Biodegradation method for deoiling tailings from oil-based drill cuttings

Abstract

The present invention relates to the field of microbial treatment of oil-containing solid waste, and specifically to a biodegradation method and a degradation device for oil-based drill cuttings deoiling tailings. The test method is as follows: 1) configuring oil-based rock cuttings, 2) preparing degradation bacteria, 3) establishing a degradation system in a degradation device, 4) starting the experimental device, setting the degradation cycle to 60 days, taking samples, measuring the sample weight and the petroleum hydrocarbon concentration in the sample, and finally calculating the degradation rate. The experimental device mainly includes a degradation barrel, a stirring shaft is provided inside the degradation barrel, an aeration pipe is provided at the inner bottom and barrel wall of the degradation barrel, and a frame-type stirring paddle, a reinforced stirring paddle and a scraping stirring paddle are rigidly connected to the stirring shaft from top to bottom. Compared with the small-scale experimental method of a triangular flask, this method can realize stirring, degradation system temperature control, aeration and other functions through the device, thereby large-scale treatment of oil-based drill cuttings deoiling tailings, and efficient treatment of the remaining tailings after deoiling, which is economical, efficient and sustainable.

Description

Technical Field

[0001] The invention relates to the field of microbial treatment of oil-containing solid waste, and in particular to a biodegradation method for oil-based drill cuttings deoiling tailings. Background Art

[0002] Oil-based mud has the advantages of high temperature resistance, good lubricity, and little damage to oil and gas layers. It is widely used in shale gas drilling and production. However, a large amount of oil-based mud drilling cuttings will be generated in this process, including backwash oil, namely diesel, white oil, bio-oil, mineral oil, synthetic oil and various oilfield chemicals. It has the characteristics of abnormal stability of the system, complex types of pollutants, and high oil content. It is very difficult to handle and has been listed as a national hazardous waste (HW08). Shale gas is gas enclosed in underground shale formations. In the process of shale gas exploration and drilling, in order to obtain more shale gas, horizontal drilling is often used when drilling to the target layer - shale formation. In order to achieve fast and safe drilling in the horizontal layer and protect the oil and gas layer, oil-based mud is often used for drilling during the drilling process. Domestic oil-based mud is mainly made of diesel or white oil as the base oil and other additives. Broken underground rock formation cuttings adhere to the oil-based mud, thus producing oil-based drilling cuttings. A single well produces about 350 m³ of oil-based drill cuttings, and a platform well group (usually 5-7 single wells) will produce about 2000-2500 m³ of oil-based drill cuttings. The oil content of oil-based drill cuttings is 15-20%, which is highly harmful to the environment and difficult to handle.

[0003] The direct discharge of oil-based drill cuttings will have the following impacts on the environment: 1. Organic pollutants pollute surface water and groundwater resources; 2. Petroleum is toxic to plant growth, and long-term retention in the soil inhibits plant growth and soil microbial reproduction; 3. High concentrations of soluble salts will cause the surrounding soil to harden and reduce soil fertility; 4. Oil-based drill cuttings contain a large amount of heavy metal ions such as copper, lead, and chromium, which enter the soil and are absorbed by crops and eventually enter the human body through the food chain, endangering human health. Therefore, research on the treatment of oil-based drill cuttings has important practical significance.

[0004] At present, the methods for treating oil-based drill cuttings are mainly divided into physical treatment, chemical treatment and biodegradation. Among them, physical and chemical treatment technology is a relatively mature method widely used at home and abroad, but the above methods have great pollution risks to the environment, high energy consumption of equipment, high cost, serious secondary pollution and poor universality. The biodegradation method has the advantages of low treatment cost and no secondary pollution to the environment. It is considered to be the most economical and sustainable environmentally friendly technology and has been widely used.

