Polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system

Abstract

The application discloses a polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system, which comprises destabilization, flocculation and degradation steps. The application can realize efficient removal of harmful substances in waste liquid through integrated destabilization-flocculation-degradation treatment, reaches the polar environment emission standard, and has the effects of less chemical waste liquid generated in the treatment process, smaller influence on environmental pollution, and the like. In the case of further biological degradation treatment by means of psychrophilic bacteria, efficient degradation can be realized in the polar low-temperature environment, the treatment efficiency is improved, and the application value is high. In practical application, the treatment method of the application can be applied to the treatment of polar drilling waste liquid, can effectively protect the polar ecological environment, and reduce environmental pollution. In addition, the treatment method of the application can also be applied to other similar waste liquid treatment, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of drilling technology in the oil and gas industry, and specifically relates to a polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system. BACKGROUND

[0002] With the continuous advancement of oil and gas exploration and development process, the oil and gas resources in the polar region will become a popular target for exploitation. Due to the influence of climate change, the glaciers in the polar region are melting, which means that the oil and gas resources that were previously covered by thick ice layers are now more easily exploited.

[0003] A large amount of drilling waste liquid will be generated during oil drilling operations, which contains various pollutants such as organic matter and heavy metals. If directly discharged into the environment, it will pollute the soil, groundwater and surface water, and cause irreversible damage to the environment and human health. Therefore, drilling waste liquid treatment has become an essential environmental protection work. Especially in the polar environment, the ecological environment is extremely fragile and cannot be repaired, so the operation must meet the requirements of harmless treatment, and the cost of waste transportation and treatment is very high, so the polar oil drilling waste liquid treatment has been facing many challenges and difficulties.

[0004] Currently, the treatment technology of oil drilling waste liquid mainly includes physical, chemical and biological methods. The physical method mainly separates the harmful substances in the waste liquid by means of precipitation, evaporation, etc., but this method has poor treatment effect. The chemical method mainly converts the harmful substances in the waste liquid into harmless substances by adding chemical agents such as flocculants and oxidizing agents, but this method will produce a large amount of chemical waste liquid, causing secondary pollution to the environment. The biological method mainly uses microorganisms to degrade the harmful substances in the waste liquid, which has the advantages of good treatment effect and environmental friendliness, but in the polar low-temperature environment, the growth of microorganisms is slow, the metabolic activity is limited, and the adaptability of microorganisms is high. Under the current technical conditions, physical, chemical and biological treatment each has certain disadvantages. SUMMARY

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0006] In view of the above, the existing technology has not formed a suitable oil drilling waste liquid treatment technology for the polar low-temperature environment, and the present application is proposed.

[0007] Therefore, the present application aims to overcome the deficiencies in the prior art of waste liquid treatment in the polar environment, and to provide a drilling waste liquid treatment technology suitable for the polar low-temperature environment.

[0008] To solve the above technical problems, the present application provides the following technical solutions: a drilling waste liquid destabilization-flocculation-degradation integrated treatment system in the polar low-temperature environment, which adds low-temperature resistant chemical agents polyvinyl alcohol acid salt and surfactant sodium dodecyl benzene sulfonate to the drilling waste liquid for destabilization treatment in the polar low-temperature environment, then adds polyaluminum chloride (PAC) and polyacrylamide (PAM) to form a mixed flocculant, performs flocculation and sedimentation, and finally screens and cultivates ice-loving bacteria groups that can effectively degrade the waste liquid in a low-temperature environment of-25℃ to achieve the final degradation treatment of the waste liquid to meet the polar ecological environment discharge standard.

[0009] As a preferred scheme of the drilling waste liquid destabilization-flocculation-degradation integrated treatment system, the addition amount of the chemical destabilizing agent and the surfactant includes,

[0010] The chemical destabilizing agent is polyvinyl alcohol acid salt and surfactant sodium dodecyl benzene sulfonate, which has low-temperature resistance and can effectively perform destabilization function in the polar low-temperature environment. The amount of the added chemical agent polyvinyl alcohol acid salt is 0.3%-1% of the total amount of the waste liquid, and the amount of the surfactant sodium dodecyl benzene sulfonate is 0.1-0.5% of the total volume of the waste liquid.

[0011] As a preferred scheme of the drilling waste liquid destabilization-flocculation-degradation integrated treatment system, the determination of the compounding ratio of the mixed flocculant includes,

[0012] The compounding ratio of PAC and PAM is 100:3, the PAC solution is configured at a concentration of 10%-20% and added at a dosage of 1-2 ml / L, and the PAM solution is configured at a concentration of 1-2‰ and added at a dosage of 1-2 ml / L.

