A resolution-promoting permeation enhancer and a method for preparing the same

Abstract

The application relates to the unconventional natural gas exploitation technical field and discloses a desorption-promoting permeation reinforcing agent and a preparation method thereof, the preparation method being as follows: adding modified sodium alginate and beta-cyclodextrin into 70-80% of deionized water of total water, stirring at 300-400 rpm until completely dissolved, then adding triethanolamine, adjusting pH to 7-8, then adding hyperbranched quaternary ammonium salt and guanidylated chitosan, and adding the rest of the deionized water, continuing to stir for 30-40 min to obtain the desorption-promoting permeation reinforcing agent. The desorption-promoting permeation reinforcing agent can promote the desorption of adsorbed methane and improve the reservoir permeability.

Description

Technical Field

[0001] This invention relates to the field of unconventional natural gas extraction technology, specifically to a desorption permeability enhancement agent and its preparation method. Background Technology

[0002] Unconventional natural gas, especially coalbed methane and shale gas, has become an important alternative energy source. In these reservoirs, the gas mainly exists in an adsorbed state within the microporous structure, and its natural permeability is extremely low, making it difficult for traditional extraction technologies to efficiently release resources. Current mainstream surfactant-based technologies can improve wettability by reducing surface tension, but their desorption-promoting ability is limited, they lack mineral dissolution effects, and their action cycle is short due to adsorption losses. Inorganic acid acidification technology can use hydrochloric acid, arginine, etc., to dissolve minerals and improve permeability, but it is highly corrosive and reacts violently, easily causing secondary damage to the reservoir. Therefore, avoiding this phenomenon is key to solving the problem. Chinese Patent 202510280167.6 discloses a self-cleaning active drag-reducing agent and its preparation method. This drag-reducing agent also has a thickening effect, enhancing the polymer's low adsorption and low residue characteristics while possessing variable viscosity and sand-carrying capacity. It also promotes the dissociation of adsorbed gas into free gas and clears and cleans the formation. However, its ability to improve reservoir permeability still needs improvement. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a desorption-enhancing permeability enhancer and its preparation method. The desorption-enhancing permeability enhancer of this invention can promote the desorption of adsorbed methane and improve reservoir permeability.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a desorption permeation enhancer comprising the following weight components: 4-6 parts by weight of hyperbranched quaternary ammonium salt, 2-4 parts by weight of guanidinolated chitosan, 3-5 parts by weight of modified sodium alginate, 1-2 parts by weight of β-cyclodextrin, 0.3-0.5 parts by weight of triethanolamine, and 70-80 parts by weight of deionized water.

[0007] Furthermore, the preparation method of the hyperbranched quaternary ammonium salt is as follows:

[0008] Step 1: Add 1,2-diaminoethane to methanol solvent and mix thoroughly under ice bath conditions at 0-5℃. Then add methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 22-26 hours. After the reaction is complete, distill under reduced pressure to obtain intermediate 1.

[0009] Step 2: Add intermediate 1 to N,N-dimethylformamide solvent and stir and mix under ice bath conditions at 0-5℃. Then add propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 25-35℃ for 30-40 hours. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt.

[0010] Furthermore, in step one, the ratio of methanol, 1,2-diaminoethane, and methyl acrylate is 5-6 mL: 0.9-1 g: 10.3-10.5 g.

[0011] Furthermore, in step two, the ratio of N,N-dimethylformamide, intermediate 1, and propanesulfonic acid lactone is 40-50 mL: 3.2-3.3 g: 2.6-2.7 g.

[0012] Further, the preparation method of the guanidinolated chitosan is as follows: 100-110 mL of 1% (w / w) dilute acetic acid solvent and 1-1.1 g of chitosan are added to a reactor and magnetically stirred until the chitosan is completely dissolved. 1.28-1.32 g of N-hydroxysuccinimide and 1.73-1.77 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide are added to the chitosan solution and stirred until uniformly mixed. Then, 0.48-0.52 g of L-arginine is added to the reaction system, and the reaction is carried out at 30-40℃ for 22-26 h. After the reaction is completed, the mixture is dialyzed using a 6000-7000 Da dialysis bag for 48-72 h, water is removed by rotary evaporation, and the mixture is dried to obtain guanidinolated chitosan.

