to the field of mineral disaster prevention and control technology, and in particular to a multi-level coordinated decompression gas control method using directional drilling in bottom drainage roadways of low-permeability coal seams. Background Technology

[0002] Gas hazards have always been a major hidden danger affecting safe production in coal mines. Especially under complex geological conditions, effective control measures are needed to reduce the gas content of coal seams and ensure safe production in coal mines.

[0003] In recent years, with the continuous development of coal mining technology, hydraulic decompression technology has been gradually applied to gas control. However, existing hydraulic decompression methods are mostly concentrated inside the coal seam. Although this local decompression method improves the permeability of the coal seam to a certain extent, it ignores the influence of the roof and floor on gas occurrence and migration, and fails to fully utilize the synergistic decompression effect of the roof and floor, resulting in limited gas control effect and affecting the production safety of high-gas, low-permeability mines.

[0004] Therefore, there is an urgent need to design a solution that can improve the efficiency of gas control to ensure safe production. Summary of the Invention

[0005] The purpose of this application is to provide a multi-level coordinated decompression gas control method using directional drilling in the bottom drainage roadway of low-permeability coal seams, which aims to solve the problem of low gas control efficiency affecting production safety.

[0006] To achieve the above objectives, this application adopts the following technical solution: This application provides a multi-level coordinated decompression gas control method using directional boreholes in a bottom drainage roadway of a low-permeability coal seam. The method includes: determining a priority decompression mode from a decompression mode library based on fundamental parameters of the roof, coal seam, and floor of the target area. These fundamental parameters include coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters, ensuring the priority decompression mode is feasible; deploying a borehole group corresponding to the priority decompression mode in a bottom drainage roadway located on the working face floor; and performing decompression operations in the borehole group according to a predetermined procedure to expand the fracture network. The fracture network is used for gas decompression and extraction in the target area. The decompression operations include fracturing, hydraulic fracturing, and cavity creation.

[0007] The low-permeability coal seam bottom drainage roadway directional drilling multi-level coordinated decompression gas control method provided in this application embodiment firstly, based on the precise matching of coal and rock physical parameters, gas occurrence parameters, and stratum characteristic parameters, a feasible decompression mode is determined, making the control scheme highly compatible with the coal seam occurrence conditions and achieving efficient gas extraction. Subsequently, a group of boreholes is laid in the bottom drainage roadway to form a three-dimensional decompression network of floor-coal seam-roof. The advantages of the floor roadway are utilized to achieve precise positioning and high-quality borehole formation of directional drilling. Then, through the coordinated process of cutting, fracturing, and cavity creation, the initial cutting forms initial guiding fractures, and the subsequent fracturing further expands the fracture network and enhances connectivity, forming a continuous gas diversion system, increasing the gas decompression range and coal seam permeability. This shortens the control cycle while achieving gas disaster prevention and control, thereby improving gas control efficiency and ensuring the safety of production operations.

[0008] In some embodiments, the aforementioned coal and rock physical properties include the soundness coefficient, Poisson's ratio, compressive strength, tensile strength, internal friction angle, cohesion, density, porosity, permeability, and hardness; the aforementioned gas occurrence parameters include gas pressure, gas content, and coal seam gas adsorption constant; the aforementioned stratigraphic characteristic parameters include the distribution of geostress field, geological structural characteristics, roof and floor lithology, and coal seam thickness; the aforementioned pressure relief mode library includes independent pressure relief mode for the floor, independent pressure relief mode for the coal seam, independent pressure relief mode for the roof, coordinated pressure relief mode for the floor and coal seam, coordinated pressure relief mode for the coal seam and roof, coordinated pressure relief mode for the floor and roof, and coordinated pressure relief mode for the floor, coal seam, and roof.

[0009] Based on this, this application refines the constituent elements of coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters to provide multi-dimensional data support for pressure relief mode matching, making mode selection more accurately adapted to geological conditions and improving the targeted nature of fracture network construction.

[0010] In some embodiments, determining the preferred pressure relief mode from the pressure relief mode library based on the basic parameters of the roof, coal seam, and floor of the target area includes: analyzing the coal seam permeability enhancement effect of each pressure relief mode in the pressure relief mode library according to coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters; determining the pressure relief mode with a coal seam permeability enhancement effect greater than a predetermined target value as a candidate pressure relief mode; and determining the preferred pressure relief mode from the candidate pressure relief modes.

[0011] Based on this, this application analyzes the feasibility of candidate pressure relief modes for dynamic matching technology of coal seam permeability enhancement, improves the pressure relief intensity in complex stress fields and high gas content areas, and enhances the controllability of pressure relief effect through synergistic pressure relief.

[0012] In some embodiments, determining the preferred depressurization mode from the candidate depressurization modes includes: predicting the gas control cost, gas control efficiency, and gas control effect of each depressurization mode in the candidate depressurization modes; and determining the depressurization mode that meets preset conditions as the preferred depressurization mode; wherein meeting the preset conditions includes: the gas control cost is less than or equal to a cost threshold; the gas control efficiency is greater than or equal to an efficiency threshold; and the gas control effect is greater than or equal to an effect threshold.

[0013] Based on this, this application selects the optimal pressure relief mode by comprehensively judging the gas control cost, gas control efficiency, and gas control effect, so as to ensure the cost-effectiveness of the final pressure relief mode.

[0014] In some embodiments, determining the preferred decompression mode from the candidate decompression modes includes: determining the decompression mode with the highest coal seam permeability enhancement effect among the candidate decompression modes as the preferred decompression mode.

[0015] Based on this, this application selects the pressure relief mode with the highest coal seam permeability enhancement effect as the final pressure relief mode to ensure the effectiveness of gas control.

[0016] In some embodiments, the aforementioned decompression operation performed in the borehole group according to a predetermined procedure includes: performing a cavity-making operation in the borehole group according to a first procedure when the hardness of the coal seam is less than a hardness threshold and the coal seam gas adsorption constant is less than an adsorption threshold; and performing a fracturing operation in the borehole group according to a second procedure when the hardness of the coal seam is greater than or equal to the hardness threshold, or the coal seam gas adsorption constant is greater than or equal to the adsorption threshold. The first procedure is: floor cutting and fracturing, coal seam cavity creation, and roof cutting and fracturing; the second procedure is: floor cutting and fracturing, coal seam fracturing, and roof cutting and fracturing.

[0017] Based on this, this application uses a dynamic adjustment process for coal quality characteristics to prioritize creating holes to strengthen initial fractures in soft coal seams, while focusing on hydraulic fracturing in hard coal seams to ensure fracture depth. This improves the compatibility of the process with the mechanical properties of the coal body and ensures effective subsequent pressure relief from the borehole.

[0018] In some embodiments, the multi-level coordinated decompression gas control method using directional drilling in the bottom drainage roadway of low-permeability coal seams provided in this application further includes: gas extraction through a group of boreholes and monitoring gas extraction parameters, including gas flow rate, extraction negative pressure and gas concentration; analyzing the gas extraction parameters to obtain decompression results, including borehole parameters and borehole quality.

[0019] Based on this, this application constructs a dynamic feedback mechanism through a group of boreholes to visualize and monitor the pressure relief effect, forming a closed-loop control for treatment and evaluation, realizing a quantitative evaluation of the pressure relief effect, reflecting the rationality of the pressure relief borehole parameters and the quality of borehole formation, so as to adjust the borehole design parameters and construction technology in a timely manner.

[0020] In some embodiments, the multi-level coordinated pressure relief gas control method for low-permeability coal seam bottom drainage directional drilling provided in this application further includes: when the drilling parameters do not meet the standard parameters, and / or the drilling quality does not meet the standard quality, determining a secondary pressure relief mode from the pressure relief mode library, wherein the secondary pressure relief mode is the highest priority pressure relief mode in the pressure relief mode library other than the primary pressure relief mode; and replacing the primary pressure relief mode with the secondary pressure relief mode.

[0021] Based on this, this application maintains the continuity and integrity of gas control by performing a secondary matching of the depressurization mode when the analysis of depressurization results fails to meet the standards.