[0005] Microbial degradation technology refers to the technology of degrading pollutants through various metabolic pathways of microorganisms under suitable environments. A large number of studies have shown that microbial degradation plays an important role in the natural degradation of petroleum hydrocarbon pollution. Adding bacteria or bacterial communities with strong environmental adaptability and high degradation efficiency to petroleum-contaminated water or soil is an important technical means to improve the efficiency of petroleum degradation. Microorganisms can degrade most saturated aliphatic hydrocarbons and aromatic hydrocarbons during aerobic metabolism. Aliphatic hydrocarbons are converted into fatty acids under the action of monooxygenases and dehydrogenases, while aromatic hydrocarbons are converted into dihydrodiols under the action of oxidases and hydrolases. Experimental results show that the invention patent with application number 201911067322.7 discloses a preparation method and application of a multi-source shale gas oil-based drill cuttings efficient degradation composite bacteria, and discloses a preparation method and application of a multi-source shale gas oil-based drill cuttings efficient degradation composite bacteria, the composite bacteria is a mixture of the culture solution of Rhodococcus baikonurensis, Rhodococcus pedocola and Dietzia maris WL-3 in a volume ratio of 1:1:1. The composite bacteria can degrade petroleum hydrocarbon pollutants in shale gas oil-based drill cuttings from multiple well sites without artificially adding carbon sources, and has a good degradation effect on oil-based drill cuttings with an oil content of less than 5%. It is an oil-resistant composite bacteria with good degradation performance for oil-based drill cuttings. Experiments have shown that this bacterial community plays a key role in the efficient degradation of multi-source shale gas and oil-based drill cuttings. Although the degradation conditions and degradation applications are explained, the degradation methods and equipment are not specifically explained.

[0006] Based on the above situation, we have developed a small device (the device can be seen in the invention patent with application number CN202311592449.7 and publication (announcement) number CN117619867A), using microbial degradation technology and an automatic speed control device to fully mix the oil-based drill cuttings with the degradation bacteria by controlling the speed and inclination angle, so as to determine the optimal degradation conditions. This combines experimental equipment with experimental methods to simulate the actual degradation environment, determine the influence of external and internal conditions on the degradation effect in the degradation experiment, and achieve the effect of efficiently treating the remaining tailings after deoiling to meet environmental protection requirements. After continuous experiments, this technology has significant effects, but the aforementioned experimental equipment can only provide small-scale experiments, which is not convenient for large-scale experiments, and the data provided is unstable, so it is necessary to continue to develop equipment that can process a large number of multi-source shale gas oil-based drill cuttings, and step by step promote this method to industrialization. Summary of the invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a biodegradation method for oil-based drill cuttings deoiling tailings. In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0008] The biodegradation method for oil-based drill cuttings deoiling tailings comprises the following steps:

[0009] 1) Configure oil-based cuttings

[0010] Adjusting the concentration of the oil-based rock cuttings to be degraded so that the oil content of the oil-based rock cuttings to be degraded is less than 2%;

[0011] 2) Prepare the degradation bacteria

[0012] The petroleum hydrocarbon-degrading bacteria Rhodococcus FL-1 ( Rhodococcus baikonurensis )、Rhodococcus NC-17( Rhodococcuspedocola )、Dietzia WL-3( Dietziamaris ) were cultured in LB medium until the logarithmic growth phase, collected and washed with inorganic salt medium, and the concentration of the bacterial solution was adjusted to OD 600 =1, mixing the degrading bacteria in an equal ratio of 1:1:1 to obtain a degrading bacterial population;

[0013] 3) Establish a degradation system

[0014] Prepare a degradation device, first add the culture medium, then add the oil-based rock chips to be degraded in step 1) and the degradation bacteria prepared in step 2) into the degradation device, the ratio of oil-based rock chips: degradation bacteria is 1:5, the solid-liquid ratio in the degradation device is maintained at 1:3-1:5, start the stirring shaft in the degradation device to stir the solid and liquid inside, and the stirring speed is 44 rpm;

[0015] During stirring, use the aeration pipe in the degradation tank to aerate the solid and liquid inside, and the aeration air intake is 67.5-135 liters / minute; at the same time, adjust the temperature in the degradation device during stirring, and keep the temperature between 25℃-30℃;

[0016] 4) After starting the experimental device, a degradation cycle was established, which was set at 60 days. During this period, the concentrations of inorganic N and P were measured, and nutrients were supplemented in time. Solid samples, liquid samples, and solid-liquid mixed samples were taken on the 0th, 10th, 20th, 30th, 40th, 50th, and 60th days, respectively. Three parallel samples were taken from each system, and a control group and a measurement group were set up. The control group was the sample on the 0th day, and the measurement group was the sample taken from the degradation system on the 10th day and above. The sample weight and the concentration of petroleum hydrocarbons in the sample were measured, and the degradation rate was finally calculated.

