Long-acting solid release scale inhibitor and preparation method

Abstract

The application discloses a preparation method of a long-acting solid sustained-release scale inhibitor, and the scale inhibitor is added into water and stirred uniformly to form solution A; polyvinyl alcohol is added into hot water to prepare solution B; solution A and silica aerogel particles are uniformly mixed, and after drying, solution B is uniformly mixed, heated at 80-90 DEG C for 2-3h, and then heated at 140-150 DEG C for 3-4h to form a mixture; the mixture is coated again by using ethylene-vinyl acetate copolymer emulsion to obtain the long-acting solid sustained-release scale inhibitor. The ethylene-vinyl acetate copolymer with good water resistance is used for secondary coating, a double-layer waterproof structure is formed on the surface of the particles, the sustained-release characteristics of the particle scale inhibitor are further enhanced, and the service life of the scale inhibitor is greatly improved. The anti-scaling period of the solid particles prepared by the application is more than one month, and the comprehensive use cost of the scale inhibitor is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of scale inhibitor preparation, and particularly relates to a long-acting capsule scale inhibitor and a preparation method. BACKGROUND

[0002] In the process of oil and gas exploitation, the produced formation water usually contains various soluble salts, such as carbonates, sulfates and silicates. When the solutes in the water exceed a certain solubility, the minerals originally dissolved in the water will be precipitated to form scale under the influence of temperature, pressure change or pH change. Scale has caused serious harm to oil and gas field production, which may cause uneven heat transfer of equipment, intensified corrosion of oil and gas pipelines, blockage of oil pipelines and even damage to equipment. Since scale is mostly a dense crystal with high crystallinity, the removal process is time-consuming and laborious, and is relatively difficult.

[0003] At present, the most important scale inhibition methods at home and abroad mainly include physical method, chemical method and process method (see Zhu Yiwu. Scale formation mechanism and prevention technology in oilfield development [M]. Xi'an: Shaanxi Science and Technology Press, 1995: 17-26.). The physical method mainly uses instruments to inhibit the deposition of scale on the pipe wall, mainly including ultrasonic scale inhibition, electromagnetic scale inhibition and seed scale inhibition; the chemical scale inhibition mainly includes scale inhibitor scale inhibition, coating scale inhibition, acid addition or CO2 injection scale inhibition; the process method is to change or control certain operation processes or conditions to destroy or reduce the possibility of scale formation.