[0013] Furthermore, the preparation method of the modified sodium alginate is as follows:

[0014] S1: Add sodium alginate and sodium periodate to deionized water, stir at room temperature in the dark for 8-10 hours, then add ethylene glycol for quenching, dialyze the resulting product with a 3500-4000 Da dialysis bag for 70-74 hours, and freeze-dry at -20℃ to -25℃ for 72-76 hours to obtain oxidized sodium alginate.

[0015] S2: Add 35-40 mL of phosphate buffer and 2.1-2.2 g of oxidized sodium alginate to the reactor and stir to dissolve at 40-50 °C. Dissolve 1.4-1.5 g of lysine in 10-15 mL of phosphate buffer and add it dropwise to the reactor. Stir at 35-40 °C in the dark for 16-20 h. Then add 0.8-0.9 g of ethylene glycol for quenching. Dialyze the obtained product using an 8000-10000 Da dialysis bag for 50-60 h and freeze-dry at -30 °C to -40 °C for 24-48 h to obtain modified sodium alginate.

[0016] Furthermore, the ratio of deionized water, sodium alginate, sodium periodate, and ethylene glycol in S1 is 50-60 mL: 2.7-2.8 g: 1.76-1.8 g: 1-1.1 g.

[0017] Furthermore, the preparation method of the desorption-enhancing and permeation-enhancing agent is as follows: add modified sodium alginate and β-cyclodextrin to deionized water accounting for 70-80% of the total water volume, stir at 300-400 rpm until completely dissolved, then add triethanolamine, adjust the pH to 7-8, then add hyperbranched quaternary ammonium salt, guanidyl chitosan, and the remaining deionized water, and continue stirring for 30-40 min to obtain the desorption-enhancing and permeation-enhancing agent.

[0018] (iii) Beneficial technical effects

[0019] Hyperbranched quaternary ammonium salts possess a strong permanent positive charge and can competitively adsorb onto the negatively charged surface of coal or shale through electrostatic interactions. This reduces the adsorption potential energy between methane molecules and the matrix surface, promoting the desorption of adsorbed methane. Furthermore, the hyperbranched structure provides a strong steric hindrance effect, effectively dispersing coal powder particles and preventing them from re-clogging pore throats, thus enhancing reservoir permeability. Guanidyl chitosan is obtained by modifying chitosan with L-arginine. The guanidinyl group maintains a strong positive charge even at near-neutral pH. This strong positive charge alters the electrical and wettability of the coal and rock surface, lowering the methane adsorption barrier and enhancing the gas desorption capacity of the intensifier. Additionally, sodium alginate and sodium periodate react to obtain aldehyde-containing oxidized sodium alginate. Modified sodium alginate is obtained by reacting aldehyde groups with lysine via a Schiff base reaction, introducing amino and carboxyl groups that can chelate minerals. This enables mild dissolution and pore-enhancing. Furthermore, guanidinolated chitosan and modified sodium alginate synergistically form a reversible supramolecular network. This network can prevent coal powder from re-aggregating and precipitating through steric hindrance and electrostatic repulsion, thereby improving the powder-carrying capacity of the system and allowing the enhancer to strengthen reservoir permeability. The hydrophobic cavity of β-cyclodextrin can selectively encapsulate methane molecules to form host-guest inclusion complexes, directly reducing the methane concentration in the gas phase. β-cyclodextrin can also adsorb onto the surface of coal powder, improving the compatibility of coal powder with water through its hydrophilic outer edge, reducing hydrophobic agglomeration of coal powder, further enhancing the dispersion effect, and strengthening reservoir permeability. Attached Figure Description

[0020] Figure 1 It is the synthesis reaction formula for hyperbranched quaternary ammonium salts. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] To better understand the above technical solutions, the following will provide a detailed description of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0023] The reagents used in the following specific embodiments are of analytical grade. Additionally:

[0024] The phosphate buffer used in this invention is a standard phosphate buffer. The preparation method of the standard phosphate buffer is described in the "Pharmacopoeia of the People's Republic of China: 2020 Edition, Part IV, 8004 Buffer". It is prepared as follows: Take 0.68g of potassium dihydrogen phosphate, add 15.2mL of 0.1mol / L sodium hydroxide solution, and dilute with water to 100mL to obtain a standard phosphate buffer with a pH of 6.5.

[0025] Example 1

[0026] This embodiment provides a desorption permeation enhancement agent, the preparation method of which specifically includes the following steps:

[0027] (1) Add 0.9 g of 1,2-diaminoethane to 5 mL of methanol solvent and mix well under ice bath conditions at 0 °C. Then add 10.3 g of methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 22 h. After the reaction is complete, distill under reduced pressure to obtain intermediate 1.

