Coal rock gas-promoting desorption-aiding integrated functional aid as well as preparation method and application of coal rock gas-promoting desorption-aiding integrated functional aid

Abstract

The invention discloses a coal rock gas desorption-aiding integrated functional aid as well as a preparation method and application thereof, and belongs to the field of coal rock gas fracturing development chemical aids. The assistant is prepared by polymerizing a fluorine-containing monomer, a hard monomer, a soft monomer and a salt-resistant monomer under the action of an initiator by adopting a pre-emulsification semi-continuous emulsion polymerization method, wherein the hard monomer is a monomer containing a benzene ring, the soft monomer is an acrylate monomer, the salt-resistant monomer is a monomer containing a sulfo group, and in the pre-emulsification semi-continuous emulsion polymerization method, an emulsion is formed by utilizing an emulsifier and a co-emulsifier. The product has good stability, temperature resistance and salt resistance, shows excellent surface and interface activity and discharge aiding performance, can effectively reduce irreducible water saturation and water locking effect, is beneficial to flowback of fracturing fluid, can be stably adsorbed on coal rock, completes surface modification, changes coal seam wettability, expands a seepage channel, and improves fracturing efficiency. The desorption of the coal-rock gas is increased, and finally the purpose of greatly increasing the yield of the coal-rock gas is achieved.

Description

Technical Field

[0001] The present invention relates to the field of chemical additives for coalbed methane, and particularly to an integrated functional additive for promoting desorption and assisting in flowback of coalbed methane fracturing, its preparation method and application. Background Art

[0002] The reserves of coalbed methane in China are very rich. At present, the development of coalbed methane mainly uses hydraulic fracturing technology to increase its production. With the large-scale use of hydraulic fracturing, the damage of hydraulic fracturing to the development of coalbed methane gradually appears. The damage mechanisms of hydraulic fracturing mainly include water sensitivity effect, water lock effect, wettability reversal and permeability damage, all of which will lead to difficult desorption of coalbed methane, showing a slow flowback rate and a low flowback ratio of fracturing fluid in the flowback stage, affecting the production and recovery rate of coalbed methane in the gas production stage.

[0003] More than 95% of the coalbed methane in the reservoir exists in the inner surface of the coal matrix in the form of physical adsorption. The quality of desorption-diffusion performance directly determines the production rate and output of coalbed methane. With the expansion of the scale of coalbed methane hydraulic fracturing, although it can increase the production of coalbed methane to a certain extent, the above side effects will also limit the increase in production.

[0004] The performance of conventional additives is unstable in the high-salt environment of coal reservoirs and is prone to failure. The flowback effect is limited by formation conditions, construction technology, etc., and it is difficult to effectively reduce water lock damage and reservoir permeability damage.

[0005] Coalbed methane requires an efficient and convenient fracturing additive to promote the desorption of coalbed methane from the coal seam through hydraulic fracturing, reduce the water lock effect, capillary force, and have excellent salt resistance performance, etc., so as to promote the rapid diffusion and seepage of coalbed methane from the coal seam, and improve the flowback rate of fracturing flowback fluid to increase the production of coalbed methane. Summary of the Invention

[0006] In order to solve at least the above problems, the present invention provides an integrated functional additive for promoting desorption and assisting in flowback of coalbed methane fracturing, its preparation method and application.

[0007] The technical solution for solving the above technical problems of the present invention is as follows: A preparation method of an integrated functional additive for promoting desorption and assisting in flowback of coalbed methane is prepared by pre-emulsification semi-continuous emulsion polymerization based on fluorine-containing monomers, hard monomers, soft monomers and salt-resistant monomers under the action of an initiator; wherein, the hard monomer is a monomer containing a benzene ring, the soft monomer is an acrylate monomer, the salt-resistant monomer is a monomer containing a sulfonic group, and in the pre-emulsification semi-continuous emulsion polymerization method, an emulsion is formed by using an emulsifier and a co-emulsifier.