[0022] In some embodiments, the aforementioned borehole groups are arranged in an alternating pattern in both the roof and the bottom of the coal seam.

[0023] Based on this, this application avoids the problem of densely arranging fracturing holes in the same area of ​​the bottom or top plate by spatially staggering the borehole groups, which would cause the bottom or top plate to be too fragmented, and reduces the difficulty of controlling the top and bottom plates of the coal mining face in the later stages.

[0024] This application provides a multi-level coordinated pressure relief gas control device for directional drilling in a bottom drainage roadway of a low-permeability coal seam. The device includes: a determination unit, used to determine a priority pressure relief mode from a pressure relief mode library based on the basic parameters of the roof, coal seam, and floor of the target area. The basic parameters include coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters, and the priority pressure relief mode is feasible; a deployment unit, used to deploy a group of boreholes corresponding to the priority pressure relief mode in a bottom drainage roadway located on the floor of the working face; and a processing unit, used to perform pressure relief operations in the borehole group according to a predetermined procedure to expand the fracture network. The fracture network is used for gas pressure relief and extraction in the target area. The pressure relief operations include fracture cutting, fracturing, and cavity creation.

[0025] In some embodiments, the aforementioned coal and rock physical properties include the soundness coefficient, Poisson's ratio, compressive strength, tensile strength, internal friction angle, cohesion, density, porosity, permeability, and hardness; the aforementioned gas occurrence parameters include gas pressure, gas content, and coal seam gas adsorption constant; the aforementioned stratigraphic characteristic parameters include the distribution of geostress field, geological structural characteristics, roof and floor lithology, and coal seam thickness; the aforementioned pressure relief mode library includes independent pressure relief mode for the floor, independent pressure relief mode for the coal seam, independent pressure relief mode for the roof, coordinated pressure relief mode for the floor and coal seam, coordinated pressure relief mode for the coal seam and roof, coordinated pressure relief mode for the floor and roof, and coordinated pressure relief mode for the floor, coal seam, and roof.

[0026] In some embodiments, the determining unit is specifically used to: analyze the coal seam permeability enhancement effect of each pressure relief mode in the pressure relief mode library based on coal and rock physical property parameters, gas occurrence parameters and formation characteristic parameters; determine the pressure relief mode with a coal seam permeability enhancement effect greater than a predetermined target value as a candidate pressure relief mode; and determine the priority pressure relief mode from the candidate pressure relief modes.

[0027] In some embodiments, the determining unit is specifically used to: predict the gas control cost, gas control efficiency, and gas control effect of each pressure relief mode in the candidate pressure relief modes; and determine the pressure relief mode that meets the preset conditions as the priority pressure relief mode; wherein, meeting the preset conditions includes: the gas control cost is less than or equal to the cost threshold; the gas control efficiency is greater than or equal to the efficiency threshold; and the gas control effect is greater than or equal to the effect threshold.

[0028] In some embodiments, the determining unit is specifically used to: determine the pressure relief mode with the highest coal seam permeability enhancement effect among the candidate pressure relief modes as the priority pressure relief mode.

[0029] In some embodiments, the above-mentioned processing unit is specifically used for: performing a cavity-making operation in the borehole group according to the first step when the hardness of the coal seam is less than the hardness threshold and the coal seam gas adsorption constant is less than the adsorption threshold; and performing a fracturing operation in the borehole group according to the second step when the hardness of the coal seam is greater than or equal to the hardness threshold, or the coal seam gas adsorption constant is greater than or equal to the adsorption threshold; wherein, the first step is: floor cutting and fracturing, coal seam cavity creation, and roof cutting and fracturing, and the second step is: floor cutting and fracturing, coal seam fracturing, and roof cutting and fracturing.

[0030] In some embodiments, the above-mentioned processing unit is further configured to: perform gas extraction through a group of boreholes and monitor gas extraction parameters, including gas flow rate, extraction negative pressure and gas concentration; analyze the gas extraction parameters to obtain pressure relief results, including borehole parameters and borehole quality.

[0031] In some embodiments, the determining unit is further configured to determine a secondary pressure relief mode from the pressure relief mode library when the drilling parameters do not meet the standard parameters and / or the drilling quality does not meet the standard quality. The secondary pressure relief mode is the pressure relief mode with the highest priority other than the primary pressure relief mode in the pressure relief mode library. The processing unit is further configured to replace the primary pressure relief mode with the secondary pressure relief mode.

[0032] In some embodiments, the aforementioned borehole groups are arranged in an alternating pattern in both the roof and the bottom of the coal seam.

[0033] This application provides an electronic device, including: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to execute instructions to implement the multi-level coordinated decompression gas control method for directional drilling at the bottom of low-permeability coal seams described above.

[0034] This application provides a computer-readable storage medium storing instructions that, when executed on a terminal, cause the terminal to perform the multi-level coordinated decompression gas control method for bottom drainage directional drilling in low-permeability coal seams described above.

[0035] This application provides a computer program product containing instructions that, when executed by a computer, cause the computer to perform the multi-level coordinated decompression gas control method for directional drilling at the bottom of low-permeability coal seams described above.

[0036] This application provides a chip, which includes a processor and a communication interface. The communication interface and the processor are coupled. The processor is used to run computer programs or instructions to implement the multi-level coordinated decompression gas control method for bottom drainage directional drilling in low-permeability coal seams described above.

[0037] Specifically, the chip provided in this application embodiment also includes a memory for storing computer programs or instructions. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A flowchart illustrating a multi-level coordinated decompression gas control method using directional drilling in a low-permeability coal seam bottom drainage roadway, provided in this application embodiment; Figure 2 A complete flowchart of a multi-level coordinated decompression gas control method using directional drilling in a low-permeability coal seam bottom drainage roadway, provided in the embodiments of this application; Figure 3 A horizontal cross-sectional view of a borehole arrangement provided in an embodiment of this application; Figure 4 A vertical cross-sectional view of a borehole arrangement provided in an embodiment of this application; Figure 5 A vertical cross-sectional view of the borehole layout under hydraulic fracturing operation provided in this application embodiment; Figure 6 A vertical cross-sectional view of the borehole arrangement under hydraulic cavity creation operation provided in an embodiment of this application; Figure 7A structural diagram of a multi-level coordinated pressure relief device for directional drilling in a low-permeability coal seam bottom extraction roadway, provided in an embodiment of this application; Figure 8 This is a structural diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] In the description of this application, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or relative positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and for simplification, 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, they should not be construed as limitations on this application. Unless otherwise specified, the above-mentioned orientational descriptions can be flexibly set in practical applications, provided that the relative positional relationships shown in the accompanying drawings are satisfied.

[0042] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0044] In some embodiments, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, article, or apparatus that includes that element.

[0045] In some embodiments, the words "exemplary" or "for example" are used to indicate that something is an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0046] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0047] Traditional gas control methods mainly focus on single gas extraction or localized pressure relief measures. However, these methods suffer from low extraction efficiency, long treatment cycles, and unstable results. Especially under complex geological conditions, single control measures are insufficient to effectively reduce coal seam gas content and ensure safe coal mine production.

[0048] In recent years, with the continuous development of coal mining technology, hydraulic decompression technology has been gradually applied to gas control. However, existing hydraulic decompression methods mostly focus on the coal seam interior, neglecting the influence of the roof and floor on gas occurrence and migration. Although this localized decompression method improves the permeability of the coal seam to some extent, it fails to fully utilize the synergistic decompression effect of the roof and floor, resulting in limited gas control effectiveness and difficulty in meeting the safety production needs of high-gas, low-permeability mines.

[0049] In summary, existing gas control solutions generally suffer from low gas control efficiency, which in turn affects production safety.

[0050] Against this backdrop, to address the problem of low gas control efficiency affecting production safety in related technologies, this application provides a multi-level synergistic decompression gas control method using directional drilling in bottom drainage roadways of low-permeability coal seams. By comprehensively considering the synergistic decompression effects of the roof, coal seam, and floor, efficient gas control is achieved, ensuring production safety.

