Paraffin inhibitor for deepwater low-temperature high-pressure environment and preparation method thereof

Abstract

The invention discloses a paraffin inhibitor for a deepwater low-temperature high-pressure environment and a preparation method of the paraffin inhibitor. The paraffin inhibitor is prepared from a main paraffin inhibitor, a salt-resistant compound surfactant, a low-temperature compatible solvent, a corrosion inhibition synergist and a stabilizer, according to the preparation method, all the components form a stable homogeneous system through a segmented temperature control shearing dispersion process. The paraffin inhibitor disclosed by the invention has excellent temperature-resistant, pressure-resistant and salt-resistant stability and efficient wax crystal regulation and control capability under the conditions that the temperature is 0-15 DEG C, the pressure is 5-150MPa and the formation water mineralization degree is 2000mg / L-50000mg / L, has good metal corrosion inhibition and non-metallic material compatibility, is high in industrial feasibility and controllable in cost, effectively solves the problem of wax deposition in the deepwater oil and gas field exploitation process, and has a wide application prospect. The method is of great significance in improving the economy and safety of deepwater oil-gas field development.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field chemical engineering technology, specifically relating to a wax inhibitor for deep-water low-temperature and high-pressure environments and its preparation method. Background Technology

[0002] Deepwater oil and gas fields are typically located at depths of 500 to 1500 meters on the seabed, characterized by a unique "three highs and one low" environment: seabed temperatures remain consistently between 2°C and 15°C; formation pressures can reach 10 MPa to 150 MPa; formation water salinity is as high as 2000 mg / L to 50000 mg / L; and crude oil generally has a high wax content (15% to 30%). Under these extreme conditions, paraffin wax (mainly composed of C16 to C35 n-alkanes) in crude oil is prone to precipitate as wax crystals due to temperature drops and pressure fluctuations, forming wax deposits. Wax deposits not only reduce the effective cross-sectional area of ​​pipelines and increase flow resistance, but also accelerate the corrosion of metal equipment, and can even cause pipeline blockages and safety accidents, severely impacting oil and gas extraction efficiency and production safety.

[0003] Currently, deep-sea anti-waxing technology mainly relies on umbilical cables to inject chemical anti-waxing agents. The diameter of the umbilical cable injection tube is generally 0.6~1.2 cm, and the length is tens or even hundreds of kilometers. The application temperature drops from about 50℃ to about 2℃ at the seabed temperature, and then rises to 100~200℃ when entering the oil and gas pipeline. The contact materials include more than 10 kinds of metals and non-metals such as stainless steel, perfluorinated rubber, polyetheretherketone, and polytetrafluoroethylene. The residence time in the tube string is as long as several days to tens of days. The delivery pressure is high (above 2MPa), and there are rapid temperature and pressure changes at the injection point. This places many requirements on the environmental adaptability, chemical stability, product cleanliness, viscosity, material compatibility, and other properties of the anti-waxing agent injected into the umbilical cable.

[0004] Existing deep-water wax inhibitors suffer from inherent structural defects: firstly, the main chain lacks rigidity, making it prone to chain coiling under high pressure, resulting in insufficient exposure of wax crystal action sites; secondly, they lack functional units resistant to extreme environments, easily undergoing structural degradation or aggregation under high salinity and wide temperature variations, leading to a significant decrease in wax-preventing efficiency. Current deep-water wax inhibitors lack adaptability to extreme conditions, failing to meet the demands of complex deep-water environments and long operating cycles, exhibiting weak versatility and an imbalance between environmental safety and economic efficiency. Therefore, developing a deep-water wax inhibitor that combines strong tolerance to extreme environments, high-efficiency wax-preventing performance, and environmental, economic, and safety factors is of great significance for ensuring the safety of deep-water crude oil flow and promoting the development of deep-water wax inhibitor technology. Summary of the Invention

[0005] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a wax inhibitor for deep-sea low-temperature and high-pressure environments and its preparation method.

[0006] This invention is achieved through the following technical solution: A wax inhibitor for use in deep-sea, low-temperature, and high-pressure environments, wherein the wax inhibitor comprises the following components and their mass percentages are as follows: Main anti-wax agent 15%~30%; Salt-resistant compound surfactants 5%~15%; Low-temperature compatible solvents: 42%~60%; Corrosion inhibitor synergist 3%~8%; Stabilizer 2%~5%.