[0008] One embodiment of the present invention is that the pre-emulsification semi-continuous emulsion polymerization method includes the following steps:

[0009] S1. Take 40 - 50 wt% of emulsifier, 40 - 50 wt% of co - emulsifier and 60 - 70 wt% of water, stir to make them evenly dispersed, then add fluorine - containing monomer, hard monomer, soft monomer and anti - salt monomer, and emulsify and disperse to obtain a pre - emulsion; Take initiator and add water to prepare an initiator solution; Take the remaining emulsifier, co - emulsifier and water, mix evenly to prepare a first emulsion;

[0010] S2. Under the conditions of deoxidation and initiation temperature, dropwise add the initiator solution and the first emulsion into the emulsion and react. After the reaction ends, it is obtained.

[0011] In one embodiment of the present invention, by mass percentage, the addition amount of the fluorine - containing monomer is 3% - 6%, the addition amount of the hard monomer is 3% - 5%, the addition amount of the soft monomer is 9% - 11%, the addition amount of the anti - salt monomer is 2% - 4%, the addition amount of the emulsifier is 14% - 18%, the addition amount of the co - emulsifier is 2% - 4%, the addition amount of the initiator is 0.3% - 0.5%, and the balance is water.

[0012] In one embodiment of the present invention, the fluorine - containing monomer is one of 2 - (trifluoromethyl) acrylic acid, trifluoropropene, perfluoroethyl vinyl ether, trifluoromethyl trifluorovinyl ether; The hard monomer is one of styrene, p - methylstyrene, phenyl methacrylate; The soft monomer is one of isooctyl acrylate, butyl acrylate, 2 - hydroxyethyl acrylate, 2 - hydroxyethyl methacrylate, lauryl acrylate, lauryl methacrylate, 2 - ethylhexyl acrylate; The anti - salt monomer is sulfobetaine methacrylate.

[0013] In one embodiment of the present invention, the initiator is persulfate, the reaction temperature is 60 - 65 °C, and the reaction time is 3 - 4 h.

[0014] In one embodiment of the present invention, the emulsifier is one of the following combinations: sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether with a mass ratio of 4 - 5:5 - 6, sodium dodecyl sulfate and ammonium cocoyl sulfate with a mass ratio of 3 - 4:6 - 7; The co - emulsifier is one of ethylene glycol, propylene glycol and n - butanol.

[0015] Another object of the present invention is to disclose an integrated function assistant for promoting coal - rock gas desorption and drainage, which is prepared by any of the above - mentioned methods.

[0016] Another object of the present invention is to disclose the application of the above - mentioned integrated function assistant for promoting coal - rock gas desorption and drainage in coal - rock hydraulic fracturing development.

[0017] The beneficial effects of the present invention are as follows: The coal-rock gas desorption promotion and drainage assistance integrated functional additive has excellent mechanical, dilution, heat, cold and storage stabilities and salt resistance performance. By stably adsorbing on the coal seam, it changes the wettability of the coal seam surface, greatly reduces the surface energy of the coal-rock surface and the adhesion work of the coal-rock to the water phase, and reduces the capillary force. At the same time, it has a good drainage assistance effect, can effectively reduce the irreducible water saturation and water lock effect of the coal seam, expand the desorption channels of coal-rock gas, reduce the damage to the coal-rock reservoir, and is beneficial to the desorption-diffusion-seepage of coal-rock gas, achieving the effects of improving the desorption of coal-rock gas and the drainage assistance of the returned liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a test result diagram of the influence of concentration on the adsorption amount.

[0019] Figure 2 It is a test result diagram of the influence of adsorption time on the adsorption amount. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The principles and features of the present invention will be described below in conjunction with the drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0021] In the following embodiments, unless otherwise specified, the parts are by weight.

[0022] In the following embodiments, unless otherwise specified, the reagents used are all conventional commercial products.

[0023] In the following embodiments, unless otherwise specified, the operations used are all conventional operations in the art.

[0024] In the following embodiments, the fatty alcohol polyoxyethylene ether is purchased from Shanghai Huijun Chemical Co., Ltd.

[0025] Example 1

[0026] The raw materials for preparing the coal-rock gas desorption promotion and drainage assistance integrated functional additive in this example are as follows: 5 parts of trifluoromethyl trifluorovinyl ether, 4 parts of styrene, 10 parts of butyl acrylate, 3 parts of sulfobetaine methacrylate, 15 parts of sodium dodecylbenzenesulfonate (SDBS) and fatty alcohol polyoxyethylene ether (AEO-9), 3 parts of ethylene glycol, 0.4 part of ammonium persulfate, and 59.6 parts of deionized water.

