Coal seam acidification permeation enhancer as well as preparation method and application thereof

Abstract

The invention relates to a coal seam acidification permeation enhancer as well as a preparation method and application thereof, and belongs to the technical field of coal bed gas exploitation or petroleum and natural gas exploitation. The coal seam acidification permeation enhancer comprises the following raw materials: potassium chloride, hydrofluoric acid, polyoxyethylene ether, sodium dodecyl benzene sulfonate, triethanolamine and ethylene glycol dimethyl ether; the raw materials are synthesized by adopting a specific chemical reaction and a regulation and control process. The coal seam acidification permeation enhancer has high permeability and porosity improving effect. In the acidification process of the coal seam, the coal seam acidification permeation enhancer can effectively dissolve mineral substances in the coal seam, remove mineral particles blocking pores, expand coal seam cracks and enhance the porosity and permeability of the coal seam, so that the gas production or oil production efficiency of the coal seam is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coalbed methane exploitation or petroleum and natural gas exploitation, and specifically relates to a coalbed acidification permeability enhancer and a preparation method and application thereof. Background Art

[0002] The permeability of coalbed methane is usually poor, especially for some low-permeability coal seams, the extraction of coalbed methane is more difficult. The production of coalbed methane is subject to the porosity and permeability of the coal seam. In many cases, the permeability of coalbed methane is insufficient, resulting in poor gas flow and difficulty in extraction. Therefore, how to improve the permeability of coal seams and improve the fluidity of coalbed methane has become a core issue in coalbed methane extraction technology.

[0003] Acidification permeability enhancement technology was initially widely used in oil and gas extraction. It aims to dissolve minerals in rocks through the chemical reaction of acid, remove sediments that block pores and cracks, expand coal seam pores, increase the connectivity of pore networks, improve permeability, and thus increase the extraction rate of coalbed methane. With the development of coalbed methane extraction technology, acidification permeability enhancement technology has gradually been introduced into the field of coalbed methane development. However, the acidification permeability enhancement technology currently applied to the field of coalbed methane development mostly uses hydrochloric acid, acetic acid, etc., which has limited effect on improving permeability. Or one or more improved acids, although they can improve the permeability of coal seams, still have shortcomings such as poor penetration, small acidification range, possible precipitates blocking pores by the reaction of acid and minerals, and water lock effect damage. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is a coal seam acidifying and permeability enhancing agent, and a preparation method and application thereof. By adjusting the raw materials and addition ratio of the coal seam acidifying and permeability enhancing agent, especially the selection of surfactants, corrosion inhibitors and stabilizers, and combining the preparation method, a new and efficient coal seam acidifying and permeability enhancing agent is obtained, which can significantly improve the permeability, porosity, gas production efficiency and long-term production stability of coal seam methane, and reduce the difficulty of coal seam methane exploitation.

[0005] A coal seam acidification permeability enhancer of the present invention comprises raw materials and the mass fractions of each raw material are as follows:

[0006] The acid is 5-30 parts, the penetration enhancer is 0.5-3 parts, the sustained-release agent is 0.5-2 parts, and the stabilizer is 0.5-3 parts.

[0007] The acid is preferably a mixture of potassium chloride and hydrofluoric acid, preferably, by mass ratio, potassium chloride: hydrofluoric acid = 1:1; the hydrofluoric acid can also be hydrochloric acid; the penetration enhancer is preferably a mixture of polyoxyethylene ether and sodium dodecylbenzene sulfonate, by mass ratio, polyoxyethylene ether: sodium dodecylbenzene sulfonate = 1:1; the sustained-release agent is preferably triethanolamine, and the stabilizer is preferably ethylene glycol dimethyl ether.

[0008] Preferably, the coal seam acidification permeability enhancer comprises raw materials and the mass fraction of each raw material is as follows:

[0009] 5-15 parts of potassium chloride, 5-15 parts of hydrofluoric acid or hydrochloric acid, 0.5-1.5 parts of polyoxyethylene ether, 0.5-1.5 parts of sodium dodecylbenzene sulfonate, 0.5-1.5 parts of triethanolamine, and 0.5-1.5 parts of ethylene glycol dimethyl ether.

