Microbial oil-displacing active agent and preparation method thereof

Abstract

The invention discloses a microbial oil-displacing active agent and a preparation method thereof, and belongs to the technical field of microbial oil recovery. The microbial oil-displacing active agent comprises the following components in percentage by mass: 5-15% of functionalized xanthan gum, 15-25% of a microbial agent and the balance of water, through the synergistic effect of the functionalized xanthan gum and the microbial agent, the oil displacement effect of the microbial oil displacement active agent is remarkably improved, and the functionalized xanthan gum not only serves as a thickening agent and an oil displacement agent, but also provides a good carrier and protection effect for the microbial agent, so that the microbial agent can be more uniformly distributed in an oil reservoir, and the oil displacement efficiency of the microbial agent is improved; the microbial oil displacement technology is adopted, the problem that a traditional chemical oil displacement agent pollutes the environment is solved, good environment friendliness is achieved, the functionalized xanthan gum and the microbial agent both have good biodegradability and can be naturally degraded in the oil reservoir environment, long-term environmental pollution cannot be caused, and the requirement for environmental protection is met.

Description

Technical Field

[0001] The invention relates to the technical field of microbial oil recovery, and in particular to a microbial oil recovery active agent and a preparation method thereof. Background Art

[0002] With the increasing depletion of global oil resources and the increasing difficulty of oil field development, traditional chemical flooding technologies (such as polymer flooding and surfactant flooding) have faced significant bottlenecks. Chemical flooding agents generally have problems such as poor temperature and salt resistance, high environmental pollution risks, and high costs. They are especially prone to degradation and failure in high-temperature and high-salt reservoirs. Microbial oil recovery technology (MEOR) is a green and efficient alternative. Through the active substances such as biosurfactants, gases, and organic acids produced by microbial metabolism, it can effectively reduce the oil-water interfacial tension, improve crude oil fluidity, and dredge formation pores, thereby increasing the recovery rate.

[0003] However, existing microbial oil recovery agents still have the following technical defects:

[0004] Xanthan gum is not only a thickener and oil displacement agent, but also provides a good carrier and protection for microbial agents. However, it has poor shear resistance and temperature resistance, and is easily degraded in high temperature (>80°C) or high shear formations, resulting in viscosity loss and reduced displacement efficiency. The metabolic efficiency of bacteria in conventional culture media is low, the production of active substances is insufficient, and the bacteria have weak stress resistance, making it difficult to adapt to extreme reservoir environments.

[0005] Chinese patent document CN106701052A discloses a microorganism-chemical composite oil-displacing agent and its preparation method and application, which is compounded by the fermentation broth of Pseudomonas aeruginosa ATCC9027 and dimethyl fatty amide propyl ammonium toluene sulfonate surfactant. By compounding the fermentation broth of Pseudomonas aeruginosa ATCC9027 with a dimethyl fatty amide propyl ammonium toluene sulfonate surfactant, a microorganism-chemical composite oil-displacing agent is obtained, which combines the advantages of simple construction, clean and environmental protection of microorganisms and significant effects and stable performance of chemical surfactants in oil recovery, which is of great significance for the future exploitation of heavy oil. However, the surfactant used in the composite oil-displacing agent of the patent is a chemical surfactant, which has a high degree of environmental pollution, and it is generally poured into the ground when exploiting oil, thereby causing great harm to the local environment. Summary of the invention

[0006] The main purpose of the present invention is to propose a microbial oil recovery agent and a preparation method thereof, aiming to provide a green and environmentally friendly microbial oil recovery agent, while overcoming the problems of poor temperature and salt resistance and high environmental pollution risk of traditional chemical oil recovery agents, significantly improving oil recovery rate and reducing the impact on the environment.

[0007] To achieve the above object, the present invention provides a microbial oil displacement surfactant, which comprises the following components in mass percentage: 5-15% of functionalized xanthan gum, 15-25% of microbial inoculum, and the balance is water.

[0008] Preferably, the preparation method of the functionalized xanthan gum is as follows:

[0009] Using sodium periodate as an oxidant, reacting with xanthan gum in the dark to obtain pretreated xanthan gum; reacting the pretreated xanthan gum with oleylamine, and reacting the obtained product with thiolated boron nitride to obtain functionalized xanthan gum.

[0010] More preferably, the preparation method of the functionalized xanthan gum comprises the following steps:

[0011] (1) Disperse xanthan gum in deionized water, add sodium periodate, adjust the pH with hydrochloric acid aqueous solution, seal and react in the dark, then add ethylene glycol to terminate the reaction, centrifuge the reaction solution to collect the solid, and wash and dry the solid to obtain pretreated xanthan gum;

[0012] (2) Disperse the pretreated xanthan gum in N,N-dimethylformamide, add oleylamine, ultrasonically disperse and then adjust the pH to weakly acidic, heat and react, after the reaction is completed, cool, filter, wash and dry to obtain a solid product;

[0013] (3) Add the solid product to N,N-dimethylformamide, add a photoinitiator and mix evenly, then add thiolated boron nitride, carry out ultraviolet light irradiation reaction, after the reaction is completed, filter, collect the solid and wash and dry to obtain functionalized xanthan gum.

[0014] Preferably, in the step (1), the mass ratio of xanthan gum, sodium periodate and ethylene glycol is 5:2-8:1-2.

