An oil-soluble viscosity reducer, its preparation method, and its application in extra-heavy oil blocks.

Abstract

This invention relates to an oil-soluble viscosity reducer, its preparation method, and its application in extra-heavy oil blocks. The viscosity reducer raw materials include the following components: methyl methacrylate, 2-acrylamidohexadecanesulfonic acid, and allylbenzene as monomers; toluene as solvent; and azobisisobutyronitrile as initiator. The mass ratio of each monomer is methyl methacrylate: 2-acrylamidohexadecanesulfonic acid: allylbenzene: = 5-7: 3.7-18: 0.9-3.7; the amount of azobisisobutyronitrile added is 1%-3% of the total mass of the system. The ester group in methyl methacrylate enhances the oil solubility of the viscosity reducer; 2-acrylamidohexadecanesulfonic acid has highly polar sulfonic acid and amide groups, which can greatly improve the dispersion effect on wax crystals, gums, and asphaltenes; allylbenzene provides a sterically hindered phenyl group, further improving the stability and temperature resistance of the viscosity reducer molecule. This invention has the advantages of simple preparation, convenient operation, and low cost, and is particularly suitable for viscosity reduction and extraction of underground extra-heavy oil with a viscosity of tens of thousands of mPa·s.

Description

Technical Field

[0001] This invention relates to an oil-soluble viscosity reducer applicable to the field of petroleum extraction, specifically to an oil-soluble viscosity reducer for the extraction of extra-heavy oil, its preparation method, and its specific applications. Background Technology

[0002] Crude oil exhibits excellent fluidity under reservoir temperature and formation pressure conditions, allowing it to flow smoothly from the oil layer into the wellbore. However, as crude oil flows upwards along the wellbore, its viscosity increases significantly due to depressurization, degassing, and heat dissipation, gradually causing it to lose fluidity and eventually clog the pipeline. This severely impacts crude oil production and prevents normal operations from proceeding smoothly.

[0003] Currently, typical methods for reducing the viscosity of heavy oil both domestically and internationally include physical viscosity reduction techniques (dilution viscosity reduction, heating methods, etc.) and chemical viscosity reduction techniques (heavy oil upgrading technology, emulsification viscosity reduction, oil-soluble viscosity reducers, etc.). However, the exploitation of ultra-deep, ultra-heavy oil resources, such as the Tarim River Oilfield, has always been a global challenge.

[0004] Currently, blending with thinner oil for viscosity reduction is a relatively economical and effective extraction method. However, this method suffers from several problems, including high thinner oil consumption, difficulty in determining the appropriate dosage, reduced thinner oil quality, decreased effective pump power, and limited thinner oil resources. Adding an oil-soluble viscosity reducer during the blending process can significantly reduce thinner oil consumption, decrease pump displacement and improve pump efficiency, and lower extraction and transportation costs. Oil-soluble viscosity reducers offer stable viscosity reduction effects, are easy to operate, require no post-processing, and show great promise for future development.

[0005] The viscosity-reducing mechanism of oil-soluble viscosity reducers involves the viscosity reducer molecules penetrating and dispersing between the asphaltenes and gum-like molecules through their strong hydrogen-bonding ability and penetrating and dispersing effects. This partially breaks down the planar aggregates formed by the stacked molecules, resulting in aggregates with a relatively loose structure, low degree of order, limited spatial extension, and the participation of viscosity reducer molecules, thereby reducing the viscosity of heavy oil. Oil-soluble viscosity reducers have achieved good results in reducing the viscosity of heavy oil. However, most current chemical viscosity reducers and methods still have problems such as insufficient viscosity reduction rates and selectivity of the viscosity reducers, especially for extra-heavy oils, which requires further exploration and research.

[0006] CN105018062A discloses a heavy oil viscosity reducer, its preparation method, and a method for reducing heavy oil viscosity. This heavy oil viscosity reducer contains 3-30% by weight of component A, which is a haloalkane or a methyl ester; 5-40% by weight of component B, which is potassium hydroxide or ammonia; and 30-92% by weight of solvent. This viscosity reducer has a certain effect on reducing the viscosity of heavy oil, but the reaction time is too long (20-100 hours), and it is specifically designed for Tarim River heavy oil with a viscosity of 935.5 mPa·s at 50°C, offering little benefit for wellbore crude oil extraction.