[0051] The following is a reference. Figures 1 to 6The method for controlling gas pressure at multiple locations through directional drilling in the bottom drainage roadway of low-permeability coal seams, as provided in the embodiments of this application, is described.

[0052] Figure 1 The flowchart of the method for multi-level coordinated decompression and gas control through directional drilling in the bottom drainage roadway of low-permeability coal seams provided in this application embodiment is shown. The main body executing this method can be an electronic device or various devices / modules in the electronic device, such as integrated circuits or chips. This application embodiment does not specifically limit this.

[0053] For example, such as Figure 1 As shown in the embodiments of this application, the multi-level coordinated decompression gas control method using directional drilling at the bottom of low-permeability coal seams provided in this application may include the following steps S101 to S103: S101. Based on the basic parameters of the roof, coal seam and floor of the target area, determine the priority pressure relief mode from the pressure relief mode library.

[0054] The basic parameters include coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters. The priority depressurization mode is feasible.

[0055] In the embodiments of this application, the physical properties of coal and rock include the soundness coefficient, Poisson's ratio, compressive strength, tensile strength, internal friction angle, cohesion, density, porosity, permeability, and hardness.

[0056] For example, the firmness coefficient is an indicator of the ability of coal and rock to resist external forces, reflecting how easily coal and rock can maintain their integrity under stress. A low firmness coefficient means that the coal and rock are more likely to break or collapse.

[0057] For example, Poisson's ratio is the ratio of transverse strain to longitudinal strain in coal or rock under uniaxial tension or compression. Poisson's ratio affects the shape change and stress distribution of coal or rock under stress.

[0058] For example, compressive strength refers to the maximum pressure that coal and rock can withstand without breaking. Low compressive strength may lead to compressive failure of coal and rock during mining.

[0059] For example, tensile strength refers to the maximum tensile force that coal and rock can withstand without fracturing when subjected to tensile force. In coal seam mining, low tensile strength may lead to tensile cracking of the roof or floor of the coal seam.

[0060] For example, the internal friction angle refers to the angle between the frictional force between particles or on the fracture surface within coal and rock, and the normal stress. The internal friction angle affects the resistance of coal and rock to shear forces. A larger internal friction angle indicates that the coal and rock have stronger shear resistance.

[0061] For example, cohesion refers to the binding force or adhesion between particles within coal or rock. High cohesion means that coal or rock will not separate or break when subjected to external forces.

[0062] For example, density refers to the mass per unit volume of coal or rock. Density is one of the fundamental parameters describing the composition and structural characteristics of coal and rock materials. Coal and rock with different densities may exhibit different physical and mechanical properties during mining.

[0063] For example, porosity refers to the ratio of pore volume to total volume in coal and rock. Porosity affects the permeability, adsorption, and gas content of coal and rock. High porosity indicates that the coal and rock have good permeability and adsorption capacity.

[0064] For example, permeability refers to the ability of coal and rock to allow fluids (such as gas, water, etc.) to pass through. Permeability affects the effectiveness of coal seam gas drainage and water hazard prevention during mining. High permeability means that coal and rock are more likely to allow fluids to pass through.

[0065] For example, hardness refers to the ability of coal or rock to resist scratching or indentation. Hardness is a fundamental parameter describing the ability of coal or rock surfaces to resist damage from external forces. Coal or rock of different hardness may require different mining methods and tools during the mining process.

[0066] In the embodiments of this application, the gas occurrence parameters include gas pressure, gas content, and coal seam gas adsorption constant.

[0067] For example, gas pressure refers to the pressure exerted by methane gas in a coal seam. The magnitude of gas pressure depends on factors such as the amount of methane generated in the coal seam, storage conditions, and the permeability of the coal seam.

[0068] For example, gas content refers to the amount of gas contained in a unit mass or volume of coal seam, usually expressed in cubic meters per ton or cubic meters per cubic meter.

[0069] For example, the coal seam gas adsorption constant refers to a set of parameters describing the coal seam's ability to adsorb gas, typically including adsorption constants a and b. Adsorption constant a reflects the limiting amount of gas that the coal seam can adsorb, that is, the maximum amount of gas that a unit mass of coal can adsorb under given conditions; while adsorption constant b is related to the temperature and pressure of the adsorption process, and it affects the adsorption rate and adsorption equilibrium.

[0070] In the embodiments of this application, the stratigraphic characteristic parameters include the distribution of the geostress field, geological structural features, lithology of the roof and floor, and coal seam thickness.

[0071] For example, the distribution of geostress field refers to the natural stress state of the rock mass inside the Earth and its spatial distribution, caused by the gravity of the overlying rock strata, tectonic movements, etc., and encompasses the magnitude and direction of stress in different directions.

[0072] For example, geological structural features refer to the structural traces and combinations left by crustal movements in rock strata, including folds, faults, and joints. Folds alter the occurrence and occurrence of coal seams; faults disrupt the continuity of coal seams, forming fracture zones that serve as channels for fluid transport; joints break up rock masses, reducing their mechanical properties and increasing the difficulty and cost of mining.

[0073] For example, roof and floor lithology refers to the type, composition, structure, and physical and mechanical properties of the rocks in the roof and floor of a coal seam. Roof lithology determines its stability; hard sandstone roofs have high strength and good stability, while soft mudstone or shale roofs are prone to deformation and breakage.

[0074] For example, coal seam thickness refers to the vertical distance between the top and bottom plates of the coal seam.

[0075] In this embodiment of the application, the pressure relief mode library includes independent pressure relief mode for the floor, independent pressure relief mode for the coal seam, independent pressure relief mode for the roof, coordinated pressure relief mode for the floor and coal seam, coordinated pressure relief mode for the coal seam and roof, coordinated pressure relief mode for the floor and roof, and coordinated pressure relief mode for the floor, coal seam, and roof.

[0076] For example, the independent pressure relief mode of the base plate refers to cutting and fracturing only the base plate to form a crack network in the base plate and directly release the gas pressure.

[0077] For example, the independent pressure relief mode of coal seam refers to the implementation of cavitation or fracturing only in the coal seam to form a fracture network in the coal seam and directly release gas pressure.

[0078] For example, the independent depressurization mode of the roof refers to cutting and fracturing only in the roof to form a fracture network in the roof and directly release the gas pressure.

[0079] For example, the floor-coal seam coordinated decompression mode refers to cutting and fracturing the floor, and then creating cavities or fracturing the coal seam to form a fracture network.

[0080] For example, the coal seam-roof coordinated decompression mode refers to creating cavitation or fracturing in the coal seam, and then cutting and fracturing the roof to form a fracture network.

[0081] For example, the bottom plate-top plate coordinated decompression mode refers to cutting and fracturing the bottom plate, and then cutting and fracturing the top plate to form a fracture network.

[0082] For example, the floor-coal seam-roof coordinated decompression mode refers to cutting and fracturing the floor, then creating cavities or fracturing the coal seam, and finally cutting and fracturing the roof to form a fracture network.

[0083] Thus, this application provides multi-dimensional data support for stress relief model matching by refining the constituent elements of coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters, making the model selection more accurately adapted to geological conditions and improving the targeted nature of fracture network construction.

[0084] In some embodiments, the coal seam permeability enhancement effect of each pressure relief mode in the pressure relief mode library can be analyzed based on coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters. Then, pressure relief modes with coal seam permeability enhancement effects greater than a predetermined target value are identified as candidate pressure relief modes.

[0085] Optionally, a quantitative analysis model can be established to evaluate the coal seam permeability enhancement effect of each decompression mode in the decompression mode library based on coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters.

[0086] In this embodiment, a corresponding geomechanics and gas migration model can be constructed based on coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters. Then, the model can be solved using numerical simulation methods or artificial intelligence algorithms to predict the change in coal seam permeability after the implementation of each pressure relief mode, and then analyze its permeability enhancement effect. Finally, the pressure relief mode with a coal seam permeability enhancement effect greater than the predetermined target value is determined as a candidate pressure relief mode.

[0087] The predetermined target value can be a manually set value, which can be flexibly adjusted according to the actual scenario. For example, the predetermined target value can be three times the coal seam permeability.

