A novel polyamidated chitosan, its preparation method, application and use method

Abstract

The present application belongs to the field of water treatment flocculation technology and metal corrosion prevention, and particularly relates to a novel polyamide chitosan, a preparation method, application and use method thereof. The preparation method of the novel polyamide chitosan comprises the following steps: (1) dispersing chitosan powder in a solution, adding methyl acrylate, heating and stirring, and obtaining a mixed system after reaction; (2) performing solid-liquid separation on the mixed system, and then dispersing the precipitate in a solution; (3) adding ethylenediamine, heating and stirring, performing solid-liquid separation after reaction, and obtaining a first generation of branched chitosan product; (4) dispersing the first generation of branched chitosan product in a solution, and repeating steps (1) to (3) to obtain the novel polyamide chitosan. The novel polyamide chitosan has excellent coagulation and flocculation effects and good acid corrosion inhibition performance, and has important significance for realizing harmless treatment of well completion fluid waste.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of water treatment flocculation technology and metal corrosion prevention, and particularly relates to a novel polyamide chitosan and a preparation method, application and use method thereof. BACKGROUND

[0002] With large-scale exploration and development of domestic offshore oil and gas fields in recent years, more and more offshore drilling and oil and gas well development projects are implemented. A large amount of waste is generated during the completion operation stage in the process, mainly including formation crude oil, formation cuttings, high-concentration salt, polymer treatment agent, flushing fluid, spacer fluid, clay and cement slurry, and residual drilling fluid. These waste additives are of various types and complex composition, and some components have great potential harm to biology and environment. Especially, the drilling waste produced in offshore drilling operation is recovered through an offshore platform, transported to a land terminal by a ship and then concentrated for treatment. Due to the inconvenience of offshore transportation, limited platform area, large amount of recovery and treatment, and other difficulties, the cost of recovering and treating the completion fluid waste is high, and is not conducive to on-site construction. Therefore, in combination with the characteristics of offshore drilling and completion construction, research on harmless treatment and resource recycling technology of offshore completion fluid waste has important practical significance for realizing offshore safe and environmentally friendly (green) completion and other operation construction and sustainable development, and is expected to create significant economic and social benefits.

[0003] The completion fluid waste has the characteristics of large viscosity, high polymer content, high salt content, high acidity and high solid content. Therefore, the harmless treatment technology is difficult, mainly because the flocculation effect of the commonly used flocculants is poor, and the solid-liquid separation is difficult. At the same time, some completion fluids are acidic and can corrode downhole pipelines, causing serious economic losses and safety hazards. SUMMARY

[0004] The present application aims at the defects of the prior art, and provides a novel polyamide chitosan and a preparation method, application and use method thereof.

[0005] Specifically, the preparation method of the novel polyamide chitosan provided by the present application comprises the following steps:

[0006] (1) dispersing chitosan powder in a solution, adding methyl acrylate, heating and stirring, and obtaining a mixed system after reaction;

[0007] (2) solid-liquid separation of the mixed system, and then dispersing the precipitate in a solution;

[0008] (3) adding ethylenediamine, heating and stirring, and then solid-liquid separation after reaction to obtain a first generation of branched chitosan product;

[0009] (4) repeating steps (1) to (3) after dispersing the first generation branched chitosan product in a solution to obtain a new polyamidated chitosan.

[0010] The preparation method of the new polyamidated chitosan, in the process of preparing the first generation branched chitosan product, the chitosan powder is mixed with the methyl acrylate at a ratio of (4-7):1, and the ethylenediamine is mixed with the product of step (2) at a ratio of (2-7):5.

[0011] The preparation method of the new polyamidated chitosan, in the process of preparing the first generation branched chitosan product, the chitosan powder is mixed with the methyl acrylate at a ratio of 5:1, and the ethylenediamine is mixed with the product of step (2) at a ratio of 2:5.

[0012] The preparation method of the new polyamidated chitosan, in the process of preparing the new polyamidated chitosan, the first generation branched chitosan product is mixed with the methyl acrylate and the ethylenediamine at a ratio of (4-7):(1):(1-3); preferably 5:1:2.

[0013] The preparation method of the new polyamidated chitosan, in the process of preparing the new polyamidated chitosan, the first generation branched chitosan product is mixed with the methyl acrylate and the ethylenediamine at a ratio of 5:1:2.

