Paraffin-inhibiting strain compound system for crude oil production and preparation method thereof

Abstract

The application discloses a paraffin-preventing strain compound system for crude oil production, which is composed of Campylobacter, Bacillus and a nutrient formula. The application also discloses a preparation method of the paraffin-preventing strain compound system, which comprises the following steps: 1, weighing each component according to the proportion of the nutrient formula, and mixing uniformly to obtain the nutrient formula; 2, carrying out moist heat sterilization on the nutrient formula to obtain a sterilized mixed solution; 3, cooling the sterilized mixed solution to normal temperature, inoculating the Campylobacter and the Bacillus to obtain a compound sterilized mixed solution; and 4, placing the compound sterilized mixed solution into a constant-temperature biochemical incubator to culture, and the paraffin-preventing strain compound system can be obtained. The paraffin-preventing strain compound system is regularly applied to the annulus of the casing of an oil well, can effectively prevent the deposition of paraffin between the sucker rod and the wellbore, is used for the subsequent microbial paraffin prevention after thermal paraffin removal, has a long action effect period of thermal paraffin removal, does not affect the production time and the oil well production, and meanwhile, the culture medium has low cost, and the paraffin-preventing functional bacteria cultivated are salt-tolerant and acid-alkali resistant.

Description

Technical Field

[0001] This invention belongs to the field of biopreparation technology and relates to a wax-resistant bacterial strain compound system for use in crude oil production. This invention also relates to a method for preparing such a wax-resistant bacterial strain compound system. Background Technology

[0002] Paraffin wax is an important component of crude oil. Under the original reservoir temperature and pressure conditions, it dissolves in the crude oil. During production, as crude oil flows from the depths of the reservoir to the bottom of the well, the pressure and temperature gradually decrease. When the pressure and temperature fall below the conditions for molten wax, it precipitates from the crude oil and becomes a solid, adhering to the surface of the well bottom, tubing, and sucker rod, thus hindering normal fluid flow. Solid petroleum wax also adheres to the well walls and sucker rods, reducing the efficiency of the pump and affecting production.

[0003] Traditional wax removal methods generally employ thermal and mechanical methods. Thermal wax removal (hot washing) is a method for removing wax from oil wells. It uses heat energy to raise the wellbore temperature above the wax melting point. At this point, the wax deposits on the pipes, well walls, and sucker rod surfaces melt and peel off from the metal surface, achieving the purpose of wax removal. However, hot washing requires shutting down the well, affecting production, and the effect is relatively short-lived. Mechanical wax removal (wax scraping) also requires production shutdown, which can also affect the production of wells intended for boosting production.

[0004] Therefore, effectively removing the effects of paraffin wax is the best way to ensure crude oil production while maintaining oil well production. Current technologies still cannot meet the needs of different reservoirs and crude oil types, and there is an urgent need for efficient paraffin removal technologies to solve similar problems. Summary of the Invention

[0005] The purpose of this invention is to provide a compound system of anti-wax bacteria for use in crude oil production, which solves the problems of short-term effect of thermal dewaxing in existing technologies, affecting production time and oil well production.

[0006] Another objective of this invention is to provide a method for preparing this anti-wax strain compound system.

[0007] The technical solution adopted in this invention is a compound system of anti-wax bacteria for crude oil production, which consists of Campylobacter, Bacillus, and a nutrient formula.

[0008] Another technical solution adopted in this invention is a method for preparing a wax-resistant bacterial strain compound system, which is implemented according to the following steps:

[0009] Step 1: Weigh each component according to the proportions of the nutritional formula, then mix them evenly to obtain the nutritional formula;

[0010] Step 2: Perform high-temperature moist heat sterilization on the nutrient formula obtained in Step 1 to obtain a sterilized mixture;

[0011] Step 3: Cool the sterilized mixture obtained in Step 2 to room temperature, and inoculate it with Campylobacter and Bacillus to obtain a compound sterilized mixture;

[0012] Step 4: Place the sterilized compound solution prepared in step 3 into a constant temperature biochemical incubator for incubation to obtain the anti-wax strain compound system.