[0004] Among the various methods and processes described above, the addition of scale inhibitors has become one of the most effective and economical methods to solve the problem of oilfield pipeline scaling (see Ling Jie, Li Zhangjie, Li Ningbo, Zhu Jinquan. Research Progress of Green Scale Inhibitor for Oilfield Development [J]. Oilfield Chemistry, 2022, 39(03): 564-570.). Currently used oilfield scale inhibitors are mostly in liquid form, which are generally injected continuously through the annular space of the oil well or injected through the wellhead at high pressure during periodic shutdown. However, the injection of scale inhibitors is far from the lower end of the oil pipe, resulting in low efficiency of scale inhibitors. Moreover, it is prone to freezing in winter, which brings inconvenience to the addition of scale inhibitors. Therefore, the research and use of solid scale inhibitors that are easy to add, have slow-release function and are low in cost have become one of the hot issues of concern in the scale inhibitor manufacturing industry. Domestic researchers have done some research in this regard. Zhang Guanghua et al. from Shaanxi University of Science and Technology (see Zhang Guanghua, Han Xiaoqian, Zhang Wanbin. Preparation method and application of a super-long slow-release solid scale inhibitor: CN202110447641.1 [P]. 2021-04-25.) modified polyaspartic acid with sodium p-aminobenzenesulfonate as a ring-opening medium to obtain a modified polymer scale inhibitor, and used polyvinyl alcohol and activated lignin sodium sulfonate as a skeleton material. A solid scale inhibitor with slow-release function was prepared by physical and chemical cross-linking of the scale inhibitor and the skeleton material with a cross-linking agent. However, the industrialized preparation process of this scale inhibitor is complex, and the cost of batch production is relatively high. Qin Liming et al. from Xiamen Bailin Water Purification Technology Co., Ltd. (see Qin Liming, Yu Shuang, Yan Jianyong. A composite slow-release solid scale inhibitor and a preparation method thereof: CN202111330603.4 [P]. 2021-11-11.) mixed the scale inhibitor, adhesive, structural glue, filler and solvent uniformly, and then obtained a composite slow-release solid scale inhibitor after heat treatment. The slow-release time of this scale inhibitor is relatively short, the processing process is complex, and the overall cost is relatively high. Pei Yuansheng et al. from Beijing Normal University (see Pei Yuansheng, Guo Dong, Hou Lian. A linear release type long-acting phosphorus-free scale inhibitor: CN202210727842.1 [P]. 2022-06-22.) used silicon dioxide as a carrier, and through a one-step calcination method, silicon dioxide and other raw materials were calcined into a shape. An amorphous material of silicon dioxide skeleton loaded with polyborate was formed. The slow linear release of active ingredients was achieved by tightly combining silicon dioxide skeleton with polyborate. This scale inhibitor needs high-temperature calcination, and the cost is relatively high. Dong Xiaohuan et al. from China Petroleum and Natural Gas Corporation (see Dong Xiaohuan, Jiang Yi, Li Qiongwei, Zhu Fanghui, Cheng Bihai, Li Mingxing, Liu Wei, Zhang Zhenyun, Yu Shuzhen. A solid particle scale inhibitor and a preparation method thereof: CN111909675 A [P]. 2020-07-17.) mixed the adhesive, adsorbent, composite scale inhibitor and slow-release agent uniformly, and then prepared pellets through a pelletizer. Finally, spherical scale inhibitor particles were prepared by soaking and cross-linking with a cross-linking agent.The prepared scale inhibitor particles have insufficient internal cross-linking and too fast early release rate, and the release stability of the scale inhibitor particles needs to be improved.

[0005] Currently, liquid scale inhibitors are mostly used in oil fields, and the anti-scale period after one-time addition is less than one week, resulting in a large number of addition times, serious waste, and ultimately high use cost. SUMMARY

[0006] To overcome the problems of short use period and relatively high cost of scale inhibitors in the prior art, the purpose of the present application is to provide a long-acting capsule scale inhibitor and a preparation method, which has high scale inhibition rate, low cost and long slow-release period.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of a long-acting solid slow-release scale inhibitor, comprising the following steps:

[0009] The scale inhibitor is added to water and stirred uniformly to form a solution A;

[0010] Polyvinyl alcohol is added to hot water to prepare a solution B;

[0011] The solution A and the silica aerogel particles are uniformly mixed to obtain a mixture C;

[0012] The mixture C is dried, and the dried mixture C and the solution B are uniformly mixed to obtain a mixture D;

[0013] The mixture D is heated at 80-90°C for 2-3h, and then heated at 140-150°C for 3-4h to form a mixture E;

[0014] The mixture E is coated with an ethylene-vinyl acetate copolymer emulsion for a second time to obtain a long-acting solid slow-release scale inhibitor.

[0015] Further, the scale inhibitor is one or more of aminotri(methylene)phosphonic acid, hydroxyethylidene diphosphonic acid, polyaspartic acid, ethylenediamine tetra(methylene)phosphonic acid sodium, hydroxyethylidene diphosphonic acid disodium, and aminotri(methylene)phosphonic acid trisodium.

[0016] Further, the mass content of the scale inhibitor in the solution A is 30%-80%.

[0017] Further, the mass content of the polyvinyl alcohol in the solution B is 20%-70%.

[0018] Further, the particle size of the silica aerogel particles is 0.2mm-4mm, the specific surface area is 700-1200m 2 ·g -1 , and the density is 0.003-0.16g·m-3 .

