Composite sulfur removal agent and preparation method thereof

Abstract

The invention relates to the technical field of crude oil hydrogen sulfide treatment, in particular to a composite sulfur removal agent and a preparation method thereof.The composite sulfur removal agent is prepared from, by mass, 35-42 parts of monoethanolamine, 20-25 parts of paraformaldehyde, 3-5 parts of ethyl alcohol, 2-8 parts of efficient scale inhibitor, 2-8 parts of composite synergist, 2-8 parts of wetting dispersant and 6-12 parts of hydrogen peroxide. The composite sulfur removal agent is prepared by adopting a one-pot method, the raw materials are easy to obtain, the components have good compatibility, the reaction time is short, the permeability is good, and the content of hydrogen sulfide in the oil well produced liquid can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of crude oil hydrogen sulfide treatment, and relates to a composite desulfurizing agent and a preparation method thereof. Background Art

[0002] In recent years, the presence of hydrogen sulfide in the production and transportation of oil and gas wells will cause corrosion to oil pipes, casings, pumps, oil gathering pipelines and other equipment, resulting in huge economic losses. At the same time, the presence of hydrogen sulfide poses a huge safety hazard to construction workers. The leakage of hydrogen sulfide directly threatens the life and property safety of construction workers. The sources of hydrogen sulfide in oil and gas well production are: first, the sulfide in the formation is dissolved in the oil and gas and brought out of the ground with the oil and gas production; second, due to the presence of sulfate-reducing bacteria, SO4 in the produced fluid of the formation is converted into 2- Etc. 2- .

[0003] At present, the use of desulfurizers to desulfurize produced fluids from oil and gas wells is a widely used and effective technology in oil fields. Generally, different types of desulfurizers have different desulfurization mechanisms. Commonly used desulfurizers include organic amine desulfurizers, heterocyclic desulfurizers, and triazine desulfurizers. During the use of existing desulfurizers on site, they are limited by site conditions. The degree of mixing between the desulfurizer and the produced fluid determines the effect of the agent reaction. Triazine desulfurizers have no special irritating odor, low toxicity, react with hydrogen sulfide to form soluble compounds, and the desulfurization reaction does not change with changes in ambient temperature, etc. They have excellent desulfurization performance and are widely used. However, triazine desulfurizers are easily hydrolyzed in low concentration and low pH environments, the products are prone to scaling, and the effect of the agent is significantly reduced; when used in the annulus of the casing, the effects are different under different working conditions, and the mixing methods after adding the agent to the self-flowing well and the pumping well are not the same, and the final dosage and the effect of the agent are significantly different; when used in ground pipelines, they are restricted by the dosing conditions, the agent in the pipeline flows with the liquid, is not easy to mix evenly, the agent penetrates and diffuses slowly, the reaction time is long, and the desulfurization effect is not ideal. Summary of the invention

[0004] The present invention provides a composite desulfurizer and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of slow penetration and diffusion of the existing desulfurizers, long reaction time and poor desulfurization effect.

[0005] One of the technical solutions of the present invention is achieved through the following measures: a composite desulfurizer, the raw materials of which include, by mass, 35 to 42 parts of monoethanolamine, 20 to 25 parts of polyformaldehyde, 3 to 5 parts of ethanol, 2 to 8 parts of high-efficiency scale inhibitor, 2 to 8 parts of composite synergist, 2 to 8 parts of wetting dispersant, and 6 to 12 parts of hydrogen peroxide.

[0006] The following are further optimizations and / or improvements to the above technical solutions: The above-mentioned high-efficiency scale inhibitor is an organic phosphoric acid scale inhibitor, specifically aminotrimethylenephosphonic acid or hydroxyethylenediphosphonic acid.

[0007] The composite synergist is ammonium dodecylbenzenesulfonate.