[0013] The beneficial effects of this invention are as follows: The innovation lies in the fact that anti-wax measures can be implemented immediately after hot washing (i.e., microbial anti-wax treatment following thermal dewaxing). Applying the anti-wax strain compound system of this invention to the production process of oil wells (added periodically to the casing annulus every two weeks) can effectively prevent the deposition of petroleum wax in the wellbore, ensuring normal flow of reservoir fluids to the bottom of the well, enabling normal production without shutting down the well, and significantly improving crude oil recovery. Simultaneously, this anti-wax strain compound system also has the advantages of low cultivation cost and resistance to salt and acids / alkalis. Attached Figure Description

[0014] Figure 1 The curves showing the change in the degradation rate of waxy crude oil by the anti-wax strain compound system of the present invention with KB bacteria and A bacteria over time are shown.

[0015] Figure 2 This is the curve showing the change in the degradation rate of waxy crude oil over time when Bacterium A is combined with a biosurfactant.

[0016] Figure 3 These are the anti-wax rate curves of KB bacteria, A bacteria, and the blank comparative petroleum hydrocarbon degrading bacteria used in this invention.

[0017] Figure 4 The wax removal rate curves of KB bacteria, A bacteria and three comparative petroleum hydrocarbon degrading bacteria of the present invention are shown.

[0018] Figure 5 These are the four-component change curves of waxy crude oil before and after degradation by KB bacteria, A bacteria, and three control strains of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] The anti-wax strain compound system of the present invention consists of three parts: Campylobacter sp. (abbreviated as KB) and Bacillus sp. (abbreviated as A) and their nutrient formula.

[0021] The preservation information for Campylobacter is: 7#, China General Microbiological Culture Collection Center (CGMCC) No. 21652, January 18, 2021.

[0022] The preservation information for Bacillus is: 5#, China General Microbiological Culture Collection Center (CGMCC) No. 21651, January 18, 2021.

[0023] Nutritional formulas are further divided into major components and trace components (the base values ​​for each component below are based on the total mass of the nutritional formula):

[0024] The main components and their contents are as follows: yeast powder: 0.05-0.1 g / L; KH2PO4: 0.5-1 g / L; MgSO4·7H2O: 0.5-1 g / L; sodium chloride: 1.5-2 g / L; potassium nitrate: 2.0-3 g / L; (NH4)2SO4: 1 g / L; sucrose or glucose: 0.02-0.5% (m / v, mass fraction per unit volume).

[0025] The trace components and their contents are as follows: FeSO4·7H2O: 0.008~0.04g / L; CaCl2: 0.008~0.02g / L; ZnCl2: 0.009~0.05g / L; Na2MoO4: 0.05~0.8g / L.

[0026] The anti-wax strain compound system of the present invention is suitable for temperatures of 25-65℃, pH values ​​of 5-9, and mineralization of 150,000-180,000 mg / L or higher, and is particularly suitable for safe and stable production in oil and gas fields with high salinity extreme environments.

[0027] The principle behind the selection of components in the anti-wax bacterial strain compound system of this invention is as follows:

[0028] (1) The basis for choosing sucrose or glucose as a carbon source is:

[0029] Carbon sources are the main nutrients in microbial growth and metabolism media, and are important characteristics of microbial metabolism, growth, and reproduction, constituting a rather complex biochemical process. However, counting viable microorganisms is complex and time-consuming; therefore, the OD (Organic Demand) of the culture medium is used. 600 The cumulative number of microorganisms was represented. Table 1 clearly shows that sucrose and its anti-waxing effect are superior to corn steep liquor powder, while the effects of sucrose and wheat bran are similar. Moreover, subsequent experiments found that the action time and stability of wheat bran are better than those of sucrose. Although wheat bran is a good activator, it leaves some residue when used to cultivate microorganisms, so sucrose is the optimal choice.

[0030] Table 1. OD of different carbon sources 600 Value and wax removal rate

[0031] Types of carbon sources sucrose Corn liquor dry powder bran OD 600 ]] 0.999 0.978 0.926 Wax resistance rate (%) 65.3 26.4 60.8

[0032] *Amount added: 0.5% carbon source, 0.2% KNO3 nitrogen source, and 0.1% yeast powder phosphorus source.

