Viscosity-reducing paraffin inhibitor for oil field and oil well production and preparation method of viscosity-reducing paraffin inhibitor

Abstract

The invention belongs to the technical field of oilfield chemistry, and particularly relates to a viscosity-reducing paraffin inhibitor for oilfield oil well production and a preparation method of the viscosity-reducing paraffin inhibitor. Comprising the following components in percentage by mass: 15.08%-17.92% of maleic anhydride, 18.01%-26.88% of nonylphenol polyoxyethylene ether, 23.2%-25.4% of a benzylamine solution, 3.97%-5.0% of a 5% ferrous sulfate aqueous solution, 3.97%-5.00% of a 5% ammonium persulfate aqueous solution and 15.87%-17.19% of a sodium hydroxide aqueous solution. The viscosity-reducing paraffin inhibitor solves the problems that the density and viscosity of crude oil are increased in the later stage of development of most oil wells in oil fields, paraffin precipitation is serious, the repair-free period is short, and the effect of the existing paraffin inhibitor becomes poor year by year, prolongs the repair-free period of the oil wells, can effectively relieve frequent well repair caused by paraffin precipitation in production of the oil wells in the oil fields, does not contain chlorine, and is environment-friendly. The paraffin control and viscosity reduction effects are considered, and meanwhile, the influence on downstream refining equipment is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of oilfield chemistry, and in particular relates to a viscosity-reducing and wax-preventing agent for oil well production in oilfields and a preparation method thereof. Background Art

[0002] Wax in crude oil usually exists in liquid form under formation conditions. During the exploitation process, with the decrease of temperature and pressure, the wax-dissolving capacity of crude oil decreases, and wax begins to crystallize and precipitate around the wellbore and inside the production casing, causing damage to the reservoir. Wax deposition in oil wells seriously affects the normal production of oil wells. Therefore, wax removal and prevention in oil wells is an important technical measure to ensure the normal production of waxy crude oil. The chemical wax removal and prevention method can change the total amount of wax in crude oil (conventional thermal methods and mechanical methods do not change the total amount of wax in crude oil). It is injected from the annulus between the oil casing and the production casing, does not affect the normal production and other operations of the oil well. In addition to achieving the effect of wax removal and prevention, using certain agents can also achieve the effects of pour point reduction, viscosity reduction and plugging removal. It can not only solve the problem of wax deposition in oil wells, but also reduce the deposition problem of crude oil in surface pipelines, oil transportation equipment and storage tanks. Therefore, it is widely used in major oilfields.

[0003] The wax deposition conditions and wax properties of oil wells in different blocks and different production layers vary greatly. At present, the main wax removal and prevention technologies are mechanical wax removal and chemical wax removal and prevention technologies. Mechanical wax removal mainly uses a wax removal truck for regular wax removal, but it is greatly restricted by weather and road conditions. Chemical wax removal and prevention mainly delays the crystallization and precipitation rate of wax on the wellbore by injecting chemical wax removal and prevention agents. Due to the lack of strong pertinence of the currently used chemical wax removal and prevention agents, the wax removal cycle of some oil wells is less than half a month. As a result, in the later stage of development of most oil wells in the oilfield, the density and viscosity of crude oil increase, wax deposition is serious, and the maintenance-free period is short. The effect of the existing wax prevention agents deteriorates year by year, resulting in a long maintenance-free period for oil wells.

[0004] Therefore, we propose a viscosity-reducing and wax-preventing agent for oil well production in oilfields and a preparation method thereof to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a viscosity-reducing and wax-preventing agent for oil well production in oilfields and a preparation method thereof in view of the above problems.

[0006] To achieve the above object, the present invention provides the following technical solution: A viscosity-reducing and wax-preventing agent for oil well production in oilfields, comprising the following components in mass percentage: maleic anhydride 15.08% - 17.92%, nonylphenol polyoxyethylene ether 18.01% - 26.88%, benzylamine solution 23.2% - 25.4%, 5% aqueous ferrous sulfate solution 3.97% - 5.0%, 5% aqueous ammonium persulfate solution 3.97% - 5.00%, aqueous sodium hydroxide solution 15.87% - 17.19%.

[0007] A viscosity reducer and paraffin inhibitor for oil well production in oil fields, comprising components in the following mass percentages: maleic anhydride 16.02% - 17.13%, nonylphenol polyoxyethylene ether 20.16% - 25.12%, benzylamine solution 23.8% - 24.8%, 5% ferrous sulfate aqueous solution 4.13% - 4.86%, 5% ammonium persulfate aqueous solution 4.13% - 4.86%, sodium hydroxide aqueous solution 16.28% - 16.86%.