[0010] The present invention provides a method for preparing a coal seam acidification permeability enhancer, comprising the following steps:

[0011] Step 1: Acid preparation

[0012] Select the corresponding acid according to the mineral composition of the coal seam, and dissolve it at room temperature to obtain an acid solution with a stable molar concentration;

[0013] Step 2: Add a penetration enhancer

[0014] According to the mass fraction of the raw materials, the penetration enhancer is slowly added to the acid solution to avoid violent reaction, and stirred and mixed for 10-15 minutes to ensure that the penetration enhancer is fully dissolved and dispersed to obtain the penetration acid solution.

[0015] Step 3: Add corrosion inhibitors and stabilizers

[0016] A corrosion inhibitor triethanolamine and a stabilizer ethylene glycol dimethyl ether are selected and added to the permeation-enhancing acid solution, wherein the mass fraction of the corrosion inhibitor is 0.5-2 parts, and the mass fraction of the stabilizer is 0.5-3 parts. The temperature of the permeation-enhancing acid solution is controlled between 25° C. and 40° C. by a temperature control device to ensure stability and avoid an overly rapid reaction; and an acidified permeation-enhancing agent mixture is obtained;

[0017] Step 4: Adjust pH and optimize acidification solution

[0018] Use a pH meter to monitor the pH value of the acidifying and permeability enhancing agent mixture, adjust the acid strength of the acidifying and permeability enhancing agent mixture as needed, and the pH value of the acidifying and permeability enhancing agent mixture should be maintained between 1.5 and 3.0 to ensure the best acidification effect. Stir the acidifying and permeability enhancing agent mixture to ensure that all components are completely dissolved to avoid precipitation; separate the solid and liquid to remove undissolved impurities and ensure that the solution is clear; and obtain the coal seam acidifying and permeability enhancing agent.

[0019] In step 1, the molar concentration of the acid solution is adjusted according to the mineral dissolution rate, preferably 0.5-1.0 mol / L of acid solution;

[0020] In the step 1, the acid is potassium chloride and hydrofluoric acid, or the acid is potassium chloride and hydrochloric acid, and the total weight of the two substances is 5-30 parts.

[0021] In step 1, the corresponding acid is selected according to the chemical properties of the mineral; since the coal contains a high content of quartz SiO2 and feldspar, an acid with strong corrosiveness or complexing properties needs to be selected, and HF can react with silicate minerals to generate volatile SiF4 gas.

[0022] In the step 2, the total weight fraction of the penetration enhancer is 0.5-3 parts.

[0023] In the step 3, after the corrosion inhibitor and stabilizer are added, the reaction is stirred for 10-15 minutes.

[0024] In step 4, in order to avoid precipitation, the stirring time is 15-20 minutes to ensure uniformity.

[0025] In step 4, the solid-liquid separation is performed by filtering the acidified permeability enhancer mixture through a filter screen or a filter to remove impurities.

[0026] Furthermore, the completed coal seam acidification and permeability enhancer is stored in a sealed container to avoid contact with air. The sealed container should be corrosion-resistant, acid-resistant, and have temperature control function; the storage temperature should be between 25℃-35℃ to avoid high temperature environment causing decomposition or reaction of the coal seam acidification and permeability enhancer.

[0027] The invention discloses an application of a coal seam acidification permeability enhancer, which is used for coal seam gas mining and can increase the permeability of columnar coal by 50%-127% and the porosity by 8.15-41.48%.

[0028] The coal seam acidification permeability enhancer of the present invention and its preparation method and application have the following beneficial effects:

[0029] 1. Improve the permeability of coal seams

[0030] Coal seam acidification permeability enhancer can significantly improve the permeability of coal seams through chemical reactions and physical effects, which is one of its most direct and important effects. The selection of raw materials and the optimization of their proportions can more effectively dissolve the minerals in the coal seams, remove the substances that block the pores, and promote the extraction of coalbed methane compared with the traditional single acid solution. The specific mechanism includes: HF can dissolve minerals such as quartz SiO2, feldspar, pyrite FeS2, etc., and react with these minerals to generate volatile gases (such as SiF4), thereby removing blocking substances and opening microcracks.

