Coal bed gas desorption promoting agent as well as preparation method and application thereof

Abstract

The invention provides a coal bed gas desorption promoting agent and a preparation method and application thereof, and belongs to the technical field of coal bed gas exploitation. The coal bed gas desorption promoting agent is composed of a high-molecular polymer HCSY and a surfactant HCBY according to a mass ratio of (10-12): 1. Wherein the high-molecular polymer HCSY is formed by copolymerizing a multifunctional cationic surface active monomer octylphenol polyoxyethylene ether-10 and a water-soluble polymer polystyrolsulfon acid, and has the characteristics of high temperature resistance, mineralization resistance, acid and alkali resistance and oil substance contamination resistance. The surfactant HCBY is mainly prepared from octadecyl dimethyl tertiary amine, alkyl ether polyoxyethylene ether, absolute ethyl alcohol and water. The coal bed gas desorption promoting agent can obviously reduce the surface tension of liquid, so that the wettability of the liquid is reversed, the capillary resistance of the coal bed gas during diffusion and seepage from pores of a coal sample is reduced, and the desorption efficiency of the coal bed gas is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coalbed methane extraction, and particularly relates to a coalbed methane desorption promoter, a preparation method thereof and an application thereof. Background Art

[0002] As an associated resource of coal, coalbed methane is an unconventional natural gas formed during the coal formation process and mainly stored in the coal reservoir in an adsorbed state, and is a new type of clean energy and high-quality chemical raw material. At present, the common methods for promoting coalbed methane desorption are as follows: (1) By draining water to reduce the pressure, the output of water reduces the reservoir pressure. When the reservoir pressure drops to the critical desorption pressure, coalbed methane begins to desorb from the coal rock fractures or matrix; (2) Replacement of methane gas in the coal rock by other substances. Research shows that the adsorption capacity of coal rock for carbon dioxide is stronger than that for methane. Therefore, carbon dioxide injection has been used in the prior art to replace methane gas in the coal rock. However, subsequent research found that injecting carbon dioxide will cause the expansion of the coal rock matrix and block the gas flow channel, which is not conducive to the production of methane gas. Therefore, it is urgent to study an efficient desorption promoter suitable for coalbed methane reservoirs to meet the compatibility requirements of different coal seams, thereby improving the recovery rate of coalbed methane. Summary of the Invention

[0003] Based on the above technical problems, the present invention provides a coalbed methane desorption promoter and a preparation method thereof. The desorption promoter can significantly reduce the surface tension of the liquid, increase the contact angle between the liquid and the coal seam, reverse the wettability of the coal seam surface, and further reduce the capillary resistance when coalbed methane diffuses and seeps from the coal seam pores, thereby improving the desorption efficiency of coalbed methane.

[0004] Specifically, in order to achieve the above object, the present invention adopts the following technical solutions: A coalbed methane desorption accelerator, comprising a polymer HCSY and a surfactant HCBY in a mass ratio of (10-12):1; the polymer HCSY comprises 25.5wt%-33.5wt% of an oil phase, 57.0wt%-67.5wt% of an aqueous phase, 0.02wt%-0.03wt% of sodium bisulfite, 0.5wt%-0.8wt% of sodium metabisulfite, and 1.6wt%-2.6wt% of octylphenol polyoxyethylene ether-10; the oil phase comprises octylphenol polyoxyethylene ether-10, Tween 80, Span 80. Polystyrene sulfonic acid is composed of a mass ratio of (1-1.2): (0.8-0.96): (1.2-1.44): (10-12); the aqueous phase includes a mixture of disodium ethylenediaminetetraacetic acid, tetramethylethylenediamine, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid in a mass ratio of (0.001-0.0012): (0.3-0.36): (0.75-0.9): (0.75-1), and the pH of the aqueous phase is 6.5-7.5; the surfactant HCBY is composed of the following components in mass percentage: 28%-30% octadecyldimethyl tertiary amine, 8%-12% alkyl ether polyoxyethylene ether, 30%-34% anhydrous ethanol, and 30%-34% water.

[0005] The polymer HCSY is a copolymer of the multifunctional cationic surfactant monomer octylphenol polyoxyethylene ether-10 and the water-soluble polymer polystyrene sulfonic acid. Octylphenol polyoxyethylene ether-10 is assembled on the surface of the polystyrene sulfonic acid, and the hydrophobic groups are wrapped inside the copolymer. The chemical interaction between the molecular bonds forms a spatial network structure, which improves the adhesion ability. The polymer HCSY is applicable in the temperature range of 30~150℃ and has a mineralization resistance of 15×10 4 mg / L Ca 2+ Mg 2+ ), acid and alkali resistance (pH value range is 5~12).

[0006] The preparation method of the coalbed methane desorption promoting agent comprises the following steps: S1. Preparation of polymer HCSY and surfactant HCBY S1-1. Preparation of polymer HCSY: Prepare the oil phase and the water phase respectively; pour the water phase into the oil phase for emulsification; after the emulsified liquid reacts for a period of time under an inert gas atmosphere, cool it to 10 - 13 °C, and add the pre-deoxygenated aqueous sodium bisulfite solution in batches to obtain a third mixed solution; add the aqueous sodium metabisulfite solution to the third mixed solution to obtain a fourth mixed solution; when the temperature of the reaction system continues to drop, add octylphenol polyoxyethylene ether - 10 to the fourth mixed solution, and stir until the reaction ends to obtain the polymer HCSY; S1-2. Preparation of surfactant HCBY Mix octadecyl dimethyl tertiary amine, alkyl ether polyoxyethylene ether, absolute ethanol and water, and heat and react under an inert gas atmosphere; after the reaction ends, distill the reaction solution until it becomes a viscous paste to obtain the surfactant HCBY; S2. Mix the polymer HCSY and the surfactant HCBY evenly according to the mass ratio to obtain the coalbed methane desorption promoter.

[0007] In a preferred embodiment, the preparation method of the water phase includes the following steps: Add acrylamide and 2 - acrylamido - 2 - methylpropane sulfonic acid to water to obtain a first mixed solution; adjust the pH of the first mixed solution to 6 to obtain a second mixed solution; add the aqueous solution of disodium ethylenediaminetetraacetate to the second mixed solution, and then add tetramethylethylenediamine, and adjust the pH to 6.5 - 7.5 to obtain the water phase.

