Corrosion and scale inhibitor for oil and gas well and preparation method of corrosion and scale inhibitor

Abstract

The invention discloses a corrosion and scale inhibitor for oil and gas wells and a preparation method thereof, and relates to the technical field of environment-friendly materials, the corrosion and scale inhibitor is prepared by compounding an imidazoline polyoxyethylene ether corrosion inhibitor, a quaternary ammonium salt corrosion inhibitor capsule and an organic phosphoric acid corrosion inhibitor; the quaternary ammonium salt corrosion inhibitor capsule is prepared by taking a quaternary ammonium salt corrosion inhibitor as a core and a dispersing agent as a wall. According to the invention, the imidazoline polyoxyethylene ether corrosion inhibitor, the quaternary ammonium salt corrosion inhibitor capsule and the organic phosphoric acid corrosion inhibitor are compounded, so that the corrosion inhibition and the long-term effect on pipelines in oil and gas wells are improved, the use amount of the corrosion and scale inhibitor is reduced, meanwhile, the deposition of inorganic sediments such as calcium carbonate on the pipelines in the oil and gas wells is reduced, and the scale inhibition is improved.

Description

Technical Field

[0001] The present application relates to the field of pipeline protection in oil and gas wells, and particularly to a corrosion inhibitor and scale inhibitor for oil and gas wells and a preparation method thereof. Background Art

[0002] In the process of oil and gas exploration and centralized transportation, due to the complex environment in oil and gas wells, high salinity liquids, carbon dioxide, hydrogen sulfide and other corrosive media often exist, resulting in the corrosion and failure of the oil pipes used therein.

[0003] Currently, in order to protect the pipelines in oil and gas wells, corrosion inhibitors are often added to oil and gas wells. For example, a super-high temperature acidizing corrosion inhibitor for Cr-containing oil pipes and a preparation method thereof (CN114989798A) uses Mannich base compounds as the main corrosion inhibition components, and a corrosion inhibitor for oilfield water injection (CN1277241) uses imidazoline derivatives as the main components, etc. Since the liquid in the oil and gas well is in a flowing state, in order to keep the concentration of the corrosion inhibition components in the liquid at an effective level all the time, a storage tank is often used to continuously add the corrosion inhibitor to the oil and gas well at a fixed flow rate.

[0004] However, as the flow distance of the fluid in the oil and gas well increases, due to the adsorption of the pipeline and the consumption of the corrosive media in the fluid, the concentration of the corrosion inhibitor gradually decreases. If the flow rate of continuously adding the corrosion inhibitor is too fast, although it can ensure that the concentration of the corrosion inhibitor in the later stage can still be maintained at an effective level, it will also increase the unnecessary consumption of the corrosion inhibitor by the corrosive media in the fluid in the early stage. If the flow rate of continuously adding the corrosion inhibitor is too slow, the adsorption efficiency of the corrosion inhibitor in the later-stage fluid on the pipeline decreases, and the coverage degree decreases, resulting in a poor corrosion inhibition effect. Summary of the Invention

[0005] In view of the above deficiencies in the related art, the purpose of the present application is to provide a corrosion inhibitor and scale inhibitor for oil and gas wells and a preparation method thereof. By compounding an imidazoline polyoxyethylene ether corrosion inhibitor, a quaternary ammonium salt corrosion inhibitor capsule and an organic phosphoric acid corrosion inhibitor, on the one hand, the imidazoline polyoxyethylene ether corrosion inhibitor is dispersed and adsorbed on the surface of the pipeline in the oil and gas well to form a basic protective layer. On the other hand, in the initial stage of adding the corrosion inhibitor, the capsule wall of the quaternary ammonium salt corrosion inhibitor capsule isolates the quaternary ammonium salt corrosion inhibitor from the fluid, thereby avoiding the premature consumption of the quaternary ammonium salt corrosion inhibitor. As the addition time increases, the capsule wall made of the dispersant dissolves, gradually releasing the quaternary ammonium salt corrosion inhibitor and increasing the dispersion effect of the quaternary ammonium salt corrosion inhibitor and the imidazoline polyoxyethylene ether corrosion inhibitor in the later stage, thereby improving the adsorption efficiency on the later-stage pipeline, increasing the coverage degree, and improving the corrosion inhibition property and long-term effectiveness.