[0007] In the above technical solution, the main anti-wax agent is a long-chain alkyl acrylate-maleic anhydride-styrene derivative ternary block copolymer; the long-chain alkyl acrylate has a carbon number of C16~C22; the molar ratio of long-chain alkyl acrylate, maleic anhydride and styrene derivative is 2:1:(0.3~0.8), and the weight average molecular weight M of the block copolymer is... w The value is 5000~15000; the long-chain alkyl acrylate is hexadecyl methacrylate or octadecyl methacrylate; the styrene derivative is at least one of α-methylstyrene, p-methylstyrene or p-tert-butylstyrene.

[0008] In the above technical solution, the preparation method of the main anti-wax agent (long-chain alkyl acrylate-maleic anhydride-styrene derivative terpolymer) includes the following steps: S1. Add long-chain alkyl acrylate, maleic anhydride and styrene derivative to a dry reactor at a molar ratio of 2:1:(0.3~0.8), and then add xylene as a polymerization solvent. The amount of the polymerization solvent is 1.5 to 2.0 times the total mass of the monomers. Start stirring to make the monomers uniformly dispersed. The total mass of the monomers refers to the sum of the masses of long-chain alkyl acrylates, maleic anhydride, and styrene derivatives; S2. Vacuum the reactor and purge with nitrogen 3 to 5 times to remove oxygen from the reactor; raise the temperature to 80 to 90°C at a rate of 2°C / min to 3°C / min, add the initiator, the amount of which is 0.3% to 1.5% of the total mass of the monomer, maintain a stirring rate of 300 to 400 rpm, and carry out the polymerization reaction at a constant temperature for 4 to 10 hours. The initiator is benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN). S3. After the polymerization reaction is completed, the reaction system is cooled to 30℃~40℃. Anhydrous ethanol with a volume of 3 to 4 times the total volume of all liquids in the reaction system is added for washing. The mixture is allowed to stand and precipitate. The liquid phase is removed by vacuum filtration. The washing is repeated 3 to 4 times to remove unreacted monomers and soluble impurities. S4. Place the washed product in a vacuum drying apparatus and dry it for 4 to 6 hours at a vacuum of -0.07 to -0.09 MPa and a temperature of 60°C to 70°C to obtain a white powdery ternary block copolymer main anti-wax agent.

[0009] In the above technical solution, the salt-resistant compound surfactant is compounded from polyoxyethylene alkylamine and sodium dodecylbenzenesulfonate in a mass ratio of (1~3):1; the degree of polymerization of the polyoxyethylene alkylamine is 20~30; the polyoxyethylene alkylamine is at least one of dodecylamine polyoxyethylene ether, stearylamine polyoxyethylene ether or cocoylamine polyoxyethylene ether.

[0010] In the above technical solution, the low-temperature compatible solvent is composed of propylene glycol methyl ether and N-methylpyrrolidone mixed in a volume ratio of 1:(2~1); In the above technical solution, the corrosion inhibitor is a thiozoline derivative; the thiozoline derivative is 2-mercaptothiazoline or 2-methyl-4-isothiazoline-3-one.

[0011] In the above technical solution, the stabilizer is sorbitan monooleate.

[0012] A method for preparing the aforementioned anti-wax agent for deep-sea low-temperature and high-pressure environments includes the following steps: S1. Add the low-temperature compatible solvent to the reactor, heat to 40℃~50℃, add the salt-resistant compound surfactant, and stir at 200rpm~300rpm for 20min~30min until completely dissolved. S2. Add the main anti-wax agent to the reaction vessel, heat to 60℃~70℃, and shear and disperse at 500rpm~800rpm for 30min~60min under vacuum of -0.05MPa~-0.08MPa to form a uniform colloid. S3. Cool the colloid after the reaction in step S2 to 30℃~40℃, add corrosion inhibitor and stabilizer in sequence, and stir at 100rpm~200rpm for 15min~25min to obtain the anti-wax agent for deep water low temperature and high pressure environment.

[0013] In the above technical solution, the temperature control and dispersion temperature in step S1 is 45℃, the stirring rate is 250rpm, and the stirring time is 25min; the temperature control and shearing temperature in step S2 is 65℃, the stirring rate is 600rpm, and the stirring time is 45min; the temperature control and mixing temperature in step S3 is 35℃, the stirring rate is 150rpm, and the stirring time is 20min.

[0014] The application of the aforementioned anti-wax agent for deep-water low-temperature and high-pressure environments in the control of wax deposition in deep-water oil and gas fields, wherein the application environment is a high-salt, high-pressure, and low-temperature working condition with a temperature of 2~15℃, a pressure of 5~150MPa, and a formation water salinity of 2000~50000mg / L.