[0008] In a preferred embodiment, in step S1-1, the emulsified liquid reacts under an inert gas atmosphere at a stirring speed of 110 - 130 r / min for 1 - 1.5 h.

[0009] In a preferred embodiment, the addition process of the aqueous sodium bisulfite solution in step S1-1 is as follows: For the first time, add the pre-deoxygenated aqueous sodium bisulfite solution to the cooled reaction system, and the mass of the solute accounts for 15% - 20% of the total mass of sodium bisulfite, and react for 10 - 15 min; for the second time, continue to add the pre-deoxygenated aqueous sodium bisulfite solution, and the mass of the solute accounts for 60% - 67% of the total mass of sodium bisulfite, and control the addition speed to add 3 - 5 g of sodium bisulfite solute per hour; after the second addition, continue to add the remaining pre-deoxygenated aqueous sodium bisulfite solution to obtain the third mixed solution.

[0010] In a further preferred embodiment, in step S1-1, before the second addition of the aqueous sodium bisulfite solution, adjust the inert gas inlet rate to 1 / 3 - 1 / 2 of the inert gas inlet rate during the reaction of the emulsified liquid.

[0011] In a preferred embodiment, the rate of adding the aqueous sodium metabisulfite solution to the third mixed solution in step S1-1 is controlled to add 3-5 g of sodium metabisulfite solute per hour.

[0012] In a preferred embodiment, the conditions for the heating reaction in step S1-2 are: water bath heating to a temperature of 50-60 °C and constant temperature reaction for 24-36 h.

[0013] In a preferred embodiment, the distillation temperature in step S1-2 is 70 °C - 85 °C.

[0014] In a preferred embodiment, the conditions for uniform mixing in step S2 are: stirring at a stirring speed of 1800-2000 r / min for 1.5-2.5 h.

[0015] The present invention also provides the application of the coalbed methane desorption promoter in promoting the desorption of coalbed methane.

[0016] In a preferred embodiment, the concentration of the coalbed methane desorption promoter is 0.1 wt% - 0.4 wt%.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The desorption promoter provided by the present invention can significantly reduce the surface tension of the liquid, increase the contact angle of the liquid on the coalbed surface, and the increase amplitude of the contact angle reaches at least 127%, reversing the wettability of the liquid on the coalbed surface from hydrophilic to hydrophobic. Furthermore, it significantly reduces the capillary force of the liquid in the coalbed fissures, increases the relative permeability of the gas phase, and thus improves the desorption efficiency of coalbed methane. Compared with the situation without using the desorption promoter, using the desorption promoter in the present invention can at least increase the desorption capacity by 22%.

[0018] (2) Adding the desorption promoter provided by the present invention to the fracturing fluid can enhance the complexity of the fracturing cracks, solve the problem of strong water lock during the backflow after the existing fracturing construction, enable the fracturing fluid to penetrate into nano micropores, fractures, and caves, change the wettability of the coalbed surface, reduce the capillary force, and relieve the liquid lock damage. It can also clean and inhibit the organic blockage in the throat, improve the flow effect, and thus promote the desorption of coalbed methane.

[0019] (3) The main component of the desorption promoter provided by the present invention, the high molecular polymer HCSY, has the characteristics of high temperature resistance, salinity resistance, acid and alkali resistance, and resistance to oil substance contamination. Therefore, it has a wide temperature application range and is also suitable for the mining environment of high temperature and high salinity coalbed methane.

[0020] (4) The desorption promoter provided by the present invention has simple components, is easy to prepare, can form a homogeneous solution, is environmentally friendly, and can adsorb on the coalbed surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the result graph of testing the surface tension of the desorption promoter liquid provided in Embodiment 1 of the present invention; in the figure, (1) is the contact angle of the simulated formation water without treatment with the desorption promoter on the surface of the natural core slice, and (2)-(6) are the contact angles of the natural core slice surface treated with 0.1wt%, 0.2wt%, 0.25wt%, 0.3wt%, and 0.4wt% desorption promoters in sequence; Figure 2 It is the curve graph of the desorption ability of the desorption promoter provided in Embodiment 1 of the present invention for the methane adsorbed by the coal sample at different concentrations. Specific Embodiments

[0022] The following content describes the technical solutions of the present application clearly and completely in combination with embodiments, so that those skilled in the art can fully understand the present application. Obviously, the described embodiments are only some preferred embodiments of the present application, rather than all embodiments. Any equivalent transformation or substitution made to the following embodiments by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0023] Embodiment 1 A coalbed methane desorption promoter is composed of a high molecular polymer HCSY and a surfactant HCBY in a mass ratio of 10:1. Among them, HCSY includes 33.29wt% oil phase, 57.38wt% water phase, 0.03wt% sodium bisulfite (NaHSO3), 0.77wt% sodium metabisulfite (Na2S2O5), and 2.56wt% octylphenol polyoxyethylene ether-10. The oil phase is composed of octylphenol polyoxyethylene ether-10, Tween 80, Span 80, and polystyrene sulfonic acid in a mass ratio of 1:0.8:1.2:10. The water phase includes a mixture of disodium ethylenediaminetetraacetate (EDTA disodium), tetramethylethylenediamine, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in a mass ratio of 0.001:0.3:0.75:0.75, and the pH = 7. HCBY is composed of the following components by mass percentage: 30% octadecyl dimethyl tertiary amine, 10% alkyl ether polyoxyethylene ether, 30% absolute ethanol, and 30% deionized water.

[0024] The preparation method of the coalbed methane desorption promoter includes the following steps: S1. Prepare the high molecular polymer HCSY and the surfactant HCBY S1-1. Prepare the high molecular polymer HCSY S1-1-1. Prepare the oil phase and the water phase Mix 50 g of octylphenol polyoxyethylene ether - 10, 40 g of Tween 80, 60 g of Span 80 and 500 g of polystyrene sulfonic acid (boiling range 95 - 100 °C), and stir magnetically to make the mixture homogeneous to obtain the oil phase, then cover it with plastic wrap.

