A kinetic hydrate inhibitor, a deepwater drilling fluid system and a preparation method thereof

Abstract

The application belongs to the technical field of deepwater oil and gas exploitation, and particularly relates to a kinetic hydrate inhibitor, a deepwater drilling fluid system and a preparation method. The preparation method of the kinetic hydrate inhibitor comprises the following steps: (1) inert gas is introduced into water to perform oxygen removal treatment, a heterocyclic end alkenyl monomer is added, and stirring is performed; (2) a hydroxyl end alkenyl monomer is added, and continuous stirring is performed until a homogeneous solution is formed; (3) the reaction system is heated, and ammonium persulfate is added under the conditions of inert gas protection and stirring to perform reaction; and (4) sodium bisulfite is added into the reaction system in step (3), and after reaction is completed, the product is sequentially subjected to filtration, washing and crushing treatment to obtain the kinetic hydrate inhibitor. The kinetic hydrate inhibitor can effectively inhibit the generation of hydrates in a wellbore under a deepwater high-pressure environment, so that complex conditions in the wellbore can be avoided, production cost and non-production time can be reduced, and development efficiency and economic benefits can be improved.

Description

Technical Field

[0001] This invention belongs to the field of deepwater oil and gas extraction technology, specifically relating to a kinetic hydrate inhibitor, a deepwater drilling fluid system, and its preparation method. Background Technology

[0002] Deepwater oil and gas reserves are vast, accounting for 60% of the world's newly discovered oil and gas reserves. Among them, oil and gas reserves discovered in deepwater and ultra-deepwater areas account for 61.99% of the total discoveries in the deepwater area. Deepwater areas will dominate global oil and gas extraction.

[0003] However, during deepwater drilling, the greater water depth means that the overlying rock layers are replaced by seawater, resulting in extremely low pressure in the overlying strata. The rocks are often loosely cemented, leading to high collapse pressure, low leakage pressure, and a narrowing drilling pressure window. The low-temperature environment also alters the rheological properties of the drilling fluid, increasing its viscosity and causing a gel effect. This generates higher frictional resistance in the wellbore, increasing the risk of formation leakage at the casing shoe. Furthermore, the high pressure of deep water makes it easier for natural gas hydrates to form in the drilling fluid circulation system, affecting normal drilling operations.

[0004] Inhibitors are crucial for suppressing hydrate formation and ensuring safe wellbore flow. Existing inhibitors mainly include salt inhibitors and alcohol inhibitors. However, in deepwater drilling, high dosages of salt and alcohol inhibitors are insufficient to meet the narrow safety density window requirements. Therefore, using kinetic inhibitors in combination with salt and alcohol inhibitors is an important way to enhance inhibition. In field drilling, thermodynamic and alcohol inhibitors are generally added to the drilling fluid, but this is insufficient to meet the narrow safety density window requirements. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a kinetic hydrate inhibitor, a deepwater drilling fluid system, and a preparation method thereof.

[0006] Specifically, the present invention is achieved through the following technical solutions:

[0007] A method for preparing a kinetic hydrate inhibitor, comprising:

[0008] (1) Inert gas is introduced into the water for deoxygenation treatment, and a terminal alkenyl monomer containing heterocyclic rings is added and stirred and mixed.

[0009] (2) Add hydroxyl-containing terminal alkenyl monomers and continue stirring until a homogeneous solution is formed in the system;

[0010] (3) Heat the reaction system and add ammonium persulfate under inert gas protection and stirring conditions to carry out the reaction;

[0011] (4) Add sodium bisulfite to the reaction system of step (3). After the reaction is completed, filter, wash and pulverize the product in sequence to obtain the kinetic hydrate inhibitor.

[0012] In the above-mentioned method for preparing kinetic hydrate inhibitors, the inert gas is one or more of nitrogen and argon.

[0013] In the above-mentioned method for preparing kinetic hydrate inhibitors, the heterocyclic terminal alkenyl monomer is N-vinylpyrrolidone; and the hydroxyl-containing terminal alkenyl monomer is N-hydroxymethylacrylamide.

[0014] In the above-mentioned method for preparing kinetic hydrate inhibitors, the weight ratio of the heterocyclic terminal alkenyl monomer to the hydroxyl-containing terminal alkenyl monomer is (7-9):1.

