Coal mine water inrush prevention and control and carbon dioxide geological sequestration collaborative grouting method

Abstract

The invention relates to the technical field of mine water disaster prevention and control and carbon dioxide sequestration, and particularly discloses a coal mine water inrush prevention and control and carbon dioxide geological sequestration collaborative grouting method. According to the method, through the synergistic mineralization reaction of the artificial water-resisting layer formed by grouting and carbon dioxide, the sealing performance of the artificial water-resisting layer in the service period is continuously enhanced, and the water inrush risk is eliminated. Meanwhile, a traditional water disaster prevention and control project is converted into a carbon dioxide storage facility, the storage potential of a grouting reformed aquifer is activated, the application scene of geological storage of a mining area is remarkably expanded, and large-scale carbon sequestration of a mine is promoted. According to the method, the construction cost is reduced through drilling reuse, the sealing reliability of the system is improved in combination with a lateral grouting curtain, efficient storage of carbon dioxide is achieved while safe mining of a coal mine is guaranteed, and technical support is provided for green mine construction and carbon neutralization targets.

Description

Technical Field

[0001] The present invention relates to the technical field of mine water hazard prevention and control and carbon dioxide sequestration, and in particular to a coordinated grouting method for coal mine water inrush prevention and control and carbon dioxide geological sequestration. Background Art

[0002] Deep saline aquifers have become one of the main target strata for large-scale carbon dioxide storage due to their wide distribution and great storage potential. However, geological storage places extremely stringent requirements on the integrity of the cap rock and the trap structure. On the one hand, the spatial distribution of high-quality natural cap rocks (such as thick mudstone and salt rock) has significant regional limitations, and such ideal cap rocks are often lacking in the deep areas of my country's major coal-producing areas. On the other hand, artificially constructed storage structures require drilling dedicated injection wells and supporting long-term monitoring systems, which are costly and have a long engineering period. Existing technologies make it difficult to achieve economical and efficient storage deployment under the complex geological conditions of mining areas.

[0003] Aquifer grouting technology has become mature for preventing and controlling water inrush disasters from coal mine floors. Cement-based slurry is injected through holes drilled on the ground or underground to form an artificial aquifer within the aquifer, blocking the upward influx of high-pressure water into the mining area. However, this technology still has two major drawbacks: First, traditional grouting materials (such as ordinary Portland cement) are susceptible to groundwater erosion over long periods of service, leading to increased permeability and decreased strength, posing a risk of sealing performance degradation; second, the aquifer after grouting is only used as an "isolation structure," and the huge water storage space and sealing potential below it remain unused, resulting in a serious waste of engineering benefits.

[0004] In summary, the two major technological systems of CO2 storage and mine water inrush prevention currently exist in a state of disconnection: Storage projects are difficult to adapt to mining area geological conditions due to caprock constraints, while the reconstructed aquifers formed by coal mine water hazard prevention have their storage potential idle. Therefore, driven by the dual goals of safe coal mining and carbon neutrality, there is an urgent need to break through the boundaries of traditional technologies and develop a synergistic approach that actively transforms water hazard prevention projects into highly reliable storage structures, achieving a multi-objective closed-loop approach of "using water control to promote carbon sequestration, and using carbon sequestration to enhance water control." Summary of the Invention

[0005] The purpose of the present invention is to provide a method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above-mentioned objectives, the present invention provides a coordinated grouting method for coal mine water inrush prevention and control and carbon dioxide geological storage, comprising the following steps: geological survey and storage area delineation, delineating the carbon dioxide storage area according to the hydrogeological parameters of the target coal seam floor aquifer; calculating the required artificial aquiclude thickness according to the hydrogeological parameters of the target coal seam floor aquifer; arranging grouting boreholes in the storage area, and determining the borehole spacing according to the slurry diffusion radius; constructing a first-level borehole to the top interface of the aquifer according to the required artificial aquiclude thickness, and inserting a first-level casing; injecting carbon dioxide reactive slurry through the grouting bare hole section of the first-level casing to form an artificial aquiclude; constructing a second-level borehole to the middle and deep part of the aquifer, and inserting a second-level casing; injecting carbon dioxide through the carbon injection bare hole section of the second-level casing; sealing all boreholes, and implementing long-term monitoring.

[0007] Preferably, the carbon dioxide reactive slurry is magnesium oxide-based cement or steel slag-silica fume composite cementitious material.