[0025] Add 300 g of acrylamide and 300 g of 2 - acrylamido - 2 - methylpropane sulfonic acid to 400 g of deionized water to obtain the first mixed solution. Under magnetic stirring, add an aqueous sodium hydroxide solution to the first mixed solution to adjust the pH value of the solution to 6 to obtain the second mixed solution. Add 4 g of 10 wt% aqueous sodium ethylenediaminetetraacetate solution to the second mixed solution, then add 150 mL (116.25 g) of tetramethylethylenediamine, and adjust the pH value to 7 with an aqueous sodium hydroxide solution to obtain the aqueous phase.

[0026] S1 - 1 - 2, Emulsification Pour the aqueous phase prepared in step S1 into the oil phase and emulsify for 20 minutes. During the emulsification process, continuously adjust the position of the beaker to make the liquid surface show ripples. Use a Brookfield DVLV - 3 viscometer with a No. 63 rotor to measure the liquid viscosity at a rotation speed of 30 revolutions per minute, and the measured viscosity is 200 mPa·s.

[0027] S1 - 1 - 3, Polymerization reaction Pour the emulsified liquid in step S2 into the reaction kettle, stir the liquid in the kettle at a speed of 120 r / min, and at the same time pass nitrogen into the kettle at a speed of 6 L / min for deoxygenation, and stir for 1 hour. Turn on the cooling water to lower the temperature in the reaction kettle to 12 °C (when the temperature is 13 °C, the cooling water can be turned off, and the remaining cold of the cooling water can basically lower the temperature in the kettle to 12 °C). Add 6 g of 2 wt% aqueous sodium bisulfite solution that has been pre - deoxygenated with nitrogen to the reaction kettle and react for ten minutes. Adjust the nitrogen flow rate to 2.5 L / min, add 20 g of 2 wt% aqueous sodium bisulfite solution that has been pre - deoxygenated with nitrogen to the reaction kettle at a rate of 4 mL / h. After adding, continue to add 6 g of 2 wt% aqueous sodium bisulfite solution that has been pre - deoxygenated with nitrogen to obtain the third mixed solution. Add 100 g of 15 wt% sodium metabisulfite aqueous solution to the third mixed solution at a rate of 4 mL / h to obtain the fourth mixed solution. When the temperature of the reaction system continues to drop, add 50 g of octylphenol polyoxyethylene ether - 10 to the fourth mixed solution with an ordinary pressure dropping funnel and stir at a speed of 120 r / min for 1 hour. Close the nitrogen, open the stopcock at the lower end of the reaction kettle, and load the sample synthesized by the reaction to obtain the high - molecular polymer HCSY.

[0028] S1 - 2, Preparation of surfactant HCBY Take a 1000 mL three-necked flask, clean it and dry it. Place the 1000 mL three-necked flask in a water bath, and configure a nitrogen inlet device, a stirring device and a condensation reflux device. Weigh 150 g of octadecyl dimethyl tertiary amine, 50 g of alkyl ether polyoxyethylene ether, 150 g of absolute ethanol, and 150 g of deionized water respectively, and add them to the three-necked flask in sequence. Then introduce nitrogen, seal and stir (the stirring speed is 120 r / min), control the water bath temperature to be (50 ± 0.5) °C, and carry out a constant temperature reaction for 24 h. After the reaction is completed, take out the three-necked flask and place it on a heating mantle to ensure that the temperature of the liquid in the three-necked flask is 75 °C, and start distillation. Distill until the liquid in the three-necked flask becomes a viscous paste. After the paste cools, a pale yellow surfactant HCBY is obtained.

[0029] S2. Prepare a coalbed methane desorption promoter Slowly add the high molecular polymer HCSY and the surfactant HCBY into a beaker at a mass ratio of 10:1. While adding, stir with a magnetic stirrer at a speed of 1800 r / min for 2 h to obtain a white transparent liquid, which is the coalbed methane desorption promoter.

[0030] Example 2 A coalbed methane desorption promoter is composed of a high molecular polymer HCSY and a surfactant HCBY at a mass ratio of 11:1. Among them, HCSY includes 33.41 wt% oil phase, 58.22 wt% water phase, 0.03 wt% sodium bisulfite (NaHSO3), 0.60 wt% sodium metabisulfite (Na2S2O5) and 2.30 wt% octylphenol polyoxyethylene ether-10. The oil phase is composed of octylphenol polyoxyethylene ether-10, Tween 80, Span 80, and polystyrene sulfonic acid at a mass ratio of 1:0.91:1.31:10. The water phase includes a mixture of disodium ethylenediaminetetraacetate (EDTA disodium), tetramethylethylenediamine, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) at a mass ratio of 0.0008:0.33:0.81:0.95, and the pH = 6.5. HCBY is composed of the following components by mass percentage: 29% octadecyl dimethyl tertiary amine, 8% alkyl ether polyoxyethylene ether, 31% absolute ethanol and 32% tap water.

[0031] The preparation method of the coalbed methane desorption promoter includes the following steps: S1. Prepare a high molecular polymer HCSY and a surfactant HCBY S1-1. Prepare a high molecular polymer HCSY S1-1-1. Prepare the oil phase and the water phase Mix 55 g of octylphenol polyoxyethylene ether-10, 50 g of Tween 80, 72 g of Span 80 and 550 g of polystyrene sulfonic acid, and stir magnetically to make the mixture homogeneous to obtain the oil phase, then cover it with plastic wrap.

[0032] Add 325 g of acrylamide and 380 g of 2-acrylamido-2-methylpropanesulfonic acid to 400 g of tap water to obtain the first mixed solution. Under magnetic stirring, add an aqueous sodium hydroxide solution to the first mixed solution to adjust the pH value of the solution to 6 to obtain the second mixed solution. Add 30 g of 1 wt% aqueous disodium ethylenediaminetetraacetate solution to the second mixed solution, then add 170 mL (131.75 g) of tetramethylethylenediamine, and adjust the pH value to 6.5 with an aqueous sodium hydroxide solution to obtain the aqueous phase.

[0033] S1-1-2, Emulsification Pour the aqueous phase prepared in step S1 into the oil phase and emulsify for 20 minutes. During the emulsification process, gently shake continuously to make the liquid surface show ripples. Use a Brookfield DVLV-3 viscometer with a No. 63 rotor to measure the liquid viscosity at a rotation speed of 30 revolutions per minute, and the measured viscosity is 180 mPa·s.

