Dynamic hydrate inhibitor, deepwater drilling fluid system and preparation method

Abstract

The invention belongs to the technical field of deepwater oil and gas exploitation, and particularly relates to a dynamic hydrate inhibitor, a deepwater drilling fluid system and a preparation method. The invention relates to a preparation method of a kinetic hydrate inhibitor, which is characterized by comprising the following steps: (1) introducing inert gas into water to carry out deoxygenization treatment, adding an alkenyl-terminated monomer containing a heterocyclic ring, and stirring and mixing; (2) adding an alkenyl-terminated monomer containing hydroxyl, and continuously stirring until the system forms a homogeneous solution; (3) heating the reaction system, and adding ammonium persulfate for reaction under inert gas protection and stirring conditions; and (4) adding sodium hydrogen sulfite into the reaction system in the step (3), and after the reaction is completed, sequentially filtering, washing and crushing the product to obtain the kinetic hydrate inhibitor. The dynamic hydrate inhibitor provided by the invention can effectively inhibit the generation of hydrates in a shaft in a deepwater and high-pressure environment, thereby avoiding the occurrence of underground complex conditions, reducing the production cost and non-production time, and improving the development efficiency and economic benefits.

Description

TECHNICAL FIELD

[0001] The present 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. BACKGROUND

[0002] Deepwater oil and gas reserves are large, and new oil and gas reserves discovered in the sea account for 60% of the total reserves in the world, among which the oil and gas reserves discovered in the deepwater-super deepwater field account for 61.99% of the total reserves discovered in the sea, and the deepwater field will dominate the global oil and gas exploitation.

[0003] However, in the process of deepwater drilling, because the water depth of the operation sea area is large, the upper section originally covered by rocks is replaced by seawater, so that the overlying rock pressure is extremely low, the rock is often loosely cemented, the collapse pressure is high, the loss pressure is low, and the drilling pressure window is narrowed. The low-temperature environment easily leads to changes in the rheological property of the drilling fluid, which can increase the viscosity of the drilling fluid to produce a gel effect, and generate high friction resistance in the wellbore flow to increase the risk of pressure leakage of the formation at the casing shoe. At the same time, under the high-pressure environment of deep water, natural gas hydrate is easy to generate in the drilling fluid circulation system, which affects the normal production drilling.

[0004] The inhibitor is an important means to inhibit the generation of hydrate and ensure the safety of wellbore flow. The existing inhibitors mainly include salt inhibitors and alcohol inhibitors. However, when drilling in deepwater areas, high amounts of salt inhibitors and alcohol inhibitors cannot meet the demand of narrow safety density window, so the use of kinetic inhibitors in combination with salt inhibitors and alcohol inhibitors is an important means to improve the inhibitory effect. In the field drilling, thermodynamic inhibitors and alcohol inhibitors are generally added to the drilling fluid, but it is difficult to meet the demand of narrow safety density window. SUMMARY

[0005] In view of the defects of the prior art, the present application provides a kinetic hydrate inhibitor, a deepwater drilling fluid system and a preparation method.

[0006] Specifically, the present application is realized by the following technical scheme:

[0007] A preparation method of a kinetic hydrate inhibitor, comprising:

[0008] (1) oxygen removal treatment is performed by introducing inert gas into water, an end-alkenyl monomer containing a heterocycle is added, and stirring is performed for mixing;

[0009] (2) an end-alkenyl monomer containing a hydroxyl group is added, and continuous stirring is performed until a homogeneous solution is formed in the system;

[0010] (3) the reaction system is heated, and ammonium persulfate is added under the conditions of inert gas protection and stirring for reaction;

[0011] (4) adding sodium bisulfite into the reaction system of step (3), and after the reaction is completed, sequentially performing filtering, washing and crushing treatment on the product to obtain the kinetic hydrate inhibitor.

[0012] The preparation method of the kinetic hydrate inhibitor, and the inert gas is one or more of nitrogen and argon.

