Clay-containing cement-based environment-friendly mixture and method for sealing gas drill hole by using same

Abstract

The invention discloses a clay-containing cement-based environment-friendly mixture and a method for sealing a gas drill hole by using the clay-containing cement-based environment-friendly mixture. The clay-containing cement-based environment-friendly mixture is prepared by mixing the following raw materials in parts by weight: 700-800 parts of Portland cement, 30-50 parts of super absorbent resin, 30-50 parts of coal gangue powder, 30-50 parts of an accelerator and 30-50 parts of a clay expanding agent. The environment-friendly mixture and water are mixed according to the mass ratio of 1: 1, and the mixture is used as a hole sealing grouting medium after being stirred evenly. The method has the following advantages: (1) the coal gangue is used as a hole sealing material, so that comprehensive utilization of industrial solid wastes is realized; and (2) the clay expanding agent is added into the material, so that expansion is realized while solidification is performed, the problem of cement shrinkage is avoided, an active supporting effect on the hole wall of the drill hole can be achieved, a hole sealing section is prevented from shrinking to form a gas leakage channel, and the gas leakage amount in the gas extraction process is reduced. And (3) the super absorbent resin is added into the material, so that the permeability of the hole sealing material can be reduced, the sealing property of the material is enhanced, and the hole sealing effect is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine gas drainage, and particularly relates to a clay-containing cement-based environment-friendly mixture and a method for sealing gas holes therewith. Background Art

[0002] Hole sealing is a key link in the pre-drainage of coal seam gas by drilling. Only a well-sealed hole can ensure that the drainage negative pressure provides continuous power for the coal seam gas to flow into the hole, so as to achieve the purpose of efficient gas drainage. In addition to coal seam conditions and hole sealing parameters, the hole sealing material is one of the important factors determining the hole sealing quality.

[0003] Traditional cement materials have defects such as low early strength and easy shrinkage due to water loss. On the one hand, it will cause air leakage in the hole between the hole sealing material body, between the hole sealing material and the drainage pipeline, and between the hole sealing material and the inner wall of the drilling hole. On the other hand, it will cause regenerated cracks in the surrounding rock that has been sealed, resulting in air leakage outside the hole. In view of the above defects, relevant research has improved the performance of cement hole sealing materials by adding reagents with special properties to the cement materials, such as adding early strength agents, clay swelling agents, and nano materials to the cement-based materials. Additives with different functions have obvious advantages in improving the performance of hole sealing cement. However, in the later stage of coal mine gas drainage, affected by the disturbance of the coal and rock mass around the drilling hole, cracks will occur again between the hole sealing material, between the hole sealing material and the inner wall of the drilling hole, and between the slurry-coal (rock) mass around the drilling hole. As the cracks further develop, a large amount of external air leaks into the drilling hole under the action of negative pressure, resulting in a significant attenuation of the drainage concentration. Summary of the Invention

[0004] In view of the above analysis, the invention provides a clay-containing cement-based environment-friendly mixture and a method for sealing gas holes therewith, which are used to solve the problems of water loss shrinkage of existing cement hole sealing materials and easy generation of cracks in the later stage of drainage.

[0005] To solve the above technical problems, the invention adopts the following technical scheme: The clay-containing cement-based environment-friendly mixture is composed of the following raw materials mixed in the following weight ratio: 700-800 parts of portland cement, 30-50 parts of superabsorbent resin, 30-50 parts of coal gangue powder, 30-50 parts of accelerating agent, and 30-50 parts of clay swelling agent.

[0006] The particle size of all raw materials is 80-200 mesh.

[0007] By weight percentage, the superabsorbent resin is composed of 75% sodium polyacrylate, 24% polyacrylic acid, 0.7% SiO2, and 0.3% Al2(SO4)3.

[0008] The portland cement is 42.5 grade ordinary portland cement.

[0009] The coal gangue powder is made by crushing the coal gangue generated during the coal mine production process.

[0010] The clay-containing cement-based environmentally friendly mixture is used for the gas drilling sealing method. The environmentally friendly sealing material is mixed with water in a mass ratio of 1:1 and used as the grouting medium for sealing after being stirred evenly.

[0011] Adopting the above technical solution, compared with the currently used sealing materials, the present invention has the following advantages: (1) Using coal gangue as the sealing material realizes the comprehensive utilization of industrial solid waste.

[0012] (2) Adding a clay swelling agent to the sealing material realizes expansion while solidifying, avoiding the problem of cement shrinkage, and can play an active supporting role on the borehole wall, preventing the formation of air leakage channels due to shrinkage in the sealed section and reducing the air leakage volume during the gas drainage process.

[0013] (3) Adding a superabsorbent resin to the material can reduce the permeability of the sealing material, enhance the sealing performance of the material, and improve the sealing effect.

[0014] (4) The proportions of the various raw materials in the present invention can also be adjusted to achieve more combination schemes. Specific Embodiments

[0015] The present invention is applied to the "two-block-one-injection" sealing process for gas drilling in coal mines. The sealed sections inside and between the two bladder bags all adopt the clay-containing cement-based environmentally friendly mixture of the present invention.