[0019] Further, the mass ratio of solution A and the silica aerogel particles is 0.5-3:1.

[0020] Further, the mass ratio of the mixture C after drying and solution B is 1:0.1-0.6.

[0021] Further, the solid content of the ethylene-vinyl acetate copolymer emulsion is 20%-50%.

[0022] Further, the mass ratio of the mixture E and the EVA emulsion is 1:0.1-1.

[0023] A long-acting solid sustained-release scale inhibitor, the density of the long-acting solid sustained-release scale inhibitor is 1.1-1.25 g·cm 3 .

[0024] Compared with the prior art, the present application has the beneficial effects:

[0025] In the present application, a large amount of scale inhibitor is adsorbed on the surface of porous fumed silica aerogel, and after drying, the scale inhibitor is first coated with polyvinyl alcohol, that is, a connection structure is formed by using the water and alcohol condensation reaction between silica and polyvinyl alcohol, the mixture D is heated at 80-90℃, the purpose is to evaporate most of the water; then heated at 140-150℃, cross-linking reaction occurs between PVA and silica aerogel, forming the primary coating of PVA on the scale inhibitor. Secondly, ethylene-vinyl acetate copolymer (EVA) with good water resistance is used for secondary coating, forming a double-layer waterproof structure on the surface of the particles, further enhancing the sustained-release characteristics of the particle scale inhibitor, and greatly improving the service life of the scale inhibitor. The anti-scaling period of the solid particles prepared by the present application is more than 1 month, which greatly reduces the comprehensive use cost of the scale inhibitor. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the reaction mechanism diagram of the present application;

[0027] Figure 2 is the schematic diagram of the double-coating structure on the surface of the scale inhibitor;

[0028] Figure 3 is the release curve of the scale inhibitor of Example 1;

[0029] Figure 4 is the scale inhibition rate of the scale inhibitor of Example 1 on Ca 2+

[0030] Figure 5 is the release curve of the scale inhibitor of Example 2;

[0031] Figure 6 ​The curve of the release of the scale inhibitor for Example 1 2+ The scale inhibition rate

[0032] Figure 7 The curve of the release of the scale inhibitor for Example 3

[0033] Figure 8 The scale inhibition rate of the scale inhibitor for Example 3 2+ The scale inhibition rate

[0034] Figure 9 The curve of the release of the scale inhibitor for Example 4

[0035] Figure 10 The scale inhibition rate of the scale inhibitor for Example 4 2+ The scale inhibition rate

[0036] Figure 11 The curve of the release of the scale inhibitor for Example 5

[0037] Figure 12 The scale inhibition rate of the scale inhibitor for Example 5 2+ The scale inhibition rate

[0038] Figure 13 The curve of the release of the scale inhibitor for Example 6

[0039] Figure 14 The scale inhibition rate of the scale inhibitor for Example 6 2+ The scale inhibition rate

[0040] In the figure, 1 is a silica aerogel, 2 is a scale inhibitor, 3 is PVA, and 4 is EVA. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application can be more thoroughly and completely understood.

[0042] The preparation method of the long-acting solid sustained-release scale inhibitor of the present application first adsorbs the scale inhibitor on the porous silica aerogel particles, then performs heat treatment, and then uses PVA for coating, and then performs drying, and then uses a sulfurization bed for double coating, thereby preparing a solid scale inhibitor with high scale inhibition rate, low cost, and long sustained-release period.

[0043] Specifically, the preparation method of the long-acting solid sustained-release scale inhibitor comprises the following steps:

[0044] One or more of the scale inhibitors (aminotri(methylphosphonic acid (ATMP), hydroxyethylidene diphosphonic acid (HEDP), polyaspartic acid (PASP), ethylenediamine tetra(methylphosphonic acid sodium (EDTMPS), disodium hydroxyethylidene diphosphonate (HEDPNa2), and trisodium aminotri(methylphosphonic acid (ATMPNa3)) is dissolved in water, stirred uniformly to form solution A;

[0045] The mass content of the scale inhibitor in solution A is 30%-80%.