[0088] For example, a geomechanical model reflecting the coal seam structure and gas occurrence state can be constructed based on the specific parameters included in the coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters. Then, numerical simulation methods or artificial intelligence algorithms can be used to analyze the permeability enhancement effect of the coal seam under different pressure relief modes, and all pressure relief modes with a permeability enhancement effect greater than three times the coal seam permeability can be identified as candidate pressure relief modes.

[0089] Specifically, when using numerical simulation methods, finite element analysis (FEA) and discrete element method (DEM) can be used to simulate the stress distribution, fracture development, and propagation of the coal and rock mass during the decompression process. Computational fluid dynamics (CFD) can then be combined to simulate the gas flow process in the coal seam, thereby quantitatively predicting the increase in coal seam permeability after decompression. For example, the changes in the fracture field caused by decompression can be calculated first using FEA or DEM, and then this fracture field can be used as input to a CFD model to simulate gas seepage, ultimately obtaining the permeability change.

[0090] Specifically, when employing artificial intelligence algorithms, a training sample set can be constructed based on historical data or numerical simulation results. The input features include coal and rock physical properties, gas occurrence parameters, formation characteristic parameters, and pressure relief mode types. The output is the corresponding coal seam permeability enhancement effect (such as the permeability multiplication factor). This sample set is used to train an artificial neural network (ANN), support vector machine (SVM), or random forest (RF) algorithm to obtain a model that can predict the permeability enhancement effect of each pressure relief mode under a given combination of parameters. After training, the current coal seam parameters and various modes from the pressure relief mode library are input into the model to efficiently evaluate the permeability enhancement effect of each mode.

[0091] Furthermore, after identifying the candidate decompression modes, a preferred decompression mode can be determined from among the candidate decompression modes.

[0092] Thus, this application improves the pressure relief intensity in complex stress fields and high gas content areas by analyzing the feasibility of dynamic matching technology for coal seam permeability enhancement, and enhances the controllability of pressure relief effect through synergistic pressure relief.

[0093] In some embodiments, a strategy can be selected from the comprehensive benefit priority strategy and the permeability enhancement priority strategy to determine the priority pressure relief mode based on the actual gas control needs or coal seam geological conditions.

[0094] In one alternative implementation, a comprehensive benefit priority strategy can be used to determine the priority decompression mode. This comprehensive benefit priority strategy is suitable for scenarios where there are balanced requirements for treatment costs, construction efficiency, and treatment effects.

[0095] In some embodiments, under the comprehensive benefit priority strategy, the gas control cost, gas control efficiency and gas control effect of each pressure relief mode in the candidate pressure relief modes can be predicted; the pressure relief mode that meets the preset conditions in the candidate pressure relief modes is determined as the priority pressure relief mode.

[0096] Among them, meeting the preset conditions includes: gas control cost is less than or equal to the cost threshold, gas control efficiency is greater than or equal to the efficiency threshold, and gas control effect is greater than or equal to the effect threshold.

[0097] In this embodiment, the cost threshold, efficiency threshold, and effect threshold can all be manually set values, which can be flexibly adjusted according to the actual scenario. For example, the cost threshold can be 1 million, the efficiency threshold can be 80%, and the effect threshold can be 90%.

[0098] For example, the same historical pressure relief mode can be determined first for each pressure relief mode in the candidate pressure relief mode. Then, based on the gas control cost, gas control efficiency and gas control effect corresponding to the historical pressure relief mode, the gas control cost, gas control efficiency and gas control effect of each pressure relief mode in the candidate pressure relief mode can be determined. Then, from multiple pressure relief modes, the pressure relief mode with a gas control cost less than or equal to the cost threshold, a gas control efficiency greater than or equal to the efficiency threshold and a gas control effect greater than or equal to the effect threshold can be selected as the optimal pressure relief mode.

[0099] Specifically, taking the candidate depressurization modes including floor independent depressurization mode, coal seam independent depressurization mode, and roof independent depressurization mode, with a cost threshold of 1 million, an efficiency threshold of 80%, and an effectiveness threshold of 90%, as an example: If the gas control cost of the floor independent depressurization mode is 950,000, the gas control efficiency is 85%, and the gas control effectiveness is 92%; the gas control cost of the coal seam independent depressurization mode is 1.2 million, the gas control efficiency is 88%, and the gas control effectiveness is 85%; and the gas control cost of the roof independent depressurization mode is 1.5 million, the gas control efficiency is 70%, and the gas control effectiveness is 85%, then since the gas control cost of the floor independent depressurization mode (950,000) is less than the cost threshold of 1 million, the gas control efficiency (85%) is greater than the efficiency threshold of 80%, and the gas control effectiveness (92%) is greater than the effectiveness threshold of 90%, the floor independent depressurization mode is determined as the optimal depressurization mode.

[0100] Thus, this application selects the optimal pressure relief mode by comprehensively judging the gas control cost, gas control efficiency, and gas control effect, ensuring the cost-effectiveness of the final implemented pressure relief mode.

[0101] In another alternative implementation, a permeability enhancement priority strategy can be used to determine the priority pressure relief mode. The permeability enhancement priority strategy is suitable for scenarios where there are extreme requirements for improving coal seam permeability and cost and efficiency are secondary factors, such as in coal seams with high gas pressure or severe outburst risk.

[0102] In some embodiments, under the permeability enhancement priority strategy, the pressure relief mode with the highest coal seam permeability enhancement effect among the candidate pressure relief modes can be determined as the priority pressure relief mode.

[0103] Specifically, taking the candidate pressure relief modes including independent floor pressure relief mode, floor-coal seam coordinated pressure relief mode, and floor-coal seam-roof coordinated pressure relief mode as examples, if the coal seam permeability enhancement effect of the independent floor pressure relief mode is 3 times the coal seam permeability, the coal seam permeability enhancement effect of the floor-coal seam coordinated pressure relief mode is 3.5 times the coal seam permeability, and the coal seam permeability enhancement effect of the floor-coal seam-roof coordinated pressure relief mode is 4 times the coal seam permeability, then since the coal seam permeability enhancement effect of the floor-coal seam-roof coordinated pressure relief mode is the highest, the floor-coal seam-roof coordinated pressure relief mode is determined as the optimal pressure relief mode.

[0104] Therefore, this application selects the pressure relief mode with the highest coal seam permeability enhancement effect as the final pressure relief mode to ensure the effectiveness of gas control.

[0105] S102. Arrange a group of boreholes corresponding to the priority pressure relief mode in the bottom drainage roadway located on the bottom plate of the working face.

[0106] Optionally, the borehole group is arranged in a staggered manner in the roof, coal seam and floor.

[0107] It should be noted that drilling holes in the bottom plate facilitates drainage, but the initial air extraction rate is low, while drilling holes in the top plate facilitates air extraction. Combining drilling holes in both the bottom and top plates increases drainage efficiency and effectiveness.

[0108] In the embodiments of this application, the working face floor refers to the rock strata below the working face during coal seam mining; the bottom drainage roadway refers to a roadway in a coal mine specifically used for gas drainage, which is usually arranged in the rock strata of the coal seam floor.

[0109] The main function of the bottom drainage roadway is to serve as the construction site for gas drainage boreholes. By constructing in the bottom drainage roadway and arranging a large number of boreholes in the coal seam, roof, and floor, a three-dimensional drainage network is formed to achieve gas drainage throughout the entire process before, during, and after mining, thereby reducing the gas content in the coal seam.

[0110] For example, taking the floor-coal seam-roof coordinated depressurization mode as an example, the corresponding borehole group includes: roof and floor boreholes and coal seam boreholes. A directional drilling rig can be used to drill directional boreholes from the bottom drainage roadway into the floor, coal seam, and roof respectively to obtain the borehole group.

[0111] It should be noted that the borehole length is determined based on actual conditions such as geological conditions, mining design, and directional drilling rig. Under the condition that all conditions permit, the borehole can be drilled to multiple adjacent working face areas in one go.

[0112] S103. Perform decompression operations in the borehole group according to the predetermined procedure to expand the fracture network.

[0113] Among them, the fracture network is used for gas decompression and extraction in the target area.