[0028] (2) Add 3.2 g of intermediate 1 to 40 mL of N,N-dimethylformamide solvent and stir and mix under ice bath conditions at 0 °C. Then add 2.6 g of propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 25 °C for 30 h. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt.

[0029] (3) Add 100 mL of 1% dilute acetic acid solvent and 1 g of chitosan to the reactor and stir magnetically until the chitosan is completely dissolved. Add 1.28 g of N-hydroxysuccinimide and 1.73 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to the chitosan solution and stir until the mixture is uniform. Then add 0.48 g of L-arginine to the reaction system and react at 30 °C for 22 h. After the reaction is completed, dialyze using a 6000 Da dialysis bag for 48 h, remove water by rotary evaporation, and dry to obtain guanidinolated chitosan.

[0030] (4) Add 2.7g of sodium alginate and 1.76g of sodium periodate to 50mL of deionized water, stir for 8h in the dark at room temperature, then add 1g of ethylene glycol for quenching, dialyze the resulting product with a 3500Da dialysis bag for 70h, freeze dry at -20℃ for 72h to obtain oxidized sodium alginate.

[0031] (5) Add 35 mL of phosphate buffer and 2.1 g of oxidized sodium alginate to the reactor and stir to dissolve at 40 °C. Dissolve 1.4 g of lysine in 10 mL of phosphate buffer and then add it dropwise to the reactor. Stir at 35 °C in the dark for 16 h. Then add 0.8 g of ethylene glycol to quench the reaction. Dialyze the resulting product with an 8000 Da dialysis bag for 50 h and freeze-dry at -30 °C for 24 h to obtain modified sodium alginate.

[0032] (6) Add 3 parts by weight of modified sodium alginate and 1 part by weight of β-cyclodextrin to 50 parts by weight of deionized water, stir at 300 rpm until completely dissolved, then add 0.3 parts by weight of triethanolamine, adjust the pH to 7, then add 4 parts by weight of hyperbranched quaternary ammonium salt, 2 parts by weight of guanidyl chitosan and 20 parts by weight of deionized water, and continue stirring for 30 min to obtain the desorption permeation enhancer.

[0033] Example 2

[0034] This embodiment provides a desorption permeation enhancement agent, the preparation method of which specifically includes the following steps:

[0035] (1) Add 1 g of 1,2-diaminoethane to 6 mL of methanol solvent and mix well under ice bath conditions at 5 °C. Then add 10.5 g of methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 26 h. After the reaction is complete, distill under reduced pressure to obtain intermediate 1.

[0036] (2) Add 3.3 g of intermediate 1 to 50 mL of N,N-dimethylformamide solvent and stir and mix under ice bath conditions at 5 °C. Then add 2.7 g of propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 35 °C for 40 h. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt.

[0037] (3) Add 110 mL of 1% dilute acetic acid solvent and 1.1 g of chitosan to the reactor and stir magnetically until the chitosan is completely dissolved. Add 1.32 g of N-hydroxysuccinimide and 1.77 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to the chitosan solution and stir until the mixture is uniform. Then add 0.52 g of L-arginine to the reaction system and react at 40 °C for 26 h. After the reaction is completed, dialyze using a 7000 Da dialysis bag for 72 h, remove water by rotary evaporation, and dry to obtain guanidinolated chitosan.

[0038] (4) Add 2.8g of sodium alginate and 1.8g of sodium periodate to 60mL of deionized water, stir for 10h in the dark at room temperature, then add 1.1g of ethylene glycol for quenching, dialyze the resulting product with a 4000Da dialysis bag for 74h, freeze dry at -25℃ for 76h to obtain oxidized sodium alginate.

[0039] (5) Add 40 mL of phosphate buffer and 2.2 g of oxidized sodium alginate to the reactor and stir to dissolve at 50 °C. Dissolve 1.5 g of lysine in 15 mL of phosphate buffer and then add it dropwise to the reactor. Stir at 40 °C in the dark for 20 h. Then add 0.9 g of ethylene glycol for quenching. Dialyze the obtained product with a 10000 Da dialysis bag for 60 h and freeze dry at -40 °C for 48 h to obtain modified sodium alginate.