[0046] Polyvinyl alcohol (PVA) is dissolved in a water solution at 90°C to prepare solution B, and the mass content of PVA in solution B is 20%-70%.

[0047] Solution A and silica aerogel particles (particle size 0.2mm-4mm, specific surface area 700-1200m 2 ·g -1 , density 0.003-0.16g·m -3 ) are uniformly mixed to enable solution A to be fully adsorbed onto the silica aerogel particles to obtain mixture C;

[0048] The mass ratio of solution A to silica aerogel particles is 0.5-3:1.

[0049] Mixture C is dried, and the dried mixture C and solution B are uniformly mixed by a high-speed mixer to obtain mixture D;

[0050] The mass ratio of the dried mixture C to solution B is 1:0.1-0.6.

[0051] Mixture D is heated at 80-90°C for 2-3h to evaporate most of the water, and then heated at 140-150°C for 3-4h to enable cross-linking reaction between PVA and silica aerogel, form the initial coating of PVA on the scale inhibitor, and form mixture E, and the reaction mechanism is shown in Figure 1 .

[0052] EVA emulsion (solid content (mass content) 20%-50%) is used to perform secondary coating on mixture E by a fluidized bed, and the mass ratio of mixture E to EVA emulsion is 1:0.1-1 to obtain double-coated granular scale inhibitor F, i.e., long-acting solid slow-release scale inhibitor.

[0053] In the present application, ethylene-vinyl acetate copolymer (EVA) with good water resistance is used for secondary coating to form a double-layer waterproof structure on the surface of the particles, as shown in Figure 2 , the scale inhibitor 2 is first adsorbed on the substrate silica aerogel 1, and the finally formed long-acting solid slow-release scale inhibitor sequentially includes the scale inhibitor 2, PVA 3, and EVA 4 from inside to outside.

[0054] The particle size of the obtained double-coated granular scale inhibitor F is mostly 0.5-3 mm, and the density is 1.1-1.25 g·cm 3 .

[0055] The prepared double-coated granular scale inhibitor F is subjected to static release test:

[0056] Take 10 g of the long-acting solid sustained-release scale inhibitor prepared in the application, soak in 1000 mL of water, change the water every day, and monitor after 30 days. The released scale inhibitor is 35%-50% of the total amount (mass) of the coating. According to the standard Q / SY 17126-2019, static scale inhibition test is carried out, and it is found that the static scale inhibition rate of Ca 2+ and Mg2+ is greater than 90% in 30 days.

[0057] Example 1

[0058] Dissolve the scale inhibitor ATMP in water and stir uniformly to form solution A, wherein the content of the scale inhibitor is 40 wt%.

[0059] Dissolve PVA in a water solution at 90°C to prepare solution B, and the content of PVA is 30 wt%.

[0060] Mix solution A and silica aerogel particles uniformly, so that solution A is fully adsorbed onto the silica aerogel particles, to obtain mixture C, wherein the mass ratio of solution A and silica aerogel particles is 0.5:1.

[0061] After drying mixture C, mix it with solution B uniformly by a high-speed mixer to obtain mixture D, wherein the mass ratio of the dried mixture C and solution B is 1:0.2.

[0062] Heat mixture D at 80°C for 2 h, and then heat it at 150°C for 4 h, to form the primary coating of PVA on the scale inhibitor through cross-linking reaction between PVA and silica aerogel, and form mixture E.

[0063] Use EVA emulsion (solid content 30%) to perform secondary coating on mixture E by fluidized bed, to obtain double-coated granular scale inhibitor F, wherein the mass ratio of mixture E and EVA emulsion is 1:0.2. The particle size of the obtained double-coated granular scale inhibitor F is mostly 0.5-3 mm, and the density is 1.1 g·cm 3 .