[0015] Preferably, in the step (2), the mass ratio of the pretreated xanthan gum to oleylamine is 1.5-2.5:1-1.2.

[0016] Preferably, in the step (3), the mass ratio of the solid product, photoinitiator and thiolated boron nitride is 3-4:0.1-0.5:2-3.

[0017] More preferably, the photoinitiator is at least one of 1-hydroxy-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and benzoin dimethyl ether.

[0018] As a displacement additive, xanthan gum has poor shear resistance and temperature resistance. During application, it will degrade due to mechanical and chemical actions, resulting in viscosity loss. Under high-temperature conditions, xanthan gum molecules are extremely sensitive to dissolved oxygen and can form hydrogen peroxide with dissolved oxygen. Hydrogen peroxide decomposes to produce free radicals and breaks down to produce free radicals, leading to the breakage of the entire chain. In the present invention, xanthan gum is modified. First, it is oxidized to improve its reactivity, and then oleylamine is grafted onto its surface to improve the dispersibility of xanthan gum in the reservoir. Then, by grafting mercapto-functionalized boron nitride, the shear resistance and heat resistance of xanthan gum can be improved. The modified xanthan gum has amphiphilicity and enhanced surface activity, which can significantly reduce the interfacial tension between oil and water, improve the fluidity of crude oil, promote the release of residual crude oil in the reservoir, and is beneficial to improving the displacement performance of the displacement agent. At the same time, the combination of the two-dimensional sheet structure of boron nitride and the xanthan gum molecular chain not only improves the mechanical strength of the functionalized xanthan gum but also restricts the slippage of the molecular chain through the formation of a cross-linked network, thereby significantly improving its shear resistance.

[0019] The preparation method of the microbial inoculum is as follows: Inoculate Bacillus subtilis into an activation medium for activation treatment to obtain an activated strain. Then, inoculate the activated strain into an enlarged medium and culture it for 40 - 48 h at a culture temperature of 25 - 32 °C and a humidity of 55 - 70% to obtain a seed liquid. Then, inoculate the seed liquid into a PDA medium at an inoculation amount of 2 - 5 wt%, ferment it at 25 - 30 °C for 25 - 30 h, adjust the pH of the fermentation broth to 6 - 7, concentrate the fermentation broth after fermentation to obtain a concentrated liquid, and freeze-dry the concentrated liquid to obtain a composite microbial inoculum.

[0020] Preferably, the composition of the activation medium is as follows: 2 - 5 wt% glucose, 5 - 10 wt% agar, 2 - 5 wt% peptone, 2 - 5 wt% beef extract, and the balance is water.

[0021] Preferably, the composition of the enlarged medium is as follows: 2 - 3 wt% yeast powder, 2 - 5 wt% glucose, 2 - 3 wt% peptone, 1 - 3 wt% sucrose, 0.1 - 0.5 wt% KH 2 H 3 PO 4 、0.1 - 0.5 wt% NaH 2 PO 4 、0.1 - 0.3 wt% Pleurotus eryngii extract, 0.01 - 0.1 wt% NaCl, and the balance is water.

[0022] Preferably, the preparation method of the Pleurotus eryngii extract is as follows:

[0023] Wash fresh Pleurotus eryngii and slice it into Pleurotus eryngii slices; dry the Pleurotus eryngii slices and then grind them to obtain Pleurotus eryngii powder; add the Pleurotus eryngii powder into a deep eutectic solvent, perform ultrasonic extraction, cool, centrifuge and filter to obtain filtrate 1 and filter residue; add the filter residue into an ethanol aqueous solution, add sodium lauroyl glutamate and vitamin E, heat and extract, after the extraction is completed, filter to collect filtrate 2, mix filtrate 1 and filtrate 2, and obtain the Pleurotus eryngii extract after evaporating the solvent under reduced pressure.

[0024] Further preferably, the deep eutectic solvent is obtained by reacting citric acid and tetrabutylammonium chloride; the mass ratio of citric acid to tetrabutylammonium chloride is 1:2 - 4.

[0025] Further preferably, the mass ratio of the filter residue, sodium lauroyl glutamate and vitamin E is 100:1 - 5:1 - 5.

[0026] In the present invention, by adding the Pleurotus eryngii extract to the microbial strain propagation medium, Pleurotus eryngii is rich in nutrients, including protein, bioactive peptides, carbohydrates, polysaccharides, vitamins and trace elements such as calcium, magnesium, copper, zinc, etc., which can participate in the metabolic regulation of the bacteria and promote better metabolism and proliferation of Bacillus subtilis. Through a specific extraction process for Pleurotus eryngii, the extraction rate of its nutritional components can be effectively improved, and its active components can be retained to the greatest extent, thereby providing better nutritional support for Bacillus subtilis. In addition, components such as bioactive peptides and polysaccharides in the Pleurotus eryngii extract can also enhance the stress resistance and environmental adaptability of the bacteria, further improving the stability and functionality of the microbial agent, and thus improving the oil displacement ability of the microbial agent.

