Polymer surfactant type kinetic hydrate inhibitor as well as preparation method and application thereof

Abstract

The invention provides a polymer surfactant type kinetic hydrate inhibitor as well as a preparation method and application thereof, and relates to the technical field of oil and gas field working fluid. The invention relates to a polymer surfactant type dynamic hydrate inhibitor. The dynamic hydrate inhibitor is formed by polymerizing a lactam ring monomer, a dimethylamino monomer and a hydrophobic monomer. The polymer surfactant type kinetic hydrate inhibitor has good inhibition performance, and can occupy a water molecule cage under an extremely low dosage, so that the effect of inhibiting the formation of hydrate by capturing methane molecules is achieved, and the problem that the dosage of methanol is large at present can be effectively solved; the problems that oil field methanol filling is tedious, and downstream production is affected are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field working fluids, and in particular to a polymer surfactant type kinetic hydrate inhibitor, a preparation method thereof, and applications thereof. Background Art

[0002] Liquid water is unavoidable during natural gas pipeline transportation and deepwater oil and gas development. Due to the complexity of the environment, some locations experience prolonged low temperatures and high pressures, making hydrate formation more likely. As hydrates accumulate, they can block pipelines, reducing transportation efficiency and increasing transportation costs. They also increase pressure differentials across the pipeline, potentially damaging it and posing a serious threat to natural gas transportation and oil and gas development. Hydrate blockage occurs through a process that begins with the formation and growth of hydrate nuclei, a process that depends on the temperature and pressure of the system. This process then progresses to hydrate aggregation, a process that depends on the size of the hydrate particles and the adhesion between them. Finally, continuous hydrate aggregation ultimately leads to pipeline blockage. Traditionally, chemical methods have been used to address this problem, using chemical additives injected into pipelines to prevent hydrate formation. Chemical additives are categorized into thermodynamic inhibitors, kinetic inhibitors, and anti-aggregation agents, based on their mechanisms of preventing hydrate formation.

[0003] Thermodynamic inhibitors have been widely used worldwide. However, their high dosage, environmental impact, high cost, and difficulty in recovery hinder natural gas pipeline transportation and deepwater oil and gas development. Compared to thermodynamic inhibitors, kinetic inhibitors offer advantages such as low dosage, significant efficacy, and minimal environmental impact. However, kinetic inhibitors also have drawbacks. Their development in my country is relatively recent, and mature kinetic inhibitors rely on imports, increasing costs. Furthermore, kinetic inhibitors are limited by the degree of supercooling. With increasing awareness of environmental protection, inhibitors with low dosage, improved efficacy, and environmental friendliness have become a development trend and research hotspot for hydrate inhibitors. Summary of the Invention

[0004] The present invention aims to provide a polymer surfactant-type kinetic hydrate inhibitor with excellent inhibitory performance. It can occupy water molecule cages at extremely low addition amounts, thereby inhibiting the capture of methane molecules and inhibiting the formation of hydrates. It can effectively solve the current problem of large methanol addition amounts and effectively address the difficult problems of cumbersome methanol injection in oil fields and the impact on downstream production.

[0005] Another object of the present invention is to provide a method for preparing a polymer surfactant type kinetic hydrate inhibitor, which has a simple preparation method, a wide range of raw material sources, and a broad market prospect.

[0006] The present invention is achieved through the following technical solutions: In one aspect, the present invention provides a polymer surfactant-type kinetic hydrate inhibitor, which is polymerized from a lactam ring monomer, a dimethylamine monomer, and a hydrophobic monomer, and has the following structural formula:

[0007] Wherein, x+y+z=1, x, y, z are the molar ratios of the monomers, m is 5 to 35, n is 11, 17 or 21, and R1 is C4H6O~C6H 10 O, R2 is C4H 10 NO or C5H 13 N2.

[0008] Furthermore, the mass ratio of the lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer is 30-80:20-60:0.1-1.

[0009] Furthermore, the lactam ring monomer includes one or two of N-vinyl pyrrolidone, N-vinyl piperidone and N-vinyl caprolactam.

[0010] Furthermore, the dimethylamino monomer includes one or both of dimethylaminopropyl methacrylamide and dimethylaminoethyl methacrylate.

[0011] Furthermore, the hydrophobic monomer includes one or two of dodecyl polyoxyethylene methacrylate, octadecyl polyoxyethylene methacrylate and behenyl polyoxyethylene methacrylate.

[0012] On the other hand, the present invention also provides a method for preparing a polymer surfactant type kinetic hydrate inhibitor, comprising the following steps: dissolving a lactam ring monomer, a dimethylamino monomer and a hydrophobic monomer in a solvent, adding an initiator, and heating the mixture in an inert atmosphere to react to obtain the kinetic hydrate inhibitor.