[0033] (2) The basis for selecting KNO3 as a nitrogen source is:

[0034] Nitrogen is the third most abundant element in the dry matter of cells, after carbon and oxygen. Nitrogen is an essential element in the formation of nucleic acids and proteins, therefore, it plays a vital role in the growth and development of microorganisms.

[0035] Table 2 shows the screening of wax-resistant functional bacteria cultured using NaNO3, KNO3, NH4NO3, and peptone as nitrogen sources. It uses 1% sucrose as a uniform carbon source and 0.1% yeast extract as a phosphorus source, determining the wax-resistant rate and OD value after 7 days for different nitrogen sources. 600 The value of .

[0036] Table 2. Wax removal rate and OD of different types of nitrogen sources 600 value

[0037]

[0038]

[0039] *Amount added: 0.2% nitrogen source, 0.5% sucrose (carbon source), and 0.1% yeast powder (phosphorus source).

[0040] Table 2 shows that when NaNO3, KNO3, and NH4NO3 are used as nitrogen sources, except for peptone, NaNO3, KNO3, and NH4NO3 have higher wax removal rates. The wax removal rate of KNO3 is related to OD... 600 The optimal value is found in KNO3. This indicates that the cell concentration is highest when KNO3 is used as the nitrogen source, with an absorbance of 1.68. Compared to the other three nitrogen sources, peptone's gas production and cell concentration are not ideal. Therefore, considering all factors, NaNO3 was selected as the optimal nitrogen source for the activator.

[0041] (3) The basis for selecting yeast powder as a phosphorus source is:

[0042] All microorganisms (bacteria) require phosphorus, which is an important raw material for the synthesis of nucleic acids, phospholipids, some important coenzymes (NAD, NADP, CoA, etc.), and high-energy phosphate compounds. Intracellular phosphate also originates from phosphorus in nutrients. Phosphorus is generally artificially provided in the form of K₂HPO₄ and KH₂PO₄. In some oil reservoirs with high salinity (150,000-180,000 mg / L), special attention must be paid to preventing precipitation after adding a phosphorus source. Inorganic phosphorus sources easily form precipitates with ions in water; therefore, both organic and inorganic phosphorus sources were selected during the screening of phosphorus sources, and a control group with added ion chelating agents was also included.

[0043] Table 3. Wax-preventing rate and OD of different phosphorus sources 600 value

[0044]

[0045] *Addition amounts: 0.1% phosphorus source, 0.5% sucrose carbon source, and 0.2% KNO3 nitrogen source.

[0046] Different phosphorus sources result in different wax removal rates and OD. 600 The values ​​differ. Table 3 shows that when using organic phosphorus yeast powder as the phosphorus source, the wax removal rate and OD... 600 The values ​​of the two groups (KH₂PO₄ and NaH₂PO₄) all showed good wax removal rates, but the differences were not significant. However, in the group with added chelating agents, although precipitation was reduced, the wax removal rate and OD (Oxygen Demand) remained relatively low. 600 The results were all poor. It is speculated that EDTANa2 inhibited microbial growth, leading to the above experimental results. Considering all factors, yeast extract was chosen as the optimal phosphorus source for the activator.

[0047] The key innovation of the anti-wax strain compound system of this invention lies in providing a carbon source other than crude oil. This carbon source includes sucrose or glucose, which is beneficial for generating sugar-containing biosurfactants (rhamnose monoester or rhamnose diester), thereby improving the emulsifying properties of crude oil. Furthermore, the use of crude oil as the main carbon source in the nutrient formulation provides abundant carbon, nitrogen, and phosphorus sources for the growth of the strains, as well as suitable pH and salinity. Compared to other commonly used culture media, the above-mentioned culture medium is beneficial for further improving the biological activity of the strains. Applying the anti-wax strain compound system of this invention to the field of oil and gas field development is suitable for oil wells in different types of reservoirs produced by pumping. It prevents paraffin precipitation caused by temperature drops when reservoir fluids flow into the well bottom, thus affecting normal oil well production. It can significantly improve the anti-wax rate during production, extend the oil well dewaxing cycle, reduce dewaxing costs, and improve production efficiency.