[0027] The present invention also provides a preparation method of the microbial oil displacement surfactant, comprising the following steps:

[0028] Weigh each component according to the formula, and mix and stir evenly functionalized xanthan gum, microbial agent and water to obtain the microbial oil displacement surfactant.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1) The microbial oil displacement surfactant provided by the present invention significantly improves the oil displacement effect of the microbial oil displacement surfactant through the synergistic effect of functionalized xanthan gum and microbial agent. Functionalized xanthan gum not only acts as a thickening agent and oil displacement agent, but also provides a good carrier and protection for the microbial agent, enabling the microbial agent to be more evenly distributed in the oil reservoir and improving its oil displacement efficiency; the present invention adopts the microbial oil displacement technology, avoiding the environmental pollution problem caused by traditional chemical oil displacement agents, having good environmental protection. Both functionalized xanthan gum and microbial agent have good biodegradability, can be naturally degraded in the oil reservoir environment, and will not cause environmental pollution, meeting the requirements of environmental protection.

[0031] 2) The present invention extracts Pleurotus eryngii by using a eutectic solvent and ultrasonic extraction in combination, with good extraction effect. For the residual nutrients in the filter residue, sodium lauroyl glutamate and vitamin E are used for extraction, which can promote the full release of the active ingredients of Pleurotus eryngii extract in the residue, further improve the extraction efficiency, stimulate the metabolic potential of microorganisms, increase the yield of microbial metabolites, and thus enhance the microbial oil displacement effect;

[0032] 3) The preparation of the functionalized xanthan gum in the present invention is first to oxidize the xanthan gum rich in hydroxyl groups to improve its reactivity. Then, the oxidized xanthan gum can react with the amino group on oleylamine to graft the oleylamine with a hydrophobic long chain onto the xanthan gum to obtain oleylamine-grafted modified xanthan gum, which improves the hydrophobicity of xanthan gum and introduces carbon-carbon double bonds. Finally, the carbon-carbon double bonds on the oleylamine-grafted modified xanthan gum react with the well-thermally-stable nanocompound mercapto-functionalized boron nitride under ultraviolet light irradiation, and then the mercapto-functionalized boron nitride is grafted onto the xanthan gum, which improves the thermal stability of xanthan gum, increases the crude oil recovery rate of the microbial oil displacement surfactant, and makes it applicable to complex reservoir environments. Specific embodiments

[0033] To avoid repetition, the items used in the following examples are all commercially available products without special instructions, and the methods used are all conventional methods without special instructions.

[0034] The preparation method of the mercapto-functionalized boron nitride used in the examples of the present invention is as follows: Disperse 20 g of boron nitride in 200 mL of 50 wt% ethanol aqueous solution, add 1.5 g of (3-mercaptopropyl)trimethoxysilane, heat and react at 50 °C for 4 h, filter, and collect the solid, wash and dry to obtain mercapto-functionalized boron nitride.

[0035] Example 1

[0036] A preparation method of a microbial oil displacement surfactant includes the following steps:

[0037] Mix 100 g of functionalized xanthan gum, 200 g of microbial inoculum, and 700 g of water and stir evenly to obtain the microbial oil displacement surfactant.

[0038] The preparation method of the functionalized xanthan gum includes the following steps:

[0039] (1) Disperse 50 g of xanthan gum in deionized water, add 45 g of sodium periodate, adjust the pH to 5 with hydrochloric acid aqueous solution, seal and react in the dark at 30 °C for 10 h, then add 15.8 g of ethylene glycol to terminate the reaction, centrifuge the reaction solution to collect the solid, and wash and dry the solid to obtain pretreated xanthan gum;

[0040] (2) Disperse 40 g of pretreated xanthan gum in 200 mL of N,N-dimethylformamide, add 22 g of oleylamine, adjust the pH to 6 after ultrasonic dispersion, heat and react at 50 °C for 2 h, cool, filter, wash, and dry after the reaction to obtain a solid product;

[0041] (3) Add 36.4 g of the solid product to 200 mL of N,N-dimethylformamide, add 3.3 g of 1-hydroxy-cyclohexyl phenyl ketone and mix evenly, then add 24.7 g of mercapto-functionalized boron nitride, and carry out a UV irradiation reaction under a UV lamp with a power of 100 W for 10 min. After the reaction is completed, filter, collect the solid, wash, and dry to obtain functionalized xanthan gum.

[0042] The preparation method of the microbial inoculant is as follows: Inoculate Bacillus subtilis into an activation medium composed of 3 wt% glucose, 8 wt% agar, 3 wt% peptone, 3 wt% beef extract, and 83 wt% water, with an inoculation amount of 3 wt%, and culture at 25 °C, 130 rpm, under dark and aerobic conditions for 48 h for activation treatment to obtain activated strains; then inoculate the activated strains into an enlarged medium composed of 2 wt% yeast powder, 3 wt% glucose, 3 wt% peptone, 2 wt% sucrose, 0.3 wt% KH 2 H 3 PO 4 、0.3 wt% NaH 2 PO 4 、0.2 wt% Pleurotus eryngii extract, 0.05 wt% NaCl, and 89.15 wt% water, with an inoculation amount of 4 wt%, culture at 30 °C and a humidity of 70% for 48 h to obtain a seed liquid, then inoculate the seed liquid into a PDA medium at an inoculation amount of 3 wt%, ferment at 28 °C for 28 h, adjust the pH of the fermentation broth to 6, concentrate the fermentation broth to 1 / 4 of the original volume after fermentation is completed to obtain a concentrated liquid, use the dilution gradient method to detect the viable bacteria count in the concentrated liquid, and the viable bacteria count is 3.2×10 9 CFU / m; Freeze-dry the concentrated liquid to obtain the microbial inoculant.

