A pinning structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa, oil well throughput enhancer and application thereof

Abstract

The invention discloses a pinning structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa, an oil well throughput enhancer and an application thereof, and belongs to the field of petroleum development. The invention obtains a biofilm secreted by Pseudomonas aeruginosa by culturing Pseudomonas aeruginosa, cross-links it with an ionic solution, and then adds a long-chain fatty acid or a long-chain fatty acid salt for modification to obtain a pinning structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa. The hydrophobically modified ion membrane is applied to an oil well as an oil well throughput enhancer, and can improve the relative permeability of the water phase and the oil phase of the oil well, improve the fluid displacement efficiency and the oil displacement effect, and has the effect of significantly improving the oil well throughput efficiency. In addition, due to its low cost and high environmental protection characteristics, it is suitable for the development of complex oil reservoirs and has certain application potential.

Description

Technical Field

[0001] The invention relates to the field of petroleum development, and in particular to a hydrophobically modified ion membrane with a pinning structure based on Pseudomonas aeruginosa, an oil well throughput enhancer and applications. Background Art

[0002] After the application of conventional oil production technology, most oil fields have entered the high water content development stage when some crude oil is still trapped in the reservoir and cannot be produced. In particular, cracks are widely developed in tight oil reservoirs. If such highly heterogeneous reservoirs are directly depleted for production without water plugging measures, it often leads to the channeling of edge and bottom water, causing premature water breakthrough in the oil wells and rapid depletion of reservoir energy. How to improve the recovery rate of oil fields in the high water content development stage is the key to the sustained and stable production of oil fields. Chemical agent huff and puff technology is one of the important measures for increasing oil in old block reservoirs. During the production process, it is attempted to use the huff and puff agent as an efficient oil recovery system to reduce the oil-water interface tension and capillary resistance, stimulate the flow of deep crude oil, improve the wettability of the oil layer rock surface, and rely on water plugging to improve the oil recovery efficiency and sweep efficiency of the reservoir, so as to suppress the energy attenuation rate of the reservoir and improve the recovery rate.

[0003] During the process of oil wells in the process of huff and puff and oil production, the injection of a large amount of water causes the surface of the rock channels in the near-well zone to be washed for a long time, forming a hydration layer, which reduces the effective diameter of the core channels and increases the relative permeability of water, hindering the seepage of oil and gas. Some problems of reservoir damage during water injection are gradually exposed, especially the decline in reservoir permeability will cause serious damage, which is also the main reason for the decline in oil well production. Due to the serious formation deficit and other problems, the current plugging and production increase technology is applied. The measures and agents used are difficult to enter the blocked target layer or partially enter the target layer, but the effect of plugging and production increase is not ideal due to the low reaction degree. Bio-based raw materials are widely distributed in soil, water, and air. They have the characteristics of simple nutritional requirements, fast proliferation rate, and wide growth range. Simple and cheap carbon and nitrogen sources can be directly used as exogenous nutrients to synthesize products with industrial uses. Due to its green, environmentally friendly and pollution-free characteristics, it has gradually been favored by the oil and gas development field and has been applied in many aspects such as crude oil viscosity reduction, oil stabilization and water control, improved recovery, and pollution degradation.

[0004] Traditional surfactant-based chemical well pumping agents increase oil production by reducing oil-water interfacial tension, increasing crude oil fluidity, and promoting oil-water diversion. However, with the deepening of oilfield development and the complexity of reservoir conditions, the limitations of this type of enhancer are gradually becoming apparent. Poor adaptability to high-temperature and high-salt environments is a major limitation of surfactant-based pumping agents. In high-temperature reservoirs, surfactants are easily degraded, resulting in the inability to maintain interfacial tension at ultra-low levels; and under high-mineralization conditions, high concentrations of salt ions affect the solubility and stability of surfactants, resulting in a significant decrease in their oil recovery effect. For example, polyether and anionic surfactants are prone to precipitation or inactivation in high-salt environments, which greatly limits their application in deep or saline-alkaline reservoirs. Traditional surfactant-based pumping agents also naturally have the problem of large adsorption losses. Since the surface of reservoir rocks is charged, surfactant molecules are easily adsorbed on the surface of the rocks, resulting in a decrease in their effective concentration in the oil layer and a weakened oil recovery effect. Especially in old oil fields, the synergistic effect of surfactants is usually difficult to maintain for a long time. The production increase cycle of a throughput usually ranges from a few weeks to a few months. As the number of throughputs increases, the increase in oil well production will be significantly reduced, and frequent injections are required to maintain production, which increases the complexity of operations. In order to maintain an effective oil recovery concentration, it is often necessary to increase the injection volume, but this invisibly increases the economic cost. In addition, the large amount of adsorption of surfactants will also lead to blockage of formation pores, affect the fluidity of the injected fluid, and increase the difficulty of subsequent oil recovery. Therefore, the economic efficiency of surfactants as synergists is obviously insufficient in many reservoir applications, especially in complex reservoir environments. How to reduce costs and improve economic benefits has become a major challenge.