[0008] Preferably, before injecting carbon dioxide into the carbon injection bare hole section through the secondary casing, the water pressure of the aquifer is reduced by drilling and draining the aquifer.

[0009] Preferably, a hydraulic expansion packer is provided at the junction between the primary casing and the grouting open hole section.

[0010] Preferably, before injecting carbon dioxide reactive slurry through the grouting bare hole section of the primary casing to form an artificial aquiclude, grouting is performed by directional drilling to form a lateral sealing curtain.

[0011] Preferably, the process of grouting using directional drilling is a forward segmented grouting process, with grouting performed once every 30 m of drilling.

[0012] Preferably, the construction method of the artificial aquiclude also includes: forming it by implementing a forward segmented grouting method through directional horizontal drilling.

[0013] Preferably, when injecting carbon dioxide through the carbon injection bare hole section of the secondary casing, sulfur hexafluoride tracer is added to the carbon dioxide, and a gas chromatograph is arranged in a peripheral drilling hole.

[0014] Preferably, the method of implementing long-term monitoring includes detecting the mineralization degree of the artificial aquiclude and the sealing performance of the lateral storage curtain through monitoring wells, and arranging surface soil carbon dioxide concentration monitoring points at the boundary of the storage area.

[0015] Preferably, the method of injecting carbon dioxide reactive slurry through the grouting bare hole section of the primary casing comprises the following steps: grouting with a high pump volume, and when the grouting pressure reaches more than 1.5 times the water pressure of the aquifer, continuing grouting with a low pump volume, stabilizing the pressure for 15 minutes, and then sealing the hole.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] The present invention provides a collaborative grouting method for coal mine water inrush prevention and control and carbon dioxide geological storage. Through the collaborative mineralization reaction between the artificial aquiclude formed by grouting and carbon dioxide, the sealing performance of the artificial aquiclude is continuously enhanced during its service life, eliminating the risk of water inrush. At the same time, it transforms traditional water hazard prevention and control projects into carbon dioxide storage facilities, activates the storage potential of grouting-transformed aquifers, significantly expands the application scenarios of geological storage in mining areas, and promotes large-scale carbon fixation in mines. This method reduces construction costs by reusing drilling holes, and improves the sealing reliability of the system by combining lateral grouting curtains. It achieves efficient carbon dioxide storage while ensuring safe mining in coal mines, providing technical support for green mine construction and carbon neutrality goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of the collaborative grouting method for coal mine water inrush prevention and control and carbon dioxide geological storage provided by the present invention;

[0020] Figure 2 A schematic diagram of the secondary drilling structure provided by the present invention;

[0021] Figure 3 A schematic diagram of the lateral sealing curtain grouting provided by the present invention;

[0022] Figure 4 A schematic diagram of the collaborative grouting drilling arrangement provided by the present invention;

[0023] In the figure: 1. Grouting borehole; 2. Primary casing; 3. Grouting open hole section; 4. Secondary casing; 5. Carbon injection open hole section; 6. Aquifer; 7. Artificial aquitard; 8. Directional drilling; 9. Lateral containment curtain; 10. Containment area. DETAILED DESCRIPTION

[0024] It should be noted that, unless there is a conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other. The embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0025] The mining face of a coal mine is located in an area with a high risk of water inrush from aquifers. A confined aquifer lies 42 meters below the working face. The aquifer has a water pressure of 5.8 MPa and a permeability of approximately 0.046 m / d. The working face lacks adequate flood control facilities, posing a potential risk of water inrush. The mining district requires that while ensuring safe mining, green mine construction be promoted and carbon neutrality supported through carbon dioxide storage technology.

[0026] like Figures 1 to 4 As shown, the present invention provides a method for synergistic grouting of coal mine water inrush prevention and control and carbon dioxide geological storage, comprising the following steps:

[0027] Geological survey and storage area delineation: Based on the hydrogeological parameters of the target coal seam floor aquifer 6, the CO2 storage area 10 is delineated as the floor aquifer within the working face area; the hydrogeological parameters include the depth (500m) and permeability (0.046m / d) of the target coal seam floor aquifer;

[0028] Calculate the required thickness of the artificial aquiclude 7 based on the hydrogeological parameters of the target coal seam floor aquifer 6;

[0029] Specifically, the safety water inrush coefficient is determined based on the requirements for water prevention and control. Since there are no structures in the area, the safety water inrush coefficient is 0.1. Based on the water pressure of aquifer 6, the required aquiclude thickness is calculated to be 16m. The specific formula is as follows:

[0030]

[0031] Where: H is the thickness of the artificial aquiclude 7, m; H1 is the thickness of the safety aquiclude, m; P is the water pressure of the aquifer 6, MPa; T is the safety water inrush coefficient, MPa / m;

[0032] Grouting boreholes 1 are arranged in the sealing area 10. The spacing between the boreholes is determined according to the slurry diffusion radius to ensure continuous coverage of the artificial waterproof layer 7. The diffusion radius can refer to the columnar grouting theory, and the formula is as follows:

[0033]

[0034] Where: r is the slurry diffusion radius, m; t is the grouting time, s; h is the grouting pressure head, m; β is the ratio of slurry viscosity to water viscosity; k is the permeability coefficient of the grouting area, m / s;

[0035] According to calculation, the slurry diffusion radius is about 12m.

[0036] Based on the desired thickness H of the artificial aquiclude 7, a primary borehole is constructed to the top interface of the aquifer 6, and the primary casing 2 is lowered. The vertical length of the primary borehole should be equal to or slightly less than the thickness H1 of the safety aquiclude, which is 42 m in this embodiment. The vertical length of the primary casing 2 should be equal to or slightly less than the thickness H1 of the original aquiclude, while ensuring that the length of the grouting bare hole section 3 is equal to or slightly greater than the thickness H of the artificial aquiclude 7.

[0037] A carbon dioxide reactive slurry is injected through the grouting open hole section 3 of the primary casing 2. After the slurry solidifies, an artificial aquiclude 7 is formed;

[0038] The secondary drilling is carried out to the middle depth of the aquifer 6 and the secondary casing 4 is lowered into the aquifer. The secondary casing 4 should be longer than the thickness of the safety aquiclude.

[0039] Carbon dioxide is injected through the carbon injection bare hole section 5 of the secondary casing 4; due to its low density, carbon dioxide preferentially flows upward and reacts with the carbon dioxide reactive slurry injected into the artificial aquiclude 7, thereby enhancing the performance of the artificial aquiclude 7;

[0040] Seal all boreholes and implement long-term monitoring.

[0041] To further optimize the solution, the carbon dioxide reactive slurry is a magnesium oxide-based cement or a steel slag-silica fume composite cementitious material, which reacts with carbon dioxide to generate dense carbonate minerals such as magnesite or calcite.

[0042] To further optimize the solution, before injecting carbon dioxide through the carbon injection bare hole section 5 of the secondary casing 4, the water pressure of the aquifer 6 is reduced by drilling and pumping.

[0043] Pumping out 20%-30% of the water volume in aquifer 6 can reduce the formation pressure of aquifer 6 by 2MPa-3MPa, which can significantly reduce the gas injection resistance.

[0044] To further optimize the solution, a hydraulic expansion packer is provided at the junction of the primary casing 2 and the grouting open hole section 3.

[0045] To further optimize the solution, before injecting carbon dioxide reactive slurry through the grouting open hole section 3 of the primary casing 2 to form an artificial aquiclude 7, directional drilling 8 is used for grouting to form a lateral sealing curtain 9, thereby constructing a vertically continuous annular grouting curtain to block the lateral migration path of carbon dioxide.

[0046] To further optimize the solution, the grouting process using the directional drilling 8 is a forward segmented grouting process, with grouting performed every 30 m of drilling.

[0047] According to a further optimization scheme, the construction method of the artificial waterproof layer 7 also includes: forming it by implementing a forward segmented grouting method through directional horizontal drilling.

[0048] When the artificial aquiclude 7 is constructed by directional horizontal hole grouting, another vertical hole needs to be drilled to extend to the middle of the aquifer 6 to inject carbon dioxide.

[0049] To further optimize the solution, when injecting carbon dioxide through the carbon injection bare hole section 5 of the secondary casing 4, sulfur hexafluoride tracer is added to the carbon dioxide, and a gas chromatograph is arranged in the surrounding drilling holes.

[0050] Further optimization of the plan will involve implementing long-term monitoring measures, including testing the mineralization of the artificial aquitard 7 and the tightness of the lateral sealing curtain 9 through monitoring wells, and deploying surface soil CO2 concentration monitoring points at the boundaries of the storage area 10. Monitoring the mineralization of the artificial aquitard 7 and the tightness of the lateral sealing curtain 9 through monitoring wells will be conducted at least once every quarter.