[0031] 2. Improve the pore structure of coal seams

[0032] Acidification treatment by adding coal seam acidification permeability enhancer can improve the pore structure of coal seams, making them more conducive to gas storage and flow. The specific mechanisms include: enhancing porosity and adjusting pore distribution. Among them, minerals such as quartz SiO2, feldspar, pyrite FeS2 in coal seams are easily dissolved in acidification permeability enhancement treatment, reacting to release gas and form pores:

[0033] 3. Promote the recovery rate of coalbed methane

[0034] Coal seam acidification permeability enhancer improves the permeability of coal seams, allowing more coal seam gas to flow and enter the wellbore, thereby significantly improving the recovery rate of coal seam gas. Specifically, the selection of this permeability enhancer not only enhances the expansion of coal seam fractures, but also improves gas fluidity, reduces gas recovery difficulty, and improves gas recovery efficiency through the action of surfactants.

[0035] KCl and HF in the raw materials of coal seam acidification permeability enhancer react with quartz, feldspar and pyrite FeS2 to generate volatile products (SiF4) to enhance cracks. In addition, the rapid release of SiF4 exerts pressure on the cracks in the coal seam, inducing crack expansion and connectivity. Polyoxyethylene ether and sodium dodecylbenzene sulfonate molecules reduce the interfacial energy of the coal surface through adsorption, reduce gas adsorption and retention, and improve gas fluidity. Triethanolamine and ethylene glycol dimethyl ether are added to prevent pore blockage.

[0036] 4. Improve the production stability of coalbed methane

[0037] Coalbed acidification permeability enhancers can improve the long-term stable production capacity of coalbed methane to a certain extent, especially for some deep coal seams or deeply buried coalbed methane reservoirs. Specifically, the selection of such corrosion inhibitors and stabilizers helps to reduce the damage to equipment caused by corrosion, maintain the stability of acidification permeability enhancers, improve the safety and efficiency of long-term operations, extend the production cycle and reduce gas depletion during mining. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments to provide a better understanding of the content of the present invention.

[0039] Experimental materials:

[0040] Potassium chloride: mass percentage 99%, Jinan Yuanlian Chemical Co., Ltd.; hydrofluoric acid: mass percentage 99%, Shaanxi Lanxin Chemical Co., Ltd.; polyoxyethylene ether: mass percentage 99%, Jinan Daorong Chemical Co., Ltd.; sodium dodecylbenzene sulfonate: model, type 60, Shandong Jinli Chemical Co., Ltd.; triethanolamine: mass percentage 99%, Jinan Zhenghai Import and Export Trading Co., Ltd.; ethylene glycol dimethyl ether: mass purity 99.5%, Jinan Shiji Tongda Chemical Co., Ltd.

[0041] Embodiment 1:

[0042] A coal seam acidification permeability enhancer comprises raw materials and their corresponding mass fractions: 5 parts of potassium chloride, 5 parts of hydrofluoric acid, 0.5 parts of polyoxyethylene ether, 0.5 parts of sodium dodecylbenzene sulfonate, 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether.

[0043] The preparation method is as follows: add 5 parts of potassium chloride and 5 parts of hydrofluoric acid into a beaker, add water to dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration of 0.5 to 1 mol / L. Slowly add 0.5 parts of polyoxyethylene ether and 0.5 parts of sodium dodecylbenzene sulfonate into the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Then add 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter or filter, remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0044] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0045] Embodiment 2:

[0046] A coal seam acidification permeability enhancer comprises raw materials and their corresponding mass fractions: 10 parts of potassium chloride, 10 parts of hydrofluoric acid, 0.5 parts of polyoxyethylene ether, 0.5 parts of sodium dodecylbenzene sulfonate, 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether.

[0047] The preparation method is as follows: add 10 parts of potassium chloride and 10 parts of hydrofluoric acid into a beaker, add water to dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration of 0.5 to 1 mol / L. Slowly add 0.5 parts of polyoxyethylene ether and 0.5 parts of sodium dodecylbenzene sulfonate into the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Then add 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter or filter, remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0048] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0049] Embodiment 3:

[0050] A coal seam acidification permeability enhancer is prepared from 15 parts of potassium chloride, 15 parts of hydrofluoric acid, 0.5 parts of polyoxyethylene ether, 0.5 parts of sodium dodecylbenzene sulfonate, 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether.