[0040] (6) Add 5 parts by weight of modified sodium alginate and 2 parts by weight of β-cyclodextrin to 60 parts by weight of deionized water, stir at 400 rpm until completely dissolved, then add 0.5 parts by weight of triethanolamine, adjust the pH to 8, then add 6 parts by weight of hyperbranched quaternary ammonium salt, 4 parts by weight of guanidyl chitosan and 20 parts by weight of deionized water, and continue stirring for 40 min to obtain the desorption permeation enhancer.

[0041] Example 3

[0042] This embodiment provides a desorption permeation enhancement agent, the preparation method of which specifically includes the following steps:

[0043] (1) Add 0.95 g of 1,2-diaminoethane to 5.5 mL of methanol solvent and mix evenly under ice bath conditions at 2 °C. Then add 10.4 g of methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 24 h. After the reaction is complete, distill under reduced pressure to obtain intermediate 1.

[0044] (2) Add 3.25 g of intermediate 1 to 45 mL of N,N-dimethylformamide solvent and stir and mix under ice bath conditions at 2 °C. Then add 2.65 g of propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 30 °C for 35 h. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt.

[0045] (3) Add 105 mL of 1% dilute acetic acid solvent and 1.05 g of chitosan to the reactor and stir magnetically until the chitosan is completely dissolved. Add 1.3 g of N-hydroxysuccinimide and 1.75 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to the chitosan solution and stir until the mixture is uniform. Then add 0.5 g of L-arginine to the reaction system and react at 35 °C for 24 h. After the reaction is completed, dialyze using a 6000 Da dialysis bag for 60 h, remove water by rotary evaporation, and dry to obtain guanidinolated chitosan.

[0046] (4) Add 2.75g of sodium alginate and 1.78g of sodium periodate to 55mL of deionized water, stir at room temperature in the dark for 9h, then add 1.05g of ethylene glycol for quenching, dialyze the obtained product with a 3500Da dialysis bag for 72h, freeze dry at -22℃ for 74h to obtain oxidized sodium alginate;

[0047] (5) Add 38 mL of phosphate buffer and 2.15 g of oxidized sodium alginate to the reactor and stir to dissolve at 45 °C. Dissolve 1.45 g of lysine in 12 mL of phosphate buffer and then add it dropwise to the reactor. Stir at 38 °C in the dark for 18 h. Then add 0.85 g of ethylene glycol for quenching. Dialyze the obtained product with a 9000 Da dialysis bag for 55 h and freeze dry at -35 °C for 36 h to obtain modified sodium alginate.

[0048] (6) Add 4 parts by weight of modified sodium alginate and 1 part by weight of β-cyclodextrin to 55 parts by weight of deionized water, stir at 300 rpm until completely dissolved, then add 0.4 parts by weight of triethanolamine, adjust the pH to 7, then add 5 parts by weight of hyperbranched quaternary ammonium salt, 3 parts by weight of guanidyl chitosan and 22 parts by weight of deionized water, and continue stirring for 35 min to obtain the desorption permeation enhancer.

[0049] Example 4

[0050] This embodiment provides a desorption permeation enhancement agent, the preparation method of which specifically includes the following steps:

[0051] (1) Add 0.92 g of 1,2-diaminoethane to 5.2 mL of methanol solvent and mix evenly under ice bath conditions at 1 °C. Then add 10.35 g of methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 23 h. After the reaction is complete, distill under reduced pressure to obtain intermediate 1.

[0052] (2) Add 3.22 g of intermediate 1 to 42 mL of N,N-dimethylformamide solvent and stir and mix under ice bath conditions at 1 °C. Then add 2.62 g of propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 28 °C for 32 h. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt.

[0053] (3) Add 102 mL of 1% dilute acetic acid solvent and 1.02 g of chitosan to the reactor and stir magnetically until the chitosan is completely dissolved. Add 1.29 g of N-hydroxysuccinimide and 1.74 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to the chitosan solution and stir until the mixture is uniform. Then add 0.49 g of L-arginine to the reaction system and react at 32 °C for 23 h. After the reaction is completed, dialyze using a 6000 Da dialysis bag for 54 h, remove water by rotary evaporation, and dry to obtain guanidinolated chitosan.