[0043] The preparation method of the Pleurotus eryngii extract is as follows:

[0044] Select fresh Pleurotus eryngii, wash it clean, cut it into thin slices with a uniform thickness of 4 mm to make Pleurotus eryngii slices; dry the Pleurotus eryngii slices at 50 °C until the moisture content is 15%, then grind them and pass through an 80-mesh sieve to obtain Pleurotus eryngii powder; mix 100 g of choline chloride and 300 g of tetrabutylammonium chloride and stir at 80 °C for 4 hours to obtain a deep eutectic solvent. Add 50 g of Pleurotus eryngii powder to the deep eutectic solvent, carry out ultrasonic extraction for 30 min, cool, centrifuge and filter to obtain filtrate 1 and filter residue; add the filter residue to a 50 wt% ethanol aqueous solution according to a solid-liquid ratio of 1:20, add sodium lauroyl glutamate and vitamin E, and the mass ratio of the filter residue, sodium lauroyl glutamate and vitamin E is 100:3:4. Heat and extract at 75 °C for 4 h, filter and collect filtrate 2 after the extraction is completed, and mix filtrate 1 and filtrate 2, and evaporate the solvent under reduced pressure to obtain the Pleurotus eryngii extract.

[0045] Example 2

[0046] A preparation method of a microbial oil-displacing surfactant, comprising the following steps:

[0047] Mix 50 g of functionalized xanthan gum, 150 g of microbial inoculum, and 800 g of water and stir evenly to obtain a microbial oil-displacing surfactant.

[0048] The preparation method of the functionalized xanthan gum comprises the following steps:

[0049] (1) Disperse 50 g of xanthan gum in deionized water, add 20 g of sodium periodate, adjust the pH to 5 with an aqueous hydrochloric acid solution, seal and react in the dark at 30 °C for 10 h, then add 10 g of ethylene glycol to terminate the reaction. Centrifuge the reaction solution to collect the solid, and after washing and drying the solid, obtain pretreated xanthan gum;

[0050] (2) Disperse 30 g of pretreated xanthan gum in 200 mL of N,N-dimethylformamide, add 20 g of oleylamine, ultrasonically disperse and then adjust the pH to 6, heat and react at 50 °C for 2 h. After the reaction is completed, cool, filter, wash and dry to obtain a solid product;

[0051] (3) Add 30 g of the solid product to 200 mL of N,N-dimethylformamide, add 1 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone and mix evenly, then add 20 g of thiolated boron nitride, and carry out ultraviolet light irradiation reaction under an ultraviolet lamp with a power of 100 W for 10 min. After the reaction is completed, filter, collect the solid, wash and dry to obtain functionalized xanthan gum.

[0052] The preparation method of the microbial inoculum is as follows: Inoculate Bacillus subtilis into an activation medium composed of 5 wt% glucose, 10 wt% agar, 5 wt% peptone, 5 wt% beef extract, and 75 wt% water, with an inoculation amount of 3 wt%. Cultivate it under the conditions of 30 °C, 130 revolutions per minute, and aerobic condition in the dark for 45 h to perform activation treatment to obtain an activated strain; then inoculate the activated strain into an enlarged medium composed of 3 wt% yeast powder, 5 wt% glucose, 3 wt% peptone, 3 wt% sucrose, 0.5 wt% K 2 H 3 PO 4 、0.5 wt% NaH 2 PO 4 、0.3 wt% Pleurotus eryngii extract, 0.1 wt% NaCl, and 84.6 wt% water, with an inoculation amount of 4 wt%. Cultivate it for 48 h under the conditions of 30 °C and a humidity of 70% to obtain a seed liquid, then inoculate the seed liquid into a PDA medium at an inoculation amount of 3 wt%, ferment at 28 °C for 28 h, adjust the pH of the fermentation broth to 7, concentrate the fermentation broth to 1 / 4 of the original volume after fermentation to obtain a concentrated liquid, and use the dilution gradient method to detect the viable bacteria count in the concentrated liquid. The viable bacteria count is 3.4×10 9 CFU / m; Freeze-dry the concentrated liquid to obtain a composite microbial inoculum.

[0053] The preparation method of the Pleurotus eryngii extract is as follows:

[0054] Select fresh Pleurotus eryngii, after cleaning it, cut it into thin slices with a thickness of 4 mm evenly to make Pleurotus eryngii slices; dry the Pleurotus eryngii slices at 50 °C until the water content is 15% and then grind them, and pass through an 80-mesh sieve to obtain Pleurotus eryngii powder; mix 100 g of choline chloride and 300 g of tetrabutylammonium chloride and stir at 80 °C for 4 hours to obtain a deep eutectic solvent, add 50 g of Pleurotus eryngii powder to the deep eutectic solvent, perform ultrasonic extraction for 30 min, cool, centrifuge and filter to obtain filtrate 1 and filter residue; add the filter residue to a 50 wt% ethanol aqueous solution according to a solid-liquid ratio of 1:20, add sodium lauroyl glutamate and vitamin E, and the mass ratio of the filter residue, sodium lauroyl glutamate, and vitamin E is 100:5:5, heat and extract at 75 °C for 4 h, filter and collect filtrate 2 after the extraction is completed, and mix filtrate 1 and filtrate 2, and remove the solvent under reduced pressure to obtain the Pleurotus eryngii extract.