[0013] Furthermore, in the reaction system, the sum of the masses of the lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer is 20 to 50 wt % of the total mass of the lactam ring monomer, the dimethylamino monomer, the hydrophobic monomer and the solvent, and the mass of the initiator is 0.3 to 1 wt % of the total mass of the lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer.

[0014] Furthermore, the solvent includes one or more of water, methanol and ethanol.

[0015] Furthermore, the initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide and azobisisobutylamidine hydrochloride.

[0016] In yet another aspect, the present invention further provides use of the polymer surfactant type kinetic hydrate inhibitor described above in inhibiting hydrate formation during oil and gas development and / or transportation.

[0017] The technical solution of the present invention has at least the following advantages and beneficial effects: (1) The polymorphic kinetic hydrate inhibitor provided by the present invention has good inhibitory performance and can occupy water molecule cages at extremely low addition amounts, thereby inhibiting the capture of methane molecules and inhibiting the formation of hydrates. It can effectively solve the current problem of large methanol addition amounts and effectively solve the difficult problems of cumbersome methanol injection in oil fields and the impact on downstream production.

[0018] (2) By introducing 5- to 7-membered lactam heterocyclic monomers, the size of the 5- and 7-membered lactam rings contained in them is similar to the pentahedron and hexahedron in the hydrate cage structure. When these rings are adsorbed on the hydrate crystals, they can effectively occupy the water molecule cage, generating steric hindrance, hindering the water molecule cage from capturing methane molecules, and inhibiting the growth of hydrate crystals. The introduction of dimethylamino monomers can enhance the interaction of water molecules by forming hydrogen bonds, inhibiting the formation of new water molecule cages; while the introduction of hydrophobic monomers can reduce the polarity of the solution, weaken the interaction between water molecules, and at the same time adsorb on the surface of the hydrate crystals, forming a hydrophobic barrier, preventing water molecules from further arranging in an orderly manner on the crystal surface, thereby inhibiting the growth of crystals; hydrophobic monomers usually form a "hydrophilic-hydrophobic" amphiphilic structure with hydrophilic groups, which can make the inhibitor soluble in water, and can also interact with the hydrate surface or gas molecules through the hydrophobic groups, reducing the interfacial energy, and preventing the nucleation and growth of hydrates.

[0019] (3) The present invention uses lactam ring monomers, dimethylamino monomers, and hydrophobic monomers as polymerization monomers to synthesize a polymer, which can give the inhibitor excellent inhibitory properties. The preparation method is simple, the raw materials are widely available, and it has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the polymer surfactant type kinetic hydrate inhibitor provided by the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise stated, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0022] Example 1 This embodiment provides a polymer surfactant type kinetic hydrate inhibitor, the preparation method of which is as follows: N-vinyl pyrrolidone, N-vinyl piperidone, dodecyl polyoxyethylene methacrylate, and dimethylaminoethyl methacrylate are dissolved in methanol at a mass ratio of 30:30:0.1:30, the total weight of N-vinyl pyrrolidone, N-vinyl piperidone, dodecyl polyoxyethylene methacrylate, dimethylaminoethyl methacrylate, and methanol is taken as the total weight, and the monomer concentration accounts for 20wt%. An initiator (azobisisobutylamidine hydrochloride) is added at 0.3wt% of the total mass of the lactam ring monomer, dimethylamine monomer, and hydrophobic monomer, and nitrogen is introduced for 30 minutes. The reaction is stirred at 60°C for 4 hours to obtain a polymer surfactant type kinetic hydrate inhibitor. The infrared spectrum of the hydrate inhibitor is shown in FIG. Figure 1 shown.

[0023] Example 2 This embodiment provides a polymer surfactant-type kinetic hydrate inhibitor, the preparation method of which is as follows: N-vinyl pyrrolidone, N-vinyl caprolactam, octadecyl polyoxyethylene methacrylate, and dimethylaminopropyl methacrylamide are dissolved in ethanol in a mass ratio of 30:30:0.5:45; the total weight of N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, dimethylaminopropyl methacrylamide, and ethanol is taken as the total weight, and the monomer concentration accounts for 25 wt %. An initiator (benzoyl peroxide) is added in an amount of 0.5 wt % of the total weight of the lactam ring monomer, dimethylamino monomer, and hydrophobic monomer. Nitrogen is introduced for 30 minutes, and the mixture is stirred at 70° C. for 6 hours to obtain a polymer surfactant-type kinetic hydrate inhibitor.

[0024] Example 3 This embodiment provides a polymer surfactant-type kinetic hydrate inhibitor, the preparation method of which is as follows: N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, and dimethylaminopropyl methacrylamide are dissolved in water at a mass ratio of 30:30:1:60; the total weight of N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, dimethylaminopropyl methacrylamide, and water is taken as the total weight, and the monomer concentration accounts for 50 wt %. An initiator (azobisisobutyronitrile) is added in an amount of 1 wt % of the total weight of the lactam ring monomer, dimethylamino monomer, and hydrophobic monomer. Nitrogen is introduced for 30 minutes, and the mixture is stirred at 80° C. for 8 hours to obtain a polymer surfactant-type kinetic hydrate inhibitor.