[0034] S1-1-3, Polymerization reaction Pour the emulsified liquid in step S2 into the reaction kettle, stir the liquid in the kettle at a speed of 110 r / min, and at the same time pass nitrogen at a speed of 6 L / min for deoxygenation, and stir for 70 min. Turn on the cooling water to lower the temperature in the reaction kettle to 10 °C. Add 4.8 g of 2 wt% aqueous sodium bisulfite solution that has been pre-deoxygenated with nitrogen into the reaction kettle and react for 12 minutes. Adjust the nitrogen flow rate to 2 L / min, add 21 g of 2 wt% aqueous sodium bisulfite solution that has been pre-deoxygenated with nitrogen into the reaction kettle at a feeding rate of 3 mL / h. After adding, continue to add 6.2 g of 2 wt% aqueous sodium bisulfite solution that has been pre-deoxygenated with nitrogen to obtain the third mixed solution. Add 100 g of 13 wt% sodium metabisulfite aqueous solution to the third mixed solution at a rate of 3 mL / h to obtain the fourth mixed solution. When the temperature of the reaction system continues to drop, add 50 g of octylphenol polyoxyethylene ether-10 to the fourth mixed solution with an ordinary pressure dropping funnel and stir at a speed of 120 r / min for 1 hour. Close the nitrogen, open the stopcock at the lower end of the reaction kettle, and load the sample synthesized by the reaction to obtain the high molecular polymer HCSY.

[0035] S1-2, Preparation of surfactant HCBY Clean and dry a 1000mL three-necked flask. Place the 1000mL three-necked flask in a water bath equipped with a nitrogen inlet, stirring apparatus, and condenser reflux apparatus. Weigh 145g of octadecyldimethylamine, 40g of alkyl ether polyoxyethylene ether, 155g of anhydrous ethanol, and 160g of tap water, respectively, and add them to the three-necked flask in that order. Pour nitrogen into the flask, seal it, and stir at 120 rpm. Maintain the water bath temperature at (55±0.5)°C and allow the reaction to continue at this constant temperature for 36 hours. After the reaction is complete, remove the three-necked flask and place it on a heating mantle, ensuring the liquid temperature is 75°C. Distillation should begin until the liquid in the flask becomes a viscous paste. Cool the paste to obtain the pale yellow surfactant HCBY.

[0036] S2. Preparation of coalbed methane desorption promoter The high molecular polymer HCSY and the surfactant HCBY were slowly added into a beaker at a mass ratio of 11:1, and stirred with a magnetic stirrer at a speed of 1900 r / min for 1.5 hours to obtain a white transparent liquid, which was the coalbed methane desorption promoter.

[0037] Example 3 A coalbed methane desorption promoter is composed of a polymer (HCSY) and a surfactant (HCBY) in a mass ratio of 10.5:1. HCSY comprises 29.84wt% oil phase, 64.22wt% aqueous phase, 0.02wt% sodium bisulfite (NaHSO3), 0.52wt% sodium metabisulfite (Na2S2O5), and 1.63wt% octylphenol polyoxyethylene ether-10. The oil phase consists of octylphenol polyoxyethylene ether-10, Tween 80, Span 80, and polystyrene sulfonic acid in a mass ratio of 1:0.9:1.35:12. The aqueous phase comprises a mixture of disodium ethylenediaminetetraacetate (disodium EDTA), tetramethylethylenediamine, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in a mass ratio of 0.0012:0.36:0.9:1, with a pH of 7.5. HCBY is composed of the following components in percentage by mass: 28% octadecyldimethyl tertiary amine, 12% alkyl ether polyoxyethylene ether, 30% anhydrous ethanol and 30% deionized water.

[0038] The preparation method of the coalbed methane desorption promoting agent comprises the following steps: S1. Preparation of polymer HCSY and surfactant HCBY S1-1. Preparation of high molecular weight polymer HCSY S1-1-1. Prepare oil phase and water phase Mix 60 g of octylphenol polyoxyethylene ether - 10, 54 g of Tween 80, 81 g of Span 80 and 720 g of polystyrene sulfonic acid, and stir magnetically to mix the mixture evenly to obtain an oil phase, then cover it with plastic wrap.

[0039] Add 540 g of acrylamide and 600 g of 2 - acrylamido - 2 - methylpropanesulfonic acid to 600 g of deionized water to obtain a first mixed solution. Under magnetic stirring, add an aqueous sodium hydroxide solution to the first mixed solution to adjust the pH value of the solution to 6 to obtain a second mixed solution. Add 12 g of 5 wt% aqueous disodium ethylenediaminetetraacetate solution to the second mixed solution, then add 280 mL (217 g) of tetramethylethylenediamine, and adjust the pH value to 7.5 with an aqueous sodium hydroxide solution to obtain an aqueous phase.

[0040] S1 - 1 - 2, Emulsification Pour the aqueous phase prepared in step S1 into the oil phase and emulsify for 20 minutes. During the emulsification process, continuously adjust the position of the beaker to make the liquid surface show ripples. Use a Brookfield DVLV - 3 viscometer with a No. 63 rotor to measure the liquid viscosity at a rotation speed of 30 revolutions per minute, and the measured viscosity is 190 mPa·s.

[0041] S1 - 1 - 3, Polymerization reaction Pour the emulsified liquid in step S2 into the reaction kettle, stir the liquid in the kettle at a speed of 130 r / min, and at the same time, pass nitrogen at a speed of 6 L / min for deoxygenation, and stir for 80 min. Turn on the cooling water to lower the temperature in the reaction kettle to 13 °C. Add 6.4 g of 2 wt% aqueous sodium bisulfite solution that has been pre - deoxygenated with nitrogen to the reaction kettle and react for 15 minutes. Adjust the nitrogen flow rate to 2 L / min, and add 19.2 g of 2 wt% aqueous sodium bisulfite solution that has been pre - deoxygenated with nitrogen to the reaction kettle at a rate of 5 mL / h. After adding, continue to add 6.4 g of 2 wt% aqueous sodium bisulfite solution that has been pre - deoxygenated with nitrogen to obtain a third mixed solution. Add 100 g of 16 wt% sodium metabisulfite aqueous solution to the third mixed solution at a rate of 5 mL / h to obtain a fourth mixed solution. When the temperature of the reaction system continues to drop, add 50 g of octylphenol polyoxyethylene ether - 10 to the fourth mixed solution with an ordinary pressure dropping funnel and stir at a speed of 120 r / min for 1 hour. Close the nitrogen, open the stopcock at the lower end of the reaction kettle, and load the sample synthesized by the reaction to obtain the high - molecular polymer HCSY.