[0114] In the embodiments of this application, the depressurization operation includes slotting operation, fracturing operation, and cavity creation operation.

[0115] For example, the slotting operation uses high-pressure water or airflow to cut flat slots in the coal and rock strata, thereby increasing the exposed area of ​​the coal body, forming a local pressure relief zone, guiding the direction of fracture development, and improving the permeability of the coal seam.

[0116] For example, fracturing is a process that involves injecting high-pressure water or gas into a coal and rock strata to create fractures and increase gas permeability.

[0117] For example, the cavity-making operation is to create a cavity by injecting high-pressure water or gas into the coal seam.

[0118] In one alternative implementation, when the hardness of the coal seam is less than the hardness threshold and the gas adsorption constant of the coal seam is less than the adsorption threshold, a cavity-making operation is performed in the borehole group according to the first step.

[0119] The first process includes: floor cutting and fracturing, coal seam cavity creation, and roof cutting and fracturing.

[0120] For example, both the hardness threshold and the adsorption threshold can be manually set values, which can be flexibly adjusted according to the actual scenario. For instance, the hardness threshold can be 2.0; the adsorption threshold can be 30m. 3 / t.

[0121] Specifically, with a hardness threshold of 2.0 and an adsorption threshold of 30m... 3 Taking / t as an example. If the hardness of the coal seam measured in real time is 1.5 and the adsorption constant of the coal seam is 15m... 3 / t, then since 1.5 is less than 2, and 15m 3 / t less than 30m 3 / t indicates that the coal seam is relatively soft, making it difficult to form effective fractures through hydraulic fracturing, but it is easy to undergo plastic deformation to achieve pressure relief and permeability enhancement. At this point, the first process of creating a cavity can be initiated.

[0122] For example, in a borehole group, floor fracturing and cutting are performed first: boreholes in the floor strata are fracturing and cutting operations are performed to reduce floor stress and prevent floor bulging or rupture. Then, high-pressure water or airflow is used to cut out larger diameter cavities in the coal seam to increase the exposed area of ​​the coal body and form a local pressure relief zone. Finally, roof fracturing and cutting are performed: boreholes in the roof strata are fracturing to cut out flat grooves and reduce roof stress. Then, fracturing is performed to form a fracture network and expand the gas migration channels.

[0123] In another alternative implementation, if the hardness of the coal seam is greater than or equal to the hardness threshold, fracturing operations are performed in the borehole group according to the second procedure.

[0124] The second process consists of: floor fracturing and hydraulic fracturing, coal seam hydraulic fracturing, and roof fracturing and hydraulic fracturing.

[0125] Specifically, taking a hardness threshold of 2.0 as an example, if the real-time measured coal seam hardness is 3, then since 3 is greater than 2, it indicates that the coal seam is relatively hard and not easy to cut, and the second process of fracturing operation can be initiated.

[0126] For example, in a borehole group, the first step is to perform floor fracturing and cutting: the boreholes in the floor strata are drilled for fracturing and cutting to reduce floor stress and prevent floor bulging or fracturing. Then, a high-pressure pump unit is used on the surface to inject fracturing fluid into the underground strata, forcing the coal seam to fracture and form cracks. The cracks are kept open by proppant (such as quartz sand), thereby establishing fluid channels. Finally, the top plate is drilled for fracturing and cutting: the boreholes in the top strata are drilled to cut flat grooves and reduce roof stress. Then, fracturing is performed to form a network of cracks and expand the gas transport channels.

[0127] In another alternative implementation, if the coal seam adsorption constant is greater than or equal to the adsorption threshold, fracturing operations are performed in the borehole group according to the second procedure.

[0128] Specifically, with an adsorption threshold of 30m 3 Taking / t as an example. If the real-time measured adsorption constant of the coal seam is 40m... 3 / t, then due to 40m 3 / t greater than 30m 3 / t indicates that the coal seam has a strong ability to absorb gas, and the second process of fracturing can be started.

[0129] Thus, this application, through a dynamic adjustment process of coal quality characteristics, prioritizes creating holes to strengthen initial fractures in soft coal seams, while focusing on hydraulic fracturing in hard coal seams to ensure fracture depth, thereby improving the compatibility of the process with the mechanical properties of the coal body and ensuring effective subsequent pressure relief of the borehole.

[0130] In the low-permeability coal seam bottom drainage roadway directional drilling multi-level coordinated decompression gas control method provided in this application embodiment, firstly, a feasible decompression mode is precisely matched based on coal and rock physical properties, gas occurrence parameters, and stratum characteristic parameters, so that the control scheme is highly adapted to the coal seam occurrence conditions, achieving efficient gas extraction; then, a group of boreholes is laid in the bottom drainage roadway to form a three-dimensional decompression network of floor-coal seam-roof, utilizing the advantages of the floor roadway to achieve precise positioning and high-quality borehole formation of directional drilling; then, through the coordinated process of cutting, fracturing, and cavity creation, the initial cutting forms initial guiding fractures, and the subsequent fracturing further expands the fracture network and enhances connectivity, forming a through gas diversion system, increasing the gas decompression range and coal seam permeability, shortening the control cycle while achieving gas disaster prevention and control, thereby improving gas control efficiency and ensuring the safety of production operations.

[0131] Optionally, after S101 above, the multi-level coordinated decompression gas control method using directional drilling in the bottom drainage roadway of low-permeability coal seams provided in this application embodiment may further include: gas extraction through a group of boreholes and monitoring the gas extraction parameters, and analyzing the gas extraction parameters to obtain decompression results.

[0132] Among them, the gas extraction parameters include gas flow rate, extraction negative pressure, and gas concentration; the pressure relief results include borehole parameters and borehole quality.

[0133] In this embodiment, the borehole group can be divided into a pressure relief borehole group and a drainage borehole group. The drainage borehole group and the pressure relief borehole group are arranged in an alternating manner in the roof, coal seam and floor.

[0134] For example, pressure relief boreholes and gas drainage boreholes are arranged alternately in the roof, in the floor, and in the coal seam.

[0135] Thus, by spatially staggering the borehole groups, this application avoids the problem of densely arranging fracturing holes in the same area of ​​the bottom or top plate, which would lead to excessive fragmentation of the bottom or top plate and reduce the difficulty of controlling the top and bottom plates of the coal mining face in the later stages.

[0136] In some embodiments, before connecting the extraction borehole group to the extraction system, each extraction borehole can be used as an observation hole for adjacent pressure relief boreholes, and the borehole wall morphology and water content of the observation holes can be analyzed to obtain pressure relief results.

[0137] In one example, if, after depressurization, the number of cracks in the borehole wall increases, and the length and width of the cracks also increase, it indicates that the drilling parameters meet the standard parameters and the drilling quality meets the standard quality.

[0138] In another example, if the water content in the observation hole increases after depressurization, it indicates that the coal seam permeability is enhanced, the drilling parameters meet the standard parameters, and the drilling quality meets the standard quality.

[0139] Thus, this application constructs a dynamic feedback mechanism through a group of boreholes to visualize and monitor the pressure relief effect, forming a closed-loop control for governance and evaluation, achieving a quantitative evaluation of the pressure relief effect, reflecting the rationality of the pressure relief borehole parameters and the quality of borehole formation, so as to adjust the borehole design parameters and construction technology in a timely manner.

[0140] Alternatively, after obtaining the pressure relief results from the analysis, if the drilling parameters do not meet the standard parameters and / or the drilling quality does not meet the standard quality, a secondary pressure relief mode can be determined from the pressure relief mode library, and the primary pressure relief mode can be replaced with the secondary pressure relief mode.

[0141] Among them, the secondary pressure relief mode is the highest priority pressure relief mode in the pressure relief mode library, excluding the primary pressure relief mode.

[0142] In this application embodiment, the highest priority is used to indicate the lowest cost of the depressurization mode.