[0013] The preparation method of the kinetic hydrate inhibitor, and the end alkenyl monomer containing a heterocycle is N-vinyl pyrrolidone; and the end alkenyl monomer containing a hydroxyl group is N-hydroxymethyl acrylamide.

[0014] The preparation method of the kinetic hydrate inhibitor, and the weight ratio of the end alkenyl monomer containing a heterocycle to the end alkenyl monomer containing a hydroxyl group is (7-9):1.

[0015] The preparation method of the kinetic hydrate inhibitor, and the temperature of heating in step (3) is 50-80℃.

[0016] The preparation method of the kinetic hydrate inhibitor, and the mass ratio of the ammonium persulfate to the sodium bisulfite is (0.5-1):1.

[0017] A kinetic hydrate inhibitor is prepared by the preparation method of the kinetic hydrate inhibitor.

[0018] A deep water drilling fluid system comprises the kinetic hydrate inhibitor.

[0019] The deep water drilling fluid system further comprises one or more of a seawater-based liquid, sodium carbonate, a fluid loss additive, a coating agent, a viscosity enhancer, a clay hydration inhibitor, a mud balling lubricant, and sodium chloride.

[0020] The deep water drilling fluid system comprises, based on 100 parts by weight of the seawater-based liquid, 0.1-0.5 parts by weight of sodium carbonate, 1-4 parts by weight of the fluid loss additive, 0.5-1 part by weight of the coating agent, 0.2-0.5 parts by weight of the viscosity enhancer, 3-6 parts by weight of the clay hydration inhibitor, 2-6 parts by weight of the mud balling lubricant, 9-19 parts by weight of sodium chloride, and 1-2 parts by weight of the kinetic hydrate inhibitor.

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

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

[0023] (2) The deep water drilling fluid system provided by the application has good rheological filtration performance, and under low temperature conditions, the rheological filtration of the system meets the production needs, effectively reduces the occurrence of gel effect, prevents well leakage, reduces the well control risk, and improves the work efficiency;

[0024] (3) The deep water drilling fluid system provided by the application can effectively inhibit the generation of natural gas hydrate under high pressure conditions, and the rheological performance change range of the drilling fluid system is small under low temperature conditions, thereby preventing the generation of hydrate in the wellbore, reducing the well leakage risk, avoiding the occurrence of downhole complex conditions, reducing the production cost and non-production time, and improving the development efficiency and economic benefits;

[0025] (4) The kinetic hydrate inhibitor and the water-based strong inhibition environment-friendly deep water drilling fluid system provided by the application have a wide access to raw material components, a simple preparation method, and low cost, and have important significance for natural gas hydrate exploitation in deep water sea areas, and are worth popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0026] 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 the preferred embodiments and are not meant to limit the present application.

[0027] Figure 1 Parameter change graph of the drilling fluid system of Comparative Example 2 in the hydrate inhibition evaluation test;

[0028] Figure 2 Parameter change graph of the drilling fluid system of Example 4 in the hydrate inhibition evaluation test. DETAILED DESCRIPTION

[0029] In order to fully understand the purposes, 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 adopts the conventional method or device in the art except the following content. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0030] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum value and the maximum value of the range, and each value between the minimum value and the maximum value. Further, when the range refers to an integer, each 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 herein should be understood to include any and all sub-ranges incorporated therein.

[0031] The application provides a kinetic hydrate inhibitor (D-PVP PRO), and constructs a deepwater drilling fluid system based on the same, which meets the requirements of good rheological and lubricating properties, wellbore stability maintenance, and hydrate non-generation in the wellbore under the conditions of deepwater, low temperature and high pressure.