[0017] Further, the method for preparing the culture medium is to take 2g of potassium dihydrogen phosphate, 3g of disodium hydrogen phosphate, 0.7g of potassium chloride, 2g of potassium nitrate, 1.03g of magnesium sulfate heptahydrate, and 20g of sodium chloride, and dissolve them in 1000ml of distilled water. According to the experimental results of the optimal degradation conditions, adjust the pH to 8, add sodium chloride to a salinity of 1%, and add 0.5ml of trace elements. A total of 90-150L is prepared, and the MSM culture medium used to prepare the inoculant needs to be sterilized at 121℃ for 20min.

[0018] Furthermore, the determination of petroleum hydrocarbons and calculation of degradation rate are as follows: petroleum hydrocarbons in samples are determined by gas chromatograph, gas chromatography conditions are capillary columns, flame ionization detector is FID, injection port temperature is 300°C, detector temperature is 280°C, injection volume is 1ul, split ratio is 30:1, column temperature is initially 40°C, maintained for 2min; increased to 300°C at 15°C / min, maintained for 10min.

[0019] Furthermore, the petroleum hydrocarbons in the degradation system samples were measured to obtain peak area data, and the oil concentration in the samples was calculated based on the standard curve of petroleum hydrocarbon peak area and concentration. The degradation rate was calculated using the 0-day sample as a control, and the degradation rate was calculated according to the following formula:

[0020] Degradation rate % = (total peak area A 对照 -Total peak area A 样品 ) / total peak area A 对照 × 100%

[0021] Furthermore, the solid samples, liquid samples and solid-liquid mixed samples taken from the test group should be tested for petroleum hydrocarbon concentration at any time to form a comparison with the control group. The following preparations need to be made before the petroleum hydrocarbon concentration measurement:

[0022] First, add 10-20 ml of n-hexane to the solid sample, liquid sample and solid-liquid mixed sample, ultrasonicate for 3 minutes, and transfer to a separatory funnel; then add 10 ml of n-hexane to the conical flask to wash the conical flask and combine it into the separatory funnel, vigorously shake the separatory funnel for 3 minutes, let it stand for 10 minutes, drop the upper layer of n-hexane into a funnel filled with an appropriate amount of anhydrous sodium sulfate for filtration, evaporate the filtrate at 45°C using a rotary evaporator, then dissolve it with 5 ml of n-hexane, make the solution dilute to 5 ml, pass it through a 0.45 µm nylon filter, and then perform data measurement.

[0023] In order to better implement the above degradation method, we designed a device for this method. The specific structure is as follows:

[0024] The biodegradation device for oil-based drill cuttings deoiling tailings comprises a degradation barrel, a fixed cover and a movable cover are arranged on the top of the degradation barrel, a water outlet is arranged at the bottom of the degradation barrel, a stirring shaft is arranged inside the degradation barrel, aeration pipes are arranged at the bottom and barrel wall of the degradation barrel, the bottom aeration pipe is installed on the stirring shaft and rotates therewith, and the barrel wall aeration pipes are fixedly distributed on both sides of the barrel wall.

[0025] The frame-type stirring paddle, the enhanced stirring paddle and the scraper stirring paddle are rigidly connected to the stirring shaft from top to bottom. The aeration pipe is arranged between the enhanced stirring paddle and the frame-type stirring paddle. Two or more one-way valve aeration joints are arranged on the aeration pipe.

[0026] The stirring shaft is hollow and connected to the aeration pipe. The top of the stirring shaft extends out of the fixed cover. A compressed air heating refrigerator is arranged next to the degradation barrel. The compressed air heating refrigerator is connected to the top of the stirring shaft by a rotary joint and a pipeline.

[0027] Furthermore, the frame-type stirring paddle is rectangular, and crushing fins are installed in a forward and reverse cross manner in the rectangular frame.

[0028] Furthermore, a water bath jacket is provided on the outer periphery of the degradation barrel, and a constant temperature water bath test tank is provided next to the degradation barrel. The water bath jacket is connected to the constant temperature water bath test tank in a circulating water manner. A temperature sensor is provided inside the degradation barrel, and the temperature sensor is connected to the constant temperature water bath test tank through a relay.