[0008] A viscosity reducer and paraffin inhibitor for oil well production in oil fields, comprising components in the following mass percentages: maleic anhydride 16.02% - 17.13%, nonylphenol polyoxyethylene ether 20.16% - 25.12%, benzylamine solution 23.8% - 24.8%, 5% ferrous sulfate aqueous solution 4.13% - 4.86%, 5% ammonium persulfate aqueous solution 4.13% - 4.86%, sodium hydroxide aqueous solution 16.28% - 16.86%.

[0009] In the above-mentioned viscosity reducer and paraffin inhibitor for oil well production in oil fields, the molar ratio of maleic anhydride, nonylphenol polyoxyethylene ether, and benzylamine solution is 1:1.2 - 1.5:2 - 2.5.

[0010] A preparation method of a viscosity reducer and paraffin inhibitor for oil well production in oil fields, comprising the following steps:

[0011] S1. Dissolve maleic anhydride, nonylphenol polyoxyethylene ether, and 5% ferrous sulfate aqueous solution in water and stir until completely dissolved;

[0012] S2. Sequentially add benzylamine solution and 5% ammonium persulfate aqueous solution to the mixed solution in S1, and the heat released by the reaction raises the temperature of the mixed solution to 90 - 95°C;

[0013] S3. When the temperature of the mixed solution in S2 drops to 65 - 70°C, dropwise add sodium hydroxide aqueous solution and control the pH value to be 6 - 8 to obtain a maleic anhydride / nonylphenol polyoxyethylene ether / benzylamine copolymer.

[0014] In the above-mentioned preparation method of a viscosity reducer and paraffin inhibitor for oil well production in oil fields, the dissolution temperature in S1 is controlled at 60 - 65°C and kept constant for 1 - 2 hours.

[0015] In the above-mentioned preparation method of a viscosity reducer and paraffin inhibitor for oil well production in oil fields, the reaction in S3 is controlled to be kept constant in a constant temperature water bath at 60 - 90°C for 4 - 7 hours.

[0016] Compared with the prior art, the present invention provides a viscosity reducer and paraffin inhibitor for oil well production in oil fields and a preparation method thereof, having the following beneficial effects:

[0017] 1. The viscosity-reducing and wax-preventing agent for oilfield oil well production and its preparation method. Through the action of the polar and non-polar groups of the demulsifying viscosity-reducing and wax-preventing agent, the non-polar group part can co-crystallize with wax to affect the arrangement of wax crystals, while the polar group distorts the crystal form of wax crystals, making the wax loose and not easily precipitated on the pipe wall. At the same time, a hydrophilic and oleophobic polar film can be formed on the metal surface to prevent wax from depositing, solving the problems of serious wax deposition, short maintenance-free period due to the increase in crude oil density and viscosity in the late development stage of most oil wells in the oilfield, and the poor effect of the existing wax-preventing agent with deteriorating effect year by year, and extending the maintenance-free period of oil wells.

[0018] 2. The viscosity-reducing and wax-preventing agent for oilfield oil well production and its preparation method can effectively alleviate the frequent well workovers caused by wax deposition in oilfield oil well production through changing the crystallization environment of paraffin and the effect of lattice distortion. And the viscosity-reducing and wax-preventing agent used in oilfield oil well production does not contain chlorine, which not only considers the wax-preventing and viscosity-reducing effect, but also will not affect the downstream refining equipment.

[0019] In summary, the present invention solves the problems of serious wax deposition, short maintenance-free period due to the increase in crude oil density and viscosity in the late development stage of most oil wells in the oilfield, and the poor effect of the existing wax-preventing agent with deteriorating effect year by year, extends the maintenance-free period of oil wells, can effectively alleviate the frequent well workovers caused by wax deposition in oilfield oil well production, and the viscosity-reducing and wax-preventing agent used in oilfield oil well production does not contain chlorine, which not only considers the wax-preventing and viscosity-reducing effect, but also will not affect the downstream refining equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the chemical formula of a viscosity-reducing and wax-preventing agent for oilfield oil well production proposed by the present invention;

[0021] Figure 2 It is a schematic diagram of the wax crystal aggregation situation without adding wax in a viscosity-reducing and wax-preventing agent for oilfield oil well production proposed by the present invention;

[0022] Figure 3 It is a schematic diagram of the wax crystal aggregation situation with adding wax in a viscosity-reducing and wax-preventing agent for oilfield oil well production proposed by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0024] Please refer to Figures 1-3 , a viscosity-reducing and wax-preventing agent for oilfield oil well production, including the following components by mass percentage: maleic anhydride 15.08%, nonylphenol polyoxyethylene ether 18.01%, benzylamine solution 23.2%, 5% ferrous sulfate aqueous solution 3.97%, 5% ammonium persulfate aqueous solution 3.97%, sodium hydroxide aqueous solution 15.87%.

