Oilfield sewage treatment composite agent and preparation process thereof

Abstract

The invention discloses an oilfield sewage treatment composite agent which comprises the following components in percentage by mass: 25%-35% of imidazoline derivative, 15%-25% of organic amine, 20%-30% of organic phosphonic acid, 10%-15% of polyaspartic acid, 8%-12% of alkyl modified quaternary ammonium salt, 3%-7% of glutaraldehyde, 3%-5% of sodium sulfite and 2%-4% of sodium hydroxide. The invention further discloses a preparation process of the oil field sewage treatment composite agent. Through the synergistic effect of all the components of the composite agent, the corrosion rate is more effectively reduced, the scale inhibition rate is improved, bacteria are killed, dissolved oxygen is removed, the pH value is adjusted, it is ensured that sewage reaches the standard for treatment, meanwhile, the composite agent can adapt to the water quality characteristics of different oil field sewage, and a good treatment effect can be achieved on sewage with different mineralization degrees, pH values and bacterium contents.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and relates to an oilfield sewage treatment composite agent and a preparation process. BACKGROUND

[0002] Oilfield sewage is complex in composition and contains a large amount of minerals such as Ca²⁺, Mg²⁺, SO4²⁻ and Cl⁻, bacteria such as sulfate-reducing bacteria, saprophytic bacteria and iron bacteria, dissolved oxygen and organic pollutants. These components may corrode equipment and pipelines, cause perforation leakage, affect normal production of oilfields and bring safety hazards. Meanwhile, mineral scale may block pipelines and equipment, reduce heat transfer efficiency, increase energy consumption and maintenance costs, and bacterial growth may also pollute the formation and reduce the oil recovery rate.

[0003] During the treatment of oilfield sewage, different functional agents are usually added. The existing agents are often not strong in specificity and are difficult to adapt to the complex changes of different oilfield sewage, and problems such as poor effect of corrosion inhibitors in high salinity sewage, limited inhibition effect of some scale inhibitors on specific scale and easy drug resistance of bactericides to bacteria may occur. SUMMARY

[0004] In view of the above problems, the application provides an oilfield sewage treatment composite agent and a preparation process, which solves the problems in the prior art.

[0005] In order to achieve the above purpose, the technical scheme adopted by the application is as follows: An oilfield sewage treatment composite agent, comprising 25-35% of imidazoline derivatives, 15-25% of organic amine, 20-30% of organic phosphonic acid, 10-15% of polyaspartic acid, 8-12% of alkyl-modified quaternary ammonium salt, 3-7% of glutaraldehyde, 3-5% of sodium sulfite and 2-4% of sodium hydroxide.

[0006] Optionally, the imidazoline derivative is one of alkyl imidazoline, dodecyl imidazoline, hexadecyl imidazoline and octadecyl imidazoline.

[0007] Optionally, the organic amine is one of diethylene triamine, triethylene tetramine, triethanolamine and ethylenediamine.

[0008] Optionally, the organic phosphonic acid is one of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylenediamine tetramethylene phosphonic acid sodium and 2-hydroxy phosphonic acid.

[0009] Optionally, the alkyl-modified quaternary ammonium salt is one of modified dodecyl dimethyl benzyl ammonium chloride, didodecyl dimethyl ammonium chloride, dioctadecyl dimethyl ammonium chloride and dodecyl dimethyl allyl ammonium chloride.

[0010] Optionally, the sodium hydroxide adjusts the pH value of the sewage to 7-8.

[0011] A preparation process, which is the preparation process of the oilfield sewage treatment composite agent described above, comprises: S1, proportionally adding imidazoline derivatives and organic amine into a first reaction kettle, stirring and reacting at 60-70 DEG C and 200-300 r / min for 2-3 h to obtain an inhibitor intermediate; S2, proportionally adding organic phosphonic acid and polyaspartic acid into a second reaction kettle, adding 0.5% of catalyst based on the total mass, and reacting at 80-90 DEG C for 4-5 h to obtain a scale inhibitor intermediate; S3, proportionally adding alkyl-modified quaternary ammonium salt and glutaraldehyde into a normal-temperature stirring kettle, stirring at 100-150 r / min for 1-2 h to obtain a bactericide; S4, proportionally adding sodium sulfite and sodium hydroxide into a pulverizer, and grinding to a particle size of less than 100 mesh; S5, proportionally adding the products in S1, S2, S3 and S4 into a mixing kettle, stirring and reacting at 40-50 DEG C and 300-400 r / min for 3-4 h to obtain the composite agent.