[0029] Furthermore, a solid discharge port is provided at the bottom of the degradation barrel, wherein the scraping surface of the scraping stirring paddle fits in contact with the upper plane of the solid discharge port.

[0030] Furthermore, the water outlet is located higher than the scraper and agitator, and a variable liquid level height drain valve is connected to the water outlet.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: compared with the previous small-scale test method using a triangular flask, the degradation test method can realize stirring, temperature control of the degradation system, aeration and other functions through the device, and can process oil-based drill cuttings deoiling tailings on a large scale. The pilot test method and the experimental degradation device can process 30 kg of oil-based drill cuttings deoiling tailings at least once, thereby processing oil-based drill cuttings deoiling tailings on a large scale, and realizing efficient processing of the remaining tailings after deoiling, which is economical, efficient and sustainable. The results of this pilot test provide feasibility for the subsequent large-scale degradation of multi-source shale gas oil-based drill cuttings. This large-scale degradation method and equipment can provide a scientific basis for the research and development and application of microbial degradation technology, and make innovations for further industrial degradation of oil-based drill cuttings deoiling tailings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a main structural view of the experimental device of the present invention;

[0033] Figure 2 It is a schematic diagram of the three-dimensional structure of the experimental device of the present invention;

[0034] Figure 3 It is a three-dimensional structural schematic diagram of the internal structure of the degradation barrel of the experimental device of the present invention;

[0035] Figure 4 This is a three-dimensional structural diagram of the reinforced agitator paddle and the scraper agitator paddle.

[0036] 1. Degradation barrel; 11. Fixed cover; 12. Movable cover; 13. Solid discharge port; 14. Variable liquid level height drain valve; 2. Stirring shaft; 3. Aeration pipe; 30. One-way valve aeration joint; 4. Frame stirring paddle; 40. Crushing fin; 5. Strengthening stirring paddle; 6. Mud scraping stirring paddle; 61. Lower scraping plate; 62. Fin; 63. Upper scraping plate; 7. Compressed air heating refrigerator; 8. Constant temperature water bath test tank; DETAILED DESCRIPTION

[0037] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0038] The biodegradation method for oil-based drill cuttings deoiling tailings comprises the following steps:

[0039] 1) Configure oil-based cuttings,

[0040] Adjusting the concentration of the oil-based rock cuttings to be degraded so that the oil content of the oil-based rock cuttings to be degraded is less than 2%;

[0041] 2) Prepare the degradation bacteria

[0042] The petroleum hydrocarbon-degrading bacteria Rhodococcus FL-1 ( Rhodococcus baikonurensis , the deposit number is CCTCCNO: 2022454), Rhodococcus NC-17 ( Rhodococcus pedocola , deposit number is CCTCC NO: M 2022453), Dietzella WL-3 ( Dietzia maris , the deposit number is CCTCC NO: 2022455) in LB medium to the logarithmic growth phase, collected and washed with inorganic salt medium, and the concentration of the bacterial solution was adjusted to OD 600 =1, and the degrading bacteria were mixed in an equal ratio of 1:1:1 to obtain a degrading bacterial population.

[0043] LB liquid culture medium: 1 g of peptone, 0.5 g of yeast powder, 1 g of NaCl, dissolved in 100 ml of distilled water, and sterilized at 121°C for 20 min.

[0044] LB solid culture medium: 1 g of peptone, 0.5 g of yeast powder, 1 g of NaCl, 1.5 g of agar powder, dissolve in 100 ml of distilled water, sterilize at 121°C for 20 min, and pour into a plate.

[0045] Among them, the preparation method of inorganic salt culture medium is to take KH2PO4 (potassium dihydrogen phosphate) 2g, Na2HPO4 (disodium hydrogen phosphate) 3g, KCl (potassium chloride) 0.7g, KNO3 (potassium nitrate) 2g, MgSO4·7H2O (magnesium sulfate heptahydrate) 1.03g, NaCl (sodium chloride) 20g, dissolve in 1000ml distilled water, according to the experimental results of the best degradation conditions optimization, adjust its pH to 8, add NaCl to a salinity of 1%, and add 0.5ml of trace elements. A total of 90-150L is prepared, and the MSM culture medium used to prepare the bacterial agent needs to be sterilized at 121℃ for 20min;

[0046] The morphological diagrams of bacteria Rhodococcus FL-1, Rhodococcus NC-17, and Dietrichia WL-3 and the preparation method of the degradation bacterial community can be referred to the invention patent with patent application number 202310851248.8 (publication number CN 116948889 A).