[0048] The preparation method of the anti-wax strain compound system of the present invention is carried out according to the following steps:

[0049] Step 1: Weigh each component according to the proportions of the nutritional formula, then mix them evenly to obtain the nutritional formula;

[0050] Step 2: Perform high-temperature moist heat sterilization on the nutrient formula obtained in Step 1 (process parameters are temperature 121℃, holding time 30mins) to obtain sterilized mixture;

[0051] Step 3: Cool the sterilized mixture obtained in Step 2 to room temperature, and inoculate it with Campylobacter and Bacillus to obtain a compound sterilized mixture;

[0052] Step 4: Place the inoculated compound sterilized mixture from Step 3 into a constant temperature biochemical incubator for incubation (process parameters are incubation temperature 37℃, incubation time 48h) to obtain the anti-wax strain compound system.

[0053] The wax-preventing evaluation of the wax-preventing bacterial strain compound system of this invention includes the following three aspects:

[0054] I. Wax Resistance Evaluation Experiment Procedure

[0055] 1. Using A3 steel sheets to simulate the surface of oil well casing and sucker rod, a static method was used to allow the A3 steel sheets to form a biofilm in a wax-resistant bacterial strain compound system. The concentration of the biofilm was measured to determine its growth on the metal surface. The specific process is as follows:

[0056] 1.1 Prepare paraffin (use 62# paraffin, the main components of which are C18-C30 straight-chain alkanes, containing a small amount of alkanes with side chains and cycloalkanes), incubate with inorganic salts, dispense 0.5g of paraffin into multiple 150mL Erlenmeyer flasks, add 100mL of produced water from a certain oilfield to each flask, with a mineralization of 15000-18000mg / L, and sterilize.

[0057] 1.2 Prepare LB liquid culture medium, dispense 100 mL into 150 mL Erlenmeyer flasks, sterilize each flask, and inoculate with strains A and KB respectively at an inoculation amount of 1%. Incubate for 36 h in a shaker (working temperature 45℃, shaking speed 150 rpm).

[0058] 1.3. Inoculate the expanded bacterial culture into each paraffin inorganic salt medium with an inoculation amount of 5% and incubate for 5 days in a shaker (working temperature 45℃, shaking speed 150rpm).

[0059] 1.4 Add the sterilized A3 steel sheet to the completed paraffin inorganic salt culture medium and let it stand in a 45℃ incubator for 2 days to complete the preparation of the bacterial film.

[0060] 1.5. Prepare physiological saline solution and sterilize it. Place the A3 steel sheet with the bacterial membrane attached into 50 mL of physiological saline solution. Use a small brush to brush the bacterial membrane off into the physiological saline solution and measure the OD of the bacterial solution. 600 Numerical value.

[0061] 2. By simulating the wax formation process of crude oil, the anti-wax effect of the microbial strains was judged by comparing the blank A3 steel sheet with the A3 steel sheet after microbial action, based on the amount of wax formation. The comparison ratios of KB bacteria, A bacteria, and the blank were used. Figure 3 As shown, the specific process is as follows:

[0062] 2.1 Prepare LB liquid culture medium and dispense it into 150mL Erlenmeyer flasks, 100mL per flask. After sterilization, inoculate KB strain and strain A strain separately, with an inoculation amount of 1%. Incubate in a shaker (working temperature 45℃, shaking speed 150rpm) for 36h.

[0063] 2.2 Prepare the crude oil inorganic salt culture by dispensing 100 mL of the solution into 150 mL Erlenmeyer flasks. Add produced water from an oilfield with a salinity of 15000-18000 mg / L to each flask. After sterilization, inoculate with two strains of bacteria (control strains T6189 and N2) that have been cultured in amplified form, with an inoculation amount of 5%. Add an A3 steel plate. No bacteria are added to the blank group. Culture in a shaker (working temperature 45℃, shaking speed 150 rpm) for 3 days.

[0064] 2.3 After the culture is completed, take out the A3 steel sheet, rinse it with distilled water, dry it and weigh it. Put it into crude oil and lower the temperature from 50℃ to 20℃ within 1 hour. After standing for 30 minutes, take out the A3 steel sheet, wash off the crude oil on the surface with isopropanol, dry it and weigh it again. Calculate the amount of wax based on the mass difference of the A3 steel sheet before and after the treatment, and compare it with the blank group to obtain the wax prevention rate of different bacterial strains.