[0012] Optionally, the catalyst in S2 is ferrous sulfate.

[0013] Compared with the prior art, the present application has the following beneficial effects: through the synergistic effect between the components of the composite agent, the corrosion rate is more effectively reduced, the scale inhibition rate is improved, bacteria are killed, dissolved oxygen is removed, and the pH value is adjusted, so that the sewage can be treated to meet the standards, and meanwhile, the water quality characteristics of different oilfield sewage can be adapted to, and good treatment effects can be achieved on sewage with different mineralization, pH value and bacterial content. On the other hand, the use of the composite agent simplifies the oilfield sewage treatment process, reduces the cumbersome operation steps of adding multiple agents, and improves the treatment efficiency. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0015] The oilfield sewage treatment composite agent disclosed by the embodiment of the present application comprises 25-35% of imidazoline derivatives, 15-25% of organic amine, 20-30% of organic phosphonic acid, 10-15% of polyaspartic acid, 8-12% of alkyl modified quaternary ammonium salt, 3-7% of glutaraldehyde, 3-5% of sodium sulfite and 2-4% of sodium hydroxide.

[0016] Specifically, the imidazoline derivatives form a dense adsorption film on the surface of the metal, isolate the metal from the corrosion medium and inhibit the corrosion reaction; the imidazoline derivatives and the organic amine consume dissolved oxygen and reduce oxygen corrosion through synergistic effect, thereby further improving the corrosion inhibition effect; the organic phosphonic acid prevents scale salt from crystallizing and precipitating through chelation; the polyaspartic acid is adsorbed on the surface of scale crystals after precipitation to prevent the growth and deposition of the scale crystals; the alkyl modified quaternary ammonium salt is adsorbed on the surface of bacteria to destroy the cell membrane; the glutaraldehyde crosslinks bacterial proteins to denature and inactivate them; the alkyl modified quaternary ammonium salt and the glutaraldehyde are compounded to expand the bactericidal spectrum and improve the bactericidal effect; the sodium sulfite eliminates oxygen corrosion through a dissolved oxygen reaction; and the sodium hydroxide is used to adjust the pH of the sewage, improve the corrosion inhibition effect and improve the flocculation effect.

[0017] In this way, the corrosion rate is effectively reduced, the scale inhibition rate is improved, the bacteria are killed, the dissolved oxygen is removed and the pH value is adjusted through the synergistic effect of the components of the composite agent, so that the sewage can be treated to meet the standards, and the water quality characteristics of different oilfield sewages can be adapted to, and good treatment effects can be achieved for the sewage with different mineralization, acid-base value and bacterial content. On the other hand, the use of the composite agent simplifies the oilfield sewage treatment process, reduces the cumbersome operation steps of adding multiple agents and improves the treatment efficiency.

[0018] In some possible modes, the imidazoline derivatives are one of alkyl imidazoline, dodecyl imidazoline, hexadecyl imidazoline and octadecyl imidazoline; the organic amine is one of diethylene triamine, triethylene tetramine, triethanolamine and ethylenediamine; the organic phosphonic acid is one of hydroxyethylidene diphosphonic acid, amino trimethylene phosphonic acid, sodium ethylenediamine tetramethylene phosphonic acid and 2-hydroxy phosphonic acid; the alkyl modified quaternary ammonium salt is one of modified dodecyl dimethyl benzyl ammonium chloride, didodecyl dimethyl ammonium chloride, dioctadecyl dimethyl ammonium chloride and dodecyl dimethyl allyl ammonium chloride; and the pH of the sewage is adjusted to 7-8 by the sodium hydroxide.