[0006] In the first aspect, a corrosion inhibitor and scale inhibitor for oil and gas wells provided by the present application adopts the following technical solution: An inhibitor and scale inhibitor for oil and gas wells is prepared by compounding an imidazoline polyoxyethylene ether inhibitor, a quaternary ammonium salt inhibitor capsule, and an organic phosphoric acid inhibitor; the quaternary ammonium salt inhibitor capsule is prepared with a quaternary ammonium salt inhibitor as the core and a dispersant as the wall.

[0007] Preferably, it includes the following components in parts by weight: 20-40 parts of imidazoline polyoxyethylene ether inhibitor, 10-20 parts of quaternary ammonium salt inhibitor capsule, and 5-10 parts of organic phosphoric acid inhibitor.

[0008] Preferably, it includes the following components in parts by weight: 30 parts of imidazoline polyoxyethylene ether inhibitor, 15 parts of quaternary ammonium salt inhibitor capsule, and 8 parts of organic phosphoric acid inhibitor.

[0009] Preferably, the quaternary ammonium salt inhibitor includes one or more of benzoic acid imidazoline quaternary ammonium salt and its derivatives, and heptadecenylamine ethyl imidazoline quaternary ammonium salt and its derivatives.

[0010] Preferably, the quaternary ammonium salt inhibitor is heptadecenylamine ethyl imidazoline quaternary ammonium salt.

[0011] Preferably, the dispersant includes one or both of sodium polyacrylate and polyacrylic acid.

[0012] Preferably, the dispersant is sodium polyacrylate.

[0013] Preferably, the imidazoline polyoxyethylene ether inhibitor includes one or more of imidazoline polyoxyethylene ether, oleic acid imidazoline polyoxyethylene ether, and rosin imidazoline polyoxyethylene ether.

[0014] Preferably, the imidazoline polyoxyethylene ether inhibitor is imidazoline polyoxyethylene ether.

[0015] Preferably, the organic phosphoric acid inhibitor includes one or more of hydroxyethylidene diphosphonic acid, amino trimethylene phosphonic acid, and ethylenediamine tetramethylene phosphonic acid.

[0016] Preferably, the organic phosphoric acid inhibitor is hydroxyethylidene diphosphonic acid.

[0017] On the other hand, the present application provides a preparation method for an inhibitor and scale inhibitor for oil and gas wells, adopting the following technical solution: A preparation method for an inhibitor and scale inhibitor for oil and gas wells includes the following steps: taking a quaternary ammonium salt inhibitor and a dispersant to make a solution, adjusting the pH of the solution to 4 during stirring, continuously stirring until precipitation occurs, centrifuging to collect the precipitate, washing and then drying to obtain the quaternary ammonium salt inhibitor capsule; mixing the quaternary ammonium salt inhibitor capsule, the imidazoline polyoxyethylene ether inhibitor, and the organic phosphoric acid inhibitor to obtain the inhibitor and scale inhibitor for oil and gas wells.

[0018] Preferably, the quaternary ammonium salt corrosion inhibitor is heptadecenylamine ethyl imidazoline quaternary ammonium salt, and the dispersant is sodium polyacrylate.

[0019] Preferably, the weight ratio of the heptadecenylamine ethyl imidazoline quaternary ammonium salt to the sodium polyacrylate is 1:1 - 2.

[0020] Preferably, the weight ratio of the heptadecenylamine ethyl imidazoline quaternary ammonium salt to the sodium polyacrylate is 1:1.5.

[0021] Preferably, the mass concentration of the quaternary ammonium salt corrosion inhibitor and the dispersant in the solution is 8% - 12%.