[0015] In the above-mentioned method for preparing kinetic hydrate inhibitors, the heating temperature in step (3) is 50-80℃.

[0016] In the above-mentioned method for preparing kinetic hydrate inhibitors, the mass ratio of ammonium persulfate to sodium bisulfite is (0.5-1):1.

[0017] A kinetic hydrate inhibitor, which is prepared by the above-described method for preparing kinetic hydrate inhibitors.

[0018] A deepwater drilling fluid system comprising the aforementioned kinetic hydrate inhibitor.

[0019] The aforementioned deepwater drilling fluid system also includes one or more of the following: seawater-based fluid, sodium carbonate, filtration reducer, coating agent, viscosifier, clay hydration inhibitor, anti-mud packing lubricant, and sodium chloride.

[0020] The aforementioned deepwater drilling fluid system, based on 100 parts by weight of seawater-based fluid, contains 0.1-0.5 parts by weight of sodium carbonate, 1-4 parts by weight of filtration loss reducer, 0.5-1 parts by weight of coating agent, 0.2-0.5 parts by weight of viscosifier, 3-6 parts by weight of clay hydration inhibitor, 2-6 parts by weight of anti-mud lubricant, 9-19 parts by weight of sodium chloride, and 1-2 parts by weight of kinetic hydrate inhibitor.

[0021] The technical solution of the present invention has the following beneficial effects:

[0022] (1) The kinetic hydrate inhibitor provided by the present invention can effectively inhibit the formation of wellbore hydrates under deep water high pressure environment (the experimental simulated pressure is 32MPa), thereby avoiding complex downhole conditions, reducing production costs and non-production time, and improving development efficiency and economic benefits.

[0023] (2) The deepwater drilling fluid system provided by the present invention has good rheological filtration performance. At the same time, under low temperature conditions, the rheological filtration of the system meets the production needs, effectively reduces the occurrence of gelation effect, prevents well leakage, reduces well control risk, and improves work efficiency.

[0024] (3) The deepwater drilling fluid system provided by the present invention can effectively suppress the formation of natural gas hydrates under high pressure conditions, and at the same time, the rheological properties of the drilling fluid system change little under low temperature conditions, thereby preventing the formation of hydrates in the wellbore, reducing the risk of well leakage, avoiding complex downhole conditions, reducing production costs and non-production time, and improving development efficiency and economic benefits.

[0025] (4) The kinetic hydrate inhibitor and water-based strong inhibitory environmentally friendly deep-water drilling fluid system provided by the present invention have a wide range of raw material components that can be obtained, and the preparation method is simple and low in cost. It is of great significance for the exploitation of natural gas hydrates in deep-water areas and is worth promoting and applying. Attached Figure Description

[0026] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention.

[0027] Figure 1 The graph shows the parameter changes of the drilling fluid system in Comparative Example 2 during the hydrate inhibition evaluation test.

[0028] Figure 2 This is a graph showing the parameter changes of the drilling fluid system in Example 4 during the hydrate inhibition evaluation test. Detailed Implementation

[0029] To fully understand the purpose, features, and effects of this invention, the following detailed embodiments are provided to illustrate the invention in detail. Except as described below, the process methods of this invention employ conventional methods or apparatus in the art. Unless otherwise specified, the terms and expressions used below have the meanings commonly understood by those skilled in the art.

[0030] When a range of values ​​is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0031] This invention provides a dynamic hydrate inhibitor (D-PVP PRO) and constructs a deepwater drilling fluid system based on it, which meets the requirements of good rheological and lubrication properties under deepwater low temperature and high pressure conditions, maintaining wellbore stability and preventing hydrate formation in the wellbore.

[0032] This invention utilizes a heterocyclic terminal alkenyl monomer and a hydroxyl-containing terminal alkenyl monomer to generate a kinetic hydrate inhibitor via a free radical reaction, specifically including the following steps:

[0033] (1) Inert gas is introduced into the water for deoxygenation treatment, and a terminal alkenyl monomer containing heterocyclic rings is added and stirred and mixed.