[0015] The beneficial effects of this invention are: This invention provides a wax inhibitor for deep-sea low-temperature and high-pressure environments and its preparation method. The prepared wax inhibitor exhibits excellent wax-preventing effect, high temperature resistance, salt resistance, high pressure resistance, and strong material compatibility in extreme deep-sea environments. Through molecular structure design, solvent system innovation, functional component compounding, and process optimization, it systematically solves the problems of efficiency degradation, equipment corrosion, and application risks of existing deep-sea wax inhibitors in extreme environments, achieving a synergistic improvement in wax crystal inhibition, equipment protection, and performance stability, and possesses significant technological advancement and industrial applicability. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below through specific embodiments. Example 1

[0017] A method for preparing a wax inhibitor for deep-sea, low-temperature, high-pressure environments includes the following steps: S1. Add 55g of low-temperature compatible solvent (including 20.53g of propylene glycol methyl ether and 29.47g of N-methylpyrrolidone) to the reactor, heat to 45℃, add 10g of salt-resistant compound surfactant (including 6.67g of polyoxyethylene alkylamine and 3.33g of sodium dodecylbenzene sulfonate), and stir at 250rpm for 25min until the solution is clear and transparent. S2. Add 25g of the main anti-wax agent (octadecyl methacrylate-maleic anhydride-α-methylstyrene terblock copolymer, molar ratio 2:1:0.5, M w =8900), heat to 65℃, turn on the vacuum pump (vacuum degree -0.06MPa), and shear disperse at 600rpm for 45min to form a homogeneous colloid; S3. Cool to 35℃, add 6g of corrosion inhibitor synergist 2-mercaptothiazoline and 4g of stabilizer sorbitan monooleate in sequence, stir at 150rpm for 20min to obtain a light yellow transparent liquid anti-wax agent. Example 2

[0018] A method for preparing a wax inhibitor for deep-sea, low-temperature, high-pressure environments includes the following steps: S1. Add 50g of low-temperature compatible solvent (including 18.66g of propylene glycol methyl ether and 31.34g of N-methylpyrrolidone) to the reactor, heat to 45℃, add 10g of salt-resistant compound surfactant (including 6.67g of polyoxyethylene alkylamine and 3.33g of sodium dodecylbenzene sulfonate), and stir at 250rpm for 25min until the solution is clear and transparent. S2. Add 30g of the main anti-wax agent (octadecyl methacrylate-maleic anhydride-p-methylstyrene terpolymer, molar ratio 2:1:0.4, M w =11400), heat to 65℃, turn on the vacuum pump (vacuum degree -0.06MPa), and shear disperse at 600rpm for 45min to form a homogeneous colloid; S3. Cool to 35℃, add 6g of corrosion inhibitor synergist 2-methyl-4-isothiazolin-3-one and 4g of stabilizer sorbitan monooleate in sequence, stir at 150rpm for 20min to obtain a light yellow transparent liquid anti-wax agent. Example 3

[0019] A method for preparing a wax inhibitor for deep-sea, low-temperature, high-pressure environments includes the following steps: S1. Add 55g of low-temperature compatible solvent (including 16.98g of propylene glycol methyl ether and 38.02g of N-methylpyrrolidone) to the reactor, heat to 45℃, add 12g of surfactant (including 6g of polyoxyethylene alkylamine and 6g of sodium dodecylbenzene sulfonate), and stir at 250rpm for 25min until the solution is clear and transparent. S2. Add 25g of the main anti-wax agent (octadecyl methacrylate-maleic anhydride-p-tert-butylstyrene ternary block copolymer, molar ratio 2:1:0.3, M w =13600), heat to 65℃, turn on the vacuum pump (vacuum degree -0.08MPa), and shear disperse at 600rpm for 45min to form a homogeneous colloid; S3. Cool to 35℃, add 5g of corrosion inhibitor synergist 2-mercaptothiazoline and 3g of stabilizer sorbitan monooleate in sequence, stir at 150rpm for 20min to obtain a light yellow transparent liquid anti-wax agent. Example 4

[0020] A method for preparing a wax inhibitor for deep-sea, low-temperature, high-pressure environments includes the following steps: S1. Add 60g of low-temperature compatible solvent (including 19.90g of propylene glycol methyl ether and 40.10g of N-methylpyrrolidone) to the reactor, heat to 45℃, add 12g of surfactant (including 9g of polyoxyethylene alkylamine and 3g of sodium dodecylbenzene sulfonate), and stir at 250rpm for 25min until the solution is clear and transparent. S2, Add 15g of the main anti-wax agent (hexadecyl methacrylate-maleic anhydride-p-tert-butylstyrene terpolymer, molar ratio 2:1:0.5, M w =14800), molar ratio 3:1, weight average molecular weight 15000), heat to 65℃, turn on the vacuum pump (vacuum degree -0.08MPa), and shear disperse at 600rpm for 45min to form a homogeneous colloid; S3. Cool to 35℃, add 8g of corrosion inhibitor synergist 2-mercaptothiazoline and 5g of stabilizer sorbitan monooleate in sequence, stir at 150rpm for 20min to obtain a light yellow transparent liquid anti-wax agent. Example 5