[0022] Preferably, the mass concentration of the quaternary ammonium salt corrosion inhibitor and the dispersant in the solution is 10%.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. By compounding an imidazoline polyoxyethylene ether corrosion inhibitor, a quaternary ammonium salt corrosion inhibitor capsule, and an organic phosphoric acid corrosion inhibitor, on the one hand, the imidazoline polyoxyethylene ether corrosion inhibitor is dispersed and adsorbed on the surface of the pipeline in the front section of the oil and gas well to form a basic protective layer, and the capsule wall of the quaternary ammonium salt corrosion inhibitor capsule isolates the quaternary ammonium salt corrosion inhibitor from the fluid, thus preventing the premature consumption of the quaternary ammonium salt corrosion inhibitor. On the other hand, as the travel of the corrosion and scale inhibitor for oil and gas wells increases, the capsule wall made of the dispersant dissolves, gradually releasing the quaternary ammonium salt corrosion inhibitor, and the dispersant dissolved in the fluid increases the dispersion effect of the quaternary ammonium salt corrosion inhibitor and the imidazoline polyoxyethylene ether corrosion inhibitor in the later stage, thereby improving the adsorption efficiency on the pipeline in the later stage, increasing the coverage degree, and also improving the chelating ability of the imidazoline polyoxyethylene ether and the organic phosphoric acid corrosion inhibitor. Under the combined action, the three produce a synergistic effect, improving the adsorption efficiency and coverage effect on the pipeline in the oil and gas well, and chelating the metal ions in the fluid, achieving the corrosion inhibition and scale inhibition effects on the front and middle section pipelines in the oil and gas well.

[0024] 2. As the addition time of the corrosion and scale inhibitor for oil and gas wells extends, the dissolution amount of the capsule wall made of the dispersant increases, the release amount of the quaternary ammonium salt corrosion inhibitor increases, and the quaternary ammonium salt corrosion inhibitor synergistically acts through multiple mechanisms of adsorption - chelation - lattice distortion. On the one hand, its strong adsorption effect is beneficial to repairing the defects in the film formed by the imidazoline polyoxyethylene ether corrosion inhibitor on the pipeline surface due to the reduction caused by water flow impact or consumption, improving the corrosion inhibition effect and its long - term effectiveness; on the other hand, it inhibits the generation and aggregation of scale on the pipeline surface, improving the scale inhibition effect.

[0025] 3. In this application, sodium polyacrylate is used as a dispersant. By controlling the pH, sodium polyacrylate is induced to precipitate from the solution and self-assemble into a wall on the surface of the quaternary ammonium salt corrosion inhibitor emulsion and then dried, thereby forming a quaternary ammonium salt corrosion inhibitor capsule. When in use, while the wall material dissolves and releases sodium polyacrylate, the quaternary ammonium salt corrosion inhibitor is also released. Utilizing the high dispersion efficiency of the imidazoline polyoxyethylene ether type corrosion inhibitor and the high adsorption capacity of the quaternary ammonium salt corrosion inhibitor, on the pipeline in the oil and gas well, a high-efficiency response film is formed through the imidazoline polyoxyethylene ether type corrosion inhibitor to improve the corrosion inhibition rate and scale inhibition rate. The defects of the imidazoline polyoxyethylene ether type corrosion inhibitor film are strengthened by the high adsorption capacity of the quaternary ammonium salt corrosion inhibitor. Under the combined action, the corrosion inhibition effect and its long-term effectiveness are improved. Detailed implementation mode

[0026] The following further elaborates on this application in conjunction with the examples. The following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those conditions not specified in the following examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. The methods used, unless otherwise specified, are all conventional methods well-known in the art. The consumables and reagents used, unless otherwise specified, are all commercially available. Unless otherwise stated, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0027] The raw materials used in the examples and comparative examples can all be obtained commercially.

[0028] Example 1

[0029] Example 1 of this application provides a corrosion and scale inhibitor for oil and gas wells, which is prepared by compounding 30 parts by weight of imidazoline polyoxyethylene ether, 15 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules, and 8 parts by weight of an organic phosphoric acid type corrosion inhibitor.

[0030] Among them, the heptadecenylamine ethyl imidazoline quaternary ammonium salt capsule is prepared by the following steps: Take 10 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt and dissolve it in cyclohexane, and add 2% mass fraction of sorbitan oleate. Take 15 parts by weight of sodium polyacrylate and dissolve it in water, mix and emulsify to form an O / W emulsion. Drop 0.1 mol / L dilute hydrochloric acid into the emulsion to adjust the solution pH to 4, continuously stir for 1 h, centrifuge at 3000 rpm for 5 min, collect the precipitate, wash it 3 times with deionized water, and dry it to obtain a heptadecenylamine ethyl imidazoline quaternary ammonium salt capsule with heptadecenylamine ethyl imidazoline quaternary ammonium salt as the core and sodium polyacrylate as the wall.

[0031] In this example, the organic phosphoric acid type corrosion inhibitor is hydroxyethylidene diphosphonic acid.

