Solid paraffin inhibitor and preparation method thereof

Abstract

The invention belongs to the technical field of crude oil solid paraffin inhibitors, and relates to a preparation method of a solid paraffin inhibitor, which comprises the following steps: (1) dissolving ethylene vinyl acetate, long-chain alkyl naphthalene high-carbon alcohol ester and a perfluoroalkyl acrylate monomer in water to obtain a water-phase solution; (2) adding cyclohexane, an emulsifier and an initiator into the water-phase solution, and stirring to obtain a water-in-oil emulsion; (3) adjusting the pH value of the water-in-oil emulsion to be alkaline, and performing inverse emulsion polymerization to obtain a synthetic agent; and (4) uniformly mixing the synthetic agent, and performing compression molding to obtain the solid paraffin inhibitor. The solid paraffin inhibitor prepared by the invention has a paraffin inhibition effect, and the paraffin inhibition rate is more than or equal to 90%. The solid paraffin inhibitor has a good slow-release paraffin inhibition effect, the related preparation method is simple, raw materials are wide in source, the solid paraffin inhibitor is suitable for solving the paraffin inhibition problem in the fields of oil and gas transportation pipelines and the like, and the solid paraffin inhibitor has very important practical application value.

Description

Technical Field

[0001] The invention belongs to the technical field of solid wax inhibitors for crude oil, and in particular relates to a solid wax inhibitor and a preparation method thereof. Background Art

[0002] In the process of oil well exploitation, wax is mainly dissolved in crude oil. Since there are large pressure and temperature changes from the formation to the ground, it provides conditions for the precipitation of paraffin. Generally speaking, the wax crystals formed are often in the form of thin sheets, forming a three-dimensional network. This structure has a certain hardness at a certain temperature and is difficult to remove, which has a great impact on the normal production of oil and gas. Therefore, in order to maintain normal exploitation and transportation, wax prevention is a necessary measure in the production management of oil and gas wells.

[0003] At present, there are two main methods of paraffin prevention: thermal paraffin prevention technology and paraffin removal agent injection. Thermal paraffin prevention technology is a method of improving the temperature of wellbore fluid by using thermal energy such as hot oil, steam, and electric heating to achieve paraffin prevention. Paraffin removal agents include liquid paraffin removal agents and solid paraffin removal agents. The working principle is to dissolve or disperse the deposited paraffin, so that it dissolves or suspends in the oil in the form of small particles and flows out with the well flow, involving processes such as penetration, dissolution and dispersion. Using chemical agents to remove paraffin is a technology widely used in oil and gas fields. This is because the agent is injected into the annular space of the oil casing, which will not affect the normal production of the oil well. On the contrary, the agent can also play a role in reducing condensation, viscosity and unblocking. However, electric heating technology consumes a lot of electricity and has certain safety hazards. The installation and operation process of liquid paraffin prevention agents is complicated and cumbersome, not easy to manage, and easy to adhere to the wall of the oil casing and not easy to flow into the bottom of the well. Because water must be added during the dosing process, there is a risk of pipeline freezing after the addition of the agent.

[0004] At present, there are two main types of solid wax inhibitor synthesis processes: one is made of high-branched polyethylene with a certain type of stabilizer, and then mixed with ethylene-vinyl acetate polymer; the other is copolymerized with acrylic ester and other monomers such as VA, maleic anhydride amide, α-olefin and vinyl pyridine. However, the current synthesis method requires multi-step reactions or special reagents and conditions, making the synthesis process more complicated. In some synthesis methods, impurities or incomplete reaction products will be produced, affecting the quality and effect of the solid wax inhibitor. Summary of the invention

[0005] The main purpose of the present invention is to provide a solid wax inhibitor and a preparation method thereof to solve the problems of complex synthesis of solid wax inhibitor and poor wax inhibitor effect.

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

[0007] The invention discloses a method for preparing a solid wax inhibitor, comprising the following steps:

[0008] (1) dissolving ethylene vinyl acetate, long-chain alkyl naphthalene higher alcohol ester and perfluoroalkyl acrylate monomers in water to obtain an aqueous solution;

[0009] (2) adding cyclohexane, an emulsifier and an initiator to the aqueous phase solution, and obtaining a water-in-oil emulsion by stirring;

[0010] (3) adjusting the pH value of the water-in-oil emulsion to alkaline, and then performing inverse emulsion polymerization to obtain a synthetic agent;

[0011] (4) The synthesized agent is mixed and kneaded, and after being uniformly mixed, it is pressed into a shape to obtain a solid wax inhibitor.