[0047] 3) Establish a degradation system

[0048] Prepare a degradation device, first add the culture medium, then add the oil-based rock chips to be degraded in step 1) and the degradation bacteria prepared in step 2) into the degradation device, the ratio of oil-based rock chips: degradation bacteria is 1:5, the solid-liquid ratio in the degradation device is maintained at 1:3-1:5, start the stirring shaft in the degradation device to stir the solid and liquid inside, and the stirring speed is 44 rpm;

[0049] During stirring, use the aeration pipe in the degradation tank to aerate the solid and liquid inside, and the aeration air intake is 67.5-135 liters / minute; at the same time, adjust the temperature in the degradation device during stirring, and keep the temperature between 25±0.5℃;

[0050] 4) After starting the experimental device, a degradation cycle was established, which was set at 60 days. During this period, the concentrations of inorganic N and P were measured, and nutrients were replenished in time. Solid samples, liquid samples and solid-liquid mixed samples were taken on the 0th, 10th, 20th, 30th, 40th, 50th and 60th days, respectively. Three parallel samples were taken from each system, and a control group and a measurement group were set up. The control group was the sample on the 0th day, and the measurement group was the sample taken from the degradation system on days 10 and above. It should be noted that the water content of the solid samples taken was also measured at the same time.

[0051] The solid samples, liquid samples and solid-liquid mixed samples taken from the test group should be tested for petroleum hydrocarbon concentration at any time to form a comparison with the control group. The following preparations need to be made before the petroleum hydrocarbon concentration measurement:

[0052] First, add 10-20 ml of n-hexane to the solid sample, liquid sample and solid-liquid mixed sample, ultrasonicate for 3 minutes, and transfer to a separatory funnel; then add 10 ml of n-hexane to the conical flask to wash the conical flask and combine it into the separatory funnel, vigorously shake the separatory funnel for 3 minutes, let it stand for 10 minutes (if the upper and lower stratification is not obvious, centrifuge at 5000g for 1 minute), drop the upper layer of n-hexane into a funnel filled with an appropriate amount of anhydrous sodium sulfate and filter, evaporate the filtrate at 45°C using a rotary evaporator, then dissolve it with 5 ml of n-hexane, make the solution dilute to 5 ml, pass it through a 0.45 µm nylon filter, and then perform data measurement.

[0053] The weight of each sample taken out and the concentration of petroleum hydrocarbons in the sample are determined according to the above method, and the degradation rate is finally calculated.

[0054] The determination of petroleum hydrocarbons and calculation of degradation rate are as follows: petroleum hydrocarbons in samples are determined by gas chromatograph, the gas chromatographic conditions are capillary columns, flame ionization detector is FID, injection port temperature is 300°C, detector temperature is 280°C, injection volume is 1ul, split ratio is 30:1, column temperature is initially 40°C, maintained for 2min; increase to 300°C at 15°C / min, maintained for 10min.

[0055] The petroleum hydrocarbons in the degradation system samples were measured to obtain the peak area data, and the oil concentration in the samples was calculated based on the standard curve of the peak area and concentration of petroleum hydrocarbons. The degradation rate was calculated using the 0-day sample as a control, and the degradation rate was calculated according to the following formula:

[0056] Degradation rate % = (total peak area A 对照 -Total peak area A 样品 ) / total peak area A 对照 × 100%

[0057] Taking 30kg as an example, the petroleum hydrocarbon content of this batch of oil-based drill cuttings samples is 10.2%. In order to obtain a sample system with an oil content of about 3%, the current sample composition is 5kg of oil-based drill cuttings + 10kg of river sand.

[0058] like Figure 1 — Figure 4 As shown, the above experimental method requires a biodegradation device during the experiment, including a degradation barrel 1, a fixed cover 11 and a movable cover 12 are provided on the top of the degradation barrel 1, a stirring shaft 2 is provided inside the degradation barrel 1, and aeration pipes 3 are provided at the inner bottom and barrel wall of the degradation barrel 1. The bottom aeration pipe 3 is installed on the stirring shaft 2 and rotates therewith, and the barrel wall aeration pipes 3 are fixedly distributed on both sides of the barrel wall.