[0032] The application generates the kinetic hydrate inhibitor by free radical reaction of the heterocycle-containing terminal alkenyl monomer and the hydroxyl-containing terminal alkenyl monomer, and specifically includes the following steps:

[0033] (1) oxygen removal treatment is performed on water by introducing inert gas, the heterocycle-containing terminal alkenyl monomer is added, and stirring is performed for mixing;

[0034] (2) the hydroxyl-containing terminal alkenyl monomer is added, and continuous stirring is performed until a homogeneous solution is formed in the system;

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

[0036] (4) a reducing initiator sodium bisulfite is added to the reaction system of step (3), and after the reaction of bisulfite and persulfate, sulfate radicals and bisulfite radicals are obtained, the high-activity radicals act on the carbon-carbon double bonds in the two monomers to form chain active centers, and then a radical chain growth reaction is performed to continuously promote the polymerization reaction to form a high molecular structure;

[0037] (5) after the reaction is completed, the product is sequentially subjected to filtration, washing and crushing treatment to obtain the kinetic hydrate inhibitor.

[0038] In the free radical reaction system, oxygen molecules can react with generated free radicals to terminate the growth or propagation steps of the free radicals. In the application, inert gas is introduced into water to protect the free radicals from the influence of oxygen, and ensure that the reaction proceeds according to the expected path. In some preferred embodiments, the inert gas is one or more of nitrogen and argon.

[0039] In some preferred embodiments, the heterocycle-containing terminal alkenyl monomer is N-vinyl pyrrolidone, and the hydroxyl-containing terminal alkenyl monomer is N-hydroxymethyl acrylamide.

[0040] The N-vinyl pyrrolidone has a CAS number of 88-12-0, a molecular weight of 111.14, and a molecular structural formula of The N-hydroxymethyl acrylamide has a CAS number of 924-42-5, a molecular weight of 101.10, and a molecular structural formula of

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

[0042] When the weight ratio of the heterocyclic-containing end-vinyl monomer to the hydroxyl-containing end-vinyl monomer is less than 7:1, incomplete crosslinking may occur in the reaction, resulting in poor performance of the synthesized product; when the weight ratio of the heterocyclic-containing end-vinyl monomer to the hydroxyl-containing end-vinyl monomer is greater than 9:1, excessive crosslinking or formation of uneven structures occurs, resulting in a decrease in the performance of the synthesized product.

[0043] In the present application, the ammonium persulfate and the sodium bisulfite are initiators for radical reactions, 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 the ammonium persulfate to the sodium bisulfite is (0.5-1):1.

[0045] Further preferably, before preparing the kinetic hydrate inhibitor, the ammonium persulfate and the sodium bisulfite are formulated into an aqueous solution, whereby the initiators are pre-dispersed in the aqueous solution, which can effectively improve the initiation efficiency, promote the uniform generation of free radicals, and prevent the probability of termination reactions caused by uneven free radical concentrations.

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

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

[0048] In another aspect, the present application also provides a deepwater drilling fluid system comprising the above-mentioned kinetic hydrate inhibitor.

[0049] In some preferred embodiments, the deepwater drilling fluid system can further comprise one or more of a seawater-based liquid, sodium carbonate, a fluid loss additive, a coating agent, a viscosity enhancer, a clay hydration inhibitor, a mud balling lubricant, and sodium chloride according to actual working conditions.

[0050] Further preferably, based on 100 parts by weight of the seawater-based liquid, the content of sodium carbonate is 0.1-0.5 parts by weight, the content of the fluid loss additive is 1-4 parts by weight, the content of the coating agent is 0.5-1 part by weight, the content of the viscosity enhancer is 0.2-0.5 parts by weight, the content of the clay hydration inhibitor is 3-6 parts by weight, the content of the mud balling lubricant is 2-6 parts by weight, the content of sodium chloride is 9-19 parts by weight, and the content of the kinetic hydrate inhibitor is 1-2 parts by weight.

[0051] The types of the fluid loss additive, the coating agent, the viscosity enhancer, the clay hydration inhibitor, the anti-mud lubricant, and the kinetic hydrate inhibitor can be routinely selected according to actual needs, and the present application does not make special limitations thereon.