[0032] Example 2

[0033] Example 2 of this application provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Example 2 and Example 1 is that Example 2 is prepared by compounding 20 parts by weight of imidazoline polyoxyethylene ether, 20 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules, and 5 parts by weight of organic phosphoric acid corrosion inhibitor.

[0034] Example 3

[0035] Example 3 of this application provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Example 3 and Example 1 is that Example 2 is prepared by compounding 40 parts by weight of imidazoline polyoxyethylene ether, 10 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules, and 10 parts by weight of organic phosphoric acid corrosion inhibitor.

[0036] Example 4

[0037] Example 4 of this application provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Example 4 and Example 1 is that when preparing the heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules in Example 4, 10 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt and 10 parts by weight of sodium polyacrylate are used.

[0038] Example 5

[0039] Example 5 of this application provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Example 5 and Example 1 is that when preparing the heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules in Example 5, 10 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt and 20 parts by weight of sodium polyacrylate are used.

[0040] Comparative Example 1

[0041] Comparative Example 1 provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules are not added, and an equal weight of hydroxyethane diphosphonic acid is used to make up.

[0042] Comparative Example 2

[0043] Comparative Example 2 provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the organic phosphoric acid corrosion inhibitor is not added, and an equal weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules is used to make up.

[0044] Comparative Example 3

[0045] Comparative Example 3 provides a corrosion inhibitor and scale inhibitor for oil and gas wells. The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the imidazoline polyoxyethylene ether is not added, and an equal weight of hydroxyethane diphosphonic acid is used to make up.

[0046] Comparative Example 4

[0047] Comparative Example 4 provides a corrosion and scale inhibitor for oil and gas wells. The difference between Comparative Example 4 and Example 1 is that: in Comparative Example 2, an equal weight portion of heptadecenylamine ethyl imidazoline quaternary ammonium salt is used to replace the heptadecenylamine ethyl imidazoline quaternary ammonium salt capsule.

[0048] Comparative Example 5

[0049] Comparative Example 5 provides a corrosion and scale inhibitor for oil and gas wells. The difference between Comparative Example 5 and Example 1 is that: in Comparative Example 5, 6 parts by weight of heptadecenylamine ethyl imidazoline quaternary ammonium salt and 9 parts by weight of sodium polyacrylate are used to replace 15 parts by weight of the heptadecenylamine ethyl imidazoline quaternary ammonium salt capsule.

[0050] Test and detection

[0051] (1) The dosage of the corrosion and scale inhibitor for oil and gas wells is 30 ppm. A 5% sodium chloride solution is used as the corrosion water sample, and 42MnMo7 steel is used as the coupon sample. A simulation experiment is carried out for 10 days under the conditions of 70 °C and 20 MPa to detect the corrosion inhibition rate (%) of the corrosion and scale inhibitors for oil and gas wells in Examples 1 - 5 and Comparative Examples 1 - 5; according to the SY / T5673 - 2020 standard, the scale inhibition rate (%) of the corrosion and scale inhibitors for oil and gas wells in Examples 1 - 5 and Comparative Examples 1 - 5 against calcium carbonate is detected respectively. The results are shown in Table 1 below.

[0052] Table 1: Data source Scale inhibition rate (%) Corrosion inhibition rate (%) Example 1 94.3 91.5 Example 2 93.2 90.8 Example 3 93.8 91.2 Example 4 91.7 90.1 Example 5 93.6 91.1 Comparative example 1 75.5 70.3 Comparative example 2 78.3 71.5 Comparative example 3 73.7 68.6 Comparative example 4 82.1 79.4 Comparative example 5 84.3 80.2 (2) The initial dosage of the corrosion and scale inhibitor for oil and gas wells is 30 ppm. A 5% sodium chloride solution is used as the corrosion water sample, and 42MnMo7 steel is used as the coupon sample and placed under the conditions of 70 °C and 20 MPa. The coupon is replaced every day, and a simulation experiment is carried out for 10 days to detect the corrosion inhibition rate (%) of the corrosion and scale inhibitors for oil and gas wells in Examples 1 - 5 and Comparative Examples 1 - 5; the corrosion and scale inhibitors for oil and gas wells in Examples 1 - 5 and Comparative Examples 1 - 5 are prepared into solutions, and 42MnMo7 steel is used as the coupon sample and placed under the conditions of 70 °C and 20 MPa. After 10 days, the coupon is removed to obtain the dilution solutions of the corrosion and scale inhibitors for oil and gas wells in Examples 1 - 5 and Comparative Examples 1 - 5. According to the SY / T5673 - 2020 standard, the scale inhibition rate (%) of the dilution solutions of the corrosion and scale inhibitors for oil and gas wells in Examples 1 - 5 and Comparative Examples 1 - 5 against calcium carbonate is detected respectively. The results are shown in Table 2 below.