[0051] The preparation method is as follows: add 15 parts of potassium chloride and 15 parts of hydrofluoric acid into a beaker, add water to dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration of 0.5 to 1 mol / L. Slowly add 0.5 parts of polyoxyethylene ether and 0.5 parts of sodium dodecylbenzene sulfonate to the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Add 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter or filter, remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0052] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0053] Embodiment 4:

[0054] A coal seam acidification permeability enhancer is prepared from 10 parts of potassium chloride, 10 parts of hydrofluoric acid, 1 part of polyoxyethylene ether, 1 part of sodium dodecylbenzene sulfonate, 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether.

[0055] The preparation method is as follows: add 10 parts of potassium chloride and 10 parts of hydrofluoric acid into a beaker, dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration. Slowly add 1 part of polyoxyethylene ether and 1 part of sodium dodecylbenzene sulfonate to the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Then add 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter screen or filter to remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0056] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0057] Embodiment 5:

[0058] A coal seam acidification permeability enhancer is prepared from 10 parts of potassium chloride, 10 parts of hydrofluoric acid, 1.5 parts of polyoxyethylene ether, 1.5 parts of sodium dodecylbenzene sulfonate, 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether.

[0059] The preparation method is as follows: add 10 parts of potassium chloride and 10 parts of hydrofluoric acid into a beaker, dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration. Slowly add 1.5 parts of polyoxyethylene ether and 1.5 parts of sodium dodecylbenzene sulfonate into the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Then add 0.5 parts of triethanolamine and 0.5 parts of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter screen or filter to remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0060] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0061] Embodiment 6:

[0062] A coal seam acidification permeability enhancer is prepared from 10 parts of potassium chloride, 10 parts of hydrofluoric acid, 1.5 parts of polyoxyethylene ether, 1.5 parts of sodium dodecylbenzene sulfonate, 1 part of triethanolamine and 1 part of ethylene glycol dimethyl ether.

[0063] The preparation method is as follows: add 10 parts of potassium chloride and 10 parts of hydrofluoric acid into a beaker, dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration. Slowly add 1.5 parts of polyoxyethylene ether and 1.5 parts of sodium dodecylbenzene sulfonate into the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Then add 1 part of triethanolamine and 1 part of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter screen or filter to remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0064] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0065] Embodiment 7:

[0066] A coal seam acidification permeability enhancer is prepared from 10 parts of potassium chloride, 10 parts of hydrofluoric acid, 1.5 parts of polyoxyethylene ether, 1.5 parts of sodium dodecylbenzene sulfonate, 1.5 parts of triethanolamine and 1.5 parts of ethylene glycol dimethyl ether.

[0067] The preparation method is as follows: add 10 parts of potassium chloride and 10 parts of hydrofluoric acid into a beaker, dissolve the acid solution to room temperature (about 25°C), and maintain a stable acid solution concentration. Slowly add 1.5 parts of polyoxyethylene ether and 1.5 parts of sodium dodecylbenzene sulfonate into the acid solution, stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed. Then add 1.5 parts of triethanolamine and 1.5 parts of ethylene glycol dimethyl ether, control the temperature between 25°C and 40°C, and react for 10-15 minutes. Adjust the acid strength of the acid solution so that the pH value is maintained between 1.5 and 3.0, filter the acidified solution through a filter screen or filter to remove undissolved impurities, ensure that the solution is clear, and obtain a coal seam acidification permeability enhancer.

[0068] Then, 50*100mm columnar coal is placed in the prepared coal seam acidification and permeability enhancer and soaked for 24 hours.

[0069] Example 8

[0070] Same as Example 4, except that hydrochloric acid is used instead of HF, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.57×10 -3 μm 2 , porosity 3.55%.

[0071] The permeability and porosity of the novel coal seam acidification permeability enhancer embodiments 1-7 were tested respectively, and the results are shown in Table 1.