[0064] The prepared double-coated granular scale inhibitor F is subjected to static release test, take 10 g of the scale inhibitor, soak in 1000 mL of water, change the water every day, and monitor after 30 days. The release curve of the scale inhibitor is as Figure 3 shown, and the release of the scale inhibitor is Figure 3It can be seen that the initial release is fast, and after 10 days it tends to be stable, and after 30 days it releases 38.7% of the coating amount. According to the Q / SY 17126-2019 standard, static anti-scaling test is carried out, and the anti-scaling rate of the scale inhibitor at different times is as shown in 2+ . Figure 4 It can be seen that the anti-scaling rate is maintained above 98% within 30 days. Figure 4

[0065] Example 2

[0066] The scale inhibitors HEDP and HEDPNa2 are dissolved in water, stirred uniformly to form solution A, and the mass ratio of the scale inhibitors HEDP, HEDPNa2 and water is 2:3:5.

[0067] PVA is dissolved in a water solution at 90°C to prepare solution B, and the content of PVA is 40wt%.

[0068] Solution A and silica aerogel particles are uniformly mixed to allow solution A to be fully adsorbed onto the silica aerogel particles to obtain mixture C, and the mass ratio of solution A and silica aerogel particles is 1:1.

[0069] After mixture C is dried, it is uniformly mixed with solution B by a high-speed mixer to obtain mixture D, and the mass ratio of the dried mixture C and solution B is 1:0.3.

[0070] Mixture D is heated at 80°C for 2h and then heated at 150°C for 4h to form a primary coating of PVA on the scale inhibitor through cross-linking reaction between PVA and silica aerogel, and mixture E is formed.

[0071] EVA emulsion (solid content 40%) is used to perform secondary coating on mixture E by fluidized bed to obtain double-coated granular scale inhibitor F, and the mass ratio of mixture E and EVA emulsion is 1:0.3.

[0072] The particle size of the obtained double-coated granular scale inhibitor F is mostly 0.5-3mm, and the density is 1.12g·cm 3 .

[0073] The prepared double-coated granular scale inhibitor F is subjected to static release test, 10g of the scale inhibitor is soaked in 1000mL of water, and the water is changed every day, and after 30 days of monitoring, the release curve of the scale inhibitor is as shown in Figure 5 . Figure 5 It can be seen that the initial release is fast, and after 10 days it tends to be stable, and after 30 days it releases 39.8% of the coating amount. According to the Q / SY 17126-2019 standard, static anti-scaling test is carried out, and the anti-scaling rate of the scale inhibitor at different times is as shown in 2+ .​Figure 6 As shown in Figure 6 It can be seen that the scale inhibition rate is maintained at more than 98% within 30 days.

[0074] Example 3

[0075] The scale inhibitor PASP is dissolved in water, stirred uniformly to form solution A, wherein the content of the scale inhibitor PASP is 55wt%.

[0076] The PVA is dissolved in a water solution at 90℃ to form solution B, and the content of the PVA is 50wt%.

[0077] The solution A and the silica aerogel particles are mixed uniformly to make the solution A fully adsorbed on the silica aerogel particles to obtain mixture C, wherein the mass ratio of the solution A and the silica aerogel particles is 1.5:1.

[0078] After the mixture C is dried, the solution B is mixed with the mixture C by a high-speed mixer to obtain mixture D, wherein the mass ratio of the mixture C and the solution B is 1:0.3.

[0079] The mixture D is heated at 80℃ for 2h and then heated at 150℃ for 4h to form a primary coating of the PVA on the scale inhibitor through a cross-linking reaction between the PVA and the silica aerogel, and to form mixture E.

[0080] The mixture E is secondarily coated by a fluidized bed using an EVA emulsion (solid content 40%) to obtain a double-coated granular scale inhibitor F, wherein the mass ratio of the mixture E and the EVA emulsion is 1:0.3. The particle size of the obtained double-coated granular scale inhibitor F is mostly 0.5-3mm, and the density is 1.15g·cm 3 .