[0053] Table 2: Data source Scale inhibition rate (%) Corrosion inhibition rate (%) Example 1 92.3 90.6 Example 2 90.8 89.5 Example 3 91.6 89.8 Example 4 88.7 87.9 Example 5 90.4 89.2 Comparative example 1 67.2 65.2 Comparative example 2 73.2 68.4 Comparative example 3 68.3 65.5 Comparative example 4 73.8 75.6 Comparative example 5 74.9 76.3 Result analysis

[0054] The following combines the data results in Table 1 and Table 2 to elaborate on this application in detail.

[0055] Referring to Table 1, the scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells in Examples 1-5 both reached over 90%. Among them, the scale inhibition rate of the corrosion and scale inhibitor for oil and gas wells in Example 1 reached 94.3%, and the corrosion inhibition rate reached 91.5%. Taking Example 1 as a reference, Comparative Examples 1-3 investigated the influence of the types of compounding materials in the corrosion and scale inhibitor for oil and gas wells on the scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells. The scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells in Example 1 were much higher than those of the scale inhibitors for oil and gas transportation in Comparative Examples 1-3. It shows that the compounding of imidazoline polyoxyethylene ether, heptadecenylamine ethyl imidazoline quaternary ammonium salt capsules, and organic phosphoric acid corrosion inhibitors has a synergistic effect in improving the scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells.

[0056] Taking Example 1 as a control, Comparative Examples 4 and 5 investigated the influence of the addition form of heptadecenylamine ethyl imidazoline quaternary ammonium salt in the corrosion and scale inhibitor for oil and gas wells on the scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells. The scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells in Example 1 were much higher than those of the scale inhibitors for oil and gas transportation in Comparative Examples 4 and 5. It shows that using sodium polyacrylate as the capsule wall for heptadecenylamine ethyl imidazoline quaternary ammonium salt is beneficial to improving the scale inhibition rate and corrosion inhibition rate of the corrosion and scale inhibitor for oil and gas wells. The analysis is that in the initial stage of adding the corrosion and scale inhibitor for oil and gas wells, part of the sodium polyacrylate dissolves in water, produces a synergistic effect with imidazoline polyoxyethylene ether to improve the dispersion effect of imidazoline polyoxyethylene ether, further improves the chelating ability of imidazoline polyoxyethylene ether and organic phosphoric acid corrosion inhibitors, the three produce a synergistic effect, achieving the effect of quickly inhibiting suspended scale in the initial stage of adding the corrosion and scale inhibitor for oil and gas wells, and accelerating the dispersion and adsorption efficiency of imidazoline polyoxyethylene ether on the sample. Under the comprehensive action, the scale inhibition rate and corrosion inhibition rate are improved.

[0057] Referring to Table 2, when the corrosion and scale inhibitor for simulated oil and gas wells is consumed, compared with the data in Table 1, the scale inhibition rate of the simulated corrosion and scale inhibitor for oil and gas transportation in Examples 1-5 decreased by 2%-3.2%, and the corrosion inhibition rate of the simulated corrosion and scale inhibitor for oil and gas transportation in Examples 1-5 decreased by 0.9%-2.2%. For the simulated corrosion and scale inhibitor for oil and gas transportation in Comparative Example 1, Comparative Example 4 and Comparative Example 5, the scale inhibition rate decreased by 8.3%-9.4%, and for the corrosion and scale inhibitor for oil and gas wells in Comparative Example 1, Comparative Example 4 and Comparative Example 5, the corrosion inhibition rate decreased by 3.9%-5.1%. This shows that adding heptadecenylamine ethyl imidazoline quaternary ammonium salt in the form of capsules to the corrosion and scale inhibitor for oil and gas wells is beneficial to improving the corrosion inhibition rate and scale inhibition rate after the well corrosion and scale inhibitor is consumed. The analysis is that the capsule wall of the quaternary ammonium salt corrosion inhibitor capsule isolates the quaternary ammonium salt corrosion inhibitor from the liquid, thus preventing the quaternary ammonium salt corrosion inhibitor from being consumed in advance by the sample. As time increases, the capsule wall made of the dispersant dissolves and gradually releases the quaternary ammonium salt corrosion inhibitor. On the one hand, its strong adsorption effect is beneficial to repairing the defects of the film formed by the imidazoline polyoxyethylene ether corrosion inhibitor on the pipeline surface, improving the corrosion inhibition effect and its long-term effectiveness; on the other hand, it inhibits the generation and aggregation of scale on the pipeline surface and improves the scale inhibition effect.

