Hydrogel gas blocking agent

Abstract

The invention relates to a hydrogel gas plugging agent, which is composed of a main component of an adhesive forming hydrogel and a complexing auxiliary agent, in the use process, the gas plugging agent is stirred and dissolved in water according to the proportion of 3-5% (wt%) to form stable viscoelastic hydrogel slurry, the slurry is pumped into a gas pipe to be grouted by a pneumatic grouting pump, and the gas pipe to be grouted is grouted. Grouting operation is completed; the hydrogel is basically stable in viscosity and resistant to hard water, cannot be reduced along with time extension, can guarantee plugging effectiveness, and is economical and practical.

Description

Technical Field

[0001] The present invention relates to a hydrogel gas plugging agent, belonging to the technical category of functional materials. Background Art

[0002] The coalbed methane associated with coal is mainly a hydrocarbon gas mainly composed of methane stored in coal in an adsorbed state, commonly known as gas. Before coal seam mining, coalbed methane drainage is generally required; during the gas drainage in coal mine coal seam mining, the "two-blocks-one-injection" gas plugging process is required.

[0003] In related technologies, the gas plugging agent is usually directly stirred and mixed with water, and then directly injected into the gas pipe to be plugged by a driving grouting pump for plugging.

[0004] The currently used plugging agents are mostly cement-based inorganic plugging agents and polymer plugging agents such as polyurethane; the publication number is CN 112110687 A, and expansion and foaming components are introduced into the cement mortar. However, after the cement-based plugging agent is cured, due to its rigidity, it is impossible to avoid the generation of microcracks caused by deformation due to vibration during coal seam mining, resulting in gas leakage; during the plugging process of the polymer material polyurethane, the safety of coal mines is affected due to the exothermic reaction.

[0005] As an environmentally friendly and safe plugging agent, viscoelastic hydrogel forms a good viscoelastic hydrogel after reacting with water, has good adhesion to the surfaces of coal and stone, has water retention, and can ensure gas plugging performance under the vibration conditions of coal seam mining; such as the publication number CN 117568002 A, but it is easily affected by the hardness of the prepared water, resulting in a decrease in the viscosity of the plugging hydrogel over time, affecting the plugging effect.

[0006] In order to improve the gas plugging quality, solve the plugging influence caused by changes in water quality hardness, and ensure the effectiveness of plugging, a hard water-resistant hydrogel gas plugging agent is provided, and the present invention is thus completed. Summary of the Invention

[0007] The object of the present invention is to provide a hydrogel gas plugging agent with a simple preparation process, hard water resistance, environmental friendliness and safety. After reacting with water, it forms a good viscoelastic hydrogel with stable viscosity, ensuring gas plugging performance during coal seam mining.

[0008] To achieve the above object, the present invention specifically adopts the following steps:

[0009] 1. Use one or a combination of polyanionic cellulose (PAC for short), carboxymethyl cellulose (CMC for short), and hydroxypropyl methyl cellulose (HPMC for short) as the main component of the adhesive for forming hydrogel in the gas sealing agent;

[0010] 2. Use one or a combination of sodium tripolyphosphate and sodium hexametaphosphate as complexing aids to form complexes with calcium and magnesium ions in water, reducing the impact of calcium and magnesium ions in hard water on the viscosity of the adhesive of the hydrogel; the addition amount of sodium tripolyphosphate and sodium hexametaphosphate does not exceed 10% of the total weight of the sealing agent.

[0011] The composition ratio (wt%) of the sealing agent is as follows:

[0012]

[0013] Among them, the sum of PAC, CMC, and HPMC is 90 - 97% of the total weight, and the sum of the complexing aids sodium tripolyphosphate and sodium hexametaphosphate is 3 - 10% of the total weight.

[0014] Mix the above components evenly according to the ratio, and then package them to obtain the gas sealing agent; pay attention to preventing the product from absorbing moisture and agglomerating during the mixing and packaging process.