[0008] The wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0009] The above composite desulfurizer is prepared by the following method: In the first step, after exhausting the air in the reactor, under vacuum conditions, a portion of monoethanolamine and a required amount of ethanol are added into the reactor, and stirred to mix evenly; The second step is to add a required amount of paraformaldehyde into the reaction kettle and react under the required conditions; In the third step, after the second step reaction is completed, the remaining amount of monoethanolamine is added to the reactor again; The fourth step is to add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence when the temperature of the reactor reaches the required temperature, stir and mix evenly, then add hydrogen peroxide to react, and after the reaction is completed, add the required amount of wetting dispersant, stir and mix evenly to obtain a composite desulfurizer.

[0010] In the first step, the amount of monoethanolamine added is 65% to 75% of the total amount.

[0011] In the above second step, the reaction conditions are reaction temperature of 50° C. to 55° C. and reaction time of 2 h to 4 h.

[0012] In the third step, after the second step reaction is completed, when the temperature of the reactor drops to 40° C. to 45° C., the remaining amount of monoethanolamine is added to the reactor again.

[0013] In the fourth step, when the temperature of the reactor reaches 30°C to 45°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, add hydrogen peroxide, react for 25min to 35min, add the required amount of wetting dispersant after the reaction is completed, stir and mix evenly to obtain a composite desulfurizer.

[0014] The second technical solution of the present invention is achieved by the following measures: A method for preparing a composite desulfurizer is carried out according to the following steps: In the first step, after exhausting the air in the reactor, under vacuum conditions, a portion of monoethanolamine and a required amount of ethanol are added into the reactor, and stirred to mix evenly; The second step is to add a required amount of paraformaldehyde into the reaction kettle and react under the required conditions; In the third step, after the second step reaction is completed, the remaining amount of monoethanolamine is added to the reactor again; The fourth step is to add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence when the temperature of the reactor reaches the required temperature, stir and mix evenly, then add hydrogen peroxide to react, and after the reaction is completed, add the required amount of wetting dispersant, stir and mix evenly to obtain a composite desulfurizer.

[0015] The composite desulfurizer of the invention is prepared by a one-pot method, the raw materials are easily available, the components have good compatibility, the reaction time is short, the permeability is good, and the hydrogen sulfide content in the oil well produced fluid can be effectively reduced. DETAILED DESCRIPTION

[0016] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is a hydrochloric acid aqueous solution; the normal temperature and room temperature in the present invention generally refer to a temperature of 15°C to 25°C, and are generally defined as 25°C.

[0017] The present invention will be further described below in conjunction with embodiments: Example 1: The raw materials of the composite desulfurizer include, by mass: 35 to 42 parts of monoethanolamine, 20 to 25 parts of paraformaldehyde, 3 to 5 parts of ethanol, 2 to 8 parts of high-efficiency scale inhibitor, 2 to 8 parts of composite synergist, 2 to 8 parts of wetting dispersant, and 6 to 12 parts of hydrogen peroxide.

[0018] Example 2: As an optimization of the above example, the high-efficiency scale inhibitor is an organic phosphoric acid scale inhibitor, specifically aminotrimethylenephosphonic acid or hydroxyethylenediphosphonic acid.

[0019] Example 3: As an optimization of the above example, the composite synergist is ammonium dodecylbenzene sulfonate. Ammonium dodecylbenzene sulfonate has strong neutralization ability, dispersion effect, corrosion inhibition effect, and oil removal effect. Embodiment 4: As an optimization of the above embodiment, the wetting and dispersing agent is dodecylbenzenesulfonic acid.

[0020] Example 5: As an optimization of the above example, the composite desulfurizer is prepared according to the following method: In the first step, after exhausting the air in the reactor, under vacuum conditions, a portion of monoethanolamine and a required amount of ethanol are added into the reactor, and stirred to mix evenly; The second step is to add a required amount of paraformaldehyde into the reaction kettle and react under the required conditions; In the third step, after the second step reaction is completed, the remaining amount of monoethanolamine is added to the reactor again; The fourth step is to add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence when the temperature of the reactor reaches the required temperature, stir and mix evenly, then add hydrogen peroxide to react, and after the reaction is completed, add the required amount of wetting dispersant, stir and mix evenly to obtain a composite desulfurizer.

[0021] Example 6: As an optimization of the above example, in the first step, the amount of monoethanolamine added is 65% to 75% of the total amount.