[0072] Table 1

[0073] Sample <![CDATA[Permeability / 10 -3 μm 2 > Porosity / % As is 0.26 2.82 Example 1 0.39 3.05 Example 2 0.41 3.11 Example 3 0.48 3.32 Example 4 0.59 3.99 Example 5 0.54 3.42 Example 6 0.51 3.29 Example 7 0.53 3.35

[0074] From the above values ​​we can see that:

[0075] After using the new coal seam acidification permeability enhancer, the permeability and porosity of the coal seam are significantly improved, wherein the permeability is increased by 50%-127%, and the porosity is increased by 8.15-41.48%. In particular, the proportioning method of Example 4 has the best effect of improving the permeability and porosity of the coal seam. This is because on the one hand, acidic substances can dissolve minerals in the coal seam (such as clay minerals, gypsum, calcite, etc.), especially the dissolution effect on carbonate and silicate minerals in the coal seam, making the pore channels more unobstructed, avoiding pore blockage caused by the deposition of minerals, thereby improving the permeability and porosity of the coal seam. On the other hand, when acidic substances react with organic matter or minerals in the coal seam, it will cause the expansion of the coal seam or the expansion of cracks. These fracture channels can effectively connect the pore system in the coal seam, thereby greatly improving the permeability of the coal seam.

[0076] Comparative Example 1

[0077] Same as Example 4, except that sodium chloride is used instead of potassium chloride, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.32×10 -3 μm 2 , the porosity is 2.93%, which indicates that the porosity improvement of sodium chloride is not obvious and cannot achieve the purpose of enhancing the expansion of coal seam cracks.

[0078] Comparative Example 2

[0079] Same as Example 4, except that hexadecyl dimethyl ammonium chloride was used instead of sodium dodecylbenzene sulfonate, an anionic surfactant. The permeability of the prepared coal seam acidification penetrant to columnar coal was 0.35×10 -3 μm 2 The porosity is 2.86%, which shows that anionic surfactants play an irreplaceable role in coal seam acidification permeability enhancers. The use of cationic surfactants cannot increase the porosity and cannot achieve the purpose of enhancing the expansion of coal seam cracks. The selection of surfactants in the permeability enhancer of the present invention not only enhances the expansion of coal seam cracks, but also improves the fluidity of gas through the action of surfactants, thereby improving gas production efficiency.

[0080] Comparative Example 3

[0081] Same as Example 4, except that acetic acid is used instead of HF, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.36×10 -3 μm 2 , porosity is 3.06%, indicating that using acetic acid to replace HF cannot significantly and simultaneously improve the permeability and porosity.

[0082] Comparative Example 4

[0083] Same as Example 4, except that there is no potassium chloride in the raw material, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.33×10 -3 μm 2 , porosity is 3.17%, indicating that there is no potassium chloride in the raw material, and the permeability and porosity are not significantly improved, indicating that potassium chloride is involved in the infiltration process and plays a role in enhancing cracks and improving permeability. Compared with the traditional single acid solution, it can more effectively dissolve minerals in the coal seam, remove substances that block the pores, and promote the exploitation of coalbed methane.

[0084] Comparative Example 5

[0085] Same as Example 4, except that there is no ethylene glycol dimethyl ether in the raw material, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.42×10 -3 μm 2, the porosity is 2.92%, indicating that the porosity is low. Ethylene glycol dimethyl ether can prevent pore blockage and play a role in improving the porosity.

[0086] Comparative Example 6

[0087] Same as Example 4, except that there is no triethanolamine in the raw material, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.40×10 -3 μm 2 , the porosity is 2.87%, indicating that the porosity is low. Triethanolamine can prevent pore blockage and play a role in improving the porosity.

[0088] Comparative Example 7

[0089] Same as Example 4, except that the permeability enhancer in the raw material is only polyoxyethylene ether, and the permeability of the prepared coal seam acidification permeability agent to columnar coal is 0.29×10 -3 μm 2 , porosity 2.81%, indicating that a single permeability enhancer cannot play a synergistic role in composite permeability enhancement.

[0090] Comparative Example 8

[0091] Same as Example 4, except that the raw material used sodium lauryl sulfate as the permeability enhancer and sodium dodecylbenzene sulfonate as the permeability enhancer. The permeability of the prepared coal seam acidification permeability enhancer to columnar coal is 0.31×10 -3 μm 2 , porosity 2.92%, indicating that not all anionic surfactants are effective in improving permeability and porosity.