[0065] II. Four-component composition analysis of crude oil before and after microbial action

[0066] Referring to the People's Republic of China Petroleum and Chemical Industry Standard [NB / SH / T0509-2010] "Determination of Four Components of Petroleum Asphalt", and making appropriate adjustments based on the actual conditions of the laboratory, the specific process is as follows:

[0067] 1. Activation of alumina. Take 100g of neutral alumina with a mesh size of 100-200 and pour it into a porcelain evaporating dish. Place the dish together in a muffle furnace and calcine at 500℃ for 6 hours. Then cool it to room temperature in a desiccator without desiccant. Place it in a ground glass conical flask and add 1% (v% is volume percentage) of distilled water. Shake well and let it stand for 24 hours before use. It is valid for one week.

[0068] 2. Take 100 mg of oil sample and pour it into a No. 1 ground glass flask. Add 25 mL of n-heptane and dissolve the two evenly. Record the mass of the flask and the oil sample.

[0069] 3. Connect the No. 1 ground glass flask to the condenser, heat under reflux for 0.5 hours, cool to room temperature, remove the No. 1 ground glass flask, stopper it, and let it settle in a dark place for 1 hour.

[0070] 4. After sedimentation, slowly filter out the insoluble matter, and wash the No. 1 ground glass flask several times with n-heptane and filter. Store the filtrate in the No. 2 flask.

[0071] 5. Place the filter paper in the extractor and connect it to bottle No. 2. Heat and reflux until the dripping n-heptane is colorless. Cool to room temperature and concentrate to 1 mL for the next separation step.

[0072] 6. Add 50 mL of toluene to the ground glass flask (No. 1) and connect it to the extractor from step 5). Heat under reflux until the dripping toluene is colorless. After cooling to room temperature, evaporate the toluene in a fume hood and then dry to constant weight. Calculate the mass of asphaltene (m1-m) using the differential method. 瓶 .

[0073] 7. Connect the adsorption column to the circulating water and control the circulating water temperature to 50℃.

[0074] 8. Soak the activated alumina in n-heptane and stir appropriately to remove residual air.

[0075] 9. Place a small amount of degreased cotton at the bottom of the adsorption column and add a small amount of n-heptane. Then slowly add the alumina from step 8 to the adsorption column. Open the control valve to add n-heptane to remove excess n-heptane. Alumina should be added in small amounts multiple times to avoid bubbles and discontinuity. You can use a double ball to pressurize the column to make the alumina compact. The column height is about 15cm.

[0076] 10. After the column is packed, use a glass dropper to add the concentrated sample from vial No. 2 into the adsorption column, and wash the vial wall with n-heptane several times. Pour the washing solution into the adsorption column as well. After all the sample has entered the adsorption column, add a small amount of alumina to cover the sample layer.

[0077] 11. Add 10 mL of n-heptane to the adsorption column, collect the separated liquid and place it in an accurately weighed bottle No. 3 to obtain the saturated fraction.

[0078] 12. After the saturated fraction is separated, add 10 mL of toluene to the adsorption column to separate the aromatic fraction. Collect the separated liquid and place it in an accurately weighed bottle No. 4 to obtain the aromatic fraction.

[0079] 13. After the aromatic fraction is separated, add 5 mL each of toluene-ethanol (1:1) solution, toluene, and ethanol (95% mass concentration) to the adsorption column in sequence. Collect the separated liquid and place it in an accurately weighed bottle No. 5 to obtain the colloidal substance.

[0080] 14. Dry bottles No. 3, No. 4, and No. 5 in a fume hood. After drying to constant weight, accurately weigh each bottle (No. 3, No. 4, and No. 5). Calculate the saturated fraction, aromatic fraction, and gum fraction using the difference method, and record them as m2 (saturated fraction), m3 (aromatic fraction), and m4 (gum fraction), respectively. Calculate the mass percentage of each component.

[0081] III. The following five examples were used to analyze the four-component composition of crude oil before and after microbial action.

[0082] Example 1

[0083] Following the aforementioned preparation process, the anti-wax strain compound system of the present invention was prepared according to the proportions in Table 1 below (no trace components were used in the nutrient formula). The final tested anti-wax rate (%) was only 75.32%, which basically meets the product quality requirements in crude oil production.