[0054] (4) Add 2.72 g of sodium alginate and 1.77 g of sodium periodate to 52 mL of deionized water, stir at room temperature in the dark for 8 h, then add 1.03 g of ethylene glycol for quenching, dialyze the obtained product with a 3500 Da dialysis bag for 71 h, freeze dry at -21 °C for 73 h to obtain oxidized sodium alginate;

[0055] (5) Add 36 mL of phosphate buffer and 2.12 g of oxidized sodium alginate to the reactor and stir to dissolve at 42 °C. Dissolve 1.42 g of lysine in 12 mL of phosphate buffer and then add it dropwise to the reactor. Stir at 36 °C in the dark for 17 h. Then add 0.82 g of ethylene glycol for quenching. Dialyze the obtained product with an 8000 Da dialysis bag for 52 h and freeze dry at -32 °C for 30 h to obtain modified sodium alginate.

[0056] (6) Add 3 parts by weight of modified sodium alginate and 1 part by weight of β-cyclodextrin to 52 parts by weight of deionized water, stir at 300 rpm until completely dissolved, then add 0.3 parts by weight of triethanolamine, adjust the pH to 7, then add 5 parts by weight of hyperbranched quaternary ammonium salt, 3 parts by weight of guanidyl chitosan and 23 parts by weight of deionized water, and continue stirring for 32 min to obtain the desorption permeation enhancer.

[0057] Example 5

[0058] This embodiment provides a desorption permeation enhancement agent, the preparation method of which specifically includes the following steps:

[0059] (1) Add 0.98 g of 1,2-diaminoethane to 5.8 mL of methanol solvent and mix evenly under ice bath conditions at 3 °C. Then add 10.45 g of methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 25 h. After the reaction is complete, distill under reduced pressure to obtain intermediate 1.

[0060] (2) Add 3.27 g of intermediate 1 to 48 mL of N,N-dimethylformamide solvent, stir and mix under ice bath conditions at 3 °C, then add 2.67 g of propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 32 °C for 38 h. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt.

[0061] (3) Add 108 mL of 1% dilute acetic acid solvent and 1.07 g of chitosan to the reactor and stir magnetically until the chitosan is completely dissolved. Add 1.31 g of N-hydroxysuccinimide and 1.76 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to the chitosan solution and stir until the mixture is uniform. Then add 0.51 g of L-arginine to the reaction system and react at 38 °C for 25 h. After the reaction is completed, dialyze using a 7000 Da dialysis bag for 66 h, remove water by rotary evaporation, and dry to obtain guanidinolated chitosan.

[0062] (4) Add 2.77 g of sodium alginate and 1.79 g of sodium periodate to 58 mL of deionized water, stir for 10 h in the dark at room temperature, then add 1.07 g of ethylene glycol for quenching, dialyze the obtained product with a 4000 Da dialysis bag for 73 h, freeze dry at -24 °C for 75 h to obtain oxidized sodium alginate;

[0063] (5) Add 39 mL of phosphate buffer and 2.17 g of oxidized sodium alginate to the reactor and stir to dissolve at 48 °C. Dissolve 1.48 g of lysine in 14 mL of phosphate buffer and then add it dropwise to the reactor. Stir at 38 °C in the dark for 19 h. Then add 0.88 g of ethylene glycol for quenching. Dialyze the obtained product with a 10000 Da dialysis bag for 58 h and freeze dry at -38 °C for 42 h to obtain modified sodium alginate.

[0064] (6) Add 5 parts by weight of modified sodium alginate and 2 parts by weight of β-cyclodextrin to 55 parts by weight of deionized water, stir at 400 rpm until completely dissolved, then add 0.4 parts by weight of triethanolamine, adjust the pH to 7, then add 5 parts by weight of hyperbranched quaternary ammonium salt, 4 parts by weight of guanidyl chitosan and 23 parts by weight of deionized water, and continue stirring for 38 min to obtain the desorption permeation enhancer.

[0065] Comparative Example 1

[0066] The main difference between this comparative example and Example 5 is that intermediate 1 is used instead of the hyperbranched quaternary ammonium salt.

[0067] Comparative Example 2

[0068] The main difference between this comparative example and Example 5 is that chitosan is used instead of guanidinolated chitosan.

[0069] Performance testing

[0070] The desorption and permeation enhancement agents prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests.