[0092] Comparative Example 9

[0093] The same as Example 4, except that all the raw materials are directly mixed in one pot, and the permeability of the prepared coal seam acidification penetrant to columnar coal is 0.34×10 -3 μm 2 , porosity 2.98%, indicating that in the preparation process, the order of adding each substance has an impact on the final reaction effect. The present invention can improve the effect of the prepared coal seam acidification permeability enhancer by controlling the addition order.

[0094] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention to be protected.

Claims

1. A coal seam acidification permeability enhancer, characterized in that: The raw materials and mass fractions of each raw material included in the coal seam acidification permeability enhancer are: The acid is 5-30 parts, the penetration enhancer is 0.5-3 parts, the sustained-release agent is 0.5-2 parts, and the stabilizer is 0.5-3 parts.

2. The coal seam acidification permeability enhancer according to claim 1, characterized in that: The acid is a mixture of potassium chloride and hydrofluoric acid, the penetration enhancer is a mixture of polyoxyethylene ether and sodium dodecylbenzene sulfonate, the sustained-release agent is triethanolamine, and the stabilizer is ethylene glycol dimethyl ether.

3. The coal seam acidification permeability enhancer according to claim 2, characterized in that: The acid is a mixture of hydrochloric acid and hydrofluoric acid.

4. The coal seam acidification permeability enhancer according to claim 2 or 3, characterized in that: The coal seam acidification permeability enhancer comprises the following components measured by mass fraction: 5-15 parts of potassium chloride, 5-15 parts of hydrofluoric acid or hydrochloric acid, 0.5-1.5 parts of polyoxyethylene ether, 0.5-1.5 parts of sodium dodecylbenzene sulfonate, 0.5-1.5 parts of triethanolamine, and 0.5-1.5 parts of ethylene glycol dimethyl ether.

5. The method for preparing the coal seam acidification permeability enhancer according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Acid preparation Select the corresponding acid according to the mineral composition of the coal seam, dissolve it at room temperature, and obtain a stable acid solution; Step 2: Add a penetration enhancer Slowly add the permeability enhancer to the acid solution according to the mass proportion of the raw materials to avoid violent reaction, and stir and mix for 10-15 minutes to ensure that the permeability enhancer is fully dissolved and dispersed to obtain a permeability-enhanced acid solution; Step 3: Add corrosion inhibitors and stabilizers Select corrosion inhibitors and stabilizers and add them to the permeation acid solution, and control the temperature at 25°C-40°C through temperature control equipment to ensure stability and avoid excessive reaction, so as to obtain an acidified permeation agent mixture; Step 4: Adjust pH and optimize acidification solution Monitor the pH of the acidified permeability enhancer mixture using a pH meter. The pH should be maintained between 1.5 and 3.

0. Continue to stir the acidified permeability enhancer mixture to ensure that all components are completely dissolved and to avoid precipitation. Solid-liquid separation is carried out to remove undissolved impurities and obtain coal seam acidification permeability enhancer.

6. The method for preparing the coal seam acidification permeability enhancer according to claim 5, characterized in that: In step 1, the molar concentration of the acid solution is adjusted according to the mineral dissolution rate.

7. The method for preparing the coal seam acidification permeability enhancer according to claim 5, characterized in that: In the step 3, after the corrosion inhibitor and stabilizer are added, the reaction is stirred for 10-15 minutes.

8. The method for preparing the coal seam acidification permeability enhancer according to claim 5, characterized in that: In the step 4, the stirring time is 15-20 minutes.

9. The method for preparing the coal seam acidification permeability enhancer according to claim 5, characterized in that: In step 4, the solid-liquid separation is performed by filtering the acidified permeability enhancer mixture through a filter screen or a filter to remove impurities.

10. The use of the coal seam acidifying permeability enhancer according to any one of claims 1 to 4 or the coal seam acidifying permeability enhancer prepared by the preparation method according to any one of claims 5 to 9 for coal seam gas mining can increase the permeability of columnar coal by 50% to 127% and the porosity by 8.15 to 41.48%.