[0025] The molar ratio of maleic anhydride, nonylphenol polyoxyethylene ether, and benzylamine solution is 1:1.2 - 1.5:2 - 2.5.

[0026] A preparation method of a viscosity reducing and wax inhibiting agent for oilfield oil well production includes the following steps:

[0027] S1. Dissolve maleic anhydride, nonylphenol polyoxyethylene ether, and 5% ferrous sulfate aqueous solution in water and stir until completely dissolved;

[0028] S2. Add benzylamine solution and 5% ammonium persulfate aqueous solution to the mixed solution in S1 in sequence. The heat released by the reaction raises the temperature of the mixed solution to 90 - 95°C;

[0029] S3. When the temperature of the mixed solution in S2 drops to 65 - 70°C, add sodium hydroxide aqueous solution dropwise and control the pH value to be 6 - 8 to obtain maleic anhydride / nonylphenol polyoxyethylene ether / benzylamine copolymer.

[0030] The dissolution temperature in S1 is controlled at 60 - 65°C and kept constant for 1 - 2 hours.

[0031] In S3, control the reaction to be kept constant in a constant temperature water bath at 60 - 90°C for 4 - 7 hours.

[0032] Refer to Figures 2-3 , through the comparison of the scanning electron microscopy of the wax morphology with and without the addition of the polymer, it can be found that after the addition of the polymer, the wax crystal has changed, and the tendency to form larger grains has been changed. This is because during the crystal growth process, the polymer is adsorbed in the crystallization growth lattice. This adsorption effect will change the normal morphology of the crystallization and hinder its growth into larger crystals. Since the paraffin remover molecules are adsorbed in the crystal, the regularity of the crystallization is greatly damaged, causing the crystals of the crystallization to deform, resulting in a decrease in the crystallization strength and becoming more loose and easy to be washed away. This is the distortion effect of the polymer;

[0033] In addition, polymer molecules can be adsorbed around crystal nuclei or crystal particles. Their polar parts face the water phase, and the non-polar parts are adsorbed on the outside of the particles. In this way, the particles all carry a weak negative charge. Due to the charge repulsion of the particles, the particles are not easy to coagulate due to collision and are not easy to grow;

[0034] Using a dynamic wax deposition rate tester, a simulation experiment on the wax deposition law of typical wells was carried out to investigate the influence of different factors on wax deposition in oil wells (influence factor order: water cut > temperature > flow rate > time), and finally a water-soluble viscosity reducing and wax inhibiting agent was developed;

[0035] Experimental conclusion: (1) The wax deposition amount gradually decreases with the increase of the water content. The decreasing rate of the wax deposition amount first increases and then decreases with the increase of the water content. There are certain differences in the decreasing rates of the wax deposition amounts in different oil wells;

[0036] (2) When the temperature of the wax - forming pipe is above the wax - precipitation point temperature, wax will not precipitate. However, when the temperature drops below the wax - precipitation temperature, wax crystals begin to precipitate. The lower the temperature, the more wax precipitates.

[0037] (3) The wax - forming amount of crude oil gradually decreases with the increase of the crude oil flow rate and finally stabilizes. The decreasing rate of the wax - forming amount of crude oil first increases and then decreases with the increase of the crude oil flow rate.

[0038] (4) The wax - forming amount of crude oil increases with the increase of wax - forming time, and the wax - forming rate decreases with the increase of wax - forming time.

[0039] Based on indoor experiments on the crude oil of typical oil wells, the optimal dosing concentration of the chemical additive is 500 mg / l.

[0040]

[0041]

[0042] Example 2:

[0043] A viscosity - reducing and wax - preventing agent for oil - field oil - well production, comprising components with the following mass percentages: maleic anhydride 17.92%, nonylphenol polyoxyethylene ether 26.88%, benzylamine solution 25.4%, 5% ferrous sulfate aqueous solution 5.0%, 5% ammonium persulfate aqueous solution 5.00%, sodium hydroxide aqueous solution 17.19%.