[0143] For example, after depressurization, if the number, length, and width of the borehole wall fissures do not change, or the water content in the borehole does not change, it indicates that the drilling parameters do not meet the standard parameters, and / or the drilling quality does not meet the standard quality. In this case, the second-lowest cost depressurization mode can be determined from the depressurization mode library and used as the secondary depressurization mode. Then, S102 and S103 are repeated to deploy the borehole group corresponding to the secondary depressurization mode until the drilling parameters meet the standard parameters and the drilling quality meets the standard quality.

[0144] In addition, the pressure relief effect can be enhanced by combining optimized parameters such as borehole spacing.

[0145] Thus, this application maintains the continuity and integrity of gas control by performing a secondary matching of the depressurization mode when the analysis of depressurization results fails to meet the standards.

[0146] The following example illustrates the complete process of the multi-level coordinated pressure relief gas control method using directional drilling at the bottom of the coal seam for gas extraction provided in this application, taking the bottom-coal-roof coordinated hydraulic pressure relief mode as an example.

[0147] For example, such as Figure 2 As shown in the embodiments of this application, the complete process of the multi-level coordinated decompression gas control method using directional drilling at the bottom of low-permeability coal seams provided in this application embodiment may include the following steps S201 to S208: S201. Determine the basic parameters of coal and rock.

[0148] For example, in the high-gas, low-permeability mining face area, through on-site sampling, geological exploration and other means, combined with geological exploration data, geophysical data and experimental parameters, physical and mechanical parameters such as the compressive strength, elastic modulus and permeability of the roof and floor coal and rock, as well as gas geological parameters, can be calculated.

[0149] Furthermore, based on physical and mechanical parameters and gas geological parameters, the physical and mechanical parameters, spatial range, and geological structure of the coal and rock in the preparation working face area can be determined. This includes determining the roof, floor, coal seam, decompression space, and location of the bottom drainage roadway.

[0150] S202, Design the drilling process.

[0151] For example, based on the pressure relief space range obtained in S201, hydraulic fracturing boreholes can be laid out in the roof, floor, coal seam, or coal seam hydraulic fracturing and gas extraction boreholes.

[0152] Specifically, the radius of influence of hydraulic fracturing boreholes is D1 (approximately 20-30m), the radius of influence of hydraulic cavity creation in coal seams is D2 (approximately 3-5m), and the radius of influence of gas drainage boreholes is D3 (approximately 2-3m).

[0153] Furthermore, combined Figure 4 Based on the borehole influence radius, the distance between the roof cutting-fracturing borehole 1 and the gas drainage borehole 13 can be set at L1; when the coal seam is depressurized by hydraulic fracturing, the distance between the coal seam hydraulic fracturing borehole 3a and the gas drainage borehole 13 can be set at L2; when the coal seam is depressurized by hydraulic cavity creation, the distance between the coal seam hydraulic cavity creation borehole 3b and the gas drainage borehole 13 can be set at L3.

[0154] S203, Conduct drilling operations.

[0155] For example, directional drilling rigs can be used to drill directional boreholes from the bottom of the roadway into the floor, coal seam and roof, respectively, according to the borehole locations set in S202.

[0156] It should be noted that during directional drilling, the drilling trajectory must avoid the coal pillars protecting the mining roadway. At the same time, when the directional drilling encounters soft and fractured sections such as tectonic coal or mudstone during the drilling process, the directional drilling rig must be withdrawn and a new set of tools such as drill rods and external casings must be provided, and casings and screens must be installed to protect the borehole.

[0157] Furthermore, after the drill rod has drilled to the soft and broken section, the central drill rod is withdrawn, and the casing is left in the hole; the screen pipe is lowered into the casing; after the screen pipe is lowered into place, the casing is withdrawn, and a directional drill bit is replaced to continue drilling.

[0158] For example, such as Figure 3 The image shown is a horizontal cross-sectional view of a borehole layout provided in an embodiment of this application. It illustrates: roof slit-fracturing borehole 1, floor slit-fracturing borehole 2, and coal seam hydraulic borehole 3 (including...). Figure 4 The coal seam hydraulic fracturing borehole 3a and coal seam hydraulic cavity drilling borehole 3b), coal seam 8, working face intake airway 9, working face bottom extraction airway 10, working face return airway 11, and opening cut 12.

[0159] For example, such as Figure 4The image shown is a vertical cross-sectional view of a borehole arrangement provided in an embodiment of this application. It shows: roof slit-fracturing borehole 1, floor slit-fracturing borehole 2, coal seam hydraulic fracturing borehole 3a, coal seam hydraulic cavity-making borehole 3b, gas extraction borehole 13, roof 16, and floor 17.

[0160] S204. Determine whether the coal seam hardness exceeds the hardness threshold. If yes, proceed to S205; otherwise, proceed to S206.

[0161] S205. The coal seam uses hydraulic fracturing to depressurize and carry out hydraulic cutting and fracturing operations on the floor, hydraulic fracturing operations on the coal seam, and hydraulic cutting and fracturing operations on the roof.

[0162] For example, a hydraulic jet device can be placed at a designated position inside the pressure relief borehole of the top and bottom plates. First, hydraulic slits are made in the pressure relief borehole of the bottom plate. Working fluids such as water, abrasives, and additives are pumped in through a ground pump. After passing through the hydraulic slit tool, the working fluid forms a high-speed jet that radially cuts the bottom plate into slotted channels. Then, hydraulic fracturing is performed.

[0163] Furthermore, fracturing fluid is injected into the coal seam using a high-pressure pump to induce fractures. Fracturing fluid is continued to be injected to extend the fractures into the coal seam, and proppant (such as quartz sand) is added to the fracturing fluid. After fracturing is completed, high-pressure water is discharged through a control hole, and the fracturing equipment is slowly withdrawn to complete the fracturing operation, forming interconnected pressure relief fractures in the coal seam.

[0164] Furthermore, hydraulic slits are made in the pressure relief boreholes in the top plate, and the top plate is radially cut into slotted channels; then hydraulic fracturing is performed.

[0165] For example, such as Figure 5 The image shown is a vertical cross-sectional view of the borehole layout under hydraulic fracturing operation provided in an embodiment of this application. It shows: roof cut-fracturing borehole 1, floor cut-fracturing borehole 2, coal seam hydraulic fracturing borehole 3a, roof hydraulic cut slot 4, roof hydraulic fracturing network 5, floor hydraulic cut slot 6, floor hydraulic fracturing network 7, coal seam 8, working face intake airway 9, working face bottom extraction airway 10, working face return airway 11, cutting hole 12, coal seam hydraulic cavity creation 15, roof 16, and floor 17.

[0166] S206. The coal seam uses hydraulic cavity creation and depressurization method to carry out hydraulic cutting and fracturing operations on the floor, hydraulic cavity creation operation in the coal seam, and hydraulic cutting and fracturing operation on the roof.

[0167] For example, a hydraulic jet device can be placed at a designated position inside the pressure relief borehole of the top and bottom plates. First, hydraulic slits are made in the pressure relief borehole of the bottom plate. Working fluids such as water, abrasives, and additives are pumped in through a ground pump. After passing through the hydraulic slit tool, the working fluid forms a high-speed jet that radially cuts the bottom plate into slotted channels. Then, hydraulic fracturing is performed.

[0168] Furthermore, the hydraulic jetting equipment can be placed at a designated position within the coal seam pressure relief borehole; the water pressure and flow rate are adjusted, the cavity-making tool begins to work, and the high-pressure water flow fully washes the coal seam to form a cavity; after the cavity is created, the water pressure and flow rate are reduced, and the cavity-making tool is closed; the drill rod is slowly withdrawn to complete the cavity-making operation.

[0169] Furthermore, hydraulic slits are made in the pressure relief boreholes in the top plate, and the top plate is radially cut into slotted channels; then hydraulic fracturing is performed.

[0170] For example, such as Figure 6 The image shown is a vertical cross-sectional view of the borehole layout under hydraulic cavity creation operation provided in an embodiment of this application. It shows: roof slit-fracturing borehole 1, floor slit-fracturing borehole 2, coal seam hydraulic cavity creation borehole 3b, roof hydraulic slit gap 4, roof hydraulic fracturing network 5, floor hydraulic slit gap 6, floor hydraulic fracturing network 7, coal seam 8, working face intake airway 9, working face bottom extraction airway 10, working face return airway 11, opening 12, coal seam hydraulic fracturing fracture 14, roof 16, and floor 17.