[0007] CN112646073A discloses an oil-soluble viscosity reducer for heavy oil and its preparation method. This viscosity reducer is prepared from four monomers: 2,2,3,3-tetrafluoropropyl methacrylate, styrene, maleic anhydride, and octadecyl methacrylate, in a molar ratio of 1:(2-4):(1-3):(9-11). The preparation process is simple, the conditions are mild, and it exhibits good oil solubility, allowing it to be mixed with toluene. However, because this viscosity reducer is prepared from four monomers, the polymerization conditions are more complex, and the degree of reaction is difficult to control. Furthermore, the oil-soluble viscosity reducer is used to reduce the viscosity of heavy oil with a viscosity of 24300-34100 mPa·s.

[0008] There are many types of oil-soluble viscosity reducers, but each method has its limitations, and most are for heavy oil with a viscosity of 50,000 mPa·s and below. There is less information on viscosity reducers for ultra-heavy oils with a viscosity of hundreds of thousands of mPa·s, such as those in the Tarim Oilfield. Summary of the Invention

[0009] To address the shortcomings of existing viscosity reducers, such as poor viscosity reduction effect, inability to meet the extraction requirements of extra-heavy oil with higher viscosity, and high selectivity, this invention provides an oil-soluble viscosity reducer, its preparation method, and its application in extra-heavy oil blocks.

[0010] The technical solution of the present invention is as follows:

[0011] An oil-soluble viscosity reducer, characterized in that the raw materials include the following components:

[0012] Methyl methacrylate, 2-acryloylaminohexadecanesulfonic acid, and allylbenzene are used as monomers, toluene is used as solvent, and azobisisobutyronitrile is used as initiator. The mass ratio of each monomer is methyl methacrylate: 2-acryloylaminohexadecanesulfonic acid: allylbenzene: = 5~7: 3.7~18: 0.9~3.7. The amount of azobisisobutyronitrile added is 1%~3% of the total mass of the system.

[0013] The aforementioned method for preparing an oil-soluble viscosity reducer is characterized by comprising the following steps:

[0014] First, methyl methacrylate, 2-acryloylaminohexadecanesulfonic acid and allylbenzene are added to a container, and then a certain amount of toluene solvent is poured in. The mixture is stirred to ensure that the reactants are fully mixed, and then the temperature is raised to the reaction temperature. The initiator azobisisobutyronitrile is added to the solution to react, and finally the viscosity reducer is obtained by distillation and purification.

[0015] Preferably, the container is a three-necked flask containing a spherical condenser, a thermometer, a magnetic stirrer, and an inlet pipe.

[0016] More preferably, the air inlet pipe is connected to nitrogen gas, and nitrogen gas is continuously supplied for protection from the time of stirring until the end of the reaction.

[0017] Preferably, the stirring time is 30 minutes.

[0018] Preferably, the reaction temperature is 60–80°C.

[0019] Preferably, the reaction time is 4-8 hours.

[0020] Preferably, the 2-acryloylaminohexadecanesulfonic acid is prepared by reacting acrylonitrile and 1-hexadecene in an organic solvent.

[0021] It also includes the application of the aforementioned oil-soluble viscosity reducer in the Tarim River heavy oil block.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] This invention discloses an oil-soluble viscosity reducer suitable for the extraction of extra-heavy oil in the petroleum extraction field. The ester group in the raw material methyl methacrylate enhances the oil solubility of the viscosity reducer. 2-Acrylamidohexadecanesulfonic acid has highly polar sulfonic acid and amide groups, which can greatly improve the dispersion effect on wax crystals, gums and asphaltenes. 2-Acrylamidohexadecanesulfonic acid is prepared in the laboratory, specifically by preparing acrylonitrile and 1-hexadecene in an organic solvent. Allylbenzene provides a sterically hindered phenyl group to further improve the stability and temperature resistance of the viscosity reducer molecule.