[0022] Example 7: As an optimization of the above example, in the second step, the reaction conditions are reaction temperature 50°C to 55°C, and reaction time 2h to 4h.

[0023] Example 8: As an optimization of the above example, in the third step, after the second step reaction is completed, when the reactor is cooled to 40°C to 45°C, the remaining amount of monoethanolamine is added to the reactor again.

[0024] Example 9: As an optimization of the above example, in the fourth step, when the temperature of the reactor reaches 30°C to 45°C, add the required amounts of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, add hydrogen peroxide, react for 25min to 35min, add the required amount of wetting dispersant after the reaction is completed, stir and mix evenly to obtain a composite desulfurizer.

[0025] The composite desulfurizer of the present invention is prepared by a one-pot method, wherein a preliminary desulfurizer is obtained by reacting monoethanolamine with polyformaldehyde, and then other reagents are added to obtain the composite desulfurizer. Among them, the monoethanolamine in the raw material has a hydroxyl group and an amino group, so that reactions unique to alcohols and amines can occur; polyformaldehyde has the characteristic of having a higher effective component than formaldehyde, and because it is a solid particle, it is more conducive to chemical synthesis such as chemical industry, pharmaceuticals and other industrial fields. The present invention mainly utilizes its desulfurization characteristics and the high purity of raw materials. The ethanol in the raw material is used for the depolymerization of polyformaldehyde, and can improve the permeability of the agent in the produced fluid and accelerate the reaction time of the agent; the high-efficiency scale inhibitor is an organic phosphoric acid scale inhibitor, which has a good integration and dispersion effect on calcium carbonate, calcium sulfate and the like in water, and can be used for the scale inhibition of formations and pipelines during oil production to prevent blockage of formations and pipelines caused by scaling. The composite synergist is ammonium dodecylbenzenesulfonate, and its acid-base balance can be used to increase the reaction rate. Wetting dispersants help the reagent components to disperse quickly in the oil phase or water phase, reverse the wetting, increase the reaction speed of desulfurization, and make the reaction more complete. In the fourth step of the preparation method, adding hydrogen peroxide can improve the product recovery rate, and hydrogen peroxide can also continue to react with unreacted formaldehyde to eliminate the residual formaldehyde of the synthesized desulfurizer. In addition, hydrogen peroxide can also play a certain bactericidal role, effectively inhibit sulfate-reducing bacteria, and reduce SO4 2- Etc. 2-The composite desulfurizer of the present invention can solve the problem of uneven mixing of reagents in the production process and can effectively shorten the desulfurization reaction time.

[0026] Example 10: The composite desulfurizer, the raw materials include by mass: 40 parts of monoethanolamine, 25 parts of paraformaldehyde, 4 parts of ethanol, 8 parts of high-efficiency scale inhibitor, 6 parts of composite synergist, 5 parts of wetting dispersant, 10 parts of hydrogen peroxide. In this embodiment, the high-efficiency scale inhibitor is aminotrimethylenephosphonic acid, the composite synergist is ammonium dodecylbenzenesulfonate, and the wetting dispersant is dodecylbenzenesulfonic acid.

[0027] The preparation process of the composite desulfurizer is as follows: In the first step, after purging with nitrogen to exhaust the air in the reactor, the reactor is dried, and under vacuum conditions, 70% of the required total amount of monoethanolamine and the required amount of ethanol are added to the reactor, and stirred to mix evenly; The second step is to slowly add the measured polyformaldehyde to the top of the kettle. The kettle temperature must not exceed 55°C. If the temperature rises too quickly, stop adding immediately. The temperature is controlled within 55°C and the measured polyformaldehyde is slowly added. After adding, the temperature is controlled between 50°C and 55°C and kept warm for 2 hours. The third step is to add the remaining amount of monoethanolamine into the reactor again when the reactor temperature drops to 45°C.

[0028] In the fourth step, when the temperature of the reactor reaches 40°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, add hydrogen peroxide, react for 30 minutes, add the required amount of wetting dispersant after the reaction is completed, stir and mix evenly to obtain a composite desulfurizer.