[0042] S1 - 2, Preparation of surfactant HCBY Take a 1000 mL three-necked flask, clean it and dry it. Place the 1000 mL three-necked flask in a water bath, and configure a nitrogen inlet device, a stirring device and a condensation reflux device. Weigh 140 g of octadecyl dimethyl tertiary amine, 60 g of alkyl ether polyoxyethylene ether, 150 g of absolute ethanol, and 150 g of deionized water respectively, and add them to the three-necked flask in sequence. Then introduce nitrogen, seal and stir (the stirring speed is 120 r / min), control the water bath temperature to be (60±0.5)°C, and carry out a constant temperature reaction for 30 h. After the reaction is completed, take out the three-necked flask and place it on a heating mantle to ensure that the temperature of the liquid in the three-necked flask is 85°C, and start distillation. Distill until the liquid in the three-necked flask becomes a viscous paste. Cool the paste to obtain a pale yellow surfactant HCBY.

[0043] S2. Prepare a coalbed methane desorption promoter Slowly add the high molecular polymer HCSY and the surfactant HCBY into a beaker according to a mass ratio of 10.5:1. While adding, stir with a magnetic stirrer at a speed of 2000 r / min for 1.5 h to obtain a white transparent liquid, which is the coalbed methane desorption promoter.

[0044] Example 4 A coalbed methane desorption promoter is composed of a high molecular polymer HCSY and a surfactant HCBY according to a mass ratio of 12:1. Among them, HCSY includes 29.64 wt% oil phase, 62.87 wt% water phase, 0.03 wt% sodium bisulfite (NaHSO3), 0.58 wt% sodium metabisulfite (Na2S2O5) and 2.06 wt% octylphenol polyoxyethylene ether-10. The oil phase consists of octylphenol polyoxyethylene ether-10, Tween 80, Span 80, and polystyrene sulfonic acid in a mass ratio of 1:0.96:1.44:11. The water phase includes a mixture of disodium ethylenediaminetetraacetate (EDTA disodium), tetramethylethylenediamine, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in a mass ratio of 0.001:0.33:0.8:0.8, and pH = 7. HCBY is composed of the following components by mass percentage: 28% octadecyl dimethyl tertiary amine, 8% alkyl ether polyoxyethylene ether, 34% absolute ethanol and 30% water.

[0045] The preparation method of the coalbed methane desorption promoter includes the following steps: S1. Prepare a high molecular polymer HCSY and a surfactant HCBY S1-1. Prepare a high molecular polymer HCSY S1-1-1. Prepare the oil phase and the water phase Mix 50 g of octylphenol polyoxyethylene ether - 10, 48 g of Tween 80, 72 g of Span 80 and 550 g of polystyrene sulfonic acid, and stir magnetically to mix the mixture evenly to obtain the oil phase, then cover it with plastic wrap.

[0046] Add 416 g of acrylamide and 416 g of 2 - acrylamido - 2 - methylpropanesulfonic acid to 520 g of water to obtain the first mixed solution. Under magnetic stirring, add an aqueous sodium hydroxide solution to the first mixed solution to adjust the pH value of the solution to 6 to obtain the second mixed solution. Add 5 g of a 10 wt% aqueous solution of disodium ethylenediaminetetraacetate to the second mixed solution, then add 220 mL (170.5 g) of tetramethylethylenediamine, and adjust the pH value to 7 with an aqueous sodium hydroxide solution to obtain the aqueous phase.

[0047] S1 - 1 - 2, Emulsification Pour the aqueous phase prepared in step S1 into the oil phase and emulsify for 20 minutes. During the emulsification process, continuously adjust the position of the beaker to make the liquid surface show ripples. Use a Brookfield DVLV - 3 viscometer with a No. 63 rotor to measure the viscosity of the liquid at a rotational speed of 30 revolutions per minute, and the measured viscosity is 195 mPa·s.

[0048] S1 - 1 - 3, Polymerization reaction Pour the emulsified liquid in step S2 into the reaction kettle, stir the liquid in the kettle at a speed of 110 r / min, and at the same time pass nitrogen at a speed of 6 L / min for deoxygenation, and stir for 1.5 hours. Turn on the cooling water to lower the temperature in the reaction kettle to 11°C. Add 5.8 g of a 2 wt% aqueous solution of sodium bisulfite that has been pre - deoxygenated with nitrogen to the reaction kettle and react for 12 minutes. Adjust the nitrogen flow rate to 3 L / min, and add 21.4 g of a 2 wt% aqueous solution of sodium bisulfite that has been pre - deoxygenated with nitrogen to the reaction kettle at a rate of 4 mL / h. After adding, continue to add 4.8 g of a 2 wt% aqueous solution of sodium bisulfite that has been pre - deoxygenated with nitrogen to obtain the third mixed solution. Add 100 g of a 14 wt% aqueous solution of sodium metabisulfite to the third mixed solution at a rate of 4 mL / h to obtain the fourth mixed solution. When the temperature of the reaction system continues to drop, add 50 g of octylphenol polyoxyethylene ether - 10 to the fourth mixed solution with an ordinary pressure dropping funnel and stir at a speed of 120 r / min for 1 hour. Close the nitrogen, open the lower stopcock of the reaction kettle, and load the sample synthesized by the reaction to obtain the high - molecular polymer HCSY.

[0049] S1 - 2, Preparation of surfactant HCBY Take a 1000 mL three-necked flask, clean it and dry it. Place the 1000 mL three-necked flask in a water bath, and configure a nitrogen inlet device, a stirring device and a condensation reflux device. Weigh 140 g of octadecyl dimethyl tertiary amine, 40 g of alkyl ether polyoxyethylene ether, 170 g of absolute ethanol, and 150 g of water respectively, and add them to the three-necked flask in sequence. Then introduce nitrogen, seal and stir (stirring speed is 120 r / min), control the water bath temperature to be (60±0.5) °C, and carry out a constant temperature reaction for 32 h. After the reaction is completed, take out the three-necked flask and place it on a heating mantle to ensure that the temperature of the liquid in the three-necked flask is 80 °C, and start distillation. Distill until the liquid in the three-necked flask becomes a viscous paste, and cool the paste to obtain a pale yellow surfactant HCBY.