[0059] The frame-type stirring paddle 4, the enhanced stirring paddle 5 and the scraper stirring paddle 6 are rigidly connected to the stirring shaft 2 from top to bottom. The aeration pipe 3 at the bottom is arranged between the enhanced stirring paddle 5 and the frame-type stirring paddle 6. The enhanced stirring paddle 5 and the scraper stirring paddle 6 are installed in a cross shape. The frame-type stirring paddle 4 is rectangular in shape, and the crushing fins 40 are installed in a positive and negative cross manner in the rectangular frame. Figure 3 As shown, in a rectangular frame, four crushing fins 10 are installed, and the cross-section of the crushing fins 10 is in an arc shape. The four crushing fins 10 are inclined at different angles, so as to more thoroughly break up the oil-based drilling cuttings deoiling tailings when rotating, so that it can fully react with the microbial degradation substances, quickly and fully decompose the petroleum hydrocarbon content in the oil-based drilling cuttings deoiling tailings, reduce the pollution rate of the waste, and make the waste discharge more environmentally friendly. The enhanced stirring paddle 5 is in a Z shape, and a plurality of first fins 50 are arranged on its surface. The scraping stirring paddle 6 is mainly composed of a 7-shaped lower scraping plate 61, a second fin 62 and an upper scraping plate 63. The lower scraping plate 61 and the upper scraping plate 63 are installed in parallel, and the second fins 62 are multiple and evenly spaced between the lower scraping plate 61 and the upper scraping plate 63. When the liquid is discharged, the solid matter is left. The thickened scraping stirring paddle 6 can smoothly squeeze the solid matter out from the bottom of the barrel when facing the resistance of the solid matter.

[0060] Two or more one-way valve aeration joints 30 are arranged on the bottom aeration pipe and the aeration pipe on the barrel wall of the degradation barrel 1. Four one-way valve aeration joints 30 are arranged on one side of the bottom aeration pipe 3, and four or more one-way valve aeration joints can be arranged on the aeration pipe on the barrel wall, and the number can be appropriately increased according to the depth of the barrel.

[0061] The stirring shaft 2 is hollow and connected to the aeration pipe 3. The top of the stirring shaft 2 extends out of the fixed cover 11. A compressed air heating refrigerator 7 is provided next to the degradation barrel 1. The compressed air heating refrigerator 7 is connected to the top of the stirring shaft by a rotary joint and a pipeline.

[0062] The bottom aeration pipe of the degradation barrel 1 and the aeration pipe of the barrel wall are connected to the compressed air heating refrigerator 7 at the same time. Under the action of the compressed air heating refrigerator, the degradation barrel is aerated regularly and quantitatively. A water bath jacket is provided on the periphery of the degradation barrel, and a constant temperature water bath test tank 8 is provided next to the degradation barrel. The water bath jacket is connected to the constant temperature water bath test tank 8 in the form of circulating water. A temperature sensor is provided inside the degradation barrel, and the temperature sensor is connected to the constant temperature water bath test tank through a relay. The air discharged from the air compressor is heated by the heating refrigerator and enters the liquid in the barrel, which balances the temperature in the reaction environment and maintains the optimal degradation environment temperature.

[0063] In addition, in order to quickly discharge the remaining solids after the degradation is completed so as to facilitate the next microbial degradation reaction, a solid discharge port 13 is provided at the bottom of the degradation barrel 1, wherein the scraping surface of the scraper and agitator fits the upper plane of the solid discharge port. A water outlet is also provided at the lower part of the degradation barrel, the water outlet position is higher than the position of the scraper and agitator, and a variable liquid level height drain valve 14 is connected at the water outlet position, the liquid is discharged first, and then the solid matter is discharged, and the liquid can be recycled or discharged after environmental protection treatment again.