[0019] In order to facilitate the preparation of the oilfield sewage treatment composite agent, the present application further discloses a preparation process, which comprises the following steps: S1, the imidazoline derivatives and the organic amine are added into a first reaction kettle in proportion, and stirred and reacted at 60-70 DEG C and 200-300 r / min for 2-3 h to obtain an inhibitor intermediate; S2, the organic phosphonic acid and polyaspartic acid are added into a second reaction kettle in proportion, 0.5% of the total mass of catalyst is added, and reaction is carried out at a temperature of 80-90℃ for 4-5h to obtain a scale inhibitor intermediate; S3, the alkyl modified quaternary ammonium salt and glutaraldehyde are added into a constant temperature stirring kettle in proportion, stirring is carried out at a speed of 100-150r / min for 1-2h to obtain a bactericide; S4, the sodium sulfite and sodium hydroxide are added into a pulverizer in proportion, and are ground to a particle size of less than 100 mesh; S5, the products in S1, S2, S3 and S4 are added into a mixing kettle in proportion, stirring is carried out at a temperature of 40-50℃ and a speed of 300-400r / min for 3-4h to obtain the composite agent.

[0020] The catalyst is ferrous sulfate.

[0021] In order to facilitate the display of the use effect of the oilfield sewage treatment composite agent, an experimental example is further disclosed in the embodiment: 1, experimental oilfield sewage: The oilfield sewage is randomly obtained, and the water quality indexes of the sewage are measured as follows: total mineralization 35000mg / L, Ca²⁺ content 1500mg / L, Mg²⁺ content 500mg / L, Cl⁻ content 18000mg / L, SO4²⁻ content 1200mg / L, pH value 6.0, dissolved oxygen content 3.5mg / L, sulfate reducing bacteria (SRB) content 10³ / mL, and saprophytic bacteria (TGB) content 10 4 ⁴ / mL.

[0022] 2, preparation of the composite agent: 2.1, 30g of alkyl imidazoline, 20g of diethylenetriamine, 25g of hydroxyethylidene diphosphonic acid, 12g of polyaspartic acid, 10g of modified dodecyl dimethyl benzyl ammonium chloride, 5g of glutaraldehyde, 4g of sodium sulfite, 4g of sodium hydroxide and 0.36g of ferrous sulfate catalyst are accurately weighed.

[0023] 2.2, the preparation is carried out according to the above preparation process, wherein the temperature of the first reaction kettle is 65℃, the stirring speed is 250r / min, and the reaction time is 2.5h; the reaction temperature of the second reaction kettle is 85℃, and the reaction time is 4.5h; the stirring speed of the constant temperature stirring kettle is 120r / min, and the stirring time is 1.5h; the temperature of the mixing kettle is controlled at 45℃, the stirring speed is 350r / min, and the mixing time is 3.5h.

[0024] 3, use of the composite agent: The composite agent is added into the oilfield sewage at a concentration of 50mg / L and 80mg / L respectively, and stirring and precipitation are carried out, and the treatment time is 24h.

[0025] 4. Set up a control group: 4.1 Single agent: Purchase commercially available imidazoline derivative corrosion inhibitors, organophosphonic acid scale inhibitors, alkyl modified quaternary ammonium salt bactericides, sodium sulfite and sodium hydroxide, and add them according to the recommended concentration in the instructions, and treat for 24 hours.

[0026] 4.2 Mixed Agents: Mix the individual agents from 4.1 according to their recommended concentrations to treat the wastewater in a manner that simulates traditional multi-agent treatment methods for 24 hours.