[0081] The static release test is performed on the prepared double-coated granular scale inhibitor F, 10g of the scale inhibitor is soaked in 1000mL of water, and the water is changed every day. After 30 days of monitoring, the release curve of the scale inhibitor is as shown in Figure 7 As shown in Figure 7 It can be seen that the initial release is fast, and after 10 days, it tends to be stable, and after 30 days, 44.8% of the coating amount is released. The static anti-scaling test is performed according to the standard Q / SY 17126-2019, and the scale inhibitor at different times has different effects on the Ca 2+ The scale inhibition rate is as shown in Figure 8 As shown in Figure 8 It can be seen that the scale inhibition rate is maintained at more than 98% within 30 days.

[0082] Example 4

[0083] Dissolve the scale inhibitor ATMPNa3 in water and stir until homogeneous to form solution A, wherein the content of scale inhibitor ATMPNa3 is 60wt%.

[0084] Solution B is prepared by dissolving PVA in an aqueous solution at 90°C, with a PVA content of 55 wt%.

[0085] Solution A and silica aerogel particles are mixed evenly to allow solution A to be fully adsorbed onto the silica aerogel particles, resulting in mixture C, wherein the mass ratio of solution A to silica aerogel particles is 2:1.

[0086] After drying, mixture C is mixed with solution B using a high-speed mixer to obtain mixture D, wherein the mass ratio of the dried mixture C to solution B is 1:0.4.

[0087] Mixture D was heated at 80°C for 2 hours, and then at 150°C for 4 hours. Through the cross-linking reaction between PVA and silica aerogel, the initial coating of the scale inhibitor by PVA was formed, resulting in mixture E.

[0088] A fluidized bed was used to perform a secondary coating of mixture E with EVA emulsion (50% solids content) to obtain a double-coated granular scale inhibitor F, wherein the mass ratio of mixture E to EVA emulsion was 1:0.4. The resulting double-coated granular scale inhibitor F had a particle size of mostly 0.5-3 mm and a density of 1.17 g·cm³. 3 .

[0089] A static release test was conducted on the prepared double-coated granular scale inhibitor F. 10 g of the scale inhibitor was soaked in 1000 mL of water, with the water changed daily. After 30 days, the release curve of the scale inhibitor was monitored as shown below. Figure 9 As shown, from Figure 9 It can be seen that the initial release is rapid, stabilizes after 10 days, and after 30 days, 47.8% of the coated amount has been released. Static scale inhibition tests were conducted using the Q / SY 17126-2019 standard to investigate the effect of scale inhibitors on Ca at different time points. 2+ scale inhibition rate, such as Figure 10 As shown, from Figure 10 It can be seen that the scale inhibition rate remained above 98% for 30 days.

[0090] Example 5

[0091] Scale inhibitors ATMP, PASP, and HEDPNa2 are dissolved in water and stirred until homogeneous to form solution A, wherein the mass ratio of scale inhibitors ATMP, PASP, HEDPNa2, and water is 1:2:3.5:3.5.

[0092] Solution B is prepared by dissolving PVA in an aqueous solution at 90°C, with a PVA content of 60 wt%.

[0093] Solution A and silica aerogel particles are mixed evenly to allow solution A to be fully adsorbed onto the silica aerogel particles, resulting in mixture C, wherein the mass ratio of solution A to silica aerogel particles is 2.5:1.

[0094] After drying, mixture C is mixed with solution B using a high-speed mixer to obtain mixture D, wherein the mass ratio of the dried mixture C to solution B is 1:0.5.

[0095] Mixture D was heated at 80°C for 2 hours, and then at 150°C for 4 hours. Through the cross-linking reaction between PVA and silica aerogel, the initial coating of the scale inhibitor by PVA was formed, resulting in mixture E.

[0096] A fluidized bed was used to coat mixture E with EVA emulsion (45% solid content) to obtain a double-coated granular scale inhibitor F, wherein the mass ratio of mixture E to EVA emulsion was 1:0.5.

[0097] The resulting double-coated granular scale inhibitor F had a particle size of mostly 0.5-3 mm and a density of 1.21 g·cm³. 3 .