[0034] (2) Add hydroxyl-containing terminal alkenyl monomers and continue stirring until a homogeneous solution is formed in the system;

[0035] (3) The reaction system is heated, and under the protection of an inert gas and stirring conditions, an oxidizing initiator, ammonium persulfate, is added to the solution to dissociate into persulfate ions;

[0036] (4) Add sodium bisulfite, a reducing initiator, to the reaction system of step (3). After the bisulfite ions react with the persulfate ions, sulfate free radicals and sulfite free radicals are obtained. The highly active free radicals act on the carbon-carbon double bonds in the two monomers to form chain active centers. Subsequently, a free radical chain growth reaction occurs to drive the polymerization reaction to continue and form a polymer structure.

[0037] (5) After the reaction is completed, the product is filtered, washed and pulverized in sequence to obtain the kinetic hydrate inhibitor.

[0038] In a free radical reaction system, oxygen molecules can react with the generated free radicals, thereby terminating the growth or propagation of the free radical chain. This invention protects the free radicals from the influence of oxygen by introducing an inert gas into the water, ensuring the reaction proceeds along the intended path. In some preferred embodiments, the inert gas is one or more of nitrogen and argon.

[0039] In some preferred embodiments, the heterocyclic terminal alkenyl monomer is N-vinylpyrrolidone, and the hydroxyl-containing terminal alkenyl monomer is N-hydroxymethylacrylamide.

[0040] N-vinylpyrrolidone, CAS number: 88-12-0, has a molecular weight of 111.14 and the following molecular structural formula: N-Hydroxymethylacrylamide, CAS No.: 924-42-5, molecular weight: 101.10, molecular structure formula:

[0041] In some preferred embodiments, the weight ratio of the heterocyclic terminal alkenyl monomer to the hydroxyl-containing terminal alkenyl monomer is (7-9):1.

[0042] When the weight ratio of heterocyclic terminal alkenyl monomers to hydroxyl-containing terminal alkenyl monomers is less than 7:1, incomplete cross-linking may occur during the reaction, resulting in poor performance of the synthesized product. When the weight ratio of heterocyclic terminal alkenyl monomers to hydroxyl-containing terminal alkenyl monomers is greater than 9:1, excessive cross-linking or the formation of an uneven structure will occur, leading to a decrease in the performance of the synthesized product.

[0043] In this invention, the ammonium persulfate and the sodium bisulfite are initiators for free radical reactions, and the mass ratio of the initiator ammonium persulfate to the monomer is (0.5-1):100, and the mass ratio of the initiator sodium bisulfite to the monomer is (1-1.5):100.

[0044] In some preferred embodiments, the mass ratio of ammonium persulfate to sodium bisulfite is (0.5-1):1.

[0045] More preferably, before preparing the kinetic hydrate inhibitor, ammonium persulfate and sodium bisulfite are prepared into an aqueous solution, thereby pre-dispersing the initiator in the aqueous solution, which can effectively improve the initiation efficiency, promote the uniform generation of free radicals, and prevent the probability of termination of the reaction caused by uneven free radical concentration.

[0046] In some preferred embodiments, the heating temperature in step (3) is 50-80°C, and more preferably 60°C.

[0047] In some preferred embodiments, the product is washed with anhydrous ethanol and pulverized using a liquid nitrogen pulverizer to obtain a powdered kinetic hydrate inhibitor.

[0048] On the other hand, the present invention also provides a deepwater drilling fluid system comprising the above-mentioned kinetic hydrate inhibitor.

[0049] In some preferred embodiments, the deepwater drilling fluid system may also include, depending on the actual working conditions, one or more of the following: seawater-based fluid, sodium carbonate, filtration reducer, coating agent, viscosity modifier, clay hydration inhibitor, anti-mud packing lubricant, and sodium chloride.

[0050] More preferably, based on 100 parts by weight of seawater-based liquid, the content of sodium carbonate is 0.1-0.5 parts by weight, the content of filtration loss reducer is 1-4 parts by weight, the content of coating agent is 0.5-1 parts by weight, the content of thickener is 0.2-0.5 parts by weight, the content of clay hydration inhibitor is 3-6 parts by weight, the content of anti-mud coating lubricant is 2-6 parts by weight, the content of sodium chloride is 9-19 parts by weight, and the content of kinetic hydrate inhibitor is 1-2 parts by weight.

[0051] The types of filtration loss reducers, coating agents, thickeners, clay hydration inhibitors, anti-mud lubricants, and kinetic hydrate inhibitors can be conventionally selected according to actual needs, and this invention does not impose any special limitations on them.