[0014] The preparation method of the new polyamidated chitosan, the heating temperature in steps (1) and (3) is 40-65℃, and the stirring time is 20-30h; preferably, the heating temperature is 50℃, and the stirring time is 24h.

[0015] In another aspect, the present application also provides a new polyamidated chitosan obtained by the above preparation method.

[0016] In yet another aspect, the present application also provides the use of the new polyamidated chitosan prepared by the above preparation method as a flocculant for well completion fluid waste.

[0017] In yet another aspect, the present application also provides the use of the new polyamidated chitosan prepared by the above preparation method as a corrosion inhibitor for downhole pipes.

[0018] In yet another aspect, the present application also provides a method for using the new polyamidated chitosan prepared by the above preparation method, which comprises: using polyaluminum chloride or polyferric sulfate as a flocculant, and using the new polyamidated chitosan as a coagulant aid, and adding them in a coagulation and sedimentation tank for rapid treatment of offshore well completion fluid waste.

[0019] The technical scheme of the present application has the following beneficial effects:

[0020] (1) The novel polyamide chitosan has excellent coagulation and flocculation effect and good acid corrosion inhibition performance, which has important significance for realizing harmless treatment of well completion fluid waste.

[0021] (2) The novel polyamide chitosan is biodegradable and environment-friendly, and has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments and are not meant to limit the present application.

[0023] Figure 1 The figure is a comparison chart of the corrosion prevention effect of the novel polyamide chitosan, wherein (a) and (b) are blank corrosion charts of 20 carbon steel, and (c) and (d) are corrosion charts of 20 carbon steel after adding 300 mg / L of polyamide chitosan. DETAILED DESCRIPTION

[0024] In order to fully understand the purpose, features and effects of the present application, the following specific embodiments are used to describe the present application in detail. The process method of the present application uses conventional methods or devices in the art except for the following content. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0025] When a numerical range is disclosed in the present application, the above range is considered to be continuous and includes the minimum value and the maximum value of the range, as well as every value between the minimum value and the maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed in the present application should be understood to include any and all sub-ranges incorporated therein. In the present application, "proportion" is "weight ratio" unless otherwise specified.

[0026] Specifically, the present application provides a preparation method of a novel polyamide chitosan, comprising the following steps: (1) dispersing chitosan powder in a solution, then adding methyl acrylate, heating and stirring, and obtaining a mixed system after the reaction is completed; (2) solid-liquid separation of the mixed system, then dispersing the precipitate in a solution; (3) adding ethylenediamine, heating and stirring, and obtaining a first generation of branched chitosan product after solid-liquid separation of the reaction; (4) dispersing the first generation of branched chitosan product in a solution, then repeating steps (1) to (3) to obtain the novel polyamide chitosan.

[0027] The preparation method of the novel polyamidated chitosan of the present application uses chitosan powder and methyl acrylate and ethylenediamine as raw materials, and obtains first generation branched chitosan product through Michael addition reaction and amidation reaction, then uses the first generation branched chitosan product, methyl acrylate and ethylenediamine as raw materials, and repeats the Michael addition reaction and amidation reaction to graft dendritic polyamide on the chitosan macromolecule, thereby obtaining the novel polyamidated chitosan, and the preparation method has the advantages of reliable reaction principle and simple operation.

[0028] In some preferred embodiments, the preparation method of the novel polyamidated chitosan of the present application comprises the following steps:

[0029] (1) Disperse the chitosan powder in a solution, then add methyl acrylate, heat and stir, and obtain a mixed system after the reaction is completed.

[0030] The chitosan powder (CS, molecular weight: 5000) is purchased from Beijing Mai Rui Da Technology Co., Ltd., and the solution is methanol.

[0031] The reaction occurring in this step is Michael addition reaction.

[0032] The ratio of chitosan powder to methyl acrylate is (4-7):1, and preferably 5:1.

[0033] The heating temperature is 40-65℃, and the stirring time is 20-30h; preferably, the heating temperature is 50℃, and the stirring time is 24h.

[0034] (2) Solid-liquid separation is performed on the mixed system, and then the precipitate is dispersed in a solution.

[0035] In order to improve the purity of the final product, preferably, the precipitate is washed with methanol for 3 times before being dispersed in a solution.