[0027] 5. Comparison of experimental data Treatment method Corrosion rate (mm / a) Calcium carbonate scale inhibition rate (%) SRB content (cells / mL) TGB content (cells / mL) Dissolved oxygen content (mg / L) pH value Example (composite agent 50 mg / L) 0.055 82 ＜10 ＜10 0.08 7.2 Example (composite agent 80 mg / L) 0.030 90 ＜10 ＜10 0.03 7.5 Single corrosion inhibitor treatment group 0.120 - - - - - Single scale inhibitor treatment group - 70 - - - - Single bactericide treatment group - - 50 100 - - Single oxygen scavenger treatment group - - - - 0.2 - Single pH regulator treatment group - - - - - 6.8 Multiple traditional agent mixed treatment group 0.080 75 20 30 0.15 7.0 The comparison of experimental data between the compound drug and the control group shows that: The corrosion rate of wastewater treated with the composite agent was significantly lower than that of the single corrosion inhibitor group and the mixed treatment group of multiple traditional agents, indicating that the corrosion-inhibiting components in the composite agent have a significant synergistic effect and can more effectively inhibit metal corrosion. The calcium carbonate scale inhibition rate of the composite agent was higher than that of the single scale inhibitor group and the mixed treatment group of multiple traditional agents. The composite agent could reduce the contents of SRB and TGB to lower levels, and its bactericidal effect was better than that of the single bactericide group and the mixed treatment group of multiple traditional agents, demonstrating a significant synergistic effect of the bactericidal components in the composite agent. The dissolved oxygen content after treatment with the composite agent was lower than that of the single oxygen scavenger group and the mixed treatment group of multiple traditional agents, indicating that the composite agent has a stronger deoxygenation capacity. The composite agent could stabilize and adjust the pH value of the wastewater to a more suitable range, and its effect was better than that of the single pH adjuster group and the mixed treatment group of multiple traditional agents.

[0028] To improve the effectiveness of the composite agent for oilfield wastewater treatment of this invention, this embodiment also discloses a method of use, wherein the composite agent is added at three locations: after the three-phase separator at a concentration of 50-80 mg / L, at the inlet of the settling tank at a concentration of 30-50 mg / L, and at the inlet of the external water injection tank at a concentration of 20-40 mg / L.

[0029] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite agent for treating oilfield wastewater, characterized in that, It includes 25%–35% imidazoline derivatives, 15%–25% organic amines, 20%–30% organic phosphonic acids, 10%–15% polyaspartic acid, 8%–12% alkyl-modified quaternary ammonium salts, 3%–7% glutaraldehyde, 3%–5% sodium sulfite, and 2%–4% sodium hydroxide.

2. The composite agent for oilfield wastewater treatment according to claim 1, characterized in that: The imidazoline derivative is one of alkylimidazoline, dodecylimidazoline, hexadecylimidazoline, and octadecylimidazoline.

3. The composite agent for oilfield wastewater treatment according to claim 1, characterized in that: The organic amine is one of diethylenetriamine, triethylenetetramine, triethanolamine, and ethylenediamine.

4. The composite agent for oilfield wastewater treatment according to claim 1, characterized in that: The organophosphonic acid is one of hydroxyethylidene diphosphonic acid, aminotrimethylphosphonic acid, sodium ethylenediaminetetramethylidene phosphonate, and 2-hydroxyphosphonoacetic acid.

5. The composite agent for oilfield wastewater treatment according to claim 1, characterized in that: The alkyl-modified quaternary ammonium salt is one of the following: modified dodecyl dimethyl benzyl ammonium chloride, bis(dodecyl dimethyl) ammonium chloride, bis(octadecyl dimethyl) ammonium chloride, and dodecyl dimethyl allyl ammonium chloride.

6. The composite agent for oilfield wastewater treatment according to claim 1, characterized in that: The sodium hydroxide is used to adjust the pH of the wastewater to 7-8.

7. A preparation process, characterized in that: The preparation process is the preparation process of the composite agent for oilfield wastewater treatment as described in claims 1-6, including: S1. Add imidazoline derivatives and organic amines to the first reaction vessel in proportion, and stir the reaction at 60-70℃ and 200-300r / min for 2-3 hours to obtain corrosion inhibitor intermediate; S2. Add organophosphonic acid and polyaspartic acid to the second reactor in proportion, add catalyst accounting for 0.5% of the total mass, and react at 80-90℃ for 4-5 hours to obtain scale inhibitor intermediate; S3. Add alkyl-modified quaternary ammonium salt and glutaraldehyde to a stirred tank at room temperature in proportion, and stir at 100-150 r / min for 1-2 h to obtain a bactericide; S4. Add sodium sulfite and sodium hydroxide in proportion and crush them until the particle size is less than 100 mesh. S5. Add the products from S1, S2, S3, and S4 to a mixing vessel in proportion, and stir the mixture at 40–50°C and 300–400 r / min for 3–4 hours to obtain the composite agent.

8. The preparation process according to claim 1, characterized in that: The catalyst in step S2 is ferrous sulfate.