Method for constructing a coal-bed gasification containment

Abstract

The application discloses a construction method of a coal seam gasification closed space, and comprises the following steps: S1, before mining of a working face, a cement wall is built on the outer surface of a non-coal mining surface along the direction of a cut, a return airway and a transportation roadway; S2, a connecting roadway penetrating the working face is excavated on the side of the working face close to a development roadway, and a cement wall is built on the outer surface of the side of the working face close to the development roadway along the direction of the connecting roadway; S3, during mining of the working face, top coal with a preset thickness is reserved; and S4, after mining of the working face is completed, the cement walls at the two ends of the connecting roadway are blocked, grouting is carried out to a parting zone above a goaf, a man-made grouting layer is formed, a microbial nutrient liquid drilling hole and a gas testing drilling hole are arranged on the ground surface corresponding to the goaf directly above, and in-situ microbial gasification mining of coal resources is realized.

Description

Technical Field

[0001] This invention relates to the field of in-situ coal microbial gasification, and more particularly to a method for constructing a closed space for coal seam gasification. Background Technology

[0002] Coal remains my country's primary energy source. Currently, coal mining in my country is mainly done underground. However, underground mining cannot extract all coal seams, especially thick ones. These limitations in coal mining technology have resulted in significant losses of coal resources.

[0003] Existing experiments have shown that microorganisms can convert coal into gas through anaerobic fermentation, leading some scholars to propose an in-situ microbial gasification mining method for coal resources. This method can further recover coal resources wasted in underground mining, while also achieving clean utilization of coal resources and increasing coalbed methane extraction. The method involves injecting gasification microorganisms and nutrient solutions into the coal seam for anaerobic fermentation. Currently, this method is limited by the site environment and cannot be implemented in the field. This is because the anaerobic fermentation microorganisms are generally strictly anaerobic, and their biological activity rapidly decreases upon contact with oxygen. After mining shallow, thick coal seams, the overlying rock fissures extend to the surface, connecting the surface with the goaf, which is unfavorable for the growth of methanogenic bacteria. When nutrient solutions are injected into the goaf, the solutions diffuse outwards due to the development of fissures, causing loss. Furthermore, the gas produced by gasification cannot be collected and extracted without sealing. However, if a closed space is artificially constructed underground, in-situ biogasification of coal can be achieved.

[0004] Overcoming existing environmental challenges and achieving in-situ microbial gasification mining of coal resources is a pressing issue that needs to be addressed in this field, and it is of great significance to the mining of coal resources in my country. Summary of the Invention

[0005] To address the problem that in-situ microbial gasification mining of coal is difficult to implement due to existing environmental factors, this invention provides a method for constructing a closed space for coal seam gasification. By artificially creating a closed underground space, in-situ biogasification mining of coal resources remaining in goaf areas can be achieved.

[0006] A method for constructing a closed space for coal seam gasification includes the following steps:

[0007] S1. Before the working face is mined, cement walls are built on the outer surface of the non-mining face along the direction of the cut-in, return airway and transport roadway.

[0008] S2. Excavate a connecting roadway through the working face on the side of the working face closest to the development roadway, and build a cement wall on the outer surface of the working face on the side of the working face closest to the development roadway along the direction of the connecting roadway.

[0009] S3. During the mining process at the working face, the top coal of the preset thickness is retained;

[0010] S4. After the working face is mined out, the cement walls at both ends of the connecting roadway are sealed, and grout is injected into the delamination zone above the goaf to form an artificial grouting layer. Microbial nutrient solution boreholes and gas testing boreholes are arranged on the ground surface directly above the goaf.

[0011] Preferably, in steps S1 and S2, a waterproof material is sprayed onto the surface of the cement wall after it is built.

[0012] Preferably, in step S1, the two ends of the cement wall in the cutting direction are connected to the cement walls in the return airway and the transport airway, respectively.

[0013] Preferably, in step S4, sealing the cement walls at both ends of the connecting lane includes: extending the cement walls at both ends of the connecting lane to connect with the cement walls in the return air lane and transport lane directions respectively, forming a closed loop.

[0014] Compared with existing technologies, the advantages and beneficial effects of this invention are as follows: After the working face is mined, a coal microbial gasification space is constructed in the goaf. First, the cement wall can always seal the goaf, preventing harmful gases from polluting other working faces. Second, the cement wall is constructed in the roadway, which is a secondary use of the roadway, improving the utilization rate of the roadway. Third, the cement wall and rock grouting isolation form a fermentation space for coal in the goaf of shallow buried coal seams, making in-situ biogasification mining of coal resources remaining in the goaf possible, improving the coal seam recovery efficiency and increasing the production of coalbed methane. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of the construction method of the present invention;

[0016] Figure 2 This is a top view of the working face before mining in this invention;

[0017] Figure 3 This is a top view of the working face after mining according to the present invention;

[0018] Figure 4 This is a cross-sectional schematic diagram of the grouting and nutrient solution inoculum injection in the separation zone after the working face is mined according to the present invention.