[0052] In an optional embodiment, the filtration loss reducer is D-FLOTROL, the coating agent is D-UCAP, the thickener is D-XC, the clay hydration inhibitor is D-PAHIB, and the anti-mud-packing lubricant is D-ABLUB.

[0053] The deepwater drilling fluid system of this invention not only incorporates traditional hydrate inhibitors (thermodynamic inhibitors) but also highly efficient kinetic inhibitors. It can effectively suppress the formation of natural gas hydrates even under the high-pressure environment of deep water. At the same time, the system has stable rheological properties under low-temperature conditions, which can prevent the formation of hydrates and blockage in the wellbore and the gel effect caused by increased drilling fluid viscosity.

[0054] Example

[0055] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments, unless otherwise specified, were performed according to conventional methods and conditions. The raw materials used in the following embodiments were all commercially available.

[0056] The raw material sources for the examples and comparative examples 1-2 are as follows:

[0057] N-Vinylpyrrolidone: CAS No. 88-12-0, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0058] N-Hydroxymethylacrylamide: CAS No. 924-42-5, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0059] Filtration loss reducer D-FLOTROL: Purchased from the Oilfield Chemicals Division of China Oilfield Services Limited, product number 2024061701;

[0060] Coating agent D-UCAP: Purchased from Oilfield Chemicals Division, China Oilfield Services Limited, product number 240809;

[0061] Tackifier D-XC: Purchased from Oilfield Chemicals Division of China Oilfield Services Limited, item number 25040501;

[0062] Clay hydration inhibitor D-PAHIB: Purchased from Oilfield Chemicals Division, China Oilfield Services Limited, product number 25010901;

[0063] Anti-mud lubricant D-ABLUB: Purchased from the Oilfield Chemicals Division of China Oilfield Services Limited, product number 25052301.

[0064] Example 1: Preparation of kinetic hydrate inhibitors

[0065] (1) Weigh 100g of distilled water and put it into a round-bottom flask. Stir at room temperature at a speed of 20r / min and purge the distilled water with nitrogen to remove oxygen. Slowly add 16g of N-vinylpyrrolidone into the round-bottom flask and stir until homogeneous. Slowly add 2g of N-hydroxymethylacrylamide into the round-bottom flask.

[0066] (2) After the round-bottom flask becomes transparent, the solution is transferred to a three-necked flask equipped with a reflux condenser, fixed on a water bath rack, and the water bath temperature is adjusted to 60°C. Stirring is started at a speed of 40 r / min, and nitrogen gas is continuously introduced. The gas flow rate is adjusted until a small number of bubbles emerge from the outlet. 3.2 g of 5% ammonium persulfate aqueous solution is slowly added to the above solution. After reacting for 30 minutes, 3.8 g of 5% sodium bisulfite aqueous solution is slowly added. After reacting for another 4 hours, the solution is filtered and washed with anhydrous ethanol to obtain a gel-like product. The product is then pulverized using a liquid nitrogen pulverizer to obtain powdered kinetic hydrate inhibitor D-PVP PRO-1.

[0067] Example 2: Preparation of kinetic hydrate inhibitors

[0068] (1) Weigh 100g of distilled water and put it into a round-bottom flask. Stir at room temperature at a speed of 20r / min and purge the distilled water with nitrogen to remove oxygen. Slowly add 14g of N-vinylpyrrolidone into the round-bottom flask and stir until homogeneous. Slowly add 2g of N-hydroxymethylacrylamide into the round-bottom flask.

[0069] (2) After the round-bottom flask becomes transparent, the solution is transferred to a three-necked flask equipped with a reflux condenser, fixed on a water bath rack, and the water bath temperature is adjusted to 60°C. Stirring is started at a speed of 40 r / min, and nitrogen gas is continuously introduced. The gas flow rate is adjusted until a small number of bubbles emerge from the outlet. 3.2 g of 5% ammonium persulfate aqueous solution is slowly added to the above solution. After reacting for 30 minutes, 4.4 g of 5% sodium bisulfite aqueous solution is slowly added. After reacting for another 4 hours, the solution is filtered and washed with anhydrous ethanol to obtain a gel-like product. The product is then pulverized using a liquid nitrogen pulverizer to obtain powdered kinetic hydrate inhibitor D-PVP PRO-2.