[0071] (1) Methane desorption test

[0072] The specific testing method is as follows: Weigh 50g of 40-60 mesh coal powder, dry it to constant weight, and put the dried coal sample into a coal sample container. Degas the coal sample in the container. After degassing, introduce high-purity methane gas into the coal sample container. Adjust the gas inlet and outlet valves to make the pressure gauge reading of the coal sample container reach the target value. When the pressure gauge reading remains stable for 2 hours, it can be considered that the methane in the container has reached adsorption equilibrium. Then, inject 10mL of the desorption permeation enhancement agent prepared in Examples 1-5 and Comparative Examples 1-2 into the coal sample container and start the stirring device for 30 minutes. After the coal sample container reaches adsorption equilibrium again, connect the gas outlet to the gas collection bag and open the gas outlet valve until the pressure gauge reading of the coal sample container is 0, then close the gas outlet valve. Open the valve between the methane metering device and the gas outlet of the coal sample container, and simultaneously start the timing device to record the cumulative desorption amount of the coal sample at each moment during the subsequent 120 minutes of desorption process, in mL / g. The test results are shown in Table 1.

[0073] Table 1: Methane Desorption Test

[0074] Group Methane desorption capacity (mL / g) Example 1 22.6 Example 2 24.0 Example 3 23.4 Example 4 22.9 Example 5 23.7 Comparative Example 1 19.5 Comparative Example 2 18.2

[0075] As can be seen from Table 1, the desorption permeation enhancers prepared in Examples 1-5 have good ability to reduce gas desorption and can promote the desorption of adsorbed methane.

[0076] (2) Permeability recovery rate test

[0077] The specific testing method is as follows: A standard coal / shale core with a diameter of 25mm × 50mm was selected, dried at 105℃ to constant weight, and then placed into a core holder. Nitrogen gas impingement and simulated formation water saturation pretreatment were performed sequentially. Simulated formation water was then injected at a constant flow rate, and the initial aqueous permeability K0 of the core was measured under reservoir temperature and salinity conditions. Next, a coal powder suspension (concentration 5%-10%) was injected to simulate actual downhole blockage. After the pressure stabilized, the post-damage permeability K1 was measured. Then, the desorption permeability enhancing agent prepared in Examples 1-5 and Comparative Examples 1-2 was injected, with an injection volume 2-3 times the core pore volume. The mixture was reacted at a constant temperature for 12-24 hours at the reservoir temperature to ensure its full dispersing, dissolving, and unblocking effects. After the reaction, simulated formation water was used to backflow the core until the pressure stabilized, and the post-treatment permeability K2 was measured. The performance was quantified by calculating the permeability recovery rate R = (K2 / K0) × 100% and the unblocking efficiency E = [(K2-K1) / (K0-K1)] × 100%. Three core samples were tested in parallel, and the average value was taken. R ≥ 100% (or E ≥ 90%) was used as the passing standard. The test results are shown in Table 2.

[0078] Table 2: Penetration Test

[0079] Group <![CDATA[Initial permeability K0 (mD)]]> Post-damage permeability K1(mD) Permeability K2 (mD) after treatment Permeability recovery rate R (%) Congestion relief efficiency E (%) Pass / Fail Status Example 1 1.30 0.45 1.31 100.8 92.9 qualified Example 2 1.20 0.40 1.27 105.8 97.5 qualified Example 3 1.18 0.38 1.22 103.4 97.5 qualified Example 4 1.22 0.41 1.24 101.6 95.1 qualified Example 5 1.25 0.42 1.30 104.0 96.4 qualified Comparative Example 1 1.28 0.43 1.00 78.1 80.0 Unqualified Comparative Example 2 1.22 0.39 0.85 69.7 73.2 Unqualified

[0080] As can be seen from Table 2, the desorption-enhancing permeability enhancers prepared in Examples 1-5 can improve reservoir permeability.

[0081] The comparison shows that, since Comparative Example 1 uses Intermediate 1 instead of hyperbranched quaternary ammonium salt, it lacks quaternary ammonium salt groups. As a result, the positive charge and steric stabilizing effect of Intermediate 1 are insufficient, leading to poor dispersion stability of coal powder and incomplete declogging. Therefore, the performance of Comparative Example 1 is lower than that of the Example. On the other hand, Comparative Example 2 uses chitosan instead of guanidinolated chitosan. Under near-neutral conditions, chitosan is almost non-positively charged and lacks guanidino groups, thus losing its desorption promoting ability. Its linear molecular structure can also cause coal powder flocculation, resulting in the worst permeability recovery effect and the greatest performance decline.