[0021] A method for preparing a wax inhibitor for deep-sea, low-temperature, high-pressure environments includes the following steps: S1. Add 42g of low-temperature compatible solvent (including 15.05g of propylene glycol methyl ether and 26.95g of N-methylpyrrolidone) to the reactor, heat to 45℃, add 15g of surfactant (including 11.25g of polyoxyethylene alkylamine and 3.75g of sodium dodecylbenzene sulfonate), and stir at 250rpm for 25min until the solution is clear and transparent. S2. Add 30g of the main anti-wax agent (hexadecyl methacrylate-maleic anhydride-α-methylstyrene ternary block copolymer, molar ratio 2:1:0.8, M w =6400), molar ratio 2:1, weight average molecular weight 11000), heat to 65℃, turn on the vacuum pump (vacuum degree -0.07MPa), and shear disperse at 600rpm for 45min to form a homogeneous colloid; S3. Cool to 35℃, add 8g of corrosion inhibitor synergist 2-methyl-4-isothiazolin-3-one and 5g of stabilizer sorbitan monooleate in sequence, stir at 150rpm for 20min to obtain a light yellow transparent liquid anti-wax agent.

[0022] Comparative Example 1 Commercially available conventional EVA wax inhibitor (excluding corrosion inhibitors and stabilizers; solvent is xylene, with solvent accounting for 85%).

[0023] The experimental testing methods referenced the standards SY / T 7549-2000 "Determination and Measurement of Crude Oil Viscosity-Temperature Curves by Rotational Viscometer Equilibrium Method (Ambient Temperature and Pressure, High Temperature and High Pressure)", NAS 1638-2011 "Cleanliness Requirements for Hydraulic System Components", GB / T21412.4-2013 "Design and Operation of Subsea Production Systems in the Oil and Gas Industry - Part 4: Subsea Wellhead Equipment and Christmas Tree Equipment", and SY / T 6300-2024 "Technical Requirements for Cleaning and Wax Inhibitors for Oil Production", etc. The evaluation test indicators are shown in the table below.

[0024] Table 1: Stability Evaluation of Deep-Water Wax Inhibitors under Normal and High Pressure Table 2: High and Low Temperature Stability Evaluation of Deep-Water Wax Inhibitors Table 3: Compatibility Evaluation of Deep-Water Wax Inhibitors Table 4: Salt resistance evaluation of deep-water wax inhibitors Comparison of the examples and comparative examples in Tables 1-4 shows that the deep-water anti-wax agent of this invention exhibits excellent stability under extreme working conditions, efficient wax crystal control, good metal corrosion inhibition, and compatibility with non-metallic materials. Under 100 MPa high pressure, the viscosity of the examples is only 13.24~16.04 mPa·s (comparative example 95.43 mPa·s), and the low-temperature viscosity at -25℃ is 72.41 mPa·s (comparative example 1185 mPa·s), with a cleanliness level of 3~5 (comparative example 9~12), meeting the requirements of low viscosity, anti-agglomeration, and high stability for long-distance deep-water umbilical cable transportation. The corrosion rate of 304 stainless steel is 0.021~0.026 mm / a (comparative example 0.057 mm / a), and the mass change of perfluorinated rubber is only 2.02~2.21% (comparative example 10.55%). The corrosion inhibitor synergist (containing thiazoline) effectively inhibits metal corrosion, and the solvent system (propylene glycol methyl ether / NMP) reduces the swelling of non-metallic materials. At a low temperature of 3℃, the wax prevention rate is 59.20%~62.91% (comparative example 34.79%). The main wax inhibitor (long-chain alkyl acrylate-maleic anhydride-styrene derivative terpolymer) modifies wax crystals through eutectic, adsorption, and dispersion. The surfactant (polyoxyethylene alkylamine + sodium dodecylbenzene sulfonate) enhances dispersion, breaking through the wax prevention bottleneck of only 35% of conventional EVA. In the future, it can be promoted for wax deposition prevention in deep-water oil and gas fields, which is of great significance for improving the safety and efficiency of deep-water mining.

