Wax crystal inhibitor for oil extraction and preparation method thereof

Abstract

The invention relates to the technical field of oil field auxiliaries, in particular to a wax crystal inhibitor for oil extraction and a preparation method thereof.The wax crystal inhibitor for oil extraction is prepared from, by weight, 10-20 parts of ethylene-vinyl acetate copolymer, 20-30 parts of aromatic hydrocarbon, 5-10 parts of fatty alcohol-polyoxyethylene ether, 2-5 parts of alcohols and 35-65 parts of water; the preparation method comprises the following steps: firstly, mixing the ethylene-vinyl acetate copolymer with aromatic hydrocarbon, then adding alcohol and water, uniformly stirring and mixing, finally adding the required amount of fatty alcohol-polyoxyethylene ether, and fully mixing to obtain the wax crystal inhibitor for oil extraction. The wax crystal inhibitor for oil extraction, which is prepared from EVA, aromatic hydrocarbon, fatty alcohol-polyoxyethylene ether and alcohol according to the proportion, can exert better wax prevention and viscosity reduction effects, ensures normal production of oil wells, and is suitable for wax prevention of oil wells in low-water-content and high-wax-content blocks.

Description

Technical Field

[0001] This invention relates to the field of oilfield additives technology, specifically a wax crystal inhibitor for oil production and its preparation method. Background Technology

[0002] During crude oil extraction, wax deposition in oil wells is common in waxy oil reservoirs. This process is caused by the decrease in temperature and pressure during the lifting of crude oil in the wellbore, which leads to the precipitation, deposition, and adhesion of dissolved wax components to the pipe wall and downhole equipment surface. This results in a decrease in oil well productivity, increased extraction costs, and safety hazards such as equipment blockage and pump jamming, seriously restricting the economic benefits and sustainable development of the oil field.

[0003] Currently, the commonly used anti-wax agent system in the main light oil blocks of a certain oilfield is mainly surfactant-type anti-wax agent. The mechanism of action of this type of agent is mainly to prevent wax crystals from agglomerating and adhering through emulsification, dispersion, and wetting. It is significantly affected by changes in the water content of the oil well, resulting in poor anti-wax effect in some oil wells in low water content and high wax content blocks.

[0004] Patent application document CN117304900B discloses an oil wellbore gelatinous plugging agent and its preparation method. The oil wellbore gelatinous plugging agent is mainly composed of dipentene, petroleum ether and straight-chain alkanes. It can effectively dissolve high-gelatinous pluggings in the wellbore. It uses ethylene-vinyl acetate copolymer and fatty alcohol polyoxyethylene ether as raw materials.

[0005] Patent application document CN119144309B discloses a wax remover and its preparation method, which uses heavy aromatic hydrocarbons, fatty alcohol polyoxyethylene ethers and modified EVA as raw materials.

[0006] Patent application document CN109897734B discloses a slow-release chemical dewaxing ball for use in oil pipelines, its preparation method and application, and discloses the use of EVA and fatty alcohol polyoxyethylene ether. Summary of the Invention

[0007] This invention provides a wax crystal inhibitor for oil production and its preparation method, which overcomes the shortcomings of the prior art and can improve the wax prevention effect.

[0008] One of the technical solutions of the present invention is achieved by the following measures: an oil extraction wax crystal inhibitor, wherein the raw materials, by weight, include 10 to 20 parts of ethylene-vinyl acetate copolymer, 20 to 30 parts of aromatic hydrocarbons, 5 to 10 parts of fatty alcohol polyoxyethylene ether, 2 to 5 parts of alcohols, and 35 to 65 parts of water.

[0009] The following are further optimizations and / or improvements to one of the above-mentioned inventive technical solutions: The alcohols mentioned above are one or more of methanol, ethanol, and ethylene glycol.

[0010] The aromatic hydrocarbons mentioned above are one or more of benzene, toluene, and xylene.

[0011] In the above-mentioned ethylene-vinyl acetate copolymer, the vinyl acetate content is 18%.