[0082] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0084] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A desorption and permeation enhancement agent, characterized in that, It includes the following components by weight: 4-6 parts by weight of hyperbranched quaternary ammonium salt, 2-4 parts by weight of guanidinolated chitosan, 3-5 parts by weight of modified sodium alginate, 1-2 parts by weight of β-cyclodextrin, 0.3-0.5 parts by weight of triethanolamine, and 70-80 parts by weight of deionized water. The hyperbranched quaternary ammonium salt is obtained by reacting 1,2-diaminoethane with methyl acrylate, followed by reaction with propanesulfonate lactone. The guanidinolated chitosan is obtained by modifying chitosan with L-arginine; The modified sodium alginate is obtained by reacting sodium alginate and sodium periodate to obtain oxidized sodium alginate, which is then reacted with lysine. The preparation method of the hyperbranched quaternary ammonium salt is as follows: Step 1: Add 1,2-diaminoethane to methanol solvent and mix thoroughly under ice bath conditions at 0-5℃. Then add methyl acrylate dropwise. After the addition is complete, reflux the reaction at room temperature for 22-26 hours. After the reaction is complete, distill under reduced pressure to obtain intermediate 1. Step 2: Add intermediate 1 to N,N-dimethylformamide solvent and stir and mix under ice bath conditions at 0-5℃. Then add propanesulfonic acid lactone dropwise. After the addition is complete, continue stirring at 25-35℃ for 30-40h. After the reaction is complete, precipitate, filter, wash and dry to obtain hyperbranched quaternary ammonium salt. The method for preparing guanidinolated chitosan is as follows: 100-110 mL of 1% (w / w) dilute acetic acid solvent and 1-1.1 g of chitosan are added to a reactor and magnetically stirred until the chitosan is completely dissolved. 1.28-1.32 g of N-hydroxysuccinimide and 1.73-1.77 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide are added to the chitosan solution and stirred until homogeneous. Then, 0.48-0.52 g of L-arginine is added to the reaction system, and the reaction is carried out at 30-40℃ for 22-26 h. After the reaction is completed, the mixture is dialyzed using a 6000-7000 Da dialysis bag for 48-72 h, water is removed by rotary evaporation, and the mixture is dried to obtain guanidinolated chitosan. The modified sodium alginate is prepared by: S1: Add sodium alginate and sodium periodate to deionized water, stir at room temperature in the dark for 8-10 hours, then add ethylene glycol for quenching, dialyze the resulting product with a 3500-4000 Da dialysis bag for 70-74 hours, and freeze-dry at -20℃ to -25℃ for 72-76 hours to obtain oxidized sodium alginate. S2: Add 35-40 mL of phosphate buffer and 2.1-2.2 g of oxidized sodium alginate to the reactor and stir to dissolve at 40-50 °C. Dissolve 1.4-1.5 g of lysine in 10-15 mL of phosphate buffer and add it dropwise to the reactor. Stir at 35-40 °C in the dark for 16-20 h. Then add 0.8-0.9 g of ethylene glycol for quenching. Dialyze the obtained product using an 8000-10000 Da dialysis bag for 50-60 h and freeze-dry at -30 °C to -40 °C for 24-48 h to obtain modified sodium alginate.

2. The desorption and permeation enhancement agent according to claim 1, characterized in that, In step one, the ratio of methanol, 1,2-diaminoethane, and methyl acrylate is 5-6 mL: 0.9-1 g: 10.3-10.5 g.

3. The desorption and permeation enhancement agent according to claim 1, characterized in that, In step two, the ratio of N,N-dimethylformamide, intermediate 1, and propanesulfonic acid lactone is 40-50 mL: 3.2-3.3 g: 2.6-2.7 g.

4. The desorption and permeation enhancement agent according to claim 1, characterized in that, The ratio of deionized water, sodium alginate, sodium periodate, and ethylene glycol in S1 is 50-60 mL: 2.7-2.8 g: 1.76-1.8 g: 1-1.1 g.

5. A method for preparing the desorption and permeation enhancement agent as described in any one of claims 1-4, characterized in that, The preparation method of the desorption-enhancing and permeation-enhancing agent is as follows: Add modified sodium alginate and β-cyclodextrin to deionized water accounting for 70-80% of the total water volume, stir at 300-400 rpm until completely dissolved, then add triethanolamine, adjust the pH to 7-8, then add hyperbranched quaternary ammonium salt, guanidyl chitosan, and the remaining deionized water, and continue stirring for 30-40 min to obtain the desorption-enhancing and permeation-enhancing agent.

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