[0025] Example 4 This embodiment provides a polymer surfactant-type kinetic hydrate inhibitor, the preparation method of which is as follows: N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, and dimethylaminopropyl methacrylamide are dissolved in water in a mass ratio of 15:15:0.5:20; the total weight of N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, dimethylaminopropyl methacrylamide, and water is taken as the total weight, and the monomer concentration accounts for 25 wt %. An initiator (azobisisobutyronitrile) is added in an amount of 0.3 wt % of the total weight of the lactam ring monomer, dimethylamino monomer, and hydrophobic monomer. Nitrogen is introduced for 30 minutes, and the mixture is stirred at 70° C. for 6 hours to obtain a polymer surfactant-type kinetic hydrate inhibitor.

[0026] Example 5 This embodiment provides a polymer surfactant-type kinetic hydrate inhibitor, the preparation method of which is as follows: N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, and dimethylaminopropyl methacrylamide are dissolved in water at a mass ratio of 40:40:1:30; the total weight of N-vinyl pyrrolidone, N-vinyl caprolactam, behenyl polyoxyethylene methacrylate, dimethylaminopropyl methacrylamide, and water is taken as the total weight, and the monomer concentration is 50 wt %. An initiator (azobisisobutyronitrile) is added in an amount of 0.5 wt % of the total weight of the lactam ring monomer, dimethylamino monomer, and hydrophobic monomer. Nitrogen is introduced for 30 minutes, and the mixture is stirred at 80° C. for 8 hours to obtain a polymer surfactant-type kinetic hydrate inhibitor.

[0027] Test Case The tetrahydrofuran evaluation method was used to measure the inhibition performance of the hydrate inhibitors. The inhibitors prepared under different implementation conditions were evaluated. The experimental results are shown in Tables 1 and 2.

[0028] Table 1 Freezing temperature after adding inhibitors in different examples

[0029] Table 2 Induction time after adding inhibitors in different examples

[0030] According to Table 1 and Table 2, the inhibitor of the present invention has a lower freezing temperature and a longer induction time, indicating that the inhibitor of the present invention has a good inhibitory effect on the formation of hydrates.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A polymer surfactant type kinetic hydrate inhibitor, characterized in that: The kinetic hydrate inhibitor is formed by polymerization of a lactam ring monomer, a dimethylamine monomer and a hydrophobic monomer, and its structural formula is as follows: Wherein, x+y+z=1, x, y, z are the molar ratios of the monomers, m is 5 to 35, n is 11, 17 or 21, and R1 is C4H6O~C6H 10 O, R2 is C4H 10 NO or C5H 13 N2.

2. The polymer surfactant type kinetic hydrate inhibitor according to claim 1, characterized in that The mass ratio of the lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer is 30-80:20-60:0.1-1.

3. The polymer surfactant type kinetic hydrate inhibitor according to claim 1 or 2, characterized in that: The lactam ring monomer includes one or two of N-vinyl pyrrolidone, N-vinyl piperidone and N-vinyl caprolactam.

4. The polymer surfactant type kinetic hydrate inhibitor according to claim 1 or 2, characterized in that: The dimethylamino monomers include one or both of dimethylaminopropyl methacrylamide and dimethylaminoethyl methacrylate.

5. The polymer surfactant type kinetic hydrate inhibitor according to claim 1 or 2, characterized in that: The hydrophobic monomer includes one or two of lauryl polyoxyethylene methacrylate, octadecyl polyoxyethylene methacrylate and behenyl polyoxyethylene methacrylate.

6. The method for preparing the polymer surfactant type kinetic hydrate inhibitor according to any one of claims 1 to 5, characterized in that: The following steps are involved: The lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer are dissolved in a solvent, an initiator is added, and the mixture is heated in an inert atmosphere to react, thereby obtaining the kinetic hydrate inhibitor.

7. The method for preparing the polymer surfactant type kinetic hydrate inhibitor according to claim 6, characterized in that: In the reaction system, the sum of the masses of the lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer is 20-50 wt % of the total mass of the lactam ring monomer, the dimethylamino monomer, the hydrophobic monomer and the solvent, and the mass of the initiator is 0.3-1 wt % of the total mass of the lactam ring monomer, the dimethylamino monomer and the hydrophobic monomer.

8. The method for preparing the polymer surfactant type kinetic hydrate inhibitor according to claim 6, characterized in that: The solvent includes one or more of water, methanol and ethanol.

9. The method for preparing the polymer surfactant type kinetic hydrate inhibitor according to claim 6, characterized in that: The initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide and azobisisobutylamidine hydrochloride.

10. Use of the polymer surfactant type kinetic hydrate inhibitor according to any one of claims 1 to 9 in inhibiting hydrate formation during oil and gas development and / or transportation.

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