[0019] Figure 5 This is a top view of the working face after mining according to the present invention;

[0020] Among them, 1-development roadway, 2-connecting roadway, 3-coal pillar, 4-cement wall, 5-return airway, 6-working face, 7-cutting hole, 8-transport roadway, 9-microbial nutrient solution borehole, 10-gas testing borehole, 11-artificial grouting layer, 12-separation zone, 13-overlying strata, 14-goaf. Detailed Implementation

[0021] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0023] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0024] like Figures 1-5 As shown, the method for constructing a closed space for coal seam gasification includes the following steps:

[0025] S1. Before the mining of working face 6, cement wall 4 is built on the outer surface of the non-mining face along the direction of cut 7, return airway 5 and transport roadway 8.

[0026] S2. Excavate the connecting roadway 2 through the working face 6 on the side of the working face 6 near the development roadway 1, and build a cement wall 4 on the outer surface of the working face 6 on the side of the working face 6 near the development roadway 1 along the direction of the connecting roadway 2.

[0027] S3, During the mining process of the 6th working face, the top coal of the preset thickness is retained;

[0028] After the mining of working face 6 is completed, the cement walls 4 at both ends of the connecting roadway 2 are sealed, and grouting is injected into the delamination zone 12 above the goaf 14 to form an artificial grouting layer 11. Microbial nutrient solution boreholes 9 and gas testing boreholes 10 are arranged on the ground surface directly above the goaf 14.

[0029] Before mining, the present invention transports materials through the main development roadway 1 and builds cement walls 4 along the direction of the cut-in 7, return airway 5, transport roadway 8, and connecting roadway 2. After mining is completed, a closed loop is formed to prevent the loss of microbial nutrient solution injected into the working face 6 and the overflow of generated gas.

[0030] After the mining of working face 6 is completed, the roof collapses, and the overlying strata 13 develop fractures. In shallow coal seams, fractures can develop to the surface, forming fracture channels. Microbial nutrient solution boreholes 9 and gas testing boreholes 10 are arranged on the surface directly above goaf 14, and grouting is injected into the delamination zone 12 above goaf 14 to form an artificial grouting layer 11. After gas is generated in goaf 14, in order to prevent the generated gas from flowing to the surface along the fractures in the overlying strata, a sealed artificial grouting layer 11 is constructed above the gas-producing space to cut off the connection between goaf 14 and the surface.

[0031] Retaining the top coal can minimize the impact of environmental changes on the entire enclosed space before the backfilling.

[0032] Preferably, in steps S1 and S2, after the cement wall 4 is built, a waterproof material is sprayed onto its surface.

[0033] Waterproofing materials such as polymer cement, polyurethane, and acrylic waterproofing materials effectively prevent generated gases from entering the main development roadway 1.

[0034] Preferably, in step S1, the two ends of the cement wall in the direction of the cut 7 are connected to the cement wall 4 in the directions of the return airway 5 and the transport airway 8, respectively.

[0035] The cement wall 4 forms a C-shaped structure, waiting for the end of mining to complete the closed loop. At the same time, the cement wall 4 prevents water and gas from overflowing into the non-coal mining face during the back-stepping process.

[0036] Preferably, in step S4, sealing the cement walls 4 at both ends of the connecting lane 2 includes: extending the cement walls 4 at both ends of the connecting lane 2 to both ends and connecting with the cement walls 4 in the direction of the return air lane 5 and the transport lane 8 respectively, forming a closed loop.

[0037] Once the cement wall 4 forms a closed loop, it can prevent water and gas from escaping, creating a sealed space.

[0038] In practical applications, this invention further includes:

[0039] S5. First, inject nutrient solution and bacteria into the goaf along the microbial nutrient solution borehole 9.

[0040] S6. Select some microbial nutrient solution boreholes 9, arrange sensors in the boreholes to monitor pH and temperature changes in the goaf 14, and seal all microbial nutrient solution boreholes 9.

[0041] S7. When the activity of microorganisms in goaf 14 decreases, open the microbial nutrient solution borehole 9 regularly to inject non-carbon source nutrient solution into goaf 14, and extract gas regularly for component testing.

[0042] S8. After the sealing time is up, open the gas test borehole 10 to extract gas for testing.

[0043] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for constructing a closed space for coal seam gasification, characterized in that, Includes the following steps: S1. Before mining the working face (6), cement walls (4) are built on the outer surface of the non-coal mining face along the direction of the cut (7), return airway (5) and transport roadway (8). After the cement walls (4) are built, waterproof material is sprayed on their surface. The two ends of the cement walls in the direction of the cut (7) are connected to the cement walls (4) in the direction of the return airway (5) and transport roadway (8) respectively. S2. Excavate a connecting roadway (2) through the working face (6) on the side of the working face (6) close to the development roadway (1), and build a cement wall (4) on the outer surface of the working face (6) on the side of the working face (6) close to the development roadway (1) along the direction of the connecting roadway (2). S3. During the mining process of the working face (6), the top coal of the preset thickness is retained; S4. After the working face (6) is finished, the cement walls (4) at both ends of the connecting roadway (2) are sealed, and grout is injected into the delamination zone (12) above the goaf (14) to form an artificial grouting layer (11). Microbial nutrient solution boreholes (9) and gas test boreholes (10) are arranged on the ground surface directly above the goaf (14). The sealing of the cement walls (4) at both ends of the connecting roadway (2) includes: the cement walls (4) at both ends of the connecting roadway (2) extend to both ends and connect with the cement walls (4) in the direction of the return air roadway (5) and the transport roadway (8) to form a closed loop.

Images