[0055] Example 3

[0056] A preparation method of a microbial oil-displacing surfactant includes the following steps:

[0057] Mix 150 g of functionalized xanthan gum, 250 g of microbial inoculum, and 600 g of water and stir evenly to obtain a microbial oil-displacing surfactant.

[0058] The preparation method of the functionalized xanthan gum includes the following steps:

[0059] (1) Disperse 50 g of xanthan gum in deionized water, add 80 g of sodium periodate, adjust the pH to 5 with hydrochloric acid aqueous solution, seal and react in the dark at 30 °C for 10 h, then add 20 g of ethylene glycol to terminate the reaction. Centrifuge the reaction solution to collect the solid, and after washing and drying the solid, obtain the pretreated xanthan gum;

[0060] (2) Disperse 44 g of the pretreated xanthan gum in 200 mL of N,N-dimethylformamide, add 26.4 g of oleylamine, ultrasonically disperse and then adjust the pH to 6, heat and react at 50 °C for 2 h. After the reaction is completed, cool, filter, wash and dry to obtain a solid product;

[0061] (3) Add 40 g of the solid product to 200 mL of N,N-dimethylformamide, add 5 g of benzoin dimethyl ether and mix evenly, then add 30 g of mercapto-functionalized boron nitride, and carry out ultraviolet irradiation reaction under an ultraviolet lamp with a power of 100 W for 10 min. After the reaction is completed, filter, collect the solid, wash and dry to obtain the functionalized xanthan gum.

[0062] The preparation method of the microbial inoculum is as follows: Inoculate Bacillus subtilis into an activation medium composed of 2 wt% glucose, 5 wt% agar, 2 wt% peptone, 2 wt% beef extract, and 88 wt% water, with an inoculation amount of 3 wt%, and culture at 30 °C, 130 rpm, in the dark and aerobic conditions for 45 h for activation treatment to obtain an activated strain; then inoculate the activated strain into an enlarged medium composed of 3 wt% yeast powder, 5 wt% glucose, 2 wt% peptone, 1 wt% sucrose, 0.1 wt% KH 2 H 3 PO 4 、0.1 wt% NaH 2 PO 4 、0.1 wt% Pleurotus eryngii extract, 0.03 wt% NaCl, and 88.67 wt% water, with an inoculation amount of 4 wt%, culture at 30 °C and a humidity of 70% for 48 h to obtain a seed liquid, then inoculate the seed liquid into a PDA medium at an inoculation amount of 3 wt%, ferment at 28 °C for 28 h, adjust the pH of the fermentation broth to 7, concentrate the fermentation broth to 1 / 4 of the original volume after fermentation is completed to obtain a concentrated solution, and use the dilution gradient method to detect the viable bacteria count in the concentrated solution. The viable bacteria count is 2.8×10 9 CFU / m; Freeze-dry the concentrated solution to obtain the compound microbial inoculum.

[0063] The preparation method of the Pleurotus eryngii extract is as follows:

[0064] Select fresh Pleurotus eryngii, wash it clean, cut it into thin slices with a uniform thickness of 4 mm to make Pleurotus eryngii slices; dry the Pleurotus eryngii slices at 50 °C until the moisture content is 15%, then grind them and pass through an 80-mesh sieve to obtain Pleurotus eryngii powder; mix 100 g of choline chloride and 300 g of tetrabutylammonium chloride, stir at 80 °C for 4 hours to obtain a deep eutectic solvent, add 50 g of Pleurotus eryngii powder to the deep eutectic solvent, perform ultrasonic extraction for 30 min, cool, centrifuge and filter to obtain filtrate 1 and filter residue; add the filter residue to a 50 wt% ethanol aqueous solution according to a solid-liquid ratio of 1:20, add sodium lauroyl glutamate and vitamin E, and the mass ratio of the filter residue, sodium lauroyl glutamate, and vitamin E is 100:1:1, heat and extract at 75 °C for 4 h, after the extraction is completed, filter to collect filtrate 2, mix filtrate 1 and filtrate 2, and remove the solvent under reduced pressure to obtain the Pleurotus eryngii extract.

[0065] Comparative Example 1

[0066] A preparation method of a microbial oil-displacing surfactant is similar to that of Example 1, the difference is that xanthan gum is not functionalized, and it specifically includes the following steps:

[0067] Mix 100 g of xanthan gum, 200 g of microbial inoculum, and 700 g of water and stir evenly to obtain a microbial oil-displacing surfactant.