[0171] S207, Gas Extraction and Observation.

[0172] For example, the process can begin by checking the equipment, preparing materials and tools, installing the sealing pipe, determining the sealing location, and cleaning the gas extraction borehole; mixing the sealing material, injecting it into the sealing section through the grouting pipe, controlling the grouting pressure, waiting for the sealing material to cure, and checking the curing effect; checking the sealing performance of the sealing section, cleaning the equipment, and recording the sealing information; and connecting the extraction pipe for network extraction.

[0173] S208. Determine whether the gas extraction meets the standards. If yes, end; if no, proceed to S202.

[0174] For example, after the gas extraction borehole is sealed, it is connected to the main pipeline of the extraction system for gas extraction. Before the extraction borehole is sealed, it can be used as an observation hole for adjacent boreholes. By observing the borehole wall morphology and water content, the effectiveness of adjacent pressure relief boreholes and the rationality of borehole parameters can be judged. Based on the amount of gas extracted, the regional gas control effect is dynamically evaluated, and areas with ineffective control are returned to S202 for enhanced control.

[0175] Thus, the aforementioned "floor-coal seam-roof" coordinated decompression gas control method achieves multiple synergistic effects by constructing a three-dimensional decompression network: On the one hand, this method improves the development of fractures in the coal and rock mass, enhances the connectivity of gas transport channels, and significantly improves the permeability of the coal seam; on the other hand, the long-distance drilling technology implemented in the rock tunnel not only increases the borehole formation rate but also reduces the gas leakage rate by optimizing the sealing process, ensuring the sealing of the extraction system; in addition, the coordinated hydraulic decompression technology solves the problem of extraction blank zones that are prone to occur in in-seam drilling, increases the borehole spacing, and reduces the amount of drilling work.

[0176] Furthermore, in terms of drainage and ventilation, the upward drilling design facilitates the discharge of water accumulated in the borehole and reduces the water-locking effect. At the same time, the synergistic effect of the roof pressure relief borehole and the coal seam pressure relief borehole provides a sufficient time window for gas extraction, further improving extraction efficiency.

[0177] Furthermore, by reducing the original stress of the coal and rock mass, the above-mentioned method extends the life cycle of the drainage boreholes, reduces the risk of borehole collapse, and allows the roof and floor drainage boreholes to continue serving the gas control of the goaf, thus achieving efficient gas drainage throughout the entire life cycle. In addition, the above-mentioned method also allows the gas drainage system to be arranged in advance and the drainage operation to be started before the excavation of the working face roadway, thus achieving early, efficient and safe treatment of high-gas and low-permeability coal seams.

[0178] The above mainly describes the solution provided by the embodiments of this application from a methodological perspective. To achieve the above functions, the low-permeability coal seam bottom drainage directional drilling multi-level coordinated depressurization gas control device or electronic device includes corresponding hardware structures and / or software modules for performing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0179] This application embodiment can, based on the above method, exemplarily divide the multi-level coordinated decompression gas control device or electronic device for directional drilling in low-permeability coal seam bottom drainage roadways into functional modules. For example, the multi-level coordinated decompression gas control device or electronic device for directional drilling in low-permeability coal seam bottom drainage roadways may include various functional modules corresponding to each functional division, or two or more functions may be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0180] Figure 7 This is a structural diagram of a multi-level coordinated decompression gas control device for directional drilling in a low-permeability coal seam bottom drainage roadway, provided in an embodiment of this application. The device 700 includes: a determining unit 701, a deployment unit 702, and a processing unit 703.

[0181] The system comprises: a determination unit 701, used to determine a priority pressure relief mode from a pressure relief mode library based on the basic parameters of the roof, coal seam, and floor of the target area. The basic parameters include coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters, and the priority pressure relief mode is feasible; a deployment unit 702, used to deploy a group of boreholes corresponding to the priority pressure relief mode in the bottom drainage roadway located on the working face floor; and a processing unit 703, used to perform pressure relief operations in the borehole group according to a predetermined procedure to expand the fracture network. The fracture network is used for gas pressure relief and extraction in the target area. The pressure relief operations include fracturing, hydraulic fracturing, and cavity creation.

[0182] In some embodiments, the aforementioned coal and rock physical properties include the soundness coefficient, Poisson's ratio, compressive strength, tensile strength, internal friction angle, cohesion, density, porosity, permeability, and hardness; the aforementioned gas occurrence parameters include gas pressure, gas content, and coal seam gas adsorption constant; the aforementioned stratigraphic characteristic parameters include the distribution of geostress field, geological structural characteristics, roof and floor lithology, and coal seam thickness; the aforementioned pressure relief mode library includes independent pressure relief mode for the floor, independent pressure relief mode for the coal seam, independent pressure relief mode for the roof, coordinated pressure relief mode for the floor and coal seam, coordinated pressure relief mode for the coal seam and roof, coordinated pressure relief mode for the floor and roof, and coordinated pressure relief mode for the floor, coal seam, and roof.

[0183] In some embodiments, the determining unit 701 is specifically used to: analyze the coal seam permeability enhancement effect of each pressure relief mode in the pressure relief mode library based on coal and rock physical property parameters, gas occurrence parameters and formation characteristic parameters; determine the pressure relief mode whose coal seam permeability enhancement effect is greater than a predetermined target value as a candidate pressure relief mode; and determine the priority pressure relief mode from the candidate pressure relief modes.

[0184] In some embodiments, the determining unit 701 is specifically used to: predict the gas control cost, gas control efficiency, and gas control effect of each pressure relief mode in the candidate pressure relief modes; and determine the pressure relief mode that meets the preset conditions as the priority pressure relief mode; wherein, meeting the preset conditions includes: the gas control cost is less than or equal to the cost threshold; the gas control efficiency is greater than or equal to the efficiency threshold; and the gas control effect is greater than or equal to the effect threshold.

[0185] In some embodiments, the determining unit 701 is specifically used to: determine the pressure relief mode with the highest coal seam permeability enhancement effect among the candidate pressure relief modes as the priority pressure relief mode.

[0186] In some embodiments, the processing unit 703 is specifically used to: perform a cavity-making operation in the borehole group according to the first step when the hardness of the coal seam is less than the hardness threshold and the coal seam gas adsorption constant is less than the adsorption threshold; and perform a fracturing operation in the borehole group according to the second step when the hardness of the coal seam is greater than or equal to the hardness threshold, or the coal seam gas adsorption constant is greater than or equal to the adsorption threshold; wherein the first step is: floor cutting and fracturing, coal seam cavity creation, and roof cutting and fracturing, and the second step is: floor cutting and fracturing, coal seam fracturing, and roof cutting and fracturing.

[0187] In some embodiments, the processing unit 703 is further configured to: perform gas extraction through a group of boreholes and monitor gas extraction parameters, including gas flow rate, extraction negative pressure and gas concentration; analyze the gas extraction parameters to obtain pressure relief results, including borehole parameters and borehole quality.

[0188] In some embodiments, the determining unit 701 is further configured to determine a secondary pressure relief mode from the pressure relief mode library when the drilling parameters do not meet the standard parameters and / or the drilling quality does not meet the standard quality. The secondary pressure relief mode is the pressure relief mode with the highest priority other than the primary pressure relief mode in the pressure relief mode library. The processing unit 703 is further configured to replace the primary pressure relief mode with the secondary pressure relief mode.

[0189] In some embodiments, the aforementioned borehole groups are arranged in an alternating pattern in both the roof and the bottom of the coal seam.