[0013] As a preferred scheme of the drilling waste liquid destabilization-flocculation-degradation integrated treatment system, the screening of the ice-loving bacteria includes,

[0014] The ice-loving bacteria group is a bacterium that can grow in a low-temperature environment and can degrade harmful substances in the waste liquid. The screened strain AR-11 that can degrade harmful substances in the waste liquid belongs to the Arthrobacter genus. As a preferred scheme of the drilling waste liquid destabilization-flocculation-degradation integrated treatment system, the culture conditions and time of the screened degradation bacteria include,

[0015] The culture time of the used degradation strain is 7-14 days, and the culture temperature of the degradation strain is-25~-30℃.

[0016] As a preferred scheme of the polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system, the waste liquid degradation effect of the bacteria includes,

[0017] The cultured degradation bacteria are added to the waste liquid after destabilization-flocculation treatment in the polar low-temperature environment, and the organic matter degradation rate in the waste liquid reaches 85%-95% after a period of time.

[0018] As a preferred scheme of the polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system, the waste liquid degradation effect of the bacteria includes,

[0019] After the waste liquid is treated by destabilization, flocculation and degradation, it can be seen that the content of these harmful substances is obviously reduced by detecting the content changes of harmful substances such as COD, NH3-N, TP, TN and petroleum hydrocarbon in the waste liquid, and the COD concentration is reduced to below 80 mg / L, and the water quality indexes such as COD, SS, color and petroleum meet the polar ecological environment emission standard.

[0020] The present application has the following advantages:

[0021] (1) The present method takes the waste drilling fluid in the polar region as the research object, and considers the fragile ecological environment and low-temperature conditions in the polar region. Therefore, an integrated waste liquid degradation system is designed by physical, chemical and biological methods during the treatment of the drilling waste liquid, which efficiently and harmlessly treats the drilling waste liquid. In particular, low-temperature resistant agents and low-temperature resistant organic matter degradation bacteria are selected, and a high-efficiency waste liquid treatment system is formed based on biological degradation and chemical agents.

[0022] (2) The present application fully considers the low-temperature operating environment in the polar region, selects low-temperature resistant and good treatment effect chemical agents, and determines the optimal proportioning amount.

[0023] (3) The present method selects and cultivates bacteria strains that have the ability to degrade main pollutants in the drilling waste liquid and adapt to the polar low-temperature environment, forms a biological degradation method, and has good benefits such as good treatment effect and environmental friendliness.

[0024] (4) The present application can be followed by using online monitoring and automatic control technology to form an informationized monitoring and processing method for real-time monitoring and regulation of the treatment process by means of sensors, computers and other modern technologies, which can improve the accuracy, efficiency and reliability of the waste liquid treatment process, and is a very important technical means.

[0025] (5) The present application has good repeatability, simple operation and low economic cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings. Among them:

[0027] Figure 1 The schematic diagram of the treatment process of the present application is shown in the figure.

[0028] Figure 2 The schematic diagram of the Psychrobacter group AR-11 of the present application is shown in the figure.

[0029] Figure 3 The schematic diagram of the comparison of the settling effects of the mixed flocculant and the single flocculant of the present application is shown in the figure.

[0030] Figure 4 The schematic diagram of the changes of the COD, NH3-N, TP and TN contents of the waste liquid samples before and after the treatment of the present application is shown in the figure.

[0031] Figure 5 The influence of different pH on the COD content of the waste liquid DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail in the following with reference to the description of the embodiments.

[0033] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be practiced in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the scope of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0034] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or alternative embodiment that excludes other embodiments.

[0035] The waste liquid used in the embodiments of the present application is a simulated polar drilling formula drilling waste liquid.

[0036] Embodiment 1

[0037] The specific setting mode of the coagulation sedimentation-high level oxidation technology for treating the waste liquid is provided in the embodiment.

[0038] Coagulation-sedimentation-advanced oxidation technology (PAC-AOP) is an effective method for drilling waste liquid treatment, which can remove or convert organic matter and heavy metals in waste liquid into more stable forms. Among them, Fenton oxidation technology is a commonly used advanced oxidation technology, which can oxidize and decompose organic matter in waste liquid.

[0039] (1) Preliminary treatment: The drilling waste liquid is treated by standing and filtering to remove precipitates and suspended particles.