[0050] S2. Preparation of coalbed methane desorption promoter Slowly add the high molecular polymer HCSY and the surfactant HCBY into a beaker at a mass ratio of 12:1, and stir with a magnetic stirrer at a speed of 1850 r / min for 2.5 h while adding, to obtain a white transparent liquid, which is the coalbed methane desorption promoter.

[0051] Example 5 A coalbed methane desorption promoter is composed of a high molecular polymer HCSY and a surfactant HCBY at a mass ratio of 11.5:1. Among them, HCSY includes 25.65 wt% oil phase, 67.28 wt% water phase, 0.02 wt% sodium bisulfite (NaHSO3), 0.58 wt% sodium metabisulfite (Na2S2O5) and 1.94 wt% octylphenol polyoxyethylene ether-10. The oil phase is composed of octylphenol polyoxyethylene ether-10, Tween 80, Span 80, and polystyrene sulfonic acid at a mass ratio of 1:0.9:1.3:10. The water phase includes a mixture of disodium ethylenediaminetetraacetate (EDTA disodium), tetramethylethylenediamine, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) at a mass ratio of 0.001:0.33:0.85:0.9, and pH = 7. HCBY is composed of the following components by mass percentage: 28% octadecyl dimethyl tertiary amine, 8% alkyl ether polyoxyethylene ether, 30% absolute ethanol and 34% water.

[0052] The preparation method of the coalbed methane desorption promoter includes the following steps: S1. Preparation of high molecular polymer HCSY and surfactant HCBY S1-1. Preparation of high molecular polymer HCSY S1-1-1. Preparation of oil phase and water phase Mix 50 g of octylphenol polyoxyethylene ether-10, 45 g of Tween 80, 65 g of Span 80 and 500 g of polystyrene sulfonic acid, and stir magnetically to make the mixture evenly mixed to obtain the oil phase, and cover it with plastic wrap.

[0053] 476 g of acrylamide and 504 g of 2-acrylamido-2-methylpropanesulfonic acid were added to 560 g of water to obtain a first mixed solution. Under magnetic stirring, an aqueous sodium hydroxide solution was added to the first mixed solution to adjust the pH value of the solution to 6, obtaining a second mixed solution. 5.5 g of a 10 wt% aqueous solution of disodium ethylenediaminetetraacetate was added to the second mixed solution, and then 240 mL (186 g) of tetramethylethylenediamine was added. The pH value was adjusted to 7 with an aqueous sodium hydroxide solution to obtain an aqueous phase.

[0054] S1-1-2, Emulsification The aqueous phase prepared in step S1 was poured into the oil phase and emulsified for 20 minutes. During the emulsification process, the position of the beaker was continuously adjusted to make the liquid surface show ripples. The viscosity of the liquid was measured with a Brookfield DVLV-3 viscometer using rotor No. 63 at a rotation speed of 30 revolutions per minute, and the measured viscosity was 185 mPa·s.

[0055] S1-1-3, Polymerization reaction The emulsified liquid in step S2 was poured into the reaction kettle, and the liquid in the kettle was stirred at a speed of 120 r / min. At the same time, nitrogen was introduced at a speed of 6 L / min for deoxygenation, and stirring was carried out for 75 min. The cooling water was turned on to lower the temperature in the reaction kettle to 12 °C. 6 g of a 2 wt% aqueous solution of sodium bisulfite that had been pre-deoxygenated with nitrogen was added to the reaction kettle, and the reaction was carried out for 10 minutes. The nitrogen flow rate was adjusted to 2.5 L / min, and 20 g of a 2 wt% aqueous solution of sodium bisulfite that had been pre-deoxygenated with nitrogen was added to the reaction kettle at a rate of 3 mL / h. After adding, 6 g of a 2 wt% aqueous solution of sodium bisulfite that had been pre-deoxygenated with nitrogen was continuously added to obtain a third mixed solution. 100 g of a 15 wt% aqueous solution of metabisulfite was added to the third mixed solution at a rate of 4 mL / h to obtain a fourth mixed solution. When the temperature of the reaction system continued to drop, 50 g of octylphenol polyoxyethylene ether-10 was added to the fourth mixed solution using an ordinary pressure dropping funnel, and stirring was carried out at a speed of 120 r / min for 1 hour. The nitrogen was turned off, the lower stopcock of the reaction kettle was opened, and the sample synthesized by the reaction was loaded to obtain the high molecular polymer HCSY.

[0056] S1-2, Preparation of surfactant HCBY Take a 1000 mL three-necked flask, clean it and dry it. Place the 1000 mL three-necked flask in a water bath, and configure a nitrogen inlet device, a stirring device and a condensing reflux device. Weigh 140 g of octadecyl dimethyl tertiary amine, 40 g of alkyl ether polyoxyethylene ether, 150 g of absolute ethanol and 170 g of water respectively, and add them to the three-necked flask in sequence. Then introduce nitrogen, seal and stir (the stirring speed is 120 r / min), control the water bath temperature at (50 ± 0.5) °C, and carry out a constant-temperature reaction for 36 h. After the reaction is completed, take out the three-necked flask and place it on a heating mantle to ensure that the temperature of the liquid in the three-necked flask is 70 °C, and start distillation. Distill until the liquid in the three-necked flask becomes a viscous paste. After the paste cools, a pale yellow surfactant HCBY is obtained.

[0057] S2. Preparation of coalbed methane desorption promoter Slowly add the high molecular polymer HCSY and the surfactant HCBY into a beaker at a mass ratio of 11.5:1. While adding, stir with a magnetic stirrer at a speed of 1950 r / min for 2 h to obtain a white transparent liquid, which is the coalbed methane desorption promoter.