[0190] In the low-permeability coal seam bottom drainage roadway directional drilling multi-level coordinated decompression gas control device provided in this application embodiment, firstly, a feasible decompression mode is precisely matched based on coal and rock physical properties, gas occurrence parameters, and stratum characteristic parameters, so that the control scheme is highly adapted to the coal seam occurrence conditions, achieving efficient gas extraction; then, a group of boreholes is laid in the bottom drainage roadway to form a three-dimensional decompression network of floor-coal seam-roof, utilizing the advantages of the floor roadway to achieve precise positioning and high-quality borehole formation of directional drilling; then, through the coordinated processes of cutting, fracturing, and cavity creation, the initial cutting forms initial guiding fractures, and the subsequent fracturing further expands the fracture network and enhances connectivity, forming a continuous gas diversion system, increasing the gas decompression range and coal seam permeability, shortening the control cycle while achieving gas disaster prevention and control, thereby improving gas control efficiency and ensuring the safety of production operations.

[0191] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0192] Figure 8 This is a structural diagram of an electronic device provided in an embodiment of this application. Figure 8 As shown, the electronic device 800 includes, but is not limited to, a processor 801 and a memory 802.

[0193] The aforementioned memory 802 is used to store the executable instructions of the aforementioned processor 801. It is understood that the aforementioned processor 801 is configured to execute instructions to implement the multi-level coordinated decompression gas control method using directional drilling at the bottom of low-permeability coal seams in the above embodiments.

[0194] It should be noted that those skilled in the art will understand that Figure 8 The electronic device structure shown does not constitute a limitation on the electronic device; the electronic device may include, but is not limited to, other electronic devices. Figure 8 This may indicate more or fewer components, or combinations of certain components, or different component arrangements.

[0195] The processor 801 is the control center of the electronic device. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in the memory 802, and by calling data stored in the memory 802, it performs various functions and processes data, thereby providing overall monitoring of the electronic device. The processor 801 may include one or more processing units. Optionally, the processor 801 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 801.

[0196] The memory 802 can be used to store software programs and various data. The memory 802 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required by at least one functional module (such as a determination unit, processing unit, etc.), etc. Furthermore, the memory 802 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0197] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 802 including instructions, which can be executed by a processor 801 of an electronic device 800 to implement the multi-level coordinated decompression gas control method for bottom drainage directional drilling in low-permeability coal seams described in the above embodiments.

[0198] In actual implementation, Figure 7 The steps performed by the determining unit 701, the deployment unit 702, and the processing unit 703 can all be performed by... Figure 8 The processor 801 calls the computer program stored in the memory 802 to implement the process. The specific execution process can be found in the method section of the previous embodiment, and will not be repeated here.

[0199] Optionally, the computer-readable storage medium may be a non-transitory computer-readable storage medium, such as a read-only memory (ROM), random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0200] In an exemplary embodiment, this application also provides a computer program product including one or more instructions, which can be executed by a processor 801 of an electronic device to complete the multi-level coordinated decompression gas control method for directional drilling at the bottom of low-permeability coal seams in the above embodiments.

[0201] It should be noted that when one or more instructions in the computer-readable storage medium or computer program product are executed by the processor of an electronic device, they implement the various processes of the above method embodiments and achieve the same technical effect as the above method. To avoid repetition, they will not be described again here.

[0202] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0203] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0204] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the classified units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0205] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0206] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiments of this application, essentially, or the part that contributes to the prior art, or a complete or partial classification of the technical solution, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0207] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for controlling gas decompression in low-permeability coal seams using multi-level coordinated decompression drilling in directional boreholes at the bottom of the drainage roadway, characterized in that... The method includes: Based on the basic parameters of the roof, coal seam and floor of the target area, a priority pressure relief mode is determined from the pressure relief mode library. The basic parameters include coal and rock physical properties, gas occurrence parameters and formation characteristic parameters. The priority pressure relief mode is feasible. A group of boreholes corresponding to the preferred pressure relief mode is arranged in the bottom dredging roadway located on the bottom plate of the working face; Decompression operations are performed in the borehole group according to a predetermined procedure to expand the fracture network, which is used for gas decompression and extraction in the target area. The decompression operations include slotting, fracturing, and cavity creation.

2. The method according to claim 1, characterized in that, The coal and rock physical properties include the soundness coefficient, Poisson's ratio, compressive strength, tensile strength, internal friction angle, cohesion, density, porosity, permeability, and hardness. The gas occurrence parameters include gas pressure, gas content, and coal seam gas adsorption constant; The stratigraphic characteristic parameters include the distribution of the geostress field, geological structural features, lithology of the roof and floor, and coal seam thickness; The pressure relief mode library includes independent pressure relief mode for the floor, independent pressure relief mode for the coal seam, independent pressure relief mode for the roof, coordinated pressure relief mode for the floor and coal seam, coordinated pressure relief mode for the coal seam and roof, and coordinated pressure relief mode for the floor, coal seam and roof.

3. The method according to claim 1 or 2, characterized in that, Based on the fundamental parameters of the roof, coal seam, and floor of the target area, the preferred pressure relief mode is determined from the pressure relief mode library, including: Based on the coal and rock physical properties, gas occurrence parameters, and formation characteristic parameters, the coal seam permeability enhancement effect of each pressure relief mode in the pressure relief mode library is analyzed. The pressure relief mode with a coal seam permeability enhancement effect greater than the predetermined target value is identified as the candidate pressure relief mode; The preferred decompression mode is determined from the candidate decompression modes.

4. The method according to claim 3, characterized in that, Determining the preferred depressurization mode from the candidate depressurization modes includes: Predict the gas control cost, gas control efficiency, and gas control effect of each of the candidate depressurization modes; The pressure relief mode that meets the preset conditions among the candidate pressure relief modes is determined as the priority pressure relief mode; The conditions for satisfying the preset conditions include: The cost of gas control is less than or equal to the cost threshold; The gas control efficiency is greater than or equal to the efficiency threshold. The gas control effect is greater than or equal to the effect threshold.

5. The method according to claim 3, characterized in that, Determining the preferred depressurization mode from the candidate depressurization modes includes: The pressure relief mode with the highest coal seam permeability enhancement effect among the candidate pressure relief modes is determined as the preferred pressure relief mode.

6. The method according to claim 2, characterized in that, The pressure relief operation performed in the borehole group according to the predetermined procedure includes: When the hardness of the coal seam is less than the hardness threshold and the gas adsorption constant of the coal seam is less than the adsorption threshold, the cavity-making operation is performed in the borehole group according to the first procedure. If the hardness of the coal seam is greater than or equal to the hardness threshold, or the gas adsorption constant of the coal seam is greater than or equal to the adsorption threshold, the fracturing operation is performed in the borehole group according to the second procedure. The first process includes: floor cutting and fracturing, coal seam cavity creation, and roof cutting and fracturing; the second process includes: floor cutting and fracturing, coal seam fracturing, and roof cutting and fracturing.

7. The method according to claim 1, characterized in that, The method further includes: Gas extraction is carried out through the borehole group and gas extraction parameters are monitored, including gas flow rate, extraction negative pressure and gas concentration. The gas extraction parameters are analyzed to obtain the pressure relief results, which include borehole parameters and borehole quality.

8. The method according to claim 7, characterized in that, The method further includes: If the drilling parameters do not meet the standard parameters, and / or the drilling quality does not meet the standard quality, a secondary pressure relief mode is determined from the pressure relief mode library. The secondary pressure relief mode is the highest priority pressure relief mode in the pressure relief mode library other than the primary pressure relief mode. Replace the primary depressurization mode with the secondary depressurization mode.

9. The method according to claim 1, characterized in that, The borehole group is arranged in an alternating pattern in the roof, the coal seam and the floor.

10. A multi-level coordinated decompression gas control device using directional drilling in a low-permeability coal seam bottom drainage roadway, characterized in that... The device includes: The determination unit is used to determine the priority pressure relief mode from the pressure relief mode library based on the basic parameters of the roof, coal seam and floor of the target area. The basic parameters include coal and rock physical property parameters, gas occurrence parameters and formation characteristic parameters. The priority pressure relief mode is feasible. A deployment unit is used to deploy a group of boreholes corresponding to the priority pressure relief mode in the bottom dredging roadway arranged on the bottom plate of the working face. The processing unit is used to perform decompression operations in the borehole group according to a predetermined procedure to expand the fracture network, which is used for gas decompression and extraction in the target area. The decompression operations include slotting, fracturing and cavity creation.

Images