[0027] S1. Take 3 parts of sodium dodecylbenzenesulfonate, 3 parts of fatty alcohol polyoxyethylene ether, 1.2 parts of ethylene glycol and 36 parts of water, stir rapidly to disperse them, and then add 5 parts of trifluoromethyl trifluorovinyl ether, 4 parts of styrene, 10 parts of butyl acrylate, and 3 parts of sulfobetaine methacrylate, and stir to emulsify to obtain a pre-emulsion; take 0.4 part of ammonium persulfate and add 1.6 parts of water to prepare an initiator solution, and take 4.5 parts of sodium dodecylbenzenesulfonate, 4.5 parts of fatty alcohol polyoxyethylene ether and 21 parts of water to prepare a first emulsion.

[0028] S2. Take the pre-emulsion, after purging with nitrogen to remove oxygen, at 65 °C, dropwise add the initiator solution and the first emulsion to the pre-emulsion. After the dropping is completed, continue to react for 3 h. After the reaction is completed, cool to room temperature to obtain the integrated function aid C1 for promoting desorption and drainage.

[0029] Example 2

[0030] Compared with Example 1, the difference is that the addition amount of trifluoromethyl trifluorovinyl ether is 4 parts, and the deionized water is 60.6 parts, and the rest are the same. Finally, the integrated function aid C2 for promoting desorption and drainage is obtained.

[0031] Example 3

[0032] Compared with Example 1, the difference is that trifluoromethyl trifluorovinyl ether is replaced by 2-(trifluoromethyl)acrylic acid, and the rest are the same. Finally, the integrated function aid C3 for promoting desorption and drainage is obtained.

[0033] Example 4

[0034] Compared with Example 1, the difference is that styrene is replaced by p-methylstyrene, and the rest are the same. Finally, the integrated function aid C4 for promoting desorption and drainage is obtained.

[0035] Example 5

[0036] Compared with Example 1, the difference is that styrene is replaced by phenyl methacrylate, and the rest are the same. Finally, the integrated function aid C5 for promoting desorption and drainage is obtained.

[0037] Example 6

[0038] Compared with Example 1, the difference is that butyl acrylate is replaced by isooctyl acrylate, and the rest are the same. Finally, the integrated function aid C6 for promoting desorption and drainage is obtained.

[0039] Example 7

[0040] Compared with Example 1, the difference is that butyl acrylate is replaced by lauryl acrylate, and the rest are the same. Finally, the integrated function aid C7 for promoting desorption and drainage is obtained.

[0041] Comparative Example 1:

[0042] Compared with Example 1, the fluorine-containing monomer trifluoromethyl trifluorovinyl ether was replaced with the same mass of water, and the rest were the same. Finally, the desorption-promoting and drainage-assisting integrated functional additive D1 sample was obtained.

[0043] Comparative Example 2:

[0044] Compared with Example 1, the hard monomer styrene was replaced with the same mass of water, and the rest were the same. Finally, the desorption-promoting and drainage-assisting integrated functional additive D2 sample was obtained.

[0045] Comparative Example 3:

[0046] Compared with Example 1, the soft monomer butyl acrylate was replaced with the same mass of water, and the rest were the same. Finally, the desorption-promoting and drainage-assisting integrated functional additive D3 sample was obtained.

[0047] Comparative Example 4:

[0048] Compared with Example 1, the salt-resistant monomer sulfobetaine methacrylate was replaced with the same mass of water, and the rest were the same. Finally, the desorption-promoting and drainage-assisting integrated functional additive D4 sample was obtained.

[0049] In order to further illustrate the performance of the products prepared in the embodiments of the present invention, the following tests were carried out on them.

[0050] 1. Stability

[0051] (1) Mechanical stability: Take the desorption-promoting and drainage-assisting integrated functional additive C1, place it in a high-speed centrifuge, and centrifuge it at rotational speeds of 1000 r / min, 2000 r / min, and 3000 r / min for 0.5 h respectively. Observe the layering or precipitation of the desorption-promoting and drainage-assisting integrated functional additive solution. If layering or precipitation occurs, it is regarded as unstable. The final test results are shown in Table 1.