[0052] In an alternative embodiment, the fluid loss additive is D-FLOTROL, the coating agent is D-UCAP, the viscosity enhancer is D-XC, the clay hydration inhibitor is D-PAHIB, and the anti-mud lubricant is D-ABLUB.

[0053] The deepwater drilling fluid system of the present application not only adds the conventional hydrate inhibitor (thermodynamic inhibitor), but also adds the high-efficiency kinetic inhibitor, and can still effectively inhibit the generation of natural gas hydrate in the high-pressure environment of deep water, and at the same time, the rheological property of the system is stable under low-temperature conditions, which can prevent the problems of hydrate generation and plugging in the wellbore and the increase of the viscosity of the drilling fluid to cause the gel effect.

[0054] Examples

[0055] The present application will be further described by way of examples, but the present application is not limited in the scope of the examples. The experimental methods not specified in the following examples are carried out according to the conventional methods and conditions. The raw materials used in the following examples are all commercially available.

[0056] The sources of raw materials in the examples and comparative examples 1-2 are as follows:

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

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

[0059] Fluid loss additive D-FLOTROL: purchased from China Offshore Oilfield Services Co., Ltd. Oilfield Chemical Business Unit, item No. 2024061701;

[0060] Coating agent D-UCAP: purchased from China Offshore Oilfield Services Co., Ltd. Oilfield Chemical Business Unit, item No. 240809;

[0061] Viscosity enhancer D-XC: purchased from China Offshore Oilfield Services Co., Ltd. Oilfield Chemical Business Unit, item No. 25040501;

[0062] Clay hydration inhibitor D-PAHIB: purchased from China Offshore Oilfield Services Co., Ltd. Oilfield Chemical Business Unit, item No. 25010901;

[0063] Anti-fouling lubricant D-AB LUB: purchased from CNOOC Oilfield Services Limited, Oilfield Chemical Division, item number 25052301.

[0064] Example 1: Preparation of kinetic hydrate inhibitor

[0065] (1) 100 g of distilled water was weighed into a round-bottom flask and stirred at room temperature at a speed of 20 r / min, and nitrogen was passed through the distilled water to remove oxygen; 16 g of N-vinylpyrrolidone was slowly added to the round-bottom flask and stirred evenly; 2 g of N-hydroxymethyl acrylamide was slowly added to the round-bottom flask;

[0066] (2) After the round-bottom flask became transparent, the solution was transferred into a three-necked flask equipped with a reflux condenser, fixed on a water bath stand, and the water bath temperature was adjusted to 60°C, and stirring was started at a speed of 40 r / min, and nitrogen was continuously passed through, and the gas flow was adjusted to have a small amount of bubbles at the outlet; 3.2 g of 5% ammonium persulfate aqueous solution was slowly added to the above solution, and after 30 minutes of reaction, 3.8 g of 5% sodium bisulfite aqueous solution was slowly added, and after 4 hours of continuous reaction, filtration was performed, and the gel-like product was washed with anhydrous ethanol, and the kinetic hydrate inhibitor D-PVP PRO-1 in powder form was obtained by using a liquid nitrogen pulverizer.

[0067] Example 2: Preparation of kinetic hydrate inhibitor

[0068] (1) 100 g of distilled water was weighed into a round-bottom flask and stirred at room temperature at a speed of 20 r / min, and nitrogen was passed through the distilled water to remove oxygen; 16 g of N-vinylpyrrolidone was slowly added to the round-bottom flask and stirred evenly; 2 g of N-hydroxymethyl acrylamide was slowly added to the round-bottom flask;

[0069] (2) After the round-bottom flask became transparent, the solution was transferred into a three-necked flask equipped with a reflux condenser, fixed on a water bath stand, and the water bath temperature was adjusted to 60°C, and stirring was started at a speed of 40 r / min, and nitrogen was continuously passed through, and the gas flow was adjusted to have a small amount of bubbles at the outlet; 3.2 g of 5% ammonium persulfate aqueous solution was slowly added to the above solution, and after 30 minutes of reaction, 3.8 g of 5% sodium bisulfite aqueous solution was slowly added, and after 4 hours of continuous reaction, filtration was performed, and the gel-like product was washed with anhydrous ethanol, and the kinetic hydrate inhibitor D-PVP PRO-1 in powder form was obtained by using a liquid nitrogen pulverizer.