[0036] The solution is methanol.

[0037] (3) Add ethylenediamine, heat and stir, and then perform solid-liquid separation after the reaction is completed, thereby obtaining the first generation branched chitosan product.

[0038] The ratio of ethylenediamine to the product of the previous step is (2-7):5, and preferably 2:5.

[0039] The reaction occurring in this step is amidation reaction.

[0040] The heating temperature is 40-65℃, and the stirring time is 20-30h; preferably, the heating temperature is 50℃, and the stirring time is 24h.

[0041] Preferably, the first generation branched chitosan product is repeatedly washed with methanol.

[0042] (4) repeating steps (1) to (3) after dispersing the first generation branched chitosan product in a solution to obtain a new polyamidated chitosan.

[0043] The ratio of the first generation branched chitosan product to the methyl acrylate and the ethylenediamine is (4-7):1:(1-3), preferably 5:1:2.

[0044] In another aspect, the application further provides a new polyamidated chitosan obtained by the above preparation method.

[0045] Optionally, the structural formula of the new polyamidated chitosan is:

[0046]

[0047] wherein n is an integer between 2x10 5 and 5x10 5 .

[0048] In another aspect, the application further provides an application of the new polyamidated chitosan as a well completion fluid waste flocculant.

[0049] In another aspect, the application further provides an application of the new polyamidated chitosan as a downhole pipeline corrosion inhibitor.

[0050] The new polyamidated chitosan contains multiple adsorption sites, which are chemically or physically adsorbed on the metal surface to form an adsorption film, thereby preventing the metal surface from contacting the corrosion medium and inhibiting corrosion.

[0051] In another aspect, the application further provides a use method of the new polyamidated chitosan prepared by the method of the application, which comprises: using polyaluminum chloride or polyferric sulfate as a flocculant, using the new polyamidated chitosan as a coagulant aid, and adding in a coagulation sedimentation tank for rapid treatment of offshore well completion fluid waste to achieve efficient solid-liquid separation of the waste.

[0052] Embodiment

[0053] The application will be further described by the following examples, but the application is not limited to the scope of the examples. The experimental methods in the following examples without specific conditions are carried out according to conventional methods and conditions. The raw materials used in the following examples are all commercially available.

[0054] Example 1

[0055] (1) After dispersing the chitosan powder in methanol, methyl acrylate was added in a ratio of 5:1 of chitosan powder to methyl acrylate, heated and stirred at 50°C for 24h, and the reaction was completed to obtain a mixed system.

[0056] (2) The mixture is separated into solid and liquid components. The precipitate is washed three times with methanol and then dispersed in methanol.

[0057] (3) Add ethylenediamine, wherein the ratio of ethylenediamine to the product of the previous step is 2:5, heat and stir at 50°C for 24 hours, and after the reaction is completed, separate the solid and liquid to obtain the first-generation branched chitosan product, and wash it repeatedly with methanol.

[0058] (4) After dispersing the first-generation branched chitosan product in a solution, repeat steps (1) to (3) to obtain a novel polyamidized chitosan. The ratio of the first-generation branched chitosan product to the methyl acrylate and the ethylenediamine is 5:1:2.

[0059] Example 2

[0060] (1) After dispersing chitosan powder in methanol, add methyl acrylate at a ratio of 6:1 between chitosan powder and methyl acrylate, heat and stir at 55°C for 22 hours, and obtain a mixed system after the reaction is completed.

[0061] (2) The mixture is separated into solid and liquid phases. The precipitate is washed three times with methanol and then dispersed in methanol.

[0062] (3) Add ethylenediamine, wherein the ratio of ethylenediamine to the product of the previous step is 1.5:5. Heat and stir at 55°C for 24 hours. After the reaction is completed, separate the solid and liquid and wash repeatedly with methanol to obtain the first-generation branched chitosan product.

[0063] (4) After dispersing the first-generation branched chitosan product in a solution, steps (1) to (3) are repeated to obtain a novel polyamidized chitosan. The ratio of the first-generation branched chitosan product to the methyl acrylate and the ethylenediamine is 6:1:2.