[0012] The above-mentioned wax crystal inhibitor for oil extraction is prepared by the following method: The required amount of ethylene-vinyl acetate copolymer is mixed evenly with aromatic hydrocarbons for 150 min to 180 min at a mixing temperature of 60 °C to 90 °C to obtain the first mixture. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 to 80 minutes, controlling the mixing temperature at 45°C to 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix and stir thoroughly for 45 to 60 minutes, control the temperature at 45°C to 60°C, and the stirring speed at 40 to 50 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

[0013] The second technical solution of the present invention is achieved by the following measures: the preparation method of the oil production wax crystal inhibitor described in one of the technical solutions is carried out by the following method: the required amount of ethylene-vinyl acetate copolymer is mixed evenly with aromatic hydrocarbons, the mixing and stirring time is 150 min to 180 min, the mixing temperature is 60°C to 90°C, and a first mixture is obtained. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 to 80 minutes, controlling the mixing temperature at 45°C to 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix and stir thoroughly for 45 to 60 minutes, control the temperature at 45°C to 60°C, and the stirring speed at 40 to 50 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

[0014] This invention relates to a wax crystal inhibitor for oil production, which is made by combining EVA, aromatic hydrocarbons, fatty alcohol polyoxyethylene ether and alcohols in the specified proportions. It inhibits the formation of wax crystals and changes the stable structure of wax crystals by participating in the formation of wax crystals, thereby achieving better wax prevention and viscosity reduction effects, ensuring normal production of oil wells, and is suitable for wax prevention in oil wells in low water-cut and high wax-content blocks. Detailed Implementation

[0015] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0016] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. All chemical reagents and chemical products mentioned in this invention, unless otherwise specified, are well-known and commonly used chemical reagents and chemical products in the prior art; percentages in this invention, unless otherwise specified, are mass percentages; solutions in this invention, unless otherwise specified, are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0017] In the following embodiments, the EVA model is Y2045.

[0018] The present invention will be further described below with reference to embodiments: Example 1: The wax crystal inhibitor for oil production comprises, by weight, 10 to 20 parts of ethylene-vinyl acetate copolymer (EVA), 20 to 30 parts of aromatic hydrocarbons, 5 to 10 parts of fatty alcohol polyoxyethylene ether, 2 to 5 parts of alcohols, and 35 to 65 parts of water.

[0019] Compared with prior art 1 (CN117304900B), the fatty alcohol polyoxyethylene ether described in prior art 1 mainly utilizes its strong permeability to improve the dissolution ability of the main agent on the blockage, while the fatty alcohol polyoxyethylene ether described in this application mainly plays a surface-active emulsifying role, improving the uniformity and stability of the emulsion product; the EVA described in prior art 1 mainly plays a penetrating and dispersing role, enabling the dissolved colloidal blockage to be dispersed in the oil well produced fluid system, while the EVA described in this application participates in the wax crystal nucleus growth process, thereby inhibiting the growth and aggregation of wax crystals, and their functions are different.

[0020] Compared with prior art 2 (CN119144309B), the product formulation of prior art 2 is mainly for wax dissolving and removing, the product is oil-based, has a low flash point, and is less safe during use. The product of this application is mainly for wax prevention, the product is emulsion-type, and has higher safety performance.

[0021] Compared with prior art 3 (CN109897734B), the EVA in prior art 3 is used as a skeletal carrier to physically remove wax, while the EVA in this application participates in the wax crystal nucleus growth process to inhibit wax crystal growth and aggregation. The functions are different.

[0022] Example 2: As an optimization of the above example, the alcohol is one or more of methanol, ethanol, and ethylene glycol.

[0023] Example 3: As an optimization of the above examples, the aromatic hydrocarbon is one or more of benzene, toluene, and xylene.

[0024] Example 4: As an optimization of the above example, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 18%.