[0098] A static release test was conducted on the prepared double-coated granular scale inhibitor F. 10 g of the scale inhibitor was soaked in 1000 mL of water, with the water changed daily. After 30 days, the release curve of the scale inhibitor was monitored as shown below. Figure 11 As shown, from Figure 11 It can be seen that the initial release is rapid, stabilizes after 10 days, and after 30 days, 47.2% of the coated amount has been released. Static scale inhibition tests were conducted using the Q / SY 17126-2019 standard to investigate the effect of scale inhibitors on Ca at different time points. 2+ scale inhibition rate, such as Figure 12 As shown, from Figure 12 It can be seen that the scale inhibition rate remained above 98% for 30 days.

[0099] Example 6

[0100] Scale inhibitors HEDP, EDTMPS, HEDPNa2, and ATMPNa3 are dissolved in water and stirred until homogeneous to form solution A, wherein the mass ratio of scale inhibitors HEDP, EDTMPS, HEDPNa2, ATMPNa3, and water is 1:2:2:2:3.

[0101] Solution B is prepared by dissolving PVA in an aqueous solution at 90°C, with a PVA content of 60 wt%.

[0102] Solution A and silica aerogel particles are mixed evenly to allow solution A to be fully adsorbed onto the silica aerogel particles, resulting in mixture C, wherein the mass ratio of solution A to silica aerogel particles is 3:1.

[0103] After drying, mixture C is mixed with solution B using a high-speed mixer to obtain mixture D, wherein the mass ratio of the dried mixture C to solution B is 1:0.6.

[0104] Mixture D was heated at 80°C for 2 hours, and then at 150°C for 4 hours. Through the cross-linking reaction between PVA and silica aerogel, the initial coating of the scale inhibitor by PVA was formed, resulting in mixture E.

[0105] A fluidized bed was used to coat mixture E with EVA emulsion (40% solid content) to obtain a double-coated granular scale inhibitor F, wherein the mass ratio of mixture E to EVA emulsion was 1:0.6.

[0106] The resulting double-coated granular scale inhibitor F had a particle size of mostly 0.5-3 mm and a density of 1.25 g·cm³. 3 .

[0107] A static release test was conducted on the prepared double-coated granular scale inhibitor F. 10 g of the scale inhibitor was soaked in 1000 mL of water, with the water changed daily. After 30 days, the release curve of the scale inhibitor was monitored as shown below. Figure 13 As shown, from Figure 13 It can be seen that the initial release is rapid, stabilizes after 10 days, and after 30 days, 48.3% of the coated amount has been released. Static scale inhibition tests were conducted using the Q / SY 17126-2019 standard to investigate the effect of scale inhibitors on Ca at different time points. 2+ scale inhibition rate, such as Figure 14 As shown, from Figure 14 It can be seen that the scale inhibition rate remained above 98% for 30 days.

[0108] Example 7

[0109] Dissolve the scale inhibitor ATMP in water and stir until homogeneous to form solution A, in which the scale inhibitor content is 30 wt%.

[0110] Solution B is prepared by dissolving PVA in an aqueous solution at 90°C, with a PVA content of 70 wt%.

[0111] Solution A and silica aerogel particles are mixed evenly to allow solution A to be fully adsorbed onto the silica aerogel particles, resulting in mixture C, wherein the mass ratio of solution A to silica aerogel particles is 2.5:1.

[0112] After drying mixture C and mixing solution B through high speed mixer, mixture D is obtained, wherein the mass ratio of dried mixture C and solution B is 1:0.1.

[0113] After heating mixture D at 90°C for 2h and then at 140°C for 4h, the primary coating of PVA on the scale inhibitor is formed through the cross-linking reaction between PVA and silica aerogel, and mixture E is formed.

[0114] Through fluidized bed, the secondary coating of mixture E is carried out by using EVA emulsion (solid content 35%), and double-coated granular scale inhibitor F is obtained, wherein the mass ratio of mixture E and EVA emulsion is 1:1.