[0024] The synthesis process is shown in the following formula:

[0025]

[0026] This invention has the advantages of simple preparation, convenient operation, and low cost. Its viscosity-reducing effect is significantly better than that of other commercially available viscosity-reducing products. It has a wide range of applications and can be used for viscosity reduction in wellbore, which can significantly reduce the amount of diluted oil used, thereby saving extraction costs. It is particularly suitable for viscosity reduction extraction of underground extra-heavy oil with a viscosity of tens of thousands of mPa·s, which can significantly reduce the viscosity of heavy oil, improve the fluidity of heavy oil, save the amount of diluted oil used, reduce production costs, increase the extraction volume of heavy oil, improve existing extraction problems, improve the extraction and transportation performance of crude oil, and increase crude oil production. Detailed Implementation

[0027] The present invention will be further described in detail below through specific embodiments, but this is not intended to limit the technical solution of the present invention. All changes or equivalent substitutions made based on the present invention should fall within the protection scope of the present invention.

[0028] Example

[0029] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0030] Example 1

[0031] First, 2-acryloylaminohexadecanesulfonic acid is prepared by reacting acrylonitrile and 1-hexadecene in toluene or xylene in a corresponding ratio.

[0032] Accurately weigh 5g of methyl methacrylate, 8.11g of 2-acrylamidohexadecanesulfonic acid, and 2.21g of allylbenzene and add them to a three-necked flask equipped with a spherical condenser, thermometer, magnetic stir bar, and gas inlet. Then pour in 34.18g of toluene solvent, purge with nitrogen gas, stir for 30 minutes to ensure the reactants are fully mixed, then heat to 70℃ and add 0.5g of azobisisobutyronitrile initiator to the solution. React for 6 hours, during which nitrogen gas must be continuously purged for protection. Finally, distill and purify to obtain the viscosity reducer.

[0033] Example 2

[0034] First, 2-acryloylaminohexadecanesulfonic acid is prepared by reacting acrylonitrile and 1-hexadecene in toluene or xylene in a corresponding ratio.

[0035] Accurately weigh 6g of methyl methacrylate, 11g of 2-acryloylamino hexadecanesulfonic acid, and 0.95g of allylbenzene and add them to a three-necked flask equipped with a spherical condenser, thermometer, magnetic stir bar, and gas inlet. Then pour in 31.05g of toluene solvent, purge with nitrogen, stir for 30 minutes to ensure the reactants are fully mixed, then heat to 60℃ and add 1g of azobisisobutyronitrile initiator to the solution. React for 5 hours, during which nitrogen must be continuously purged for protection. Finally, distill and purify to obtain the viscosity reducer.

[0036] Performance test comparison:

[0037] Based on the viscosity-reducing effect testing method of the viscosity reducer currently used in the Tarim Oilfield, and in accordance with patent CN201210537135.2 "Method for Determining the Viscosity-Reducing Effect of Oil-Soluble Viscosity Reducer Applicable to Extra-Heavy Oil and Its Application", the viscosity-reducing effect of the viscosity reducer was tested. Heavy oil samples A and B from the same extra-heavy oil well were diluted in batches using thin oil. The oil-soluble viscosity reducer prepared in the example was added to the mixed sample B, and then diluted again in batches using thin oil. For the data of the viscosity-to-thickness ratio Φ and viscosity τ of sample A, a functional relationship between the viscosity-to-thickness ratio Φ and viscosity τ was fitted; where the viscosity-to-thickness ratio Φ is the ratio of the weight of the added thin oil to the original weight of the heavy oil used. The final viscosity value of the mixed system after viscosity-reducing and dilution was substituted into the fitted relationship to obtain the viscosity-to-thickness ratio Φ. a剂 The final viscosity value τ of the mixed system was obtained by testing.剂n And calculate the actual thin-to-thickness ratio Φ corresponding to this viscosity value. 剂n The formula for calculating the decrease in the dilute-to-thickness ratio is η = (Φ a剂 -Φ 剂n ) / Φ a剂 *100%.

[0038] Taking the extra-heavy oil from a heavy oil well in Block 12 of the Tarim Oilfield as an example, the viscosity-reducing effect of the oil-soluble viscosity reducer obtained in the test example was investigated.