[0015] During use, dissolve the gas sealing agent in water at a ratio of 3 - 5% (wt%) to form a viscoelastic hydrogel slurry, and use a pneumatic grouting pump to pump the slurry into the gas pipeline to be grouted to complete the grouting operation, which can effectively seal the gas.

[0016] The advantages of the present invention are as follows:

[0017] The gas sealing agent is composed of an adhesive mainly containing PAC, HPMC, and CMC, and is compounded with one or a combination of the complexing aids sodium tripolyphosphate and sodium hexametaphosphate. After being mixed with the water in the coal mine mining environment, it can form a stable viscoelastic hydrogel with basically stable viscosity, resistance to hard water, and does not decrease over time, which can ensure the effectiveness of the sealing, and the product is economical and practical.

[0018] Table Explanation

[0019] Table 1: The proportions of each component in each control example and example, and the viscosity values of 1% (wt%) aqueous solutions. The water for preparing the hydrogel is hard water with a calcium ion concentration of 1000 ppm and a magnesium ion concentration of 200 ppm.

[0020] Since the aqueous solutions of the hydrogel gas sealant above 2.5% (wt%) basically form viscoelastic hydrogels, the measured viscosity values are too large and the reproducibility of the test data is poor. The aqueous solution of 1% (wt%) is used as the measured viscosity value for evaluation. Detailed implementation manners

[0021] The present invention will be further described below in conjunction with specific embodiments:

[0022] 1. Mixing of each component powder:

[0023] Using a double-cone mixer, add each component in proportion, mix for 1 hour, discharge, weigh and package, and leave the factory after passing the sampling inspection.

[0024] 2. Proportions of each component in each comparative example and example and viscosity value of 1% (wt%) aqueous solution:

[0025] For the viscosity value test of the hydrogels in each comparative example and example, weigh 5.0 ± 0.1 g of the sample, and add it to a 600 mL plastic beaker containing 495 ± 1 g of hard water with a calcium ion concentration of 1000 ppm and a magnesium ion concentration of 200 ppm under stirring conditions (carefully add the sample powder to avoid flying loss). At an ambient temperature between 20 and 30 °C, stir electrically for 60 minutes to prepare a 1% solution, and the liquid should be uniform and free of lumps.

[0026] Cover the prepared sample liquid with plastic wrap to keep it sealed, and place it in an environment of 25.0 ± 1.0 °C for 1 hour. Take it out, immediately measure the viscosity with a BROOKFEILD RVDV viscometer, select rotor Spindle 5#, measure at a rotation speed of 60 RPM, record the reading in 30 seconds, test three samples in parallel, and take the average value, with the unit of millipascal-second (mPa·s). Place each sample in an environment of 25.0 ± 1.0 °C for different times, and test the stability of its viscosity over time.

[0027] Table 1. Proportions of each component in each example and viscosity value of 1% (wt%) aqueous solution

[0028]

[0029] As can be seen from Table 1, the hydrogel after adding the complexing auxiliary has better viscosity stability in hard water than the hydrogel without adding the complexing auxiliary.

[0030] It should be noted that the above-described specific embodiments can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way. Therefore, although the embodiments of this specification have described the present invention in detail, those skilled in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and their improvements that do not depart from the spirit and scope of the present invention should be covered by the protection scope of this invention patent.

Claims

1. A hydrogel gas plugging agent, characterized in that: The hydrogel gas plugging agent is composed of a main component of an adhesive forming a hydrogel and a complexing auxiliary agent; the main component of the adhesive forming the hydrogel is one of polyanioniccellulose (PAC), carboxymethyl cellulose (CMC), and hydroxypropyl methyl cellulose (HPMC) or a combination thereof; the complexing auxiliary agent is one of sodium tripolyphosphate and sodium hexametaphosphate or a combination thereof; The weight ratio of each component of the hydrogel gas plugging agent is: The sum of PAC, CMC and HPMC accounts for 90-97% of the total weight; the sum of complexing aids sodium tripolyphosphate and sodium hexametaphosphate accounts for 3-10% of the total weight.

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