[0115] Example 8

[0116] The scale inhibitor ATMP is dissolved in water to form solution A, wherein the content of scale inhibitor is 80wt%.

[0117] PVA is dissolved in water solution at 90°C to form solution B, wherein the content of PVA is 20wt%.

[0118] Solution A and silica aerogel particles are mixed uniformly to make solution A fully adsorbed on the silica aerogel particles, and mixture C is obtained, wherein the mass ratio of solution A and silica aerogel particles is 3:1.

[0119] After drying mixture C and mixing solution B through high speed mixer, mixture D is obtained, wherein the mass ratio of dried mixture C and solution B is 1:0.4.

[0120] After heating mixture D at 80°C for 3h and then at 145°C for 3h, the primary coating of PVA on the scale inhibitor is formed through the cross-linking reaction between PVA and silica aerogel, and mixture E is formed.

[0121] Through fluidized bed, the secondary coating of mixture E is carried out by using EVA emulsion (solid content 20%), and double-coated granular scale inhibitor F is obtained, wherein the mass ratio of mixture E and EVA emulsion is 1:0.8.

[0122] The above only describes the best embodiments of the present application, but cannot be understood as the limitation of claims. The present application is not limited to the above embodiments, and the specific structure allows changes. Any changes made within the protection scope of the independent claims of the present application are within the protection scope of the present application.

[0123] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

Claims

1. A process for the preparation of a long-acting solid slow-release scale inhibitor, characterized in that, The method comprises the following steps: adding scale inhibitor into water and stirring to form solution A; adding polyvinyl alcohol into hot water to form solution B; mixing solution A and silica aerogel particles to form mixture C; drying mixture C and mixing the dried mixture C with solution B to form mixture D; heating mixture D at 80-90 DEG C for 2-3 hours and then heating at 140-150 DEG C for 3-4 hours to make cross-linking reaction between polyvinyl alcohol and silica aerogel, form primary coating of polyvinyl alcohol on scale inhibitor, and form mixture E; The mixture E is coated for the second time by using ethylene-vinyl acetate copolymer emulsion, and the mass ratio of the mixture E and the ethylene-vinyl acetate copolymer emulsion is 1:0.1-1, so that a long-acting solid slow-release scale inhibitor is obtained; the long-acting solid slow-release scale inhibitor comprises, from inside to outside, the scale inhibitor, polyvinyl alcohol and ethylene-vinyl acetate copolymer; and the density of the long-acting solid slow-release scale inhibitor is 1.1-1.25 g·cm 3 . the scale inhibitor is one or more of aminotri (methylphosphine) acid, hydroxyethylidene diphosphonic acid, polyaspartic acid, ethylenediamine tetra (methylphosphine) sodium, disodium hydroxyethylidene diphosphonate and trisodium aminotri (methylphosphine) acid; The particle size of the silica aerogel particles is 0.2 mm-4 mm, the specific surface area is 700-1200 m 2 ·g -1 , the density is 0.003-0.16 g·m -3 .

2. The method of claim 1, wherein the long-acting solid slow-release scale inhibitor is prepared by the steps of: the mass content of scale inhibitor in solution A is 30%-80%.

3. The method for preparing the long-acting solid slow-release scale inhibitor according to claim 1, characterized in that, the mass content of polyvinyl alcohol in solution B is 20%-70%.

4. The method for preparing the long-acting solid slow-release scale inhibitor according to claim 1, characterized in that, the mass ratio of solution A to silica aerogel particles is 0.5-3:

1.

5. The method for preparing the long-acting solid slow-release scale inhibitor according to claim 1, characterized in that, the mass ratio of the dried mixture C to solution B is 1:0.1-0.

6.

6. The method for preparing the long-acting solid slow-release scale inhibitor according to claim 1, characterized in that, the solid content of the ethylene-vinyl acetate copolymer emulsion is 20%-50%.

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