[0025] Example 5: This oilfield wax crystal inhibitor was prepared according to the following method: The required amount of ethylene-vinyl acetate copolymer is mixed evenly with aromatic hydrocarbons for 150 min to 180 min at a mixing temperature of 60 °C to 90 °C to obtain the first mixture. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 to 80 minutes, controlling the mixing temperature at 45°C to 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix and stir thoroughly for 45 to 60 minutes, control the temperature at 45°C to 60°C, and the stirring speed at 40 to 50 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

[0026] Example 6: The wax crystal inhibitor for oil production comprises, by weight, 10 parts of ethylene-vinyl acetate copolymer (vinyl acetate content of 18%), 20 parts of aromatic hydrocarbon (toluene), 5 parts of fatty alcohol polyoxyethylene ether, 2 parts of alcohol (ethanol), and 63 parts of water. The first mixture was obtained by mixing the required amount of ethylene-vinyl acetate copolymer with aromatic hydrocarbons at a mixing and stirring time of 150 min and a mixing temperature of 60 °C. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 minutes, controlling the mixing temperature at 45°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix thoroughly for 45 minutes, control the temperature at 45℃, and control the stirrer speed at 40 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

[0027] Example 7: The wax crystal inhibitor for oil production comprises, by weight, 15 parts of ethylene-vinyl acetate copolymer (vinyl acetate content of 18%), 25 parts of aromatic hydrocarbon (benzene), 10 parts of fatty alcohol polyoxyethylene ether, 5 parts of alcohol (ethylene glycol), and 45 parts of water. The first mixture was obtained by mixing the required amount of ethylene-vinyl acetate copolymer with aromatic hydrocarbons at a mixing and stirring time of 160 min and a mixing temperature of 80 °C. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 70 minutes, controlling the mixing temperature at 50°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix thoroughly for 45 minutes, control the temperature at 50℃, and control the stirrer speed at 45 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

[0028] Example 8: The wax crystal inhibitor for oil production comprises, by weight percentage, 20 parts of ethylene-vinyl acetate copolymer (vinyl acetate content of 18%), 30 parts of aromatic hydrocarbon (xylene), 10 parts of fatty alcohol polyoxyethylene ether, 5 parts of alcohol (methanol), and 35 parts of water. The first mixture was obtained by mixing the required amount of ethylene-vinyl acetate copolymer with aromatic hydrocarbons at a mixing and stirring time of 180 min and a mixing temperature of 90 °C. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 80 minutes, controlling the mixing temperature at 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix thoroughly for 50 minutes, control the temperature at 60℃, control the stirrer speed at 50 r / min, and stir until uniform to obtain the wax crystal inhibitor for oil production.

[0029] Comparative Example 1: The difference from Example 5 is that 5 parts of ethylene-vinyl acetate copolymer (vinyl acetate content of 18%) were used.

[0030] Comparative Example 2: The difference from Example 5 is that 30 parts of ethylene-vinyl acetate copolymer (vinyl acetate content of 18%) were used.

[0031] Comparative Example 3: Existing wax crystal inhibitor (composed of EVA + diesel).

[0032] The performance of the wax crystal inhibitors prepared in Examples 5 to 7 and the wax crystal inhibitors prepared in Comparative Examples 1 to 3 were evaluated. The current testing standard for wax crystal inhibitors for oil production is based on the technical requirements for wax removal and anti-wax agents for oil production, SY / 6300—2024. The performance was evaluated according to the test method for wax crystal modified anti-wax agents in this standard. The evaluation results are shown in Table 1.

[0033] Table 1 shows that the wax crystal inhibitors for oil production prepared in Examples 5 to 7 have better wax prevention rate, viscosity reduction rate, and pour point reduction than those in Comparative Examples 1 to 3, indicating that the wax crystal inhibitors for oil production prepared according to the present invention can achieve better wax prevention and viscosity reduction effects.

[0034] Furthermore, from the differences between Examples 5 to 7 and Comparative Examples 1 to 3, it can be seen that the EVA content used in Comparative Example 1 is lower than that in the present application, while the EVA content used in Comparative Example 2 is higher than that in the present application. As shown in Table 1, if the EVA content is too low or too high, the wax crystal inhibitor prepared by it will have a lower wax prevention rate and viscosity reduction rate than that of the present application. This indicates that the present application has achieved better wax prevention and viscosity reduction effects by using raw materials in a specific ratio.