[0084] Example 2 (as a control example)

[0085] When Campylobacter was used alone, prepared according to the proportions in Table 4 above and following the aforementioned preparation process, and then used for wax prevention in the wellbore of oil production, the final tested wax prevention rate (%) was only 56.41%, which could not meet the product quality requirements in crude oil production.

[0086] Example 3 (as a control example)

[0087] When Bacillus was used alone, and the formulation was prepared according to the proportions in Table 4 above and the preparation process described above, and then used for wax prevention in the wellbore of oil production, the final tested wax prevention rate (%) was only 70.28%, which barely met the product quality requirements in crude oil production.

[0088] Example 4 (as a control example)

[0089] Following the aforementioned preparation process, the wax-preventing bacterial strain compound system of the present invention (without using trace components) was prepared according to the proportions in Table 4 above. The final tested wax prevention rate (%) reached 76.76%. It is evident that using the wax-preventing bacterial strain compound system of the present invention for wellbore wax prevention in crude oil production essentially meets the product quality requirements in crude oil production.

[0090] Example 5

[0091] Following the aforementioned preparation process and referring to the proportions in Table 4 above, the anti-wax strain compound system of the present invention was prepared, and the final tested anti-wax rate reached a maximum of 90.34%. It is evident that using the anti-wax strain compound system of the present invention for wellbore anti-wax treatment in crude oil production fully meets the product quality requirements in crude oil production.

[0092] Table 4. Component content of the anti-wax strain compound system prepared in five examples

[0093] Example 1 Example 2 Example 3 Example 4 Example 5 Campylobacter 1.5 3 1.5 2.5 Bacillus 1.5 3 1.5 2.5 Yeast powder (g / L) 0.05 0.075 0.075 0.1 0.1 KH2PO4 (g / L) 0.5 0.5 0.5 0.5 0.5 MgSO4.7H2O (g / L) 0.5 0.5 0.5 Sodium chloride (g / L) 2 2 2 2 2 Potassium nitrate (g / L) 2 1.5 1.5 2 2 (NH4)2SO4(g / L) 1 1 1 1 1 Sucrose (m / v) 1.5 1 0.5 Glucose (m / v) 2 1.5 FeSO4-7H2O (g / L) 0.01 0.01 <![CDATA[CaCl2(g / L)]]> 0.01 0.01 <![CDATA[ZnCl2(g / L)]]> 0.01 0.01 <![CDATA[Na2MoO4(g / L)]]> 0.08 0.08 Wax resistance rate (%) 75.3 56.4 70.3 76.8 90.3

[0094] Reference Figure 1 and Figure 2Comparing Examples 1 and 2, it is evident that the combination of the two strains of the present invention provides a better anti-wax effect than using either strain alone, increasing the anti-wax rate by 18.9%. Comparing Examples 2 and 3, it was found that the trace components in the nutrient formula play a crucial role in the anti-wax effect; adding the trace components increased the anti-wax effect by 13.9%. As seen in Example 5, the present invention combines two strains and adds a nutrient formula (especially the trace components), achieving a maximum anti-wax rate of 90.3%.

[0095] The following tests were performed:

[0096] (1) Degradation experiment of dominant bacterial strains in high-content crude oil (>1000mg / L), the specific process is as follows:

[0097] With the addition of medium-wax crude oil (wax content between 10% and 20%), the crude oil removal rates of both strains and mixed bacteria (1:1), with an inoculation rate of 5%, all showed an increasing trend with increasing degradation time. Strain A exhibited the highest removal rate, reaching a maximum of 55.45%, while the removal rate of KB crude oil was only 48.49%. The highest removal rate of the mixed bacteria was 64.86%, indicating that the combined effect of the two mixed bacteria was superior to that of strain A alone.

[0098] (2) Degradation experiment of dominant bacterial strains in low-content crude oil (<1000mg / L), the specific process is as follows:

[0099] Figure 1 The curves showing the change in the degradation rate of waxy crude oil by the anti-wax strain compound system of the present invention with KB bacteria and A bacteria over time are shown. Figure 2 This is a curve showing the degradation rate of waxy crude oil over time when strain A is combined with a biosurfactant. With increasing degradation time, the crude oil removal rate of both strains showed a significant upward trend; strain A exhibited the highest removal rate, reaching a maximum of 79.98%, while the crude oil removal rate of strain KB was slightly lower than that of strain A. Based on strain A, the addition of a biosurfactant (rhamnolipin, dosage 100 mg / L) increased the hydrophilicity of the crude oil, making it easier for the petroleum hydrocarbon-degrading bacteria to utilize the crude oil, thus increasing the crude oil removal rate from 79.98% to 86.52%.