[0064] Performance testing

[0065] 1. Flocculation Experiment Test

[0066] Flocculation tests were conducted by adding different amounts of polyferric sulfate (PFS) and polyaluminum chloride (PAC) separately to completion fluid (waste fluid from offshore well completion), and by separately adding a certain amount of polyamidized chitosan (PACS) to polyferric sulfate (PFS) and polyaluminum chloride (PAC). The specific experimental steps are as follows:

[0067] (1) Take multiple portions of well completion fluid wastewater, 100 mL each, and add them to beakers, labeling them accordingly;

[0068] (2) Add different coagulants to each beaker in turn, and stir in a centrifuge at a speed of 1000 r / min for 2 min;

[0069] (3) Take the supernatant, measure the turbidity of the supernatant, and calculate the turbidity removal rate.

[0070] In the flocculation experiment of the polyaluminum chloride PAC completion fluid, the PAC addition amount, the polyamidated chitosan addition amount, and the turbidity value in each beaker are shown in Table 1. In the flocculation experiment of the polyferric sulfate PFS completion fluid, the PFS addition amount, the polyamidated chitosan addition amount, and the turbidity value in each beaker are shown in Table 2.

[0071] Table 1 Flocculation experiment results (turbidity, NTU) of the polyaluminum chloride PAC completion fluid

[0072]

[0073] Table 1 is the flocculation experiment result of the completion fluid after adding the polyaluminum chloride (PAC) alone and compounding with the polyamidated chitosan (PACS). It can be seen that the initial turbidity value of the completion fluid is 581 NTU. After adding the polyaluminum chloride alone, the flocculation effect is good. When the concentration of the polyaluminum chloride is 2000 mg / L, the turbidity value of the supernatant after centrifugation is reduced to 63 NTU, and the turbidity removal rate of the completion fluid is 89.16%. In comparison, after adding the polyaluminum chloride (PAC) and 200 mg / L of the coagulant polyamidated chitosan (PACS) in the completion fluid, when the amount of the polyaluminum chloride is 2000 mg / L, the turbidity value of the supernatant after centrifugation is reduced to 22 NTU, and the corresponding turbidity removal rate is 96.21%. The flocculation effect of the completion fluid is significantly improved.

[0074] Table 2 Flocculation experiment results (turbidity, NTU) of the polyferric sulfate PFS completion fluid

[0075]

[0076] Table 2 is the flocculation experiment result of the completion fluid after adding the polyferric sulfate (PFS) alone and compounding with the polyamidated chitosan (PACS). The initial turbidity value of the completion fluid is 581 NTU. After adding the polyferric sulfate alone, the flocculation effect is general. Even when the addition amount of the polyferric sulfate in the completion fluid reaches 2000 mg / L, the turbidity value of the supernatant after centrifugation is reduced to 126 NTU, and the turbidity removal rate of the completion fluid is 78.16%. In comparison, while keeping other conditions unchanged, after adding 200 mg / L of the coagulant polyamidated chitosan (PACS) in the completion fluid, the flocculation effect is significantly improved. When the addition amount of the polyferric sulfate is 2000 mg / L, the turbidity value of the supernatant after centrifugation is reduced to 38 NTU, and the corresponding turbidity removal rate is 93.46%.

[0077] 2. Anti-corrosion effect test

[0078] Anti-corrosion effect evaluation: The weight method is a method for determining the corrosion rate by comparing the mass change of the sample before and after corrosion under certain conditions after a certain period of time. The weight method is a reliable, effective and widely used experimental method.

[0079] (1) Take several carbon steel samples (P110 steel) of the same size, and ultrasonically clean them with petroleum ether and ethanol for 20 minutes, and then dry and weigh them at room temperature.

[0080] (2) Prepare 1 mol / L hydrochloric acid solution as the corrosion medium. Immerse the carbon steel samples in the corrosion medium solution, ensuring that the entire surface of the sample is in complete contact with the corrosion medium solution. Add different concentrations of polyamide chitosan (PACS) to the corrosion medium in turn, and place them in a 70°C constant temperature water bath for 3 days.

[0081] (3) After the corrosion experiment, remove the samples, rinse them with water to remove the corrosion products on the surface of the samples, and dry them in a nitrogen environment and weigh them. Calculate the corrosion rate and inhibition rate (Table 3).