[0070] Example 3: Preparation of kinetic hydrate inhibitor

[0071] (1) Take 100 g of distilled water into a round-bottom flask, stir at room temperature at a speed of 20 r / min, and remove oxygen by passing nitrogen gas through the distilled water; slowly add 18 g of N-vinylpyrrolidone into the round-bottom flask and stir uniformly; slowly add 2 g of N-hydroxymethyl acrylamide into the round-bottom flask;

[0072] (2) When the round-bottom flask becomes transparent, transfer the solution into a three-necked flask with a reflux condenser, fix it on a water bath rack, adjust the water bath temperature to 70°C, start stirring at a speed of 40 r / min, and continuously pass nitrogen gas, and adjust the gas amount to have a small amount of bubbles at the outlet; slowly add 3.2 g of 5% ammonium persulfate aqueous solution into the above solution, react for 30 minutes, slowly add 5 g of 5% sodium bisulfite aqueous solution, continue to react for 4 hours, filter, wash with anhydrous ethanol, and obtain a gelatinous product, which is crushed by a liquid nitrogen crusher to obtain a powder-shaped kinetic hydrate inhibitor D-PVP PRO-3.

[0073] Example 4: Preparation of a deepwater drilling fluid system

[0074] Take 400 ml of seawater into a beaker, stir at a speed of 11000 r / min, and sequentially add 4 g of the kinetic hydrate inhibitor (D-PVP PRO-1) prepared in Example 1, 0.8 g of the tackifier (D-XC), 8 g of the fluid loss additive (D-FLOTROL), 2 g of the coating agent (D-UCAP), 12 g of the anti-mud lubricant (D-ABLUB), 12 g of the clay hydration inhibitor (D-PAHIB), 0.8 g of sodium carbonate, and 38 g of sodium chloride.

[0075] Comparative Example 1: Preparation of a drilling fluid system

[0076] Take 400 ml of seawater into a beaker, stir at a speed of 11000 r / min, and sequentially add 0.8 g of the tackifier (D-XC), 8 g of the fluid loss additive (D-FLOTROL), 2 g of the coating agent (D-UCAP), 12 g of the anti-mud lubricant (D-ABLUB), 12 g of the clay hydration inhibitor (D-PAHIB), and 0.8 g of sodium carbonate.

[0077] Comparative Example 2: Preparation of a drilling fluid system

[0078] Take 400 ml of seawater into a beaker, stir at a speed of 11000 r / min, and sequentially add 0.8 g of the tackifier (D-XC), 8 g of the fluid loss additive (D-FLOTROL), 2 g of the coating agent (D-UCAP), 12 g of the anti-mud lubricant (D-ABLUB), 12 g of the clay hydration inhibitor (D-PAHIB), 0.8 g of sodium carbonate, and 38 g of sodium chloride.

[0079] Test Example 1: Rheological Filtration Performance Test

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

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

[0082]

[0083] Table 2 is the test results of rheological filtration performance at low temperature:

[0084]

[0085] As can be seen from the results shown in Tables 1 and 2, the deepwater drilling fluid system with the addition of the kinetic hydrate inhibitor has good rheological filtration performance, and at low temperature, the rheological filtration of the system meets the production needs, effectively reduces the occurrence of gel effect, prevents well leakage, reduces the risk of well control, and improves work efficiency.

[0086] Test Example 2: Hydrate Inhibition Evaluation Test

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

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

[0089] (2) Add the experimental solution to the high-pressure reaction kettle, and arrange the experimental device according to the requirements.

[0090] (3) Open the vacuum pump and vacuum for 15 minutes.