[0100] Figure 3 This compares the wax-preserving rates of KB bacteria with those of A bacteria, Blank bacteria, T6189, and N2 petroleum hydrocarbon-degrading bacteria. Figure 3 The aforementioned material uses A3 steel sheets to simulate the surface of oil well walls and sucker rods, and a static method is used to allow the steel sheets to form a film in the bacterial solution. Under this nutrient system, the wax prevention rates of KB bacteria and A bacteria are 86.6% and 80.9%, respectively.

[0101] Figure 4 The wax removal rate of KB bacteria, A bacteria, Blank, T6189, and N2 petroleum hydrocarbon degrading bacteria. Figure 4 This indicates that, under this nutrient system, KB bacteria and A bacteria significantly improved the wax removal rate, both reaching 51.8%, and exhibited the best emulsification effect.

[0102] Figure 5 This refers to the changes in four components of waxy crude oil before and after degradation by KB bacteria, A bacteria, the initial sample, T6189, and N2. Figure 5 It is evident that, compared to the initial crude oil sample, the relative content of saturated components decreased in the biodegraded crude oil, while the relative content of aromatic and non-hydrocarbon components increased, and the relative content of asphaltenes remained essentially unchanged. Bacterium A showed the largest decrease in the relative content of saturated components and the largest increase in the relative content of aromatic and non-hydrocarbon components, while Bacterium N2 showed the smallest decrease in the relative content of saturated components and the smallest increase in the relative content of aromatic and non-hydrocarbon components. Bacterium A exhibited the best biodegradation effect on crude oil, followed by Bacterium KB.

Claims

1. A compound system of anti-wax bacteria strains for use in crude oil production, characterized in that: Made from Campylobacter and Bacillus, along with a nutritional formula; Campylobacter 7#, preservation information: China General Microbiological Culture Collection Center (CGMCC) No. 21652, January 18, 2021; Bacillus subtilis #5, preservation information: China General Microbiological Culture Collection Center (CGMCC) No. 21651, January 18, 2021; Nutritional formulas are divided into major components and trace components. The base values ​​of the major components below are based on the total mass of the nutritional formula. The main components and their contents are as follows: yeast powder: 0.05~0.1g / L; KH2PO4: 0.5~1g / L; MgSO4·7H2O: 0.5~1g / L; sodium chloride: 1.5~2g / L; potassium nitrate: 2.0~3g / L; (NH4)2SO4: 1g / L; sucrose or glucose: 0.02~0.5%, in m / v. The components and their contents in the trace components are as follows: FeSO4·7H2O: 0.008~0.04 g / L; CaCl2: 0.008~0.02 g / L; ZnCl2: 0.009~0.05 g / L; Na2MoO4: 0.05~0.8 g / L.

2. A method for preparing the anti-wax-resistant bacterial strain compound system according to claim 1, characterized in that, Follow these steps: Step 1: Weigh each component according to the proportions of the nutritional formula, then mix them evenly to obtain the nutritional formula; Step 2: Perform moist heat sterilization on the nutrient formula obtained in Step 1 to obtain a sterilized mixture; Step 3: Cool the sterilized mixture obtained in Step 2 to room temperature, and inoculate it with Campylobacter and Bacillus to obtain the compound sterilized mixture; Step 4: Place the sterilized compound solution prepared in step 3 into a constant temperature biochemical incubator for incubation to obtain the anti-wax strain compound system.

3. The method for preparing the anti-wax-resistant bacterial strain compound system according to claim 2, characterized in that: In step 2, the process parameters are a temperature of 121℃ and a holding time of 30 mins.

4. The method for preparing the anti-wax-resistant bacterial strain compound system according to claim 2, characterized in that: In step 4, the process parameters are: culture temperature 37℃ and culture time 48h.

Images