[0012] Furthermore, in step (1), the molar ratio of ethylene vinyl acetate, long-chain alkyl naphthalene high carbon alcohol ester and perfluoroalkyl acrylate monomer is (70-80): (20-30): (0.1-0.2).

[0013] Furthermore, the structural formula of the perfluoroalkyl acrylate monomer is CH2=CHCOO(CH2) m (CF2CF2) n F, where m is a natural number from 1 to 3, and n is a natural number from 3 to 6.

[0014] Furthermore, in step (2), the emulsifier is a mixture of sorbitan oleate and polyoxyethylene sorbitan stearate, and the mass ratio of the two is 1:1.

[0015] Furthermore, in step (2), the initiator is azobisisobutyronitrile.

[0016] Furthermore, in step (2), in the water-in-oil emulsion, the mass percentage of cyclohexane is 30% to 55%, the mass percentage of the initiator is 0.01% to 0.3%, and the mass percentage of the emulsifier is 10% to 40%.

[0017] Furthermore, in step (2), the stirring speed is 5000 to 15000 r / min, and the stirring time is 20 min to 40 min;

[0018] In step (3), the stirring speed during the inverse emulsion polymerization is 500 r / min to 1000 r / min.

[0019] Furthermore, in step (3), the pH value is 9 to 9.5; the temperature of the inverse emulsion polymerization is 40 to 60° C., and the time is 120 min to 160 min.

[0020] Furthermore, step (4) is specifically as follows: putting the synthetic agent into a rubber mixer for mixing, and after mixing evenly, putting it into a mold, and pressing and molding it through a vulcanizer to obtain a solid wax inhibitor.

[0021] The invention also discloses a solid wax-proofing agent prepared by the preparation method, and the wax-proofing rate of the solid wax-proofing agent is ≥90%.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] The invention discloses a solid wax inhibitor and a preparation method thereof. Water is used as a solvent, ethylene vinyl acetate, long-chain alkyl naphthalene high-carbon alcohol ester and perfluoroalkyl acrylate are used as monomers, and the agent is obtained by reverse emulsion polymerization under an alkaline environment. The alcohol group in the long-chain alkyl naphthalene high-carbon alcohol ester monomer reacts with the ester group in another long-chain alkyl naphthalene high-carbon alcohol ester monomer. At the same time, the initiator will cause the double bonds in the perfluoroalkyl acrylate and ethylene vinyl acetate monomers to crack and generate free radicals. These free radicals will polymerize and react with each other to form a chain polymerization product. The agent is mixed and uniformly pressed to obtain a solid wax inhibitor. The preparation method also adopts a synchronous hydrolysis process, which can hydrolyze the ester bond in the monomer into the corresponding alcohol and acid during the polymerization process, thereby simplifying the preparation process, avoiding the subsequent hydrolysis step, and improving the preparation efficiency; the fluorine-containing long-chain alkyl naphthalene high-carbon alcohol ester-ethylene vinyl acetate solid wax inhibitor prepared by the invention has a good sustained-release wax inhibitor effect, and the wax inhibitor rate is ≥ 90%.

[0024] The solid wax inhibitor of the present invention has a simple preparation method and a wide range of raw material sources, is suitable for solving wax prevention problems in the fields of oil and gas transportation pipelines, and has very important practical application value. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention clearer, the following is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents a selected embodiment of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the protection scope of the present invention.

[0027] The invention discloses a method for preparing a solid wax inhibitor, comprising the following steps:

[0028] (1) dissolving ethylene vinyl acetate, long-chain alkyl naphthalene higher alcohol ester and perfluoroalkyl acrylate monomers in water to obtain an aqueous solution;

[0029] (2) adding cyclohexane, an emulsifier and an initiator to the aqueous phase solution, and obtaining a water-in-oil emulsion by stirring;

[0030] (3) adjusting the pH value of the water-in-oil emulsion to alkaline, and then performing inverse emulsion polymerization to obtain a synthetic agent;

[0031] (4) The synthesized agent is mixed and kneaded, and after being uniformly mixed, it is pressed into a shape to obtain a solid wax inhibitor.

[0032] The structural formula of the perfluoroalkyl acrylate monomer is CH2=CHCOO(CH2) m (CF2CF2) n F, where m is a natural number from 1 to 3, and n is a natural number from 3 to 6.

[0033] The features and performances of the present invention are further described in detail below in conjunction with the embodiments.