[0082] The corrosion rate vi (g·(m ·h)

[0001] ) is calculated according to the following formula:

[0083]

[0084] In formula (1), Δm (g) is the weight loss of the carbon steel sample after corrosion, Δt (hour) is the corrosion time, and Ai (cm ) is the surface area of the sample. The inhibition rate (IR) is obtained according to the following formula (2):

[0085]

[0086] Vi(blank) is the blank corrosion rate of the carbon steel sample calculated according to formula (1), and Vi(inh) is the corrosion rate of the carbon steel sample after adding the corrosion inhibitor.

[0087] Table 3 is the experimental results of the carbon steel sample measured by the weight loss method after adding different concentrations of polyamide chitosan to 1.0 mol / L HCl solution at 70°C. As shown in Table 3, after adding polyamide chitosan, the corrosion rate of the carbon steel sample is significantly reduced, and with the increase of the concentration of the corrosion inhibitor, the corrosion rate continues to decrease. Specifically, when the concentration of the corrosion inhibitor in the corrosion medium reaches 300 mg / L, the corrosion rate of the carbon steel sample decreases from 16.12 to 5.08 g·(m

[0002] ·h) , and the inhibition rate is 73.51%.

[0088] Table 3 Weight loss test results of carbon steel in 1 mol / L HCl at 70℃ with different concentrations of PACS

[0089]

[0090] In order to further study the corrosion inhibition effect of the corrosion inhibitor on the carbon steel sample, the micro-morphology of the sample surface after blank corrosion and after adding polyamide chitosan (PACS) is observed by using a scanning electron microscope (SEM). The micro-morphology of the carbon steel sample is shown in Figure 1 .

[0091] Figure 1 (a) and (b) are carbon steel samples subjected to blank corrosion, and the carbon steel samples are corroded by hydrochloric acid and dissolved oxygen, the surface of the carbon steel samples is rough, and a large amount of corrosion products are generated, and the corrosion is very serious. Figure 1 (c) and (d) are carbon steel samples after adding 300 mg / L of the corrosion inhibitor polyamide chitosan (PACS), and the surface of the carbon steel samples tends to be flat, and the corrosion products on the surface of the carbon steel samples are significantly reduced, which indicates that the corrosion inhibitor has a good inhibition effect on corrosion. The scanning electron microscope analysis result proves that the synthesized polyamide chitosan has a good corrosion inhibition effect.

[0092] The present application has been disclosed in the foregoing by preferred embodiments, but those skilled in the art should understand that these embodiments are only used to depict the present application, and should not be understood as limiting the scope of the present application. It should be noted that any equivalent changes and substitutions of these embodiments should be considered as being covered in the scope of the claims of the present application. Therefore, the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. Use of a polyamidated chitosan as a completion fluid waste flocculant, characterized in that, The application uses polyaluminum chloride or polyferric sulfate as a flocculant, and the polyamidated chitosan as a coagulant aid; The preparation method of the polyamidated chitosan comprises the following steps: (1) dispersing chitosan powder in a solution, adding methyl acrylate, heating and stirring at 40-65 DEG C for 20-30 h, and obtaining a mixed system after the reaction; (2) solid-liquid separation is performed on the mixed system, and then the precipitate is dispersed in a solution; (3) adding ethylenediamine, heating and stirring at 40-65 DEG C for 20-30 h, and performing solid-liquid separation after the reaction to obtain a first generation of branched chitosan product; In the preparation of the first generation of branched chitosan product, the ratio of the chitosan powder to the methyl acrylate is (4-7): 1, and the ratio of the ethylenediamine to the product of step (2) is (2-7):

5. (4) dispersing the first generation of branched chitosan product in a solution, and repeating steps (1) to (3) to obtain the polyamidated chitosan; In step (4), the ratio of the first generation of branched chitosan product to methyl acrylate and ethylenediamine is (4-7): 1: (1-3).

2. Use according to claim 1, characterized in that, In the preparation of the first generation of branched chitosan product, the ratio of the chitosan powder to the methyl acrylate is 5:1, and the ratio of the ethylenediamine to the product of step (2) is 2:

5.

3. Use according to claim 1, characterized in that, In step (4), the ratio of the first generation of branched chitosan product to methyl acrylate and ethylenediamine is 5:1:

2.

4. Use according to claim 1, characterized in that, The heating temperature in steps (1) and (3) is 50 DEG C, and the stirring time is 24 h.

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