[0035] On-site application results: A field test of wax prevention was conducted on well 5D2222. The well has a daily fluid production of 4.5 tons / day. The on-site dosage (adding the wax crystal inhibitor for oil production described in this application) was 4.5 kg / day, which was added through a continuous dosing device at the wellhead. Before the dosing test, the pump inspection cycle was 144 days. After the dosing test, the pump inspection cycle was 797 days, which is an extension of 653 days. It can be seen that the wax crystal inhibitor for oil production described in this application has a significant wax prevention effect.

[0036] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A wax crystal inhibitor for oil extraction, characterized in that, The raw materials, by weight, include 10 to 20 parts of ethylene-vinyl acetate copolymer, 20 to 30 parts of aromatic hydrocarbons, 5 to 10 parts of fatty alcohol polyoxyethylene ether, 2 to 5 parts of alcohols, and 35 to 65 parts of water.

2. The wax crystal inhibitor for oil production according to claim 1, characterized in that, The alcohols are one or more of methanol, ethanol, and ethylene glycol.

3. The oilfield wax crystal inhibitor according to claim 1 or 2, characterized in that, The aromatic hydrocarbon is one or more of benzene, toluene, and xylene; and / or the ethylene-vinyl acetate copolymer contains 18% vinyl acetate.

4. The wax crystal inhibitor for oil production according to claim 1 or 2, characterized in that, It is prepared by the following method: The required amount of ethylene-vinyl acetate copolymer is mixed evenly with aromatic hydrocarbons for 150 min to 180 min at a mixing temperature of 60 °C to 90 °C to obtain the first mixture. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 to 80 minutes, controlling the mixing temperature at 45°C to 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix and stir thoroughly for 45 to 60 minutes, control the temperature at 45°C to 60°C, and the stirring speed at 40 to 50 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

5. The oilfield wax crystal inhibitor according to claim 3, characterized in that, It is prepared by the following method: The required amount of ethylene-vinyl acetate copolymer is mixed evenly with aromatic hydrocarbons for 150 min to 180 min at a mixing temperature of 60 °C to 90 °C to obtain the first mixture. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 to 80 minutes, controlling the mixing temperature at 45°C to 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix and stir thoroughly for 45 to 60 minutes, control the temperature at 45°C to 60°C, and the stirring speed at 40 to 50 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

6. A method for preparing an oilfield wax crystal inhibitor according to claim 1, characterized in that, Perform the following steps: The required amount of ethylene-vinyl acetate copolymer is mixed evenly with aromatic hydrocarbons for 150 min to 180 min at a mixing temperature of 60 °C to 90 °C to obtain the first mixture. Add the required amount of alcohol and water to the first mixture and stir until homogeneous. Stir thoroughly for 60 to 80 minutes, controlling the mixing temperature at 45°C to 60°C, to obtain the second mixture. Add the required amount of fatty alcohol polyoxyethylene ether to the second mixture, mix and stir thoroughly for 45 to 60 minutes, control the temperature at 45°C to 60°C, and the stirring speed at 40 to 50 r / min until uniform, and the wax crystal inhibitor for oil production is obtained.

7. The method for preparing wax crystal inhibitors for oil production according to claim 6, characterized in that, The alcohols are one or more of methanol, ethanol, and ethylene glycol.

8. The method for preparing oilfield wax crystal inhibitor according to claim 6 or 7, characterized in that, Aromatic hydrocarbons are one or more of benzene, toluene, and xylene.

9. The method for preparing oilfield wax crystal inhibitor according to claim 6 or 7, characterized in that, In the ethylene-vinyl acetate copolymer, the vinyl acetate content is 18%.

10. The method for preparing wax crystal inhibitors for oil extraction according to claim 8, characterized in that, In the ethylene-vinyl acetate copolymer, the vinyl acetate content is 18%.

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