[0034] Example 1

[0035] The invention discloses a method for preparing a solid wax inhibitor, which specifically comprises the following steps:

[0036] 1) Dissolve 25 g of ethylene vinyl acetate, 7.24 g of long-chain alkyl naphthalene high-carbon alcohol ester and 0.1056 g of perfluoroalkyl acrylate monomer represented by CH2=CHCOOCH2(CF2CF2)3F in 50 g of water, and stir until mixed to obtain an aqueous phase solution;

[0037] 2) Add 50 g of cyclohexane, 25 g of emulsifier (12.5 g each of sorbitan oleate Span80 and polyoxyethylene sorbitan stearate Tween60) and 0.1125 g of initiator azobisisobutyronitrile AIBN to the aqueous phase solution, and stir at a stirring speed of 15000 r / min for 20 min until mixed to obtain a stable water-in-oil emulsion;

[0038] In the water-in-oil emulsion, the mass percentage of cyclohexane is 32%, the mass percentage of the mixture of Span80 and Tween60 is 16%; the mass percentage of AIBN is 0.07%;

[0039] 3) adding sodium hydroxide to the above stable water-in-oil microemulsion to adjust the pH value to 9;

[0040] Alkaline conditions can ensure that the repulsion and attraction between the emulsion particles are balanced, thus maintaining the stability of the emulsion;

[0041] 4) heating the stable water-in-oil microemulsion to 45° C. under stirring at 500 r / min to carry out inverse emulsion polymerization for 120 min to obtain a synthetic agent;

[0042] 5) The above-mentioned synthetic agent is put into a rubber mixer for mixing. After being uniform, it is put into a mold and pressed into shape by a vulcanizer to obtain a fluorinated long-chain alkyl naphthalene high-carbon alcohol ester-ethylene vinyl acetate solid wax inhibitor.

[0043] Evaluation method of wax prevention rate: wax prevention rate of the synthetic solid wax prevention agent in the example was measured. Wax precipitation amount was measured by hanging plate method. A wax-coated hanging plate was made from crude oil from B03 well, and kept at a constant temperature of 2-4°C (near 20°C) below the freezing point of the crude oil for 30 minutes. The weight of the hanging plate before and after was measured to calculate the wax prevention rate.

[0044] The wax resistance rate of the polyolefin higher alcohol ester-ethylene vinyl acetate prepared in this example is 95.8%.

[0045] Example 2

[0046] The invention discloses a method for preparing a solid wax inhibitor, which specifically comprises the following steps:

[0047] 1) Dissolve 25 g of ethylene vinyl acetate, 9.5 g of long-chain alkyl naphthalene high-carbon alcohol ester and 0.2112 g of perfluoroalkyl acrylate monomer represented by CH2=CHCOO(CH2)3(CF2CF2)6F in 50 g of water, and stir until mixed to obtain an aqueous phase solution;

[0048] 2) Add 50g of cyclohexane, 25g of emulsifier (including 12.5g of Span80 and Tween60 respectively) and 0.2250g of initiator AIBN to the above aqueous phase solution, and stir for 40min at a stirring speed of 10000r / min until mixed to obtain a stable water-in-oil emulsion; in the water-in-oil emulsion, the mass percentage of cyclohexane is 31%, the mass percentage of the mixture of Span80 and Tween60 is 15.5%; and the mass percentage of AIBN is 0.14%;

[0049] 3) adding sodium hydroxide to the above stable water-in-oil microemulsion to adjust the pH value to 9.5;

[0050] 4) heating the stable water-in-oil microemulsion to 55° C. under stirring at 1000 r / min to carry out inverse emulsion polymerization for 160 min to obtain a synthetic agent;

[0051] 5) The above-mentioned synthetic agent is put into a rubber mixer for mixing, and after being uniformly mixed, it is put into a mold and pressed into shape by a vulcanizer to obtain a fluorinated long-chain alkyl naphthalene high-carbon alcohol ester-ethylene vinyl acetate solid wax inhibitor.

[0052] Evaluation method of wax prevention rate: wax prevention rate of the synthetic solid wax prevention agent in the example was measured. Wax precipitation amount was measured by hanging plate method. A wax-coated hanging plate was made from crude oil from B03 well, and kept at a constant temperature of 2-4°C (near 20°C) below the freezing point of the crude oil for 30 minutes. The weight of the hanging plate before and after was measured to calculate the wax prevention rate.