[0029] Example 11: The composite desulfurizer, the raw materials by mass include: 42 parts of monoethanolamine, 25 parts of paraformaldehyde, 3 parts of ethanol, 6 parts of high-efficiency scale inhibitor, 4 parts of composite synergist, 8 parts of wetting dispersant, 12 parts of hydrogen peroxide. In this embodiment, the high-efficiency scale inhibitor is hydroxyethylidene diphosphonic acid, the composite synergist is ammonium dodecylbenzene sulfonate, and the wetting dispersant is dodecylbenzene sulfonic acid.

[0030] The preparation process of the composite desulfurizer is as follows: In the first step, after purging with nitrogen to exhaust the air in the reactor, the reactor is dried, and under vacuum conditions, 70% of the required total amount of monoethanolamine and the required amount of ethanol are added to the reactor, and stirred to mix evenly; The second step is to slowly add the measured polyformaldehyde to the top of the kettle. The kettle temperature must not exceed 55°C. If the temperature rises too quickly, stop adding immediately. The temperature is controlled within 55°C and the measured polyformaldehyde is slowly added. After adding, the temperature is controlled between 50°C and 55°C and kept warm for 2.5 hours. The third step is to add the remaining amount of monoethanolamine into the reactor again when the reactor temperature drops to 45°C; In the fourth step, when the temperature of the reactor reaches 35°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, add hydrogen peroxide, react for 30 minutes, add the required amount of wetting dispersant after the reaction is completed, stir and mix evenly to obtain a composite desulfurizer.

[0031] Example 12: The composite desulfurizer, the raw materials include by mass: 35 parts of monoethanolamine, 20 parts of paraformaldehyde, 5 parts of ethanol, 8 parts of high-efficiency scale inhibitor, 8 parts of composite synergist, 8 parts of wetting dispersant, 12 parts of hydrogen peroxide. In this embodiment, the high-efficiency scale inhibitor is aminotrimethylenephosphonic acid, the composite synergist is ammonium dodecylbenzenesulfonate, and the wetting dispersant is dodecylbenzenesulfonic acid.

[0032] The preparation process of the composite desulfurizer is as follows: In the first step, after purging with nitrogen to exhaust the air in the reactor, the reactor is dried, and under vacuum conditions, 70% of the required total amount of monoethanolamine and the required amount of ethanol are added to the reactor, and stirred to mix evenly; The second step is to slowly add the measured polyformaldehyde to the top of the kettle. The kettle temperature must not exceed 55°C. If the temperature rises too quickly, stop adding immediately. The temperature is controlled within 55°C and the measured polyformaldehyde is slowly added. After adding, the temperature is controlled between 50°C and 55°C and kept warm for 2 hours. The third step is to add the remaining amount of monoethanolamine into the reactor again when the reactor temperature drops to 45°C; In the fourth step, when the temperature of the reactor reaches 35°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, add hydrogen peroxide, react for 30 minutes, add the required amount of wetting dispersant after the reaction is completed, stir and mix evenly to obtain a composite desulfurizer.

[0033] Example 13: The composite desulfurizer, the raw materials include by mass percentage: 38 parts of monoethanolamine, 25 parts of paraformaldehyde, 5 parts of ethanol, 8 parts of high-efficiency scale inhibitor, 8 parts of composite synergist, 5 parts of wetting dispersant, 10 parts of hydrogen peroxide. In this embodiment, the high-efficiency scale inhibitor is hydroxyethylidene diphosphonic acid, the composite synergist is ammonium dodecylbenzene sulfonate, and the wetting dispersant is dodecylbenzene sulfonic acid.

[0034] The preparation process of the composite desulfurizer is as follows: In the first step, after purging with nitrogen to exhaust the air in the reactor, the reactor is dried, and under vacuum conditions, 70% of the required total amount of monoethanolamine and the required amount of ethanol are added to the reactor, and stirred to mix evenly; The second step is to slowly add the measured polyformaldehyde to the top of the kettle. The kettle temperature must not exceed 55°C. If the temperature rises too quickly, stop adding immediately. The temperature is controlled within 55°C and the measured polyformaldehyde is slowly added. After adding, the temperature is controlled between 50°C and 55°C and kept warm for 3 hours. The third step is to add the remaining amount of monoethanolamine into the reactor again when the reactor temperature drops to 45°C; In the fourth step, when the temperature of the reactor reaches 35°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, add hydrogen peroxide, react for 30 minutes, add the required amount of wetting dispersant after the reaction is completed, stir and mix evenly to obtain a composite desulfurizer.