[0064] In order to prevent the stirring motor and aeration motor from overheating, the device can be automatically started and stopped through the control system when in use, and the continuous working time and intermittent time can be customized, such as the stirring time and the aeration time. Generally, the stirring intermittent time is half an hour, and the aeration intermittent time is half an hour. In order to keep the degradation system in an aerobic environment, the stirring and aeration are intermittent respectively. The control system can realize remote system modification. First, pour 30 kg of oil-based drill cuttings deoiled tailings on the top of the degradation barrel, and then pour the prepared culture solution and bacterial solution, close the flip cover, adjust the temperature of the constant temperature water bath experimental tank, so that the temperature in the degradation barrel is maintained between 25±0.5°C, with 25°C as the control temperature of this embodiment. After temperature control, stir again, turn on the compressed air heating refrigerator during stirring, and use the multiple one-way valve aeration joints inside to aerate, so that the internal microbial degradation reacts fully, and take samples according to the method in step 4) according to the reaction time, take the sample taken on day 0 (i.e., just mixed with the oil-based drill cuttings deoiled tailings and bacterial solution) as the control group, and calculate the petroleum hydrocarbon content of the taken samples respectively. The lower the petroleum hydrocarbon content, the more ideal the degradation system effect is.

[0065] The above is a detailed introduction to the biodegradation method for oil-based drill cuttings deoiling tailings provided by the present invention. The description of the specific embodiment is only used to help understand the method and its core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A biodegradation method for oil-based drill cuttings deoiling tailings, characterized in that: The following steps are involved: 1) Configure oil-based cuttings Adjusting the concentration of the oil-based rock cuttings to be degraded so that the oil content of the oil-based rock cuttings to be degraded is less than 2%; 2) Prepare the degradation bacteria Petroleum hydrocarbon-degrading bacteria Rhodococcus FL-1, Rhodococcus NC-17, and Dietzella WL-3 were cultured in LB medium until the logarithmic growth phase, collected and washed with inorganic salt medium, and the concentration of the bacterial solution was adjusted to OD 600 =1, mixing the degrading bacteria in an equal ratio of 1:1:1 to obtain a degrading bacterial population; 3) Establish a degradation system Prepare a degradation device, first add the culture medium, then add the oil-based rock chips to be degraded in step 1) and the degradation bacteria prepared in step 2) into the degradation device, the ratio of oil-based rock chips: degradation bacteria is 1:5, the solid-liquid ratio in the degradation device is maintained at 1:3-1:5, start the stirring shaft in the degradation device to stir the solid and liquid inside, and the stirring speed is 44 rpm; During stirring, the aeration pipe in the degradation tank is used to aerate the solid and liquid, and the aeration air intake is 67.5-135 liters / minute; at the same time, the temperature in the degradation device is adjusted during stirring, and the temperature is maintained at 25±0.5℃, and the stirring time and aeration time are intermittent, and the stirring interval time is half an hour, and the aeration interval time is half an hour; The degradation device described above comprises a degradation barrel, a fixed cover and a movable cover are arranged on the top of the degradation barrel, a water outlet is arranged at the bottom of the degradation barrel, a stirring shaft is arranged inside the degradation barrel, aeration pipes are arranged at the inner bottom and barrel wall of the degradation barrel, the bottom aeration pipe is installed on the stirring shaft and rotates therewith, the barrel wall aeration pipes are fixedly distributed on both sides of the barrel wall, and a frame stirring paddle, a strengthening stirring paddle and a mud scraping stirring paddle are rigidly connected to the stirring shaft from top to bottom, the strengthening stirring paddle and the mud scraping stirring paddle are installed in a cross shape, the frame stirring paddle is rectangular in shape, and crushing fins are installed in a positive and negative cross in the rectangular frame, and four crushing fins are installed in a rectangular frame, the cross section of the crushing fin is arc-shaped, and the inclination angles of the four crushing fins are different. The enhanced stirring paddle is in a Z-shape, and a plurality of first fins are arranged on its surface. The scraper and agitator paddle is mainly composed of a 7-shaped lower scraper plate, a second fin and an upper scraper plate. The lower scraper plate and the upper scraper plate are installed in parallel. The second fins are multiple and are arranged at equal intervals between the lower scraper plate and the upper scraper plate. The aeration pipe is arranged between the enhanced stirring blade and the frame stirring blade, and two or more one-way valve aeration joints are arranged on the aeration pipe. The frame stirring blade is rectangular in shape, and the crushing fins are installed in a positive and negative cross manner in the rectangular frame; The stirring shaft is hollow and connected to the aeration pipe. The top of the stirring shaft extends out of the fixed cover. A compressed air heating refrigerator is provided next to the degradation barrel. The compressed air heating refrigerator is connected to the top of the stirring shaft via a rotary joint and a pipeline. A water bath jacket is arranged on the periphery of the degradation barrel, and a constant temperature water bath test tank is arranged next to the degradation barrel. The water bath jacket is connected to the constant temperature water bath test tank in a circulating water manner. A temperature sensor is arranged inside the degradation barrel, and the temperature sensor is connected to the constant temperature water bath test tank through a relay. 4) After starting the experimental device, a degradation cycle was established, which was set at 60 days. During this period, the concentrations of inorganic N and P were measured, and nutrients were supplemented in time. Solid samples, liquid samples, and solid-liquid mixed samples were taken on the 0th, 10th, 20th, 30th, 40th, 50th, and 60th days, respectively. Three parallel samples were taken from each system, and a control group and a measurement group were set up. The control group was the sample on the 0th day, and the measurement group was the sample taken from the degradation system on the 10th day and above. The sample weight and the concentration of petroleum hydrocarbons in the sample were measured, and the degradation rate was finally calculated.