[0039] Two 100g oil samples from the well were taken and placed in two 250mL beakers, A and B, respectively. The beakers were placed in a 50℃ water bath and heated continuously with a glass rod to ensure uniform heating of the extra-heavy oil. Once the oil was completely softened and homogeneous, its viscosity at 50℃ was measured and recorded as τa0 = 349800 mPa·s and τb0 = 351100 mPa·s. Using the aforementioned method, the corresponding functional relationship between viscosity τ and the viscosity-to-thickness ratio Φ was finally obtained: Φ = ln(414510 / τ) / 7.88, R 2 =0.996>0.99.

[0040] The viscosity reducer prepared in the examples was added to the mixed oil at a dosage of 0.1-0.5%, and the viscosity-reducing effect was tested according to the aforementioned test method. The results showed that the viscosity-reducing effect of the viscosity reducer on heavy oil increased significantly with the increase of the dosage. When the dosage reached 0.5 mg / L, the viscosity reduction rate reached 25%, indicating that the viscosity reducer has an excellent viscosity-reducing effect on heavy oil. The results are shown in Table 1.

[0041] Table 1. Effect of viscosity reducer dosage on viscosity reduction effect

[0042]

[0043] Compared with existing technologies:

[0044] Taking a heavy oil well in Block 10 of the Tarim Oilfield as an example, the viscosity-reducing effects of three viscosity reducers from different sources were tested. The viscosity reducer prepared in Example 1 was compared with existing viscosity reducers FSJ (from the Petroleum Engineering Technology Research Institute of China Petroleum & Chemical Corporation) and SHY-1 (purchased from Dongying Oufide Petroleum Technology Co., Ltd.). The viscosity-reducing effects were tested according to the aforementioned testing methods. The results showed that the viscosity-reducing effect of Example 1 was significantly higher than the other two products, indicating that the newly synthesized oil-soluble viscosity reducer ZY-2 has a significantly improved viscosity-reducing effect and can be used in heavy oil blocks to reduce the amount of diluted oil and viscosity reducers required, thereby increasing the recovery rate of heavy oil. The results are shown in Table 2.

[0045] Table 2 Comparison of the effects of different viscosity reducers

[0046]

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection defined in the claims.

Claims

1. An oil-soluble viscosity reducer characterized by The raw material comprises the following components: Methyl methacrylate, 2-acrylamido hexadecane sulfonic acid and allyl benzene are monomers, toluene is solvent, and azobis isobutyronitrile is initiator, wherein the mass ratio of each monomer is methyl methacrylate: 2-acrylamido hexadecane sulfonic acid: allyl benzene: = 5-7: 3.7-18: 0.9-3.7; the addition amount of azobis isobutyronitrile is 1%-3% of the total mass of the system.

2. A process for the preparation of an oil soluble viscosity reducer as claimed in claim 1, characterized in that The method comprises the following steps: First, methyl methacrylate, 2-acrylamido hexadecane sulfonic acid and allyl benzene are added to a container, a certain amount of toluene solvent is poured, the reactants are fully mixed by stirring, the temperature is raised to the reaction temperature, the initiator azobis isobutyronitrile is added to the solution for reaction, and finally the said viscosity reducer is obtained by distillation and purification.

3. The method of claim 2, wherein The container is a three-necked flask provided with a spherical condenser, a thermometer, a magnetic stirring rod and a gas inlet pipe.

4. The method of claim 3, wherein The gas inlet pipe is connected to nitrogen, and nitrogen is continuously introduced for protection during stirring to the end of the reaction.

5. The method of claim 2, wherein The stirring time is 30 min.

6. The method of claim 2, wherein The reaction temperature is 60-80℃.

7. The method of claim 2, wherein The reaction time is 4-8 h.

8. The method of claim 2, wherein The 2-acrylamido hexadecane sulfonic acid is prepared by using acrylonitrile and 1-hexadecene in an organic solvent.

9. The use of the oil-soluble viscosity reducer of claim 1 in Tahe heavy oil blocks.

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