[0070] Example 3: Preparation of kinetic hydrate inhibitors

[0071] (1) Weigh 100g of distilled water and put it into a round-bottom flask. Stir at room temperature at a speed of 20r / min and purge the distilled water with nitrogen to remove oxygen. Slowly add 18g of N-vinylpyrrolidone into the round-bottom flask and stir until homogeneous. Slowly add 2g of N-hydroxymethylacrylamide into the round-bottom flask.

[0072] (2) After the round-bottom flask becomes transparent, the solution is transferred to a three-necked flask equipped with a reflux condenser, fixed on a water bath rack, and the water bath temperature is adjusted to 70°C. Stirring is started at a speed of 40 r / min, and nitrogen gas is continuously introduced. The gas flow rate is adjusted until a small number of bubbles emerge from the outlet. 3.2 g of 5% ammonium persulfate aqueous solution is slowly added to the above solution. After reacting for 30 minutes, 5 g of 5% sodium bisulfite aqueous solution is slowly added. After reacting for another 4 hours, the solution is filtered and washed with anhydrous ethanol to obtain a gel-like product. The product is then pulverized using a liquid nitrogen pulverizer to obtain powdered kinetic hydrate inhibitor D-PVP PRO-3.

[0073] Example 4: Preparation of Deepwater Drilling Fluid System

[0074] 400 ml of seawater was measured into a measuring cylinder and placed in a slurry cup. The mixture was stirred at 11,000 r / min. Then, 4 g of the kinetic hydrate inhibitor (D-PVP PRO-1) prepared in Example 1, 0.8 g of thickener (D-XC), 8 g of filtration loss reducer (D-FLOTROL), 2 g of coating agent (D-UCAP), 12 g of anti-mud lubricant (D-ABLUB), 12 g of clay hydration inhibitor (D-PAHIB), 0.8 g of sodium carbonate, and 38 g of sodium chloride were added sequentially.

[0075] Comparative Example 1: Preparation of Drilling Fluid System

[0076] Measure 400ml of seawater into a measuring cylinder and stir at 11000r / min. Then add 0.8g of thickener (D-XC), 8g of filtration loss reducer (D-FLOTROL), 2g of coating agent (D-UCAP), 12g of anti-mud lubricant (D-ABLUB), 12g of clay hydration inhibitor (D-PAHIB), and 0.8g of sodium carbonate in sequence.

[0077] Comparative Example 2: Preparation of Drilling Fluid System

[0078] Measure 400ml of seawater into a measuring cylinder and stir at 11000r / min. Then add 0.8g of thickener (D-XC), 8g of filtration loss reducer (D-FLOTROL), 2g of coating agent (D-UCAP), 12g of anti-mud lubricant (D-ABLUB), 12g of clay hydration inhibitor (D-PAHIB), 0.8g of sodium carbonate, and 38g of sodium chloride.

[0079] Test Example 1: Rheological Filtration Performance Test

[0080] Drilling fluid systems were prepared according to the formulations of Example 4 and Comparative Examples 1-2. After the systems were stirred and mixed evenly, rheological filtration performance tests were conducted at room temperature and low temperature (2°C). The test results are shown in Table 1 and Table 2, respectively.

[0081] Table 1 shows the test results of rheological filtration performance at room temperature:

[0082]

[0083] Table 2 shows the test results of low-temperature rheological filtration performance:

[0084]

[0085] The results shown in Tables 1 and 2 indicate that the deepwater drilling fluid system with added kinetic hydrate inhibitors has good rheological filtration performance. At the same time, under low temperature conditions, the rheological filtration of the system meets the production requirements, effectively reduces the occurrence of gelation effect, prevents well leakage, reduces well control risk, and improves work efficiency.

[0086] Test Example 2: Evaluation Test of Hydrate Inhibition

[0087] The hydrate formation inhibition of the drilling fluid systems prepared in Example 4 and Comparative Example 2 was evaluated. The experimental test methods included the following steps:

[0088] (1) Open the high-pressure reactor and clean the inner wall.

[0089] (2) Add the experimental solution to the high-pressure reactor and set up the experimental apparatus as required.

[0090] (3) Turn on the vacuum pump and evacuate for 15 minutes.