[0044] Example 3:

[0045] A viscosity - reducing and wax - preventing agent for oil - field oil - well production, comprising components with the following mass percentages: maleic anhydride 16.68%, nonylphenol polyoxyethylene ether 23.28%, benzylamine solution 24.3%, 5% ferrous sulfate aqueous solution 4.56%, 5% ammonium persulfate aqueous solution 4.56%, sodium hydroxide aqueous solution 16.486%.

[0046] Through the action of the polar groups and non - polar groups of the demulsifying viscosity - reducing and wax - preventing agent, the non - polar group part can co - crystallize with wax to affect the wax crystal arrangement, while the polar groups distort the crystal form of wax crystals, making the wax become loose and not easy to precipitate on the pipe wall. At the same time, a hydrophilic and oleophobic polar film can be formed on the metal surface to prevent wax from depositing. This solves the problems that in the later stage of the development of most oil - field oil wells, the density and viscosity of crude oil increase, wax - forming is serious, the trouble - free period is short, and the effect of the existing wax - preventing agents deteriorates year by year. It can extend the trouble - free period of oil wells. By changing the wax - crystallization environment and the lattice distortion effect, it can effectively alleviate the frequent well - workovers caused by wax - forming in the production of oil - field oil wells. Moreover, the viscosity - reducing and wax - preventing agent used in oil - field oil - well production does not contain chlorine, which not only considers the wax - preventing and viscosity - reducing effects but also will not affect the downstream refining equipment.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A viscosity-reducing and paraffin-inhibiting agent for oil well production in oilfields, characterized in that, Comprising components in the following mass percentages: maleic anhydride 15.08% - 17.92%, nonylphenol polyoxyethylene ether 18.01% - 26.88%, benzylamine solution 23.2% - 25.4%, 5% aqueous ferrous sulfate solution 3.97% - 5.0%, 5% aqueous ammonium persulfate solution 3.97% - 5.00%, aqueous sodium hydroxide solution 15.87% - 17.19%.

2. A viscosity reducer and paraffin inhibitor for oil well production in oil fields, characterized in that, Comprising components in the following mass percentages: maleic anhydride 16.02% - 17.13%, nonylphenol polyoxyethylene ether 20.16% - 25.12%, benzylamine solution 23.8% - 24.8%, 5% aqueous ferrous sulfate solution 4.13% - 4.86%, 5% aqueous ammonium persulfate solution 4.13% - 4.86%, aqueous sodium hydroxide solution 16.28% - 16.86%.

3. A viscosity-reducing and paraffin-inhibiting agent for oil well production in oil fields, characterized in that, Comprising components in the following mass percentages: maleic anhydride 16.02% - 17.13%, nonylphenol polyoxyethylene ether 20.16% - 25.12%, benzylamine solution 23.8% - 24.8%, 5% aqueous ferrous sulfate solution 4.13% - 4.86%, 5% aqueous ammonium persulfate solution 4.13% - 4.86%, aqueous sodium hydroxide solution 16.28% - 16.86%.

4. A viscosity reducer and paraffin inhibitor for oilfield well production according to claim 1, characterized in that, The molar ratio of the maleic anhydride, nonylphenol polyoxyethylene ether, and benzylamine solution is 1:1.2 - 1.5:2 - 2.

5.

5. A preparation method of a viscosity-reducing and paraffin-inhibiting agent for oilfield oil well production according to any one of claims 1-4, characterized in that, Comprising the following steps: S1. Dissolve maleic anhydride, nonylphenol polyoxyethylene ether, and 5% aqueous ferrous sulfate solution together in water and stir until completely dissolved; S2. Sequentially add benzylamine solution and 5% aqueous ammonium persulfate solution to the mixed solution in S1, and the heat released by the reaction raises the temperature of the mixed solution to 90 - 95°C; S3. When the temperature of the mixed solution in S2 drops to 65 - 70°C, add aqueous sodium hydroxide solution dropwise, control the pH value to be 6 - 8, and obtain a maleic anhydride / nonylphenol polyoxyethylene ether / benzylamine copolymer.

6. The preparation method of a viscosity-reducing and paraffin-inhibiting agent for oilfield oil well production according to claim 5, characterized in that, The dissolution temperature in S1 is controlled at 60 - 65°C and kept at a constant temperature for 1 - 2 hours.

7. The preparation method of a viscosity-reducing and paraffin-inhibiting agent for oilfield oil well production according to claim 5, characterized in that, The reaction in S3 is controlled to be kept at a constant temperature in a constant temperature water bath at 60 - 90°C for 4 - 7 hours.

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