[0052] (2) Dilution stability: Take the desorption-promoting and drainage-assisting integrated functional additive C1, and prepare solutions with mass ratios of one-thousandth, five-thousandths, and one-hundredth respectively by adding water. Let them stand at room temperature for 7 days, and observe whether there is layering or precipitation. If layering or precipitation occurs, it is regarded as unstable. The final test results are shown in Table 1.

[0053] (3) Thermal stability: Take the desorption-promoting and drainage-assisting integrated functional additive C1, place it in an oven at 35 ± 10 °C respectively, keep it for 1 h, cool it to room temperature, and repeat this 5 times. Observe whether there is layering or aggregation. The final test results are shown in Table 1.

[0054] (4) Cold stability: Take an appropriate amount of the desorption-promoting and drainage-assisting integrated functional additive and place it in a low-temperature oven at -10 ± 5 °C for 24 h to 1 h at room temperature, and observe whether there is condensation or caking. The final test results are shown in Table 1.

[0055] (5) Storage stability: Take an appropriate amount of the integrated function additive for promoting desorption and assisting drainage of coalbed methane, seal it and place it in a cool place at room temperature. After storing for 1 month, 3 months, and 6 months respectively, observe whether the integrated function additive for promoting desorption and assisting drainage shows stratification or precipitation. The final test results are shown in Table 1.

[0056] Table 1 Stability test of the integrated function additive for promoting desorption and assisting drainage

[0057]

[0058] It can be obtained from Table 1 that the integrated function additive for promoting desorption and assisting drainage of coalbed methane shows excellent stability in the tests of mechanical stability, dilution stability, thermal stability, cold stability, and storage stability. The integrated function additive for promoting desorption and assisting drainage of coalbed methane in the present invention has good mechanical stability, thermal stability, cold stability, dilution stability, and storage stability, which is beneficial to the storage and transportation of the products in the embodiments of the present invention.

[0059] 2. Adsorption performance

[0060] Experimental instrument: UV-1800 ultraviolet-visible spectrophotometer

[0061] (1) Influence of concentration on adsorption capacity

[0062] Prepare solutions of the integrated function additives C1, C6, and C7 for promoting desorption and assisting drainage with concentrations of 100, 500, 1000, 2000, and 5000 mg / L respectively using deionized water. Take appropriate amounts of coal sample powder (No. 8 coal in the deep layer of Daning-Jixian block, Shanxi) and mix it with the integrated function additive solutions with different concentrations. Add the mixed samples into a conical flask, seal it, and place it in a constant temperature shaker at room temperature for oscillation. After 24 h, centrifuge and separate, and measure the adsorption capacity of the integrated function additives for promoting desorption and assisting drainage on the coal sample powder at different concentrations. The experimental results are as Figure 1 shown.

[0063] (2) Influence of adsorption time on adsorption capacity

[0064] According to the preparation method described in step (1) above, prepare solutions of the integrated function additives C1, C6, and C7 for promoting desorption and assisting drainage with a concentration of 1000 mg / L. Take appropriate amounts of coal sample powder and mix it, place it in a conical flask, seal it, and place it in a constant temperature shaker at room temperature for oscillation. After 0.5, 1, 2, 3, and 4 h, centrifuge and sample respectively, and measure the adsorption capacity of the coal sample powder at different adsorption times. The experimental results are as Figure 2 shown.

[0065] It can be seen from the experimental results that when the concentration of the integrated function aid for promoting desorption and drainage is 1000 mg / L and the adsorption time is more than 1 h, it can be stably adsorbed on the coal sample. It can be seen that the product prepared in the embodiment of the present invention can be quickly adsorbed on the coal rock; after the adsorption is stable, oscillation does not affect the adsorption capacity of the integrated function aid for promoting desorption and drainage of coalbed methane, and the integrated function aid for promoting desorption and drainage of coalbed methane has good adsorption stability.

[0066] 3. Surface activity test

[0067] 3.1. Conventional surface activity test: Take the integrated function aids for promoting desorption and drainage in Examples 1 to 7 and Comparative Examples 1 to 4, add water to prepare a concentration of 1000 mg / L, test their surface tension, and at the same time test their interfacial tension with kerosene. The test temperature is 25 °C, and the drainage aid SAZP-1 of Sichuan Shenhe New Material Technology Co., Ltd. is used as a comparative sample for the experiment.