[0091] (4) Close the intake valve and open the gas booster device to pressurize; first, increase the pressure to 35 MPa, adjust the pressure to 25 MPa, open the intake valve, and close the intake valve after the target pressure is reached; increase the pressure to 37 MPa, adjust the pressure to 32 MPa, open the intake valve, and close the intake valve after the target pressure is reached.

[0092] (5) Open the high-pressure gas outlet valve of the booster pump. After the high-pressure reactor reaches the target pressure, close the high-pressure gas outlet valve of the booster pump.

[0093] (6) Set parameters such as temperature, stirring time, and speed through the computer program, and start stirring after setting.

[0094] (7) After the temperature and pressure stabilize, pressurize again to keep the pressure inside the reactor at 32MPa when the constant rate of cooling begins.

[0095] (8) By observing the historical curve, the pressure change in the hydrate reactor is recorded once per minute. After the pressure stabilizes for 30 minutes, the natural gas hydrate is considered to be fully formed.

[0096] (9) Close the experimental apparatus and pipeline valves, clean the experimental instruments and arrange them neatly.

[0097] The parameter changes of the well fluid system throughout the entire process in Comparative Example 2 and Drilling Example 4 are shown in the figure below. Figure 1 and Figure 2 As shown. Comparison Figure 1 and Figure 2 It can be seen that when only salt inhibitors are added to the original drilling fluid system, the inhibitory effect fails at low temperatures, leading to the formation and accumulation of large amounts of hydrates. Figure 1 The observed changes were an increase in liquid phase temperature and a decrease in the number of gas moles; when a kinetic hydrate inhibitor was added to the system, no significant hydrate formation was observed under low-temperature conditions within the same time frame. Figure 2 This is characterized by a stable liquid phase temperature and no fluctuation in the number of gas moles.

[0098] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of the invention and should not be construed as limiting its scope. It should be noted that any variations and substitutions equivalent to these embodiments should be considered to be covered within the scope of the claims. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing a kinetic hydrate inhibitor, characterized in that, include: (1) Inert gas is introduced into the water for deoxygenation treatment, and a terminal alkenyl monomer containing heterocyclic rings is added and stirred to mix. (2) Add hydroxyl-containing terminal alkenyl monomers and continue stirring until a homogeneous solution is formed in the system; (3) Heat the reaction system and add ammonium persulfate under inert gas protection and stirring conditions to carry out the reaction; (4) Add sodium bisulfite to the reaction system of step (3). After the reaction is completed, filter, wash and pulverize the product in sequence to obtain the kinetic hydrate inhibitor. Wherein, the heterocyclic terminal alkenyl monomer is N-vinylpyrrolidone; and the hydroxyl-containing terminal alkenyl monomer is N-hydroxymethylacrylamide.

2. The preparation method according to claim 1, characterized in that, The inert gas is one or more of nitrogen and argon.

3. The preparation method according to claim 1, characterized in that, The weight ratio of the heterocyclic terminal alkenyl monomer to the hydroxyl-containing terminal alkenyl monomer is (7-9):

1.

4. The preparation method according to claim 1, characterized in that, The heating temperature in step (3) is 50-80℃.

5. The preparation method according to claim 1, characterized in that, The mass ratio of ammonium persulfate to sodium bisulfite is (0.5-1):

1.

6. A kinetic hydrate inhibitor, characterized in that, It is prepared by the method for preparing kinetic hydrate inhibitors according to any one of claims 1-5.

7. A deepwater drilling fluid system, characterized in that, Including the kinetic hydrate inhibitor as described in claim 6.

8. The deepwater drilling fluid system according to claim 7, characterized in that, Also includes: One or more of the following: seawater-based liquid, sodium carbonate, filtration loss reducer, coating agent, thickener, clay hydration inhibitor, anti-mud lubricant, and sodium chloride.

9. The deepwater drilling fluid system according to claim 8, characterized in that, Based on 100 parts by weight of seawater-based liquid, the content of sodium carbonate is 0.1-0.5 parts by weight, the content of filtration loss reducer is 1-4 parts by weight, the content of coating agent is 0.5-1 parts by weight, the content of thickener is 0.2-0.5 parts by weight, the content of clay hydration inhibitor is 3-6 parts by weight, the content of anti-mud coating lubricant is 2-6 parts by weight, the content of sodium chloride is 9-19 parts by weight, and the content of kinetic hydrate inhibitor is 1-2 parts by weight.

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