[0091] (4) Close the air inlet valve and open the gas pressure device for pressurization; first increase the pressure to 35 MPa, adjust to 25 MPa, open the air inlet valve, and close the air inlet valve after reaching the target pressure; increase the pressure to 37 MPa, adjust to 32 MPa, open the air inlet valve, and close the air inlet valve after reaching the target pressure.

[0092] (5) Open the high-pressure gas outlet valve of the pressure pump, and close the high-pressure gas outlet valve of the pressure pump after the high-pressure reaction kettle reaches the target pressure.

[0093] (6) Set the temperature, stirring time, and rotation speed parameters through the computer, and start stirring after setting is complete.

[0094] (7) After the temperature and pressure are stable, perform a pressure compensation again, so that the pressure in the reaction kettle remains at 32 MPa when the constant-speed cooling begins.

[0095] (8) By observing the history curve, the pressure change in hydrate reactor is recorded once per minute, and the natural gas hydrate is considered to be completely generated after the pressure is stable for 30 minutes.

[0096] (9) Close the experimental device and pipeline valve, clean the experimental instrument and place it neatly.

[0097] The whole process parameter change graph of the well fluid system of Comparative Example 2 and Well Fluid System of Drilling Example 4 is shown in Figure 1 and Figure 2 By comparing Figure 1 and Figure 2 , it can be obtained that when only salt inhibitor is added to the original drilling fluid system, the inhibition effect is invalid at low temperature, resulting in a large amount of hydrate generation and aggregation, which is manifested as the increase of liquid phase temperature and the decrease of gas molar number in Figure 1 ; when the kinetic hydrate inhibitor is added to the system, no obvious hydrate is generated in the same time under low temperature conditions, which is manifested as the liquid phase temperature tends to be stable and the gas molar number has no fluctuation in Figure 2 .

[0098] 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 with these embodiments should be considered as 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. A method of preparing a kinetic hydrate inhibitor, characterized by, The method comprises the following steps: (1) introducing inert gas into water for oxygen removal treatment, adding end-alkenyl monomer containing heterocycle, and stirring the mixture; (2) adding end-alkenyl monomer containing hydroxyl group, and continuously stirring until the system forms a homogeneous solution; (3) heating the reaction system, and adding ammonium persulfate under the conditions of inert gas protection and stirring for reaction; (4) adding sodium bisulfite to the reaction system of step (3), and after the reaction is completed, the product is sequentially subjected to filtration, washing and crushing treatment to obtain the kinetic hydrate inhibitor.

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

3. The preparation method according to claim 1, characterized in that The end-alkenyl monomer containing heterocycle is N-vinyl pyrrolidone; and the end-alkenyl monomer containing hydroxyl group is N-hydroxymethyl acrylamide.

4. The method of claim 1, wherein, The weight ratio of the end-alkenyl monomer containing heterocycle to the end-alkenyl monomer containing hydroxyl group is (7-9):

1.

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

6. The method of claim 1, wherein, The mass ratio of the ammonium persulfate to the sodium bisulfite is (0.5-1):

1.

7. A kinetic hydrate inhibitor characterized in that, The kinetic hydrate inhibitor is prepared by the method of any one of claims 1-7.

8. A deep water drilling fluid system characterized by, The kinetic hydrate inhibitor of claim 8 is included.

9. The deep water drilling fluid system of claim 8, wherein, Further included are: one or more of seawater-based liquid, sodium carbonate, fluid loss additive, coating agent, viscosity enhancer, clay hydration inhibitor, anti-mud lubricant, sodium chloride.

10. The deep water drilling fluid system of claim 9, wherein, The content of sodium carbonate is 0.1-0.5 parts by weight, the content of fluid loss additive is 1-4 parts by weight, the content of coating agent is 0.5-1 part by weight, the content of viscosity enhancer is 0.2-0.5 part by weight, the content of clay hydration inhibitor is 3-6 parts by weight, the content of anti-mud 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, based on 100 parts by weight of seawater-based liquid.

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