[0068] Table 2 Surface and interfacial tensions of C1, C4, C5 and comparative examples prepared with clear water

[0069] Sample C1 C2 C3 C4 C5 C6 C7 Surface tension (mN / m) 21.14 22.16 21.37 21.78 21.29 21.48 21.51 Interfacial tension (mN / m) 0.25 0.43 0.25 0.41 0.27 0.49 0.51 Sample D1 D2 D3 D4 Control sample / / Surface tension (mN / m) 26.76 21.55 21.78 22.34 24.20 / / Interfacial tension (mN / m) 0.93 0.36 0.44 0.49 0.55 / /

[0070] 3.2. Surface activity test after gel breaking:

[0071] Prepare fracturing fluid: 0.4% SFY-2, 0.03% breaker ammonium persulfate, and the rest is water. Take the integrated function aids for promoting desorption and drainage C1, C4, C5 and the comparative sample SZAP-1 and add them to the above-mentioned fracturing fluid at a concentration of 1000 mg / L.

[0072] Test condition ①: After preparing the fracturing fluid, break the gel at 90 °C for 4 h and then cool to obtain the gel-breaking fluid. Divide the gel-breaking fluid into four groups, and add C1, C4, C5 and SZAP-1 at the above concentrations respectively. After mixing evenly, test their surface and interfacial tensions.

[0073] Test condition ②: After preparing the fracturing fluid, divide it into four groups on average, and add C1, C4, C5 and SZAP-1 at the above concentrations respectively. After breaking the gel of several groups of fracturing fluids at 90 °C for 4 h, cool and then test the surface and interfacial tensions of the gel-breaking fluid of the fracturing fluid.

[0074] The test results are shown in Table 3.

[0075] Table 3 Test of surface and interfacial tensions of gel-breaking fluids of fracturing fluids prepared under different conditions

[0076]

[0077] The results show that: after the desorption-promoting and drainage-aiding integrated functional additive provided by the present invention is compounded with the fracturing fluid, it can effectively reduce the surface and interfacial tensions of the gelled fluid, far lower than the technical requirements of the industry standard that the surface tension is lower than 28 mN / m and the interfacial tension is lower than 2 mN / m. After the compared SZAP-1 drainage-aiding agent is compounded with the system, the ability to reduce the surface and interfacial tensions is small; more importantly, under the conditions of simulating the gelling temperature and gelling time of the formation, the surface and interfacial tensions of the comparative example are greatly affected, while the desorption-promoting and drainage-aiding integrated functional additive provided by the present invention has good temperature resistance, and its surface activity is not affected by the condition of long-term heating, which is closely related to the molecular design during its synthesis.

[0078] 3.3. Surface activity test under high-salt conditions: Prepare brines with salinities of 1000, 5000, 10000, 50000, 1000000, and 150000 mg / L respectively. Use different brines to prepare the solutions of the desorption-promoting integrated functional additive C1 and SAZP-1. The sample concentration is 1000 mg / L, and test their surface tensions at a test temperature of 25°C; at the same time, add kerosene and test their interfacial tensions. The final results are shown in Table 4.

[0079] Table 4 Surface and interfacial tensions of C1 and the comparative example prepared with brines of different salinities

[0080]

[0081] The above test results show that: compared with the comparative SAZP-1, the desorption-promoting and drainage-aiding integrated functional additive provided by the present invention shows lower surface and interfacial tensions both in fresh water and fracturing fluid. At the same time, high-salinity brine has little effect on the surface and interfacial activities of the desorption-promoting and drainage-aiding integrated functional additive. Even in brine with a salinity of 150000 mg / L, it shows excellent performance in reducing interfacial and surface tensions, fully reflecting its excellent salt tolerance. For the case where the formation water salinity in the coal-rock reservoir reaches 150000 mg / L, the desorption-promoting and drainage-aiding integrated functional additive still maintains its good performance.