[0040] (2) Coagulation: The suspended solids and part of the dissolved solids in the waste liquid are coagulated by adding coagulant polyaluminum chloride (PAC) 1 g / L, so that larger particles are formed to facilitate subsequent sedimentation treatment. Under the condition of 1 g PAC and room temperature 20℃, the pH of the waste liquid is adjusted, and the COD content of the water quality is detected, and the results are shown in Figure 5

[0041] (3) Separation: The precipitate and clear liquid are separated, and the clear liquid can be treated subsequently, and the precipitate is treated in the next step.

[0042] (4) Advanced oxidation: The waste liquid after filtration is treated by adding Fenton reagent for oxidation and decomposition. Fenton reagent is composed of Fe 2+ and H2O2, which can oxidize and decompose organic matter in waste liquid into harmless substances such as CO2 and H2O. The dosage of Fenton reagent is Fe 2+ : H2O2 = 1:2, the Fenton oxidation reaction is carried out at room temperature 20℃, the reaction time is 1 hour, and the pH value of the reaction system is maintained in the range of 3-4.

[0043] (5) Neutralization treatment: The waste liquid after Fenton oxidation reaction has high acidity and needs to be treated. The neutralizing agent sodium hydroxide is used to adjust the pH to 7.0.

[0044] The waste liquid after neutralization can meet the discharge standard. But the effect is significantly affected by the dosage of reagent, temperature, pH and reaction time. Fenton oxidation method cannot be suitable for polar low temperature environment, and the solubility and flocculation effect of coagulant are significantly reduced in low temperature environment, and the treated water quality index cannot reach the treatment effect in normal environment.

[0045] Fenton oxidation treatment is a commonly used high-efficiency treatment process for drilling waste liquid, which is widely used and has significant effect. But in polar low temperature environment, the solubility and coagulation and sedimentation performance of coagulant are greatly reduced, and single flocculant has poor separation effect. In addition, the coagulation effect is also affected by the pH content and temperature of the waste liquid. The Fenton reagent reaction requires strict temperature and pH, which cannot effectively meet the polar drilling environmental conditions in polar environment, and it is difficult to adapt to low temperature environment. Although there are fewer by-products, it still does not meet the environmental protection requirements in polar environment. ​

[0046] Example 2

[0047] This embodiment provides a specific setup method for an integrated treatment system for drilling waste fluid destabilization-flocculation-degradation:

[0048] (1) Take 1L of the collected waste liquid sample for pretreatment. Filter to remove some large suspended particles and let it settle and remove them. Measure the water quality indicators such as total nitrogen, total phosphorus, COD, color and oil in the initial waste liquid to facilitate comparison of water quality before and after treatment.

[0049] (2) Add 0.3% of the total waste liquid as destabilizer polyvinyl alcohol and 0.1% of the total waste liquid as surfactant sodium dodecylbenzene sulfonate to the pre-treated waste liquid sample to separate the oil and water in the waste liquid and reduce the degree of mud formation in the waste liquid.

[0050] (3) Add 2 ml of 10% PAC solution and 1 ml of 3‰ PAM solution to the waste liquid from the previous step, and stir at 60 r / min for 30 minutes to form flocs and suspension. After the flocs settle, collect the supernatant for the next step of treatment. Observe and measure the water quality indicators of the treated supernatant. Visual observation shows that the treated supernatant changed from the original dark brown to reddish brown, the pH became 6.0, and the COD value decreased to 10296 ppm. The color and water quality were significantly improved, but the chemical oxygen demand still exceeded the standard and was not suitable for polar water quality discharge.

[0051] The data before and after the appropriate processing are as follows: Figure 3 As shown, by Figure 3 Therefore, the destabilization performed in this embodiment can effectively reduce the degree of sewage pollution.

[0052] Example 3

[0053] (1) Soil samples were collected from the surface (0–10 cm) and deep (10–30 cm) soil layers of the Arctic permafrost region using sterile tools at the location (in actual sampling, multiple locations and depths were sampled, with as many sampling sites as possible). The coordinates and depth of each sample were marked during collection. The collected soil samples were transferred to sterile containers, such as sterile test tubes or bottles. Ensure the containers were clean and free of residue. Non-sterile tools and materials were avoided during sample processing. Appropriate dilutions were made in prepared R2A medium. Typically, a suitable bacterial concentration was obtained through a dilution series (10⁻¹ to 10⁻⁶). The appropriately diluted sample was then inoculated onto the medium, either by spreading it evenly on the surface or by thorough mixing. The inoculated medium was placed in a freezer or incubator and cultured at -25°C. The medium and culture conditions were ensured to be suitable for the growth of ice-loving bacteria. After a certain period of culture (14 days), growth was observed on the medium. Ice-loving bacteria typically grow at low temperatures, thus requiring longer incubation times to assess growth. Once colonies form, individual colonies can be selected and isolated from the medium using a sterile bacterial loop or pipette. These individual colonies are then transferred to a fresh medium to obtain a pure culture of the ice-loving bacterial strain. Individual colonies can be selected from the sample and transferred to sterile medium under aseptic conditions using a pipette or needle. Finally, incubation at -25°C simulates the growth conditions of the ice-loving strain in its natural environment. The strain is then cultured for 14 days on a medium containing drilling wastewater.