[0016] Inject the clay-containing cement-based environmentally friendly mixture sealing material into the two bladder bags through the grouting pipe. When the pressure value reaches the set threshold (such as 1.5 Mpa - 2 Mpa), the blasting valve between the two bladder bags blasts, and the grouting pipe grouts into the voids in the sealed section between the two bladder bags to achieve the sealing of the extraction borehole.

[0017] (1) Embodiment 1 The clay-containing cement-based environmentally friendly mixture (sealing material) is composed of the following raw materials mixed in the following weight ratios: 700 parts of portland cement, 30 parts of superabsorbent resin, 50 parts of coal gangue powder, 50 parts of accelerating agent, and 50 parts of clay swelling agent.

[0018] Mix the above raw materials in proportion, stir evenly, mix with water in a mass ratio of 1:1, stir, and use for grouting.

[0019] (2) Embodiment 2 The clay-containing cement-based environmentally friendly mixture (sealing material) is composed of the following raw materials mixed in the following weight ratios: 800 parts of portland cement, 30 parts of superabsorbent resin, 50 parts of coal gangue powder, 50 parts of accelerating agent, and 50 parts of clay swelling agent.

[0020] Mix the above raw materials in proportion, stir evenly, mix with water at a mass ratio of 1:1, stir, and use for grouting.

[0021] (3) Example 3 The clay-containing cement-based environmentally friendly mixture (sealing material) is composed of the following raw materials mixed in the following weight ratio: 700 parts of portland cement, 30 parts of superabsorbent resin, 50 parts of coal gangue powder, 30 parts of accelerating agent, and 50 parts of clay swelling agent.

[0022] Mix the above raw materials in proportion, stir evenly, mix with water at a mass ratio of 1:1, stir, and use for grouting.

[0023] (4) Example 4 The clay-containing cement-based environmentally friendly mixture (sealing material) is composed of the following raw materials mixed in the following weight ratio: 800 parts of portland cement, 30 parts of superabsorbent resin, 50 parts of coal gangue powder, 30 parts of accelerating agent, and 50 parts of clay swelling agent.

[0024] Mix the above raw materials in proportion, stir evenly, mix with water at a mass ratio of 1:1, stir, and use for grouting.

[0025] (5) Example 5 The clay-containing cement-based environmentally friendly mixture (sealing material) is composed of the following raw materials mixed in the following weight ratio: 800 parts of portland cement, 30 parts of superabsorbent resin, 30 parts of coal gangue powder, 30 parts of accelerating agent, and 50 parts of clay swelling agent.

[0026] The particle sizes of all raw materials in the above Examples 1-5 are 80-200 mesh. By weight percentage, the superabsorbent resin is composed of 75% sodium polyacrylate, 24% polyacrylic acid, 0.7% SiO2 and 0.3% Al2(SO4)3. The portland cement is 42.5 grade ordinary portland cement. The coal gangue powder is made from coal gangue produced during the coal mining process by crushing.

[0027] Preparation method of the above clay-containing cement-based environmentally friendly mixture sealing material: Mix the sealing raw materials in proportion and stir evenly to obtain the sealing material.

[0028] The above clay-containing cement-based environmentally friendly mixture sealing material is used for the gas drilling sealing method: Mix the sealing material with water at a mass ratio of 1:1, stir, and use for grouting.

[0029] After testing, the material properties of the above Examples 1-5 are as follows: The above embodiments illustrate the basic principles and features of the present invention. However, the above only illustrates the preferred embodiments of the present invention and is not limited by the described embodiments. Those of ordinary skill in the art, inspired by this patent, can also make many forms of deformation and improvement without departing from the spirit of the present invention and the scope protected by the claims. These all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. Clay-containing cement-based environmentally friendly mixture, characterized in that: It is composed of the following raw materials mixed in the following weight ratios: 700-800 parts of portland cement, 30-50 parts of superabsorbent resin, 30-50 parts of coal gangue powder, 30-50 parts of quick-setting agent, and 30-50 parts of clay swelling agent.

2. The environmentally friendly clay-containing cement-based mixture according to claim 1, characterized in that: The particle size of all raw materials is 80-200 mesh.

3. The environmentally friendly clay-containing cement-based mixture according to claim 1, characterized in that: By weight percentage, the superabsorbent resin is composed of 75% sodium polyacrylate, 24% polyacrylic acid, 0.7% SiO2, and 0.3% Al2(SO4)3.

4. The environmentally friendly mixture of clay-containing cementitious material according to claim 1, characterized in that: The portland cement is 42.5 grade ordinary portland cement.

5. The environmentally friendly clay-containing cement-based mixture according to claim 1, characterized in that: The coal gangue powder is made from the coal gangue generated during the coal mining process through crushing.

6. A method for sealing gas drilling holes with a clay-containing cement-based environmentally friendly mixture, characterized in that: Mix the environmentally friendly hole-sealing material and water in a mass ratio of 1:1, and use it as the hole-sealing grouting medium after stirring evenly.

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