[0035] Comparative Example 1: On-site agent used in vehicle 510: commercially available organic amine desulfurizer.

[0036] Comparative Example 2: The reagent used on site in vehicle 89: a commercially available triazine desulfurizer.

[0037] Composite desulfurizer performance evaluation 1: The composite desulfurizer obtained in Example 10 to Example 13 and the desulfurizer of Comparative Examples 1 and 2 were used to carry out a desulfurization test on the sulfur-containing oil wells in Xinjiang Oilfield, and the residual hydrogen sulfide concentrations at 5min, 30min, 60min, and 90min of desulfurization were tested respectively. The experimental results are shown in Table 1. According to the technical indicators of "Q / SY XJ0294-2019 Technical Specifications for Hydrogen Sulfide Treatment Agents for Oil and Gas Gathering and Transportation", the composite desulfurizer obtained in Example 10 to Example 13 and Comparative Examples 1 and 2 were tested for soluble sulfide removal rate and sulfur dissolution technical indicators, and the test results are shown in Table 1. As can be seen from Table 1, the residual hydrogen sulfide concentration of the composite desulfurizer of the present invention at 30min and 60min of desulfurization is significantly lower than that of the on-site agent, indicating that the composite desulfurizer of the present invention has better permeability and diffusivity than the existing desulfurizer. The composite desulfurizer of the present invention has a higher hydrogen sulfide removal rate and higher sulfur dissolution than the desulfurizers of Comparative Examples 1 and 2, indicating that the composite desulfurizer of the present invention has an excellent desulfurization effect.

[0038] Composite desulfurizer performance evaluation 2: The desulfurization agent (triazine desulfurization agent) used on-site in the oil production operation area was compared with the composite desulfurization agent prepared in Example 10 of the present invention in terms of hydrogen sulfide removal rate.

[0039] Taking the sixth oil production area of ​​the first oil production plant of Karamay Oilfield as an example, the single-well concentration of hydrogen sulfide in the produced fluid can reach more than 1000ppm during the development of the oilfield, which restricts the crude oil production in this area to a certain extent. The composite desulfurizer prepared in Example 10 of the present invention was used for the experiment, and the desulfurizer used on site in the operation area was used as a reference. The concentration of hydrogen sulfide in the produced fluid was more than 1000ppm, and the produced fluid temperature was about 70°C.

[0040] Referring to the oil and gas industry standard of the People's Republic of China "Q / SY XJ0294-2019 Technical Specifications for Hydrogen Sulfide Treatment Agents for Oil and Gas Gathering and Transportation" and the new Ke'ao enterprise standard "Q / XKA 603-2021 Hydrogen Sulfide Treatment Agents for Oilfields", a desulfurization agent evaluation test was conducted on the produced fluid of the sixth oil production operation area of ​​Karamay Oil Production Plant No. 1 at a temperature of 70°C, and the experimental results are shown in Table 2. It can be seen from Table 2 that the composite desulfurizer prepared by the present invention has a better effect on removing hydrogen sulfide on the site of the sixth oil production operation area of ​​Karamay Oil Production Plant No. 1 than the desulfurizer used on site.

[0041] Composite desulfurizer quality test: Through the dual standard detection of "Q / SY XJ0294-2019 Technical Specifications for Hydrogen Sulfide Treatment Agents for Oil and Gas Gathering and Transportation" and "Q / XKA 603-2021 Hydrogen Sulfide Treatment Agents for Oil Fields", the composite desulfurizer product of the present invention has excellent performance, and the test indicators all meet the standard requirements. The pH value, density, hydrogen sulfide participation value, hydrogen sulfide removal rate, and sulfur capacity value detection indicators are shown in Table 3.