[0058] Performance evaluation of coalbed methane desorption promoter Prepare aqueous solutions of the coalbed methane desorption promoter prepared in Example 1 with mass percentages of 0.1%, 0.2%, 0.25%, 0.3% and 0.4% (hereinafter referred to as desorption promoter), and evaluate their surface tension, contact angle change and desorption amount at normal pressure.

[0059] 1. Evaluation of surface and interfacial tension Adopt the ring method, and use a BZY-1 type surface and interfacial tension tester to measure the surface tension values of the desorption promoter at different concentrations. The specific experimental procedures and principles are as follows: Prepare simulated formation water according to the actual formation water salinity of the coalbed methane reservoir (add 5 g of sodium chloride, 5 g of calcium chloride and 5 g of potassium chloride to 100 g of water, stir evenly to obtain simulated formation water), and prepare a desorption promoter solution with a certain concentration using the simulated formation water. First, fill the sample cylinder with distilled water and alcohol respectively to calibrate the instrument. Then drop the desorption promoter solution into a clean sample cell, start the equipment, and measure the surface tension values of the desorption promoter at different concentrations. Take the average value of three measurements for each concentration of the desorption promoter solution. The test results are shown in Table 1.

[0060] Table 1 Surface tension test results of desorption promoters at different concentrations

[0061] According to the surface tension test results, the surface tension values of the five desorption promoters from low to high are as follows: Desorption promoter E < Desorption promoter D < Desorption promoter C < Desorption promoter B < Desorption promoter A. When the concentration of the desorption promoter is 0.1% - 0.4%, the surface tension gradually decreases with the increase of concentration. When the concentration rises above 0.3%, with the continuous increase of concentration, the surface tension of the desorption promoter basically remains unchanged. That is, the surface tension values of desorption promoter D and desorption promoter E are relatively close, and both are less than 23 mN / m. For coalbed methane reservoirs, it is mainly the surface tension during the process of changing wettability.

[0062] 2. Evaluation of wettability improvement Using the "pendant drop method", the rock contact angle on the surface of core slices soaked in simulated formation water was measured at room temperature using a C601 type contact angle tester. The specific experimental procedure is as follows: (1) Place the untreated natural core slices in the simulated formation water, and drop the desorption promoters at different concentrations on the lower surface of the core slices through a micropipette. Measure the contact angle of the desorption promoters on the core surface at different concentrations using a contact angle tester.

[0063] (2) Place the untreated natural core slices in desorption promoter solutions at different concentrations and soak them for more than 72 hours. Then take out the core slices, wipe them clean, put the core slices treated with the desorption promoter back into the simulated formation water, and use the method in step (1) to measure the contact angle on the core surface.

[0064] (3) Compare the rock contact angles on the surface of the core slices in the simulated formation water before and after treatment with the desorption promoter, and evaluate the improvement effect of the desorption promoter at different concentrations on the contact angle. The results are shown in Table 2 and Figure 1 .

[0065] Table 2 Improvement effect of desorption promoters at different concentrations on contact angle

[0066] From the data in Table 2 and Figure 1 it can be seen that desorption promoter D has the best effect on changing wettability, followed by desorption promoter E. The ranking of the effects of five different concentrations of coalbed methane desorption promoters on wetting change is as follows: Desorption promoter D > Desorption promoter E > Desorption promoter C > Desorption promoter B > Desorption promoter A.

[0067] 3. Evaluation of the cumulative desorption capacity of coal and rock under atmospheric pressure Referring to the method in GB / T19560 - 2008 "Experimental Method for High - Pressure Isothermal Adsorption of Coal", an experimental evaluation of the influence of desorption promoters on the desorption capacity of coalbed methane was carried out using a high - pressure coalbed methane adsorption tester (model: 3H - 2000PD). The main experimental steps are as follows: (1)Preparation of coal samples: The coal samples were crushed and screened to collect coal sample particles with a mesh size of 60 - 80. Then the coal samples were placed in a constant-temperature drying oven and dried at 105°C for 12 hours. Subsequently, the coal samples were fully soaked in clean water and desorption promoters with different concentrations, and the moisture was filtered off. After natural drying until the moisture content of the coal samples reached 15%, the coal samples were put into sealed bags for standby.

[0068] (2)Detection of device airtightness: Open the device inlet valve, fill helium to a certain pressure, close the inlet valve, and observe the pressure changes in the sample cylinder and the reference cylinder. The pressure change should be controlled within 0.01 MPa.

[0069] (3)Determination of the free space volume of the sample cylinder: Put the coal samples into the sample cylinder, and refer to the method in GB / T19560 - 2008 to measure the free space volume of the sample cylinder using helium, and then calculate the volume of the coal samples from this.

[0070] (4)Adsorption experiment: Set the system temperature to 25°C, open the inlet valve of the sample cylinder, fill in high-purity (purity 99.9%) methane gas until the pressure reaches 7 MPa. After reaching adsorption equilibrium, record the adsorption equilibrium pressure.

[0071] (5)Desorption experiment: Open the outlet valve of the sample cylinder to reduce the pressure to atmospheric pressure and start the desorption experiment. Record the gas desorption amount at different times until no gas is produced from the experimental coal samples. Calculate the desorbed gas amount per unit mass of the coal samples. The experimental results are as Figure 2 shown. When conducting the variable-pressure desorption experiment, adjust the desorption experiment pressure through the pressure control device. The pressure decreases by 1 MPa every 6 hours, and start the variable-pressure desorption experiment from high pressure to low pressure.

[0072] It can be seen from Figure 2 above that under the same experimental conditions, the desorption amount of the blank hard coal sample (the coal sample that has not been treated with any reagents after reaching methane adsorption equilibrium) is 3.35 cm 3 / g; with the increase in the concentration of the desorption promoter, the desorption degree of the coal samples has all increased. The desorption capacity of desorption promoter A for coalbed methane (4.09 cm 3 / g) has increased by 22.1% compared to the blank sample, the desorption capacity of desorption promoter B for coalbed methane (4.55 cm 3 / g) has increased by 35.8% compared to the blank coal sample, and the desorption capacity of desorption promoter C for coalbed methane (4.55 cm 3 / g) has increased by 62.4% compared to the blank coal sample. The desorption amounts of desorption promoter D (concentration 0.3 wt%) and desorption promoter E (concentration 0.3 wt%) tend to be stable, being 5.92 cm 3 / g and 5.93 cm 3 / g, the desorption capacity relative to the blank coal sample increased by 77.0%. Therefore, after the coal samples were treated with different concentrations of desorption promoters, their cumulative desorption amounts at atmospheric pressure showed an increasing trend to varying degrees and tended to be stable at a desorption promoter concentration of 0.3 wt%.