[0025] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A wax inhibitor for use in deep-sea, low-temperature, high-pressure environments, characterized in that: The components of the wax inhibitor and the mass percentage of each component are as follows: Main anti-wax agent 15%~30%; Salt-resistant compound surfactants 5%~15%; Low-temperature compatible solvents: 42%~60%; Corrosion inhibitor synergist 3%~8%; Stabilizer 2%~5%.

2. The anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 1, characterized in that: The primary anti-wax agent is a ternary block copolymer of long-chain alkyl acrylate, maleic anhydride, and styrene derivative; the long-chain alkyl acrylate has a carbon number of C16~C22; the molar ratio of long-chain alkyl acrylate, maleic anhydride, and styrene derivative is 2:1:(0.3~0.8), and the weight-average molecular weight M of the block copolymer is... w The value is 5000~15000; the long-chain alkyl acrylate is hexadecyl methacrylate or octadecyl methacrylate; the styrene derivative is at least one of α-methylstyrene, p-methylstyrene or p-tert-butylstyrene.

3. The anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 2, characterized in that: The preparation method of the main anti-wax agent includes the following steps: S1. Add long-chain alkyl acrylate, maleic anhydride and styrene derivative to the reactor, then add polymerization solvent and stir until uniformly dispersed; S2. After removing oxygen from the reactor, raise the temperature to 80℃~90℃, add the initiator, and polymerize at a constant temperature for 4h~10h under stirring. S3. After the polymerization reaction is completed, the reaction system is cooled, washed with anhydrous ethanol, allowed to stand to precipitate, and the liquid phase is removed to obtain the solid product. S4. Vacuum dry the solid product to obtain a white powdery ternary block copolymer main anti-wax agent.

4. The anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 3, characterized in that: The polymerization solvent is xylene; the amount of the polymerization solvent used is 1.5 to 2.0 times the total mass of the long-chain alkyl acrylate, maleic anhydride, and styrene derivative monomers. The initiator is benzoyl peroxide or azobisisobutyronitrile; the amount of the initiator is 0.3% to 1.5% of the total mass of the long-chain alkyl acrylate, maleic anhydride and styrene derivative monomers.

5. The anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 1, characterized in that: The salt-resistant compound surfactant is compounded from polyoxyethylene alkylamine and sodium dodecylbenzenesulfonate in a mass ratio of (1~3):1; the degree of polymerization of the polyoxyethylene alkylamine is 20~30, and the polyoxyethylene alkylamine is at least one of dodecylamine polyoxyethylene ether, stearylamine polyoxyethylene ether or cocoylamine polyoxyethylene ether.

6. The anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 1, characterized in that: The low-temperature compatible solvent is composed of propylene glycol methyl ether and N-methylpyrrolidone mixed in a volume ratio of 1:(2~1); the corrosion inhibitor is a sulfur-containing zoline derivative; the sulfur-containing zoline derivative is 2-mercaptothiazoline or 2-methyl-4-isothiazoline-3-one.

7. The anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 1, characterized in that: The stabilizer is sorbitan monooleate.

8. A method for preparing a wax inhibitor for deep-sea low-temperature and high-pressure environments as described in any one of claims 1 to 7, characterized in that: Includes the following steps: S1. Add the low-temperature compatible solvent to the reactor, heat to the dispersion temperature, add the salt-resistant compound surfactant, and stir until completely dissolved. S2. Add the main anti-wax agent to the reaction vessel, heat to the shear temperature, and shear and disperse under vacuum to form a uniform colloid; S3. Cool the colloid after the reaction in step S2 to the mixing temperature, add the corrosion inhibitor and stabilizer in sequence, and after stirring, obtain the anti-wax agent for deep-water low-temperature and high-pressure environments.

9. The method for preparing the anti-wax agent for deep-sea low-temperature and high-pressure environments according to claim 8, characterized in that: The dispersion temperature in step S1 is 40℃~50℃, the stirring rate is 200rpm~300rpm, and the stirring time is 20min~30min; the shear temperature in step S2 is 60℃~70℃, the stirring rate is 500rpm~800rpm, the stirring time is 30min~60min, and the vacuum degree is -0.05MPa~-0.08MPa; the mixing temperature in step S3 is 30℃~40℃, the stirring rate is 100rpm~200rpm, and the stirring time is 15min~25min.

10. The application of the anti-wax agent for deep-water low-temperature and high-pressure environments as described in any one of claims 1 to 7 in the control of wax deposition in deep-water oil and gas fields, characterized in that: The application environment is a high-salt, high-pressure, low-temperature condition with a temperature of 2℃~15℃, a pressure of 5MPa~150MPa, and a formation water salinity of 2000mg / L~50000mg / L.

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