[0053] The wax resistance rate of the polyolefin higher alcohol ester-ethylene vinyl acetate prepared in this example is 96.1%.

[0054] Example 3

[0055] The invention discloses a method for preparing a solid wax inhibitor, which specifically comprises the following steps:

[0056] 1) Dissolve 25 g of ethylene vinyl acetate, 7.32 g of long-chain alkyl naphthalene high-carbon alcohol ester and 0.1584 g of perfluoroalkyl acrylate monomer represented by CH2=CHCOO(CH2)3(CF2CF2)6F in 50 g of water, and stir until mixed to obtain an aqueous phase solution;

[0057] 2) Add 50g of cyclohexane, 25g of emulsifier (including 12.5g of Span80 and Tween60 respectively) and 0.1687g of initiator AIBN to the above aqueous phase solution, and stir for 30min at a stirring speed of 7500r / min until mixed to obtain a stable oil-in-water emulsion; in the oil-in-water emulsion, the mass percentage of cyclohexane is 32%, the mass percentage of the mixture of Span80 and Tween60 is 16%; and the mass percentage of AIBN is 0.11%;

[0058] 3) adding sodium hydroxide to the above stable water-in-oil microemulsion to adjust the pH value to 9.5;

[0059] 4) heating the stable water-in-oil microemulsion to 55° C. under stirring at 600 r / min to carry out inverse emulsion polymerization for 160 min to obtain a synthetic agent;

[0060] 5) The above-mentioned synthetic agent is put into a rubber mixer for mixing, and after being uniformly mixed, it is put into a mold and pressed into shape by a vulcanizer to obtain a fluorinated long-chain alkyl naphthalene high-carbon alcohol ester-ethylene vinyl acetate solid wax inhibitor.

[0061] Evaluation method of wax prevention rate: wax prevention rate of the synthetic solid wax prevention agent in the example was measured. Wax precipitation amount was measured by hanging plate method. A wax-coated hanging plate was made from crude oil from B03 well, and kept at a constant temperature of 2-4°C (near 20°C) below the freezing point of the crude oil for 30 minutes. The weight of the hanging plate before and after was measured to calculate the wax prevention rate.

[0062] The wax resistance rate of the polyolefin higher alcohol ester-ethylene vinyl acetate prepared in this example is 94.9%.

[0063] Example 4

[0064] The invention discloses a method for preparing a solid wax inhibitor, which specifically comprises the following steps:

[0065] 1) Dissolve 25 g of ethylene vinyl acetate, 7.32 g of long-chain alkyl naphthalene high-carbon alcohol ester and 0.212 g of perfluoroalkyl acrylate monomer represented by CH2=CHCOO(CH2)2(CF2CF2)4F in 50 g of water, and stir until well mixed to obtain an aqueous solution;

[0066] 2) Add 50g of cyclohexane, 25g of emulsifier (including 12.5g of Span80 and Tween60 respectively) and 0.1125g of initiator AIBN to the above aqueous phase solution, and stir for 40min at a stirring speed of 6000r / min until mixed to obtain a stable water-in-oil emulsion; in the water-in-oil emulsion, the mass percentage of cyclohexane is 32%, the mass percentage of the mixture of Span80 and Tween60 is 16%; and the mass percentage of AIBN is 0.07%;

[0067] 3) adding sodium hydroxide to the above stable water-in-oil microemulsion to adjust the pH value to 9;

[0068] 4) heating the stable water-in-oil microemulsion to 45° C. under stirring at 800 r / min to carry out inverse emulsion polymerization for 130 min to obtain a synthetic agent;

[0069] 5) The above-mentioned synthetic agent is put into a rubber mixer for mixing, and after being uniformly mixed, it is put into a mold and pressed into shape by a vulcanizer to obtain a fluorinated long-chain alkyl naphthalene high-carbon alcohol ester-ethylene vinyl acetate solid wax inhibitor.

[0070] Evaluation method of wax prevention rate: wax prevention rate of the synthetic solid wax prevention agent in the example was measured. Wax precipitation amount was measured by hanging plate method. A wax-coated hanging plate was made from crude oil from B03 well, and kept at a constant temperature of 2-4°C (near 20°C) below the freezing point of the crude oil for 30 minutes. The weight of the hanging plate before and after was measured to calculate the wax prevention rate.

[0071] The wax resistance rate of the polyolefin higher alcohol ester-ethylene vinyl acetate prepared in this example is 96.6%.