[0073] In summary, according to the surface tension test results, the desorption promoter E has slightly better effects than the desorption promoter D. According to the wetting reversal effect, the desorption promoter D has better effects than the desorption promoter E. According to the desorption capacity, the desorption promoter E and the desorption promoter D have comparable effects. Therefore, when the desorption promoter in this application is used to promote the desorption of coalbed methane, the selected concentration range is 0.1 wt% to 0.4 wt%, preferably 0.2 wt% to 0.4 wt%, more preferably 0.25 wt% to 0.4 wt%, and even more preferably 0.3 wt% to 0.4 wt%. Considering the various properties of the desorption promoter and the cost performance, the optimal concentration of the desorption promoter is 0.3 wt%.

[0074] The above-described embodiments are only the preferred embodiments of this application and are not used to limit the protection scope of this application. For any person skilled in the art, various changes and modifications can be made to this application. Any simple equivalent changes and modifications made based on the protection scope and the content of the specification of this application shall be included in the protection scope of this application.

Claims

1. A coalbed methane desorption promoter, characterized in that, The coalbed methane desorption promoter is composed of a high molecular polymer HCSY and a surfactant HCBY in a mass ratio of (10 - 12):1; the high molecular polymer HCSY includes 25.5wt% - 33.5wt% oil phase, 57.0wt% - 67.5wt% water phase, 0.02wt% - 0.03wt% sodium bisulfite, 0.5wt% - 0.8wt% sodium metabisulfite, and 1.6wt% - 2.6wt% octylphenol polyoxyethylene ether - 10; the oil phase is composed of octylphenol polyoxyethylene ether - 10, Tween 80, Span 80, and polystyrene sulfonic acid in a mass ratio of (1 - 1.2):(0.8 - 0.96):(1.2 - 1.44):(10 - 12); the water phase includes a mixture of disodium ethylenediaminetetraacetate, tetramethylethylenediamine, acrylamide, and 2 - acrylamido - 2 - methylpropanesulfonic acid in a mass ratio of (0.001 - 0.0012):(0.3 - 0.36):(0.75 - 0.9):(0.75 - 1), and the pH of the water phase is 6.5 - 7.5; the surfactant HCBY is composed of the following components by mass percentage: 28% - 30% octadecyl dimethyl tertiary amine, 8% - 12% alkyl ether polyoxyethylene ether, 30% - 34% absolute ethanol, and 30% - 34% water.

2. The preparation method of the coalbed methane desorption promoter according to claim 1, characterized in that, Comprising the following steps: S1. Prepare the high molecular polymer HCSY and the surfactant HCBY S1 - 1. Prepare the high molecular polymer HCSY: respectively prepare the oil phase and the water phase; pour the water phase into the oil phase for emulsification; after the emulsified liquid reacts for a period of time under an inert gas atmosphere, cool it to 10 - 13°C, and add the pre - deoxygenated sodium bisulfite aqueous solution in batches to obtain a third mixed liquid; add the sodium metabisulfite aqueous solution to the third mixed liquid to obtain a fourth mixed liquid; when the temperature of the reaction system continuously drops, add octylphenol polyoxyethylene ether - 10 to the fourth mixed liquid, and stir until the reaction ends to obtain the high molecular polymer HCSY; S1 - 2. Prepare the surfactant HCBY Mix octadecyl dimethyl tertiary amine, alkyl ether polyoxyethylene ether, absolute ethanol, and water, and heat and react under an inert gas atmosphere; after the reaction ends, distill the reaction liquid to a viscous paste to obtain the surfactant HCBY; S2. Mix the high molecular polymer HCSY and the surfactant HCBY evenly according to the mass ratio to obtain the coalbed methane desorption promoter.

3. The preparation method according to claim 2, characterized in that, The preparation method of the water phase includes the following steps: add acrylamide and 2 - acrylamido - 2 - methylpropanesulfonic acid to water to obtain a first mixed liquid; adjust the pH of the first mixed liquid to 6 to obtain a second mixed liquid; add the disodium ethylenediaminetetraacetate aqueous solution to the second mixed liquid, and then add tetramethylethylenediamine, and adjust the pH to 6.5 - 7.5 to obtain the water phase.

4. The preparation method according to claim 2, wherein In step S1 - 1, the emulsified liquid is stirred and reacted at a stirring speed of 110 - 130 r / min for 1 - 1.5 h under an inert gas atmosphere.

5. The preparation method according to claim 2, characterized in that, In step S1-1, the addition process of the aqueous sodium bisulfite solution is as follows: First, add the pre-deoxygenated aqueous sodium bisulfite solution to the cooled reaction system, where the solute mass accounts for 15% - 20% of the total mass of sodium bisulfite, and react for 10 - 15 minutes; Second, continue to add the pre-deoxygenated aqueous sodium bisulfite solution, where the solute mass accounts for 60% - 67% of the total mass of sodium bisulfite, and control the addition rate to be 3 - 5 g of sodium bisulfite solute per hour; After the second addition, continue to add the remaining pre-deoxygenated aqueous sodium bisulfite solution to obtain the third mixed solution.

6. The preparation method according to claim 2, wherein In step S1-1, the addition rate of the aqueous sodium metabisulfite solution to the third mixed solution is controlled to be 3 - 5 g of sodium metabisulfite solute per hour.

7. The preparation method according to claim 2, wherein The conditions for the heating reaction in step S1-2 are: water bath heating to a temperature of 50 - 60 °C and constant temperature reaction for 24 - 36 h.

8. The preparation method according to claim 2, wherein The distillation temperature in step S1-2 is 70 °C - 85 °C.

9. The preparation method according to claim 2, characterized in that, The conditions for uniform mixing in step S2 are: stirring at a stirring speed of 1800 - 2000 r / min for 1.5 - 2.5 h.

10. Use of the coalbed methane desorption promoter according to claim 1 in promoting coalbed methane desorption.

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