[0082] 4. Wettability test

[0083] Experimental instrument: Contact angle measuring instrument. Preparation of coal sample thin slices: Grind the coal sample to 200 mesh, weigh 0.5 g of the coal sample after drying to constant weight and put it into a mold for pressurization, and press it into a uniform thin slice under a pressure of 15 MPa.

[0084] Wetting contact angle test under clear water conditions: Take the integrated function aids for promoting desorption and drainage C1, C2, and C3, as well as D1 - D4. Prepare solutions with a concentration of 1000 mg / L using clear water. Then soak the coal samples and coal slices in the clear water and the aforementioned 7 groups of test samples for 2 hours respectively. Take out the slices and place them on the stage of the contact angle measuring instrument. Drop distilled water onto the coal samples and conduct contact angle tests using the protractor method respectively. The results are shown in Table 5.

[0085] Wetting contact angle test under fracturing fluid conditions: Prepare fracturing fluid: 0.4% SFY - 2, 0.03% breaker, and the rest is water. Take the integrated function aids for promoting desorption and drainage C1, C2, and C3, and prepare test solutions with a concentration of 1000 mg / L of the integrated function aids for promoting desorption and drainage using the aforementioned fracturing fluid. After the four groups of liquids are broken at 90°C for 4 hours, take the aforementioned coal slices and soak them for 2 hours respectively. Take out the slices and place them on the stage of the contact angle measuring instrument. Drop distilled water onto the coal slices and conduct contact angle tests using the protractor method respectively. The results are shown in Tables 5 and 6.

[0086] Table 5 Test results of wetting contact angle under clear water conditions

[0087] Sample Clear water C1 C2 C3 D1 D2 D3 D4 Contact angle ° 72.578 124.784 126.681 127.289 66.34 105.743 110.411 120.674

[0088] Table 6 Test results of wetting contact angle under fracturing fluid conditions

[0089] Sample Fracturing fluid C1 C2 C3 Contact angle ° 68.17 98.097 98.128 96.504

[0090] It can be seen from Tables 5 and 6 respectively that under initial conditions, the initial coal samples can be wetted by water and fracturing breaker fluid. Adding the integrated function aids for promoting desorption and drainage to clear water can make the contact angle of the liquid on the coal seam surface up to 127.289° at most; after adding the integrated function aids for promoting desorption and drainage C1, C2, and C3 to the fracturing fluid and breaking it, the contact angle of the liquid on the coal seam surface can also be greater than 90°. The above experimental results show that the integrated function aids for promoting desorption and drainage can significantly increase the contact angle of the coal seam, thereby increasing the functional performance of the coal seam surface, effectively increasing the gas-phase seepage channels, and being beneficial to the desorption of coalbed methane.

[0091] 5. Drainage aid rate test

[0092] Prepare solutions with a concentration of 1000 mg / L using clear water with the integrated function aids for promoting desorption and drainage C1 - C7 and D1 - D4. Determine the drainage aid rate with reference to the method in 6.8.1 of SY / T 5755 - 2016 "Performance Evaluation Method for Drainage Aids Used in Fracturing and Acidizing". Use the drainage aid SAZP - 1 of Sichuan Shenhe New Materials Technology Co., Ltd. as a comparison sample for testing. Among them, comparison sample one, comparison sample two, and comparison sample three refer to the samples with SAZP - 1 added at concentrations of 1000 mg / L, 2000 mg / L, and 3000 mg / L respectively. The final test results are shown in Table 7.

[0093] Table 7 Testing of surface tension, interfacial tension, and displacement efficiency

[0094] Sample C1 C2 C3 C4 C5 C6 C7 Drainage assistance rate % 88.2 82.4 87.9 90.8 87.3 85.5 83.5 Sample D1 D2 D3 D4 Control sample 1 Control sample 2 Control sample 3 Drainage assistance rate % 38.7 63.3 68.4 72.4 40.8 63.7 75.2

[0095] From the data in the above table, it can be seen that the desorption-promoting and displacement-integrated additive of the present invention has good surface tension and interfacial tension. At a concentration of 1000 mg / L, the displacement efficiency of C1-C7 is all higher than 80%, while the displacement efficiency of the comparative SAZP-1 is only 40.8% at a concentration of 1000 mg / L; when the concentration of the comparative sample SAZP-1 is increased to 3000 mg / L, its surface and interfacial tensions are lower than those of C1-C7, but the displacement efficiency is still only 75%, far lower than the test indexes of the samples provided by the present invention, indicating that the excellent displacement performance of the desorption-promoting and displacement-integrated additive provided by the present invention is endowed by the superposition of its multiple comprehensive performances.