2. The biodegradation method for oil-based drill cuttings deoiling tailings according to claim 1, characterized in that: Preparation method of culture medium: Take 2g of potassium dihydrogen phosphate, 3g of disodium hydrogen phosphate, 0.7g of potassium chloride, 2g of potassium nitrate, 1.03g of magnesium sulfate heptahydrate, and 20g of sodium chloride, dissolve them in 1000ml of distilled water, adjust the pH to 8 according to the experimental results of the best degradation conditions optimization, add sodium chloride to a salinity of 1%, add 0.5ml of trace elements, and prepare a total of 90-150L. The MSM culture medium used to prepare the bacterial agent needs to be sterilized at 121℃ for 20min.

3. The biodegradation method for oil-based drill cuttings deoiling tailings according to claim 1, characterized in that: The determination of petroleum hydrocarbons and calculation of degradation rate are as follows: petroleum hydrocarbons in samples are determined by gas chromatograph, the gas chromatographic conditions are capillary columns, flame ionization detector is FID, injection port temperature is 300°C, detector temperature is 280°C, injection volume is 1ul, split ratio is 30:1, column temperature is initially 40°C, maintained for 2min; increase to 300°C at 15°C / min, maintained for 10min.

4. The biodegradation method for oil-based drill cuttings deoiling tailings according to claim 3, characterized in that: The petroleum hydrocarbons in the degradation system samples were measured to obtain the peak area data, and the oil concentration in the samples was calculated based on the standard curve of the peak area and concentration of petroleum hydrocarbons. The degradation rate was calculated using the 0-day sample as a control, and the degradation rate was calculated according to the following formula: Degradation rate % = (total peak area A 对照 -Total peak area A 样品 ) / total peak area A 对照 × 100%.

5. The biodegradation method for oil-based drill cuttings deoiling tailings according to claim 1, characterized in that: The solid samples, liquid samples and solid-liquid mixed samples taken from the test group should be tested for petroleum hydrocarbon concentration at any time to form a comparison with the control group. The following preparations need to be made before the petroleum hydrocarbon concentration measurement: First, add 10-20 ml of n-hexane to the solid sample, liquid sample and solid-liquid mixed sample, ultrasonicate for 3 minutes, and transfer to a separatory funnel; then add 10 ml of n-hexane to the conical flask to wash the conical flask and combine it into the separatory funnel, vigorously shake the separatory funnel for 3 minutes, let it stand for 10 minutes, drop the upper layer of n-hexane into a funnel filled with an appropriate amount of anhydrous sodium sulfate for filtration, evaporate the filtrate at 45°C using a rotary evaporator, then dissolve it with 5 ml of n-hexane, make the solution dilute to 5 ml, pass it through a 0.45 µm nylon filter, and then perform data measurement.

6. The biodegradation method for oil-based drill cuttings deoiling tailings according to claim 1, characterized in that: A solid discharge port is arranged at the bottom of the degradation barrel, wherein the scraping surface of the scraping stirring paddle fits the upper plane of the solid discharge port.

7. The biodegradation method for oil-based drill cuttings deoiling tailings according to claim 6, characterized in that: The water outlet position is higher than the position of the scraper and agitator paddle, and a variable liquid level height drain valve is connected at the water outlet position.

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