[0051] A further optimized solution is to inject carbon dioxide reactive slurry through the grouting open hole section 3 of the primary casing 2, comprising the following steps:

[0052] Use high pump volume grouting with a grouting flow rate of 390L / min. When the grouting pressure reaches more than 1.5 times the water pressure of aquifer 6, use low pump volume continuous grouting with a grouting flow rate of 52L / min. After stabilizing the pressure for 15 minutes, seal the hole.

[0053] The present invention injects carbon dioxide reactive slurry into the aquifer through a grouting borehole 1 to construct an artificial aquiclude, which is preset as a carbon dioxide storage cap layer. Carbon dioxide is injected in a same-hole manner, and the floating property of carbon dioxide is utilized to make it fully contact with the carbon dioxide reactive slurry, causing a mineralization reaction to generate dense carbonate minerals, thereby further enhancing the sealing performance of the cap layer.

[0054] This method uses the water hazard prevention and control grouting transformation layer as the carbon dioxide storage cap layer, transforming the traditional water-proof structure into a key component of the storage system. While ensuring the safe mining of the coal mine, it activates the carbon dioxide storage potential of the grouting transformation aquifer. Preliminary estimates show that nearly 200,000 tons of carbon dioxide have been stored. At the same time, the combined effect of carbon dioxide and slurry has been effectively utilized, saving nearly 10% of the grouting material cost and achieving significant economic benefits.

[0055] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for synergistic grouting of coal mine water inrush prevention and control and carbon dioxide geological storage, characterized in that: The following steps are involved: Geological survey and storage area delineation: based on the hydrogeological parameters of the target coal seam floor aquifer (6), the CO2 storage area (10) is delineated; Calculating the required thickness of the artificial aquiclude (7) according to the hydrogeological parameters of the target coal seam floor aquifer (6); Arranging grouting boreholes (1) in the sealing area (10), with the borehole spacing being determined according to the slurry diffusion radius; According to the required thickness of the artificial aquiclude (7), a first-level borehole is constructed to the top interface of the aquifer (6), and a first-level casing (2) is lowered; Injecting carbon dioxide reactive slurry through the grouting open hole section (3) of the primary casing (2) to form an artificial aquiclude (7); The secondary drilling is carried out to the middle depth of the aquifer (6) and the secondary casing (4) is lowered; Injecting carbon dioxide through the carbon injection bare hole section (5) of the secondary casing (4); Seal all boreholes and implement long-term monitoring.

2. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: The carbon dioxide reactive slurry is magnesium oxide-based cement or steel slag-silica fume composite cementitious material.

3. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: Before injecting carbon dioxide through the carbon injection bare hole section (5) of the secondary casing (4), the water pressure of the aquifer (6) is reduced by drilling and pumping the aquifer (6).

4. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: A hydraulic expansion packer is provided at the junction between the primary casing (2) and the grouting open hole section (3).

5. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: Before injecting carbon dioxide reactive slurry through the grouting open hole section (3) of the primary casing (2) to form an artificial water-proof layer (7), directional drilling (8) is used for grouting to form a lateral sealing curtain (9).

6. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 5, characterized in that: The process of grouting by using directional drilling (8) is a forward-type segmented grouting process, and grouting is performed once every 30m of drilling.

7. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: The construction method of the artificial waterproof layer (7) also includes: It is formed by implementing forward segmented grouting through directional horizontal drilling.

8. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: When carbon dioxide is injected through the carbon injection bare hole section (5) of the secondary casing (4), sulfur hexafluoride tracer is added to the carbon dioxide, and a gas chromatograph is arranged in a peripheral drilling hole.

9. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: The method of implementing long-term monitoring includes detecting the mineralization degree of the artificial aquiclude (7) and the sealing performance of the lateral storage curtain (9) through monitoring wells, and arranging surface soil carbon dioxide concentration monitoring points at the boundary of the storage area (10).

10. The method for coordinated grouting of coal mine water inrush prevention and control and carbon dioxide geological storage according to claim 1, characterized in that: The method for injecting carbon dioxide reactive slurry through the grouting open hole section (3) of the primary casing (2) comprises the following steps: Use high pumping volume for grouting. When the grouting pressure reaches 1.5 times or more of the water pressure of the aquifer (6), use low pumping volume for continuous grouting. After stabilizing the pressure for 15 minutes, seal the hole.

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