[0068] The preparation method of the microbial inoculum is as follows: Take Bacillus subtilis inoculum and inoculate it into an activation medium composed of 3 wt% glucose, 8 wt% agar, 3 wt% peptone, 3 wt% beef extract, and 83 wt% water, with an inoculation amount of 3 wt%, culture at 25 °C, 130 rpm, and in the dark and aerobic conditions for 48 h to perform activation treatment to obtain an activated strain; then inoculate the activated strain into an enlarged medium composed of 2 wt% yeast powder, 3 wt% glucose, 3 wt% peptone, 2 wt% sucrose, 0.3 wt% K 2 H 3 PO 4 、0.3 wt% NaH 2 PO 4 、0.2 wt% Pleurotus eryngii extract, 0.05 wt% NaCl, and 89.15 wt% water, with an inoculation amount of 4 wt%, culture at 30 °C and a humidity of 70% for 48 h to obtain a seed liquid, then inoculate the seed liquid at an inoculation amount of 3 wt% into a PDA medium, ferment at 28 °C for 28 h, adjust the pH of the fermentation broth to 6, after the fermentation is completed, concentrate the fermentation broth to 1 / 4 of the original volume to obtain a concentrated liquid, use the dilution gradient method to detect the viable bacteria count in the concentrated liquid, and the viable bacteria count is 3.2×10 9 CFU / m; freeze-dry the concentrated liquid to obtain a microbial inoculum.

[0069] The preparation method of the Pleurotus eryngii extract is as follows:

[0070] Select fresh Pleurotus eryngii, wash it clean, cut it into thin slices with a uniform thickness of 4 mm to make Pleurotus eryngii slices; dry the Pleurotus eryngii slices at 50 °C until the moisture content is 15%, then grind them and pass through an 80-mesh sieve to obtain Pleurotus eryngii powder; mix 100 g of choline chloride and 300 g of tetrabutylammonium chloride, stir at 80 °C for 4 hours to obtain a deep eutectic solvent, add 50 g of Pleurotus eryngii powder to the deep eutectic solvent, perform ultrasonic extraction for 30 min, cool, centrifuge and filter to obtain filtrate 1 and filter residue; add the filter residue to a 50 wt% ethanol aqueous solution according to a solid-liquid ratio of 1:20, add sodium lauroyl glutamate and vitamin E, and the mass ratio of the filter residue, sodium lauroyl glutamate, and vitamin E is 100:3:4, heat and extract at 75 °C for 4 h, after the extraction is completed, filter to collect filtrate 2, mix filtrate 1 and filtrate 2, and evaporate the solvent under reduced pressure to obtain the Pleurotus eryngii extract.

[0071] Comparative Example 2

[0072] A preparation method of a microbial oil displacement surfactant is similar to Example 1, the difference is that Pleurotus eryngii extract is not added during the preparation process of the microbial inoculum, and it specifically includes the following steps:

[0073] Mix 100 g of functionalized xanthan gum, 200 g of microbial inoculum, and 700 g of water and stir evenly to obtain a microbial oil displacement surfactant.

[0074] The preparation method of the functionalized xanthan gum includes the following steps:

[0075] (1) Disperse 50 g of xanthan gum in deionized water, add 45 g of sodium periodate, adjust the pH to 5 with hydrochloric acid aqueous solution, seal and react in the dark at 30 °C for 10 h, then add 15.8 g of ethylene glycol to terminate the reaction, centrifuge the reaction solution to collect the solid, and after washing and drying the solid, obtain pretreated xanthan gum;

[0076] (2) Disperse 40 g of pretreated xanthan gum in 200 mL of N,N-dimethylformamide, add 22 g of oleylamine, after ultrasonic dispersion, adjust the pH to 6, heat and react at 50 °C for 2 h, after the reaction is completed, cool, filter, wash, and dry to obtain a solid product;

[0077] (3) Add 36.4 g of the solid product to 200 mL of N,N-dimethylformamide, add 3.3 g of 1-hydroxy-cyclohexyl phenyl ketone and mix evenly, then add 24.7 g of mercapto-functionalized boron nitride, perform ultraviolet light irradiation reaction under an ultraviolet lamp with a power of 100 W for 10 min, after the reaction is completed, filter, collect the solid and wash and dry to obtain functionalized xanthan gum.

[0078] The preparation method of the microbial inoculum is as follows: Take Bacillus subtilis and inoculate it into an activation medium composed of 3 wt% glucose, 8 wt% agar, 3 wt% peptone, 3 wt% beef extract, and 83 wt% water. The inoculation amount is 3 wt%. Cultivate it at 25 °C, 130 revolutions per minute, under dark and aerobic conditions for 48 h for activation treatment to obtain activated strains; then inoculate the activated strains into an enlarged medium composed of 2 wt% yeast powder, 3 wt% glucose, 3 wt% peptone, 2 wt% sucrose, 0.3 wt% K 2 H 3 PO 4 、0.3 wt% NaH 2 PO 4 、0.05 wt% NaCl, and 89.35 wt% water. The inoculation amount is 4 wt%. Cultivate it at 30 °C and a humidity of 70% for 48 h to obtain a seed solution. Then inoculate the seed solution into a PDA medium at an inoculation amount of 3 wt% and ferment it at 28 °C for 28 h. Adjust the pH of the fermentation broth to 6. After fermentation is completed, concentrate the fermentation broth to 1 / 4 of the original volume to obtain a concentrated solution. Use the dilution gradient method to detect the viable bacteria count in the concentrated solution. The viable bacteria count is 3.2×10 9 CFU / m; Freeze-dry the concentrated solution to obtain the microbial inoculum.