[0054] (2) The selected strains with degradation capabilities were used for biodegradation treatment. The strains were cultured in a low-temperature environment. The criterion for judging biodegradation ability was: culture at -25℃. The degradation ability of the ice-loving strains was judged by measuring the concentration of organic matter in the waste liquid. Based on the experimental results, the optimal amount of strains and waste liquid to be added was determined. The strains that showed corresponding effects during the above isolation and purification were divided into equal portions according to the predetermined amount of purified strains to be added, and then mixed and added to the waste liquid for treatment.

[0055] (3) The treated wastewater was tested for water quality indicators such as COD, NH3-N, TP, and TN to evaluate the treatment effect of the wastewater treatment system. The data obtained are as follows: Figure 4 As shown.

[0056] Depend on Figure 4 As can be seen, the water purification method provided in Example 3 can significantly reduce the degree of water pollution. Based on indicators such as total sulfur and COD, it can reduce the pollution of the purified water in a full range, that is, it can treat polluted water by taking samples on-site in the polar environment.

[0057] Therefore, the polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system comprehensively uses physical, chemical and biological methods, and can efficiently remove harmful substances in the waste liquid through the treatment of multiple links of destabilization, flocculation and degradation, so as to meet the polar environment discharge standard, and the amount of chemical waste liquid generated in the treatment process is small, and the secondary pollution to the environment is small. Meanwhile, the polar drilling waste liquid destabilization-flocculation-degradation integrated treatment system uses psychrophilic bacteria for degradation treatment, can efficiently degrade in the polar low-temperature environment, improves the treatment efficiency, and has high practical application value.

[0058] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. An integrated treatment method for destabilization-flocculation-degradation of polar drilling wastewater, characterized in that: It comprises the following steps, In the polar low temperature environment, the drilling waste liquid is treated as follows: Destabilization: chemical destabilizing agent is put into the drilling waste liquid, and then surfactant is added and stirred uniformly, and then it is placed for a period of time; Flocculation: mixed flocculant is prepared, and then the placed drilling waste liquid is mixed with appropriate amount of flocculant, and then it is stirred uniformly, and then it is layered to form flocculating material and suspension, and then the flocculating material is removed, and then the suspended supernatant is collected for next step treatment; Degradation: in the low temperature environment, the suspended supernatant is degraded by psychrophilic bacteria, and then the physicochemical indexes of the waste liquid are reduced, including COD, NH3-N, TP and TN water quality indexes; In the degradation, the low temperature environment is-25℃ to-30℃ low temperature environment; In the destabilization, the chemical destabilizing agent is polyvinyl alcohol acid salt, and the surfactant is sodium dodecyl benzene sulfonate; The use amount of the chemical destabilizing agent is 0.3% of the total mass of the waste liquid, and the use amount of the surfactant is 0.1 to 0.5% of the total weight of the waste liquid; In the flocculation, the mixed flocculant comprises the following components according to weight: the ratio of PAC and PAM is 100:3, the PAC used for preparing the mixed flocculant is 10 to 20% PAC solution, the dosing amount is 1 to 2 mL, the PAM is 1 to 2‰ PAM solution, and the dosing amount is 1 to 2 mL; In the degradation, the strain of the psychrophilic bacteria is bacteria which can grow and reproduce in the low temperature environment, and it can reduce the harmful components and organic matters in the waste liquid.

2. The polar drilling waste fluid destabilization-flocculation-degradation integrated treatment method according to claim 1, characterized in that: After the degradation, the degradation rate of the organic matter in the waste liquid reaches 85 to 95%.

3. The polar drilling waste fluid destabilization-flocculation-degradation integrated treatment method according to claim 1, characterized in that: In the degradation, after the destabilization, flocculation and degradation treatment, the content of the harmful substances is measured, in which the COD concentration is reduced to below 80 mg / L, and the water quality indexes of COD, SS, color and petroleum reach the polar ecological environment discharge standard.

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