[0072] Example 5

[0073] The invention discloses a method for preparing a solid wax inhibitor, which specifically comprises the following steps:

[0074] 1) Dissolve 25 g of ethylene vinyl acetate, 9.5 g of long-chain alkyl naphthalene high-carbon alcohol ester and 0.1056 g of perfluoroalkyl acrylate monomer represented by CH2=CHCOO(CH2)3(CF2CF2)5F in 50 g of water, and stir until mixed to obtain an aqueous phase solution;

[0075] 2) Add 50g of cyclohexane, 25g of emulsifier (including 12.5g of Span80 and Tween60 respectively) and 0.1687g of initiator AIBN to the above aqueous phase solution, and stir for 35min at a stirring speed of 8500r / min until mixed to obtain a stable water-in-oil emulsion; in the water-in-oil emulsion, the mass percentage of cyclohexane is 31%, the mass percentage of the mixture of Span80 and Tween60 is 15.5%; and the mass percentage of AIBN is 0.11%;

[0076] 3) adding sodium hydroxide to the above stable water-in-oil microemulsion to adjust the pH value to 9.5;

[0077] 4) heating the stable water-in-oil microemulsion to 50° C. under stirring at 900 r / min to carry out inverse emulsion polymerization for 150 min to obtain a synthetic agent;

[0078] 5) The above-mentioned synthetic agent is put into a rubber mixer for mixing, and after being uniformly mixed, it is put into a mold and pressed into shape by a vulcanizer to obtain a fluorinated long-chain alkyl naphthalene high-carbon alcohol ester-ethylene vinyl acetate solid wax inhibitor.

[0079] Evaluation method of wax prevention rate: wax prevention rate of the synthetic solid wax prevention agent in the example was measured. Wax precipitation amount was measured by hanging plate method. A wax-coated hanging plate was made from crude oil from B03 well, and kept at a constant temperature of 2-4°C (near 20°C) below the freezing point of the crude oil for 30 minutes. The weight of the hanging plate before and after was measured to calculate the wax prevention rate.

[0080] The wax resistance rate of the polyolefin higher alcohol ester-ethylene vinyl acetate prepared in this example is 95.1%.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a solid wax inhibitor, characterized in that: The steps include: (1) dissolving ethylene vinyl acetate, long-chain alkyl naphthalene higher alcohol ester and perfluoroalkyl acrylate monomers in water to obtain an aqueous solution; (2) adding cyclohexane, an emulsifier and an initiator to the aqueous phase solution, and obtaining a water-in-oil emulsion by stirring; (3) adjusting the pH value of the water-in-oil emulsion to alkaline, and then performing inverse emulsion polymerization to obtain a synthetic agent; (4) The synthesized agent is mixed and kneaded, and after being uniformly mixed, it is pressed into a shape to obtain a solid wax inhibitor.

2. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: In step (1), the molar ratio of ethylene vinyl acetate, long-chain alkyl naphthalene high carbon alcohol ester and perfluoroalkyl acrylate monomer is (70-80): (20-30): (0.1-0.2).

3. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: The structural formula of the perfluoroalkyl acrylate monomer is CH2=CHCOO(CH2) m (CF2CF2) n F, where m is a natural number from 1 to 3, and n is a natural number from 3 to 6.

4. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: In step (2), the emulsifier is a mixture of sorbitan oleate and polyoxyethylene sorbitan stearate, and the mass ratio of the two is 1:

1.

5. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: In step (2), the initiator is azobisisobutyronitrile.

6. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: In step (2), in the water-in-oil emulsion, the mass percentage of cyclohexane is 30% to 55%, the mass percentage of the initiator is 0.01% to 0.3%, and the mass percentage of the emulsifier is 10% to 40%.

7. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: In step (2), the stirring speed is 5000 to 15000 r / min, and the stirring time is 20 min to 40 min; In step (3), the stirring speed during the inverse emulsion polymerization is 500 r / min to 1000 r / min.

8. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: In step (3), the pH value is 9 to 9.5; the temperature of the inverse emulsion polymerization is 40 to 60° C., and the time is 120 min to 160 min.

9. The method for preparing a solid wax inhibitor according to claim 1, characterized in that: Step (4) is specifically as follows: putting the synthesized agent into a rubber mixer for mixing, and after mixing evenly, putting it into a mold, and pressing and molding it through a vulcanizer to obtain a solid wax inhibitor.

10. The solid wax inhibitor prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The wax resistance rate of the solid wax resistance agent is ≥90%.