[0096] 6. Performance test comparison between Example 1 and its comparative examples

[0097] Using the samples prepared in Example 1 and Comparative Examples 1-4, the adsorption performance, surface tension, wettability, temperature resistance stability, and salt resistance stability were evaluated respectively according to the above methods, and the test results are shown in Table 8.

[0098] Table 8 Statistical results of performance tests of different samples (concentration 1000 mg / L)

[0099]

[0100] According to the understanding of the conventional technical means for preparing surfactants by those skilled in the art, it may be considered that functional monomers only affect surface tension and wetting contact angle, hard monomers only affect temperature resistance stability, and anti-salt monomers only affect salt resistance stability. If one of them is missing, the corresponding performance will be affected and other performances will not be affected. However, from the test results, no matter which component changes, the performances of the prepared surfactants will be affected to varying degrees. Therefore, the roles of several components are indispensable, and combination experiments of different components and dosages need to be carried out according to their roles to achieve the desired best effect.

[0101] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A preparation method of an integrated functional additive for promoting coalbed methane desorption and drainage, characterized in that, It is prepared by pre-emulsifying semi-continuous emulsion polymerization based on fluorine-containing monomers, hard monomers, soft monomers and anti-salt monomers under the action of an initiator; wherein, the hard monomer is a monomer containing a benzene ring, the soft monomer is an acrylate monomer, the anti-salt monomer is a monomer containing a sulfo group, and in the pre-emulsifying semi-continuous emulsion polymerization method, an emulsion is formed by using an emulsifier and a co-emulsifier.

2. The method according to claim 1, characterized in that, The pre-emulsifying semi-continuous emulsion polymerization method comprises the following steps: S1. Take 40-50 wt% of emulsifier, 40-50 wt% of co-emulsifier and 60-70 wt% of water, stir to make them evenly dispersed, then add fluorine-containing monomers, hard monomers, soft monomers and anti-salt monomers, and emulsify and disperse to obtain a pre-emulsion; Take an initiator and add water to prepare an initiator solution; Take the remaining emulsifier, co-emulsifier and water, mix evenly to prepare a first emulsion; S2. Under the conditions of deoxygenation and initiation temperature, dropwise add the initiator solution and the first emulsion to the emulsion and react, and obtain the product after the reaction ends.

3. The method according to claim 1 or 2, characterized in that, By mass percentage, the addition amount of the fluorine-containing monomer is 3%-6%, the addition amount of the hard monomer is 3%-5%, the addition amount of the soft monomer is 9%-11%, the addition amount of the anti-salt monomer is 2%-4%, the addition amount of the emulsifier is 14%-18%, the addition amount of the co-emulsifier is 2%-4%, the addition amount of the initiator is 0.3%-0.5%, and the balance is water.

4. The method according to claim 1 or 2, characterized in that The fluorine-containing monomer is one of 2-(trifluoromethyl)acrylic acid, trifluoropropene, perfluoroethyl vinyl ether, trifluoromethyl trifluoro vinyl ether; the hard monomer is one of styrene, p-methylstyrene, phenyl methacrylate; the soft monomer is one of isooctyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate; the anti-salt monomer is sulfobetaine methacrylate.

5. The method according to claim 1, wherein The initiator is a persulfate, the reaction temperature is 60-65 °C, and the reaction time is 3-4 h.

6. The method according to claim 2, wherein The emulsifier is one of the following combinations: sodium dodecyl benzene sulfonate and fatty alcohol polyoxyethylene ether with a mass ratio of 4-5:5-6, sodium dodecyl sulfate and ammonium cocoyl sulfate with a mass ratio of 3-4:6-7; the co-emulsifier is one of ethylene glycol, propylene glycol and n-butanol.

7. A coalbed methane desorption promotion and drainage integration functional additive is prepared by using the method according to any one of claims 1-6.

8. An application of the coalbed methane desorption promotion and drainage integration functional additive according to claim 7 in coalbed methane hydraulic fracturing development.

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