[0058] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively according to needs, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An inhibitor for corrosion and scale in oil and gas wells, characterized in that: It is obtained by compounding an imidazoline polyoxyethylene ether corrosion inhibitor, a quaternary ammonium salt corrosion inhibitor capsule, and an organic phosphoric acid corrosion inhibitor; the quaternary ammonium salt corrosion inhibitor capsule is prepared with a quaternary ammonium salt corrosion inhibitor as the core and a dispersant as the wall.

2. An anti-corrosion and scale inhibitor for oil and gas wells according to claim 1, characterized in that: It includes the following components in parts by weight: 20-40 parts of an imidazoline polyoxyethylene ether corrosion inhibitor, 10-20 parts of a quaternary ammonium salt corrosion inhibitor capsule, and 5-10 parts of an organic phosphoric acid corrosion inhibitor.

3. An anti-corrosion and scale inhibitor for oil and gas wells according to claim 1, characterized in that: The quaternary ammonium salt corrosion inhibitor includes one or more of benzoic acid imidazoline quaternary ammonium salt and its derivatives, and heptadecenylamine ethyl imidazoline quaternary ammonium salt and its derivatives.

4. An anti-corrosion and scale inhibitor for oil and gas wells according to claim 1, characterized in that: The dispersant includes one or both of sodium polyacrylate and polyacrylic acid.

5. An anti-corrosion and scale inhibitor for oil and gas wells according to claim 1, characterized in that: The imidazoline polyoxyethylene ether corrosion inhibitor includes one or more of imidazoline polyoxyethylene ether, oleic acid imidazoline polyoxyethylene ether, and rosin imidazoline polyoxyethylene ether.

6. A corrosion inhibitor and scale inhibitor for oil and gas wells according to claim 1, characterized in that: The organic phosphoric acid corrosion inhibitor includes one or more of hydroxyethylidene diphosphonic acid, amino trimethylene phosphonic acid, and ethylenediamine tetramethylene phosphonic acid.

7. The preparation method of an anti-corrosion and scale inhibitor for oil and gas wells according to any one of claims 1-6, characterized in that: It includes the following steps: Take the quaternary ammonium salt corrosion inhibitor and dissolve it in an organic solvent as the oil phase, take the dispersant and make it into an aqueous solution as the water phase, mix the oil phase and the water phase, adjust the pH of the water phase to 4, continuously stir for 0.5-1.5 h, centrifuge to collect the precipitate, wash and dry to obtain the quaternary ammonium salt corrosion inhibitor capsule; Mix the quaternary ammonium salt corrosion inhibitor capsule, the imidazoline polyoxyethylene ether corrosion inhibitor, and the quaternary organic phosphoric acid corrosion inhibitor to obtain the corrosion and scale inhibitor for oil and gas wells.

8. The preparation method of a corrosion inhibitor and scale inhibitor for oil and gas wells according to claim 7, characterized in that: The quaternary ammonium salt corrosion inhibitor is heptadecenylamine ethyl imidazoline quaternary ammonium salt, and the dispersant is sodium polyacrylate.

9. The preparation method of a corrosion inhibitor and scale inhibitor for oil and gas wells according to claim 8, characterized in that: The weight ratio of the heptadecenylamine ethyl imidazoline quaternary ammonium salt to the sodium polyacrylate is 1:1-2.

10. The preparation method of an anti-corrosion and scale inhibitor for oil and gas wells according to claim 7, characterized in that: A lipophilic nonionic dispersant with a mass fraction of 2% is added to the oil phase.