[0079] Comparative Example 3

[0080] A preparation method of a microbial oil-displacing surfactant is similar to that of Example 1, except that thiolated boron nitride is not added during the preparation process of functionalized xanthan gum, and it specifically includes the following steps:

[0081] Mix 100 g of functionalized xanthan gum, 200 g of microbial inoculum, and 700 g of water and stir evenly to obtain the microbial oil-displacing surfactant.

[0082] The preparation method of the functionalized xanthan gum includes the following steps:

[0083] (1) Disperse 50 g of xanthan gum in deionized water, add 45 g of sodium periodate, adjust the pH to 5 with hydrochloric acid aqueous solution, seal it and react at 30 °C in the dark for 10 h, then add 15.8 g of ethylene glycol to terminate the reaction. Centrifuge the reaction solution to collect the solid matter, and after washing and drying the solid matter, obtain pretreated xanthan gum;

[0084] (2) Disperse 40 g of pretreated xanthan gum in 200 mL of N,N-dimethylformamide, add 22 g of oleylamine, ultrasonically disperse it and then adjust the pH to 6, heat and react at 50 °C for 2 h. After the reaction is completed, cool, filter, wash, and dry to obtain a solid product, which is the functionalized xanthan gum.

[0085] The preparation method of the microbial inoculum is as follows: Inoculate Bacillus subtilis into an activation medium composed of 3 wt% glucose, 8 wt% agar, 3 wt% peptone, 3 wt% beef extract, and 83 wt% water, with an inoculation amount of 3 wt%. Culture at 25 °C, 130 rpm, under dark and aerobic conditions for 48 h for activation treatment to obtain activated strains; then inoculate the activated strains into an enlarged medium composed of 2 wt% yeast powder, 3 wt% glucose, 3 wt% peptone, 2 wt% sucrose, 0.3 wt% K 2 H 3 PO 4 、0.3 wt% NaH 2 PO 4 、0.2 wt% Pleurotus eryngii extract, 0.05 wt% NaCl, and 89.15 wt% water. With an inoculation amount of 4 wt%, culture at 30 °C and a humidity of 70% for 48 h to obtain a seed liquid. Then inoculate the seed liquid into a PDA medium at an inoculation amount of 3 wt%, ferment at 28 °C for 28 h, adjust the pH of the fermentation broth to 6. After fermentation is completed, concentrate the fermentation broth to 1 / 4 of the original volume to obtain a concentrated liquid. Use the dilution gradient method to detect the viable bacteria count in the concentrated liquid, and the viable bacteria count is 3.2×10 9 CFU / m; Freeze-dry the concentrated liquid to obtain the microbial inoculum.

[0086] The preparation method of the Pleurotus eryngii extract is as follows:

[0087] Select fresh Pleurotus eryngii, after cleaning, cut it into thin slices with a thickness of 4 mm to make Pleurotus eryngii slices; dry the Pleurotus eryngii slices at 50 °C until the moisture content is 15% and then grind them, and pass through an 80-mesh sieve to obtain Pleurotus eryngii powder; mix 100 g of choline chloride and 300 g of tetrabutylammonium chloride and stir at 80 °C for 4 hours to obtain a deep eutectic solvent. Add 50 g of Pleurotus eryngii powder to the deep eutectic solvent, perform ultrasonic extraction for 30 min, cool, centrifuge and filter to obtain filtrate 1 and filter residue; add the filter residue to a 50 wt% ethanol aqueous solution according to a solid-liquid ratio of 1:20, add sodium lauroyl glutamate and vitamin E, and the mass ratio of the filter residue, sodium lauroyl glutamate, and vitamin E is 100:3:4. Heat and extract at 75 °C for 4 h. After extraction is completed, filter to collect filtrate 2, and mix filtrate 1 and filtrate 2, and remove the solvent under reduced pressure to obtain the Pleurotus eryngii extract.

[0088] Performance Test

[0089] Thermal resistance performance test:

[0090] Add the microbial oil-displacing surfactants obtained in Example 1 and Comparative Examples 1-3 to 2 L of formation water (with a salinity of 14692 mg / L), and then heat to 45 - 100 °C. Use a rheometer to measure the apparent viscosity of each microbial oil-displacing surfactant, and the shear rate is 170 s-1 , the test results are shown in Table 1:

[0091]

[0092] Shear resistance performance test:

[0093] The apparent viscosities of the microbial oil-displacing surfactants obtained in Example 1 and Comparative Examples 1-3 were tested using a rheometer at a temperature of 25 °C and a shear rate of 400 - 1000 s -1 , the test results are shown in Table 2:

[0094]

[0095] Oil displacement experiment

[0096] Dry a 5-cm artificial core and conduct displacement experiments after establishing oil saturation. First, perform water flooding using formation water for displacement until the core containing saturated oil stops producing oil. At this time, the water flooding limit has been reached. According to the scale readings of the oil-water separator and the oil production, the oil displacement efficiency (calculation formula: oil production / original oil content in the core × 100%) is 48.37%. Then continue to use the microbial oil-displacing surfactant of the present invention for oil displacement. Saturate and displace the simulated oil with more than 10 PV of the microbial oil-displacing surfactants prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention, and record the first oil production; close the front and rear valves of the instrument, maintain the confining pressure at 2 MPa, and incubate in the holder at the simulated formation temperature for 7 days; displace with formation water until no oil is produced, and record the second oil production; the total oil production is the sum of the two oil productions, and the final recovery rate is calculated based on the total oil production. The results are shown in Table 3:

[0097] Final recovery rate (%) = total oil production / original oil content in the core × 100%

[0098] Table 3 Results of oil displacement experiment

[0099] Final recovery rate (%) Example 1 75.52 Example 2 74.83 Example 3 76.25 Comparative Example 1 60.38 Comparative Example 2 65.47 Comparative Example 3 69.63

[0100] From the data in Table 1 and Table 2, it can be seen that the microbial oil-displacing surfactant prepared in Example 1 of the present invention has good temperature resistance and shear resistance. From the experimental results in Table 3, it can be seen that the microbial oil-displacing surfactant prepared by the present invention has a good oil displacement effect.

[0101] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the patent protection scope of the present invention.

Claims

1. A microbial oil displacement active agent, characterized in that: The invention comprises the following components in percentage by mass: 5-15% of functionalized xanthan gum, 15-25% of microbial agent, and the balance of water.

2. The microbial oil displacement active agent according to claim 1, characterized in that The preparation method of the functionalized xanthan gum is as follows: Sodium periodate is used as an oxidant to react with xanthan gum in the dark to obtain pretreated xanthan gum; the pretreated xanthan gum is reacted with oleylamine, and the obtained product is reacted with thiolated boron nitride to obtain functionalized xanthan gum.

3. The microbial oil displacement active agent according to claim 2, characterized in that: The preparation method of the functionalized xanthan gum comprises the following steps: (1) dispersing xanthan gum in deionized water, adding sodium periodate, adjusting the pH with aqueous hydrochloric acid, sealing to avoid light, adding ethylene glycol to terminate the reaction, centrifuging the reaction solution to collect solids, washing and drying the solids to obtain pretreated xanthan gum; (2) dispersing the pretreated xanthan gum in N,N-dimethylformamide, adding oleylamine, adjusting the pH to weak acidity after ultrasonic dispersion, heating for reaction, cooling, filtering, washing, and drying after the reaction is completed to obtain a solid product; (3) The solid product is added to N,N-dimethylformamide, a photoinitiator is added and mixed evenly, and then thiolated boron nitride is added to react with ultraviolet light. After the reaction is completed, the solid is filtered, collected, washed, and dried to obtain functionalized xanthan gum.

4. The microbial oil displacement active agent according to claim 3, characterized in that: In the step (1), the mass ratio of xanthan gum, sodium periodate and ethylene glycol is 5:2-8:1-2.

5. The microbial oil displacement active agent according to claim 3, characterized in that: In the step (2), the mass ratio of pretreated xanthan gum to oleylamine is 1.5-2.5:1-1.

2.

6. The microbial oil displacement active agent according to claim 3, characterized in that: In the step (2), the mass ratio of the solid product, the photoinitiator and the mercapto boron nitride is 3-4:0.1-0.5:2-3.

7. The microbial oil displacement active agent according to claim 1, characterized in that: The preparation method of the microbial agent is as follows: taking a Bacillus subtilis species and inoculating it into an activation culture medium, performing an activation treatment to obtain an activated strain; then inoculating the activated strain into an expansion culture medium, culturing for 40-48 hours under the culture conditions of 25-32° C. and 55-70% humidity to obtain a seed liquid, then inoculating the seed liquid into a PDA culture medium at an inoculation amount of 2-5wt%, fermenting at 25-30° C. for 25-30 hours, adjusting the pH of the fermentation liquid to 6-7, concentrating the fermentation liquid after the fermentation is completed to obtain a concentrated liquid, and freeze-drying the concentrated liquid to obtain a composite microbial agent.

8. The microbial oil displacement active agent according to claim 7, characterized in that: The composition of the expansion medium is as follows: 2-3wt% yeast powder, 2-5wt% glucose, 2-3wt% peptone, 1-3wt% sucrose, 0.1-0.5wt% K2H3PO4, 0.1-0.5wt% NaH2PO4, 0.1-0.3wt% Pleurotus eryngii extract, 0.01-0.1wt% NaCl, and the balance is water.

9. The microbial oil displacement active agent according to claim 8, characterized in that The preparation method of the Pleurotus eryngii extract is as follows: Fresh Pleurotus eryngii is washed and sliced ​​to prepare Pleurotus eryngii slices; the Pleurotus eryngii slices are dried and ground to obtain Pleurotus eryngii powder; the Pleurotus eryngii powder is added to a low eutectic solvent, ultrasonically extracted, cooled, centrifuged, and filtered to obtain a filtrate 1 and a filter residue; the filter residue is added to an ethanol aqueous solution, sodium lauroyl glutamate and vitamin E are added, and heated for extraction, and after the extraction is completed, the filtrate 2 is collected by filtering, the filtrate 1 and the filtrate 2 are mixed, and the solvent is evaporated under reduced pressure to obtain the Pleurotus eryngii extract.

10. A method for preparing the microbial oil displacement active agent according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: weighing each component according to the formula, mixing and stirring the functionalized xanthan gum, microbial agent and water evenly to obtain the microbial oil displacement active agent.

Images