[0042] The composite desulfurizer prepared by the present invention has high desulfurization efficiency, low dosage, water-soluble products, good dispersibility, no corrosion and no scaling, and can be added to the oil pipeline at the same time to significantly remove H2S in the three phases of oil, gas and water in crude oil. The desulfurizer's high efficiency in absorbing H2S can effectively reduce the pollution caused to the environment, and has broad application prospects in the process of oil and gas field exploitation.

[0043] In summary, the composite desulfurizer of the present invention can effectively remove hydrogen sulfide in oil well produced fluid, has a short reaction time, good permeability, good compatibility with produced fluid, and can effectively reduce the hydrogen sulfide content in oil well produced fluid. The raw materials of the present invention are easily available and the components have good compatibility with each other, and the desulfurization effect is significant.

[0044] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A composite desulfurizer, characterized in that The raw materials include, by mass: 35 to 42 parts of monoethanolamine, 20 to 25 parts of paraformaldehyde, 3 to 5 parts of ethanol, 2 to 8 parts of high-efficiency scale inhibitor, 2 to 8 parts of composite synergist, 2 to 8 parts of wetting dispersant, and 6 to 12 parts of hydrogen peroxide.

2. The composite desulfurizer according to claim 1, characterized in that The high-efficiency scale inhibitor is an organic phosphoric acid scale inhibitor, specifically aminotrimethylenephosphonic acid or hydroxyethylenediphosphonic acid.

3. The composite desulfurizer according to claim 1 or 2, characterized in that The composite synergist is ammonium dodecylbenzenesulfonate.

4. The composite desulfurizer according to any one of claims 1 to 3, characterized in that The wetting and dispersing agent is dodecylbenzenesulfonic acid.

5. The composite desulfurizer according to any one of claims 1 to 4, characterized in that Prepared as follows: In the first step, after exhausting the air in the reactor, under vacuum conditions, a portion of monoethanolamine and a required amount of ethanol are added into the reactor, and stirred to mix evenly; The second step is to add a required amount of paraformaldehyde into the reaction kettle and react under the required conditions; In the third step, after the second step reaction is completed, the remaining amount of monoethanolamine is added to the reactor again; The fourth step is to add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence when the temperature of the reactor reaches the required temperature, stir and mix evenly, then add hydrogen peroxide to react, and after the reaction is completed, add the required amount of wetting dispersant, stir and mix evenly to obtain a composite desulfurizer.

6. The composite desulfurizer according to claim 5, characterized in that In the first step, monoethanolamine is added in an amount of 65% to 75% of the total amount.

7. The composite desulfurizer according to claim 5 or 6, characterized in that In the second step, the reaction conditions are reaction temperature of 50° C. to 55° C. and reaction time of 2 h to 4 h.

8. The composite desulfurizer according to any one of claims 5 to 7, characterized in that In the third step, after the second step reaction is completed, when the temperature of the reactor drops to 40° C. to 45° C., the remaining amount of monoethanolamine is added to the reactor again.

9. The composite desulfurizer according to any one of claims 5 to 8, characterized in that In the fourth step, when the temperature of the reactor reaches 30°C to 45°C, add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence, stir and mix evenly, then add hydrogen peroxide and react for 25min to 35min. After the reaction is completed, add the required amount of wetting dispersant, stir and mix evenly to obtain a composite desulfurizer.

10. A method for preparing the composite desulfurizer according to claim 1 or 2 or 3 or 4 or 6 or 7 or 8, characterized in that Follow these steps: In the first step, after exhausting the air in the reactor, under vacuum conditions, a portion of monoethanolamine and a required amount of ethanol are added into the reactor, and stirred to mix evenly; The second step is to add a required amount of paraformaldehyde into the reaction kettle and react under the required conditions; In the third step, after the second step reaction is completed, the remaining amount of monoethanolamine is added to the reactor again; The fourth step is to add the required amount of high-efficiency scale inhibitor and composite synergist to the reactor in sequence when the temperature of the reactor reaches the required temperature, stir and mix evenly, then add hydrogen peroxide to react, and after the reaction is completed, add the required amount of wetting dispersant, stir and mix evenly to obtain a composite desulfurizer.

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