[0005] In addition, polymer oil well chemical huff and puff agents (such as polyacrylamide and its derivatives) are widely used to improve oil reservoir recovery. By injecting a certain amount of huff and puff agents from the oil well and combining them with appropriate water plugging measures, the huff and puff agents are used as an efficient oil recovery system during the production process and rely on water plugging to improve the oil recovery efficiency and sweep efficiency of the reservoir, so as to achieve the purpose of inhibiting the energy decay rate of the reservoir and improving the recovery rate. However, the technology of this type of enhancer also has limitations, and it shows obvious defects in complex reservoir environments, which limits its application effect. It is difficult for polymer oil well chemical huff and puff agents to achieve selective regulation of oil and water during application, which may increase the output of oil and water at the same time, thereby reducing the oil-water ratio, and even leading to an increase in water production, resulting in a decrease in the input-output ratio of the enhancer and reducing economic benefits. Problems such as reservoir pore blockage, clay particle migration, and expansion caused by long-term injection and polymerization affect the normal flow of fluids, especially in low-permeability reservoirs, resulting in the deterioration of reservoir injection conditions year by year, a sharp increase in injection pressure, and the injection pressure of some wells approaching or reaching the fracture pressure of the oil layer. The injection wells cannot meet the injection requirements, and the problem of injection-production imbalance is becoming increasingly serious. In the process of long-term water injection and polymerization, a serious inefficient cycle of injected water and chemical agents has been formed, and the contradictions between layers and within layers of the reservoir have intensified, resulting in an increase in the water content of the oil field in the middle and late stages of development. A large amount of residual oil cannot be produced. At present, there is still about 50% of the oil remaining underground. The distribution of this part of the residual oil is more scattered and complex, and the development is more difficult. The existing chemical flooding technology can no longer meet the further development needs of my country's old oil fields. In the future, safe and effective new technologies for improving the recovery rate of old oil fields are urgently needed to stabilize crude oil production and ensure energy security. Summary of the invention

[0006] The purpose of the present invention is to provide a pinned structure hydrophobic modified ion membrane based on Pseudomonas aeruginosa, an oil well throughput enhancer and an application thereof, so as to solve the problems existing in the above-mentioned prior art. The hydrophobic modified ion membrane is used as an oil well throughput enhancer, which can improve the relative permeability of the water phase and the oil phase of the oil well, improve the fluid displacement efficiency and the oil recovery effect, and has the effect of significantly improving the oil well throughput efficiency. In addition, due to its low cost and high environmental protection characteristics, it is suitable for the development of complex oil reservoirs and has certain application potential.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a "pinning" structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa, which is obtained by cross-linking the biofilm secreted by Pseudomonas aeruginosa with an ion solution, and then adding long-chain fatty acids or long-chain fatty acid salts for modification;

[0009] The long-chain fatty acid or long-chain fatty acid salt includes a fatty acid or fatty acid salt containing an alkyl chain of ≥12 carbons. In the embodiments of the present invention, the long-chain fatty acid is described by taking stearic acid, palmitic acid, and lauric acid as examples, but the present invention is not limited thereto.

[0010] The present invention also provides a method for preparing the "pinning" structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa, comprising the following steps: cross-linking the biofilm secreted by Pseudomonas aeruginosa with an ion solution, and then adding long-chain fatty acids or long-chain fatty acid salts for modification to obtain the "pinning" structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa.

[0011] Optionally, the ionic solution includes a CaCl2 solution, a MgCl2 solution and a NaCl solution, the concentration of the ionic solution is 0.1-0.5M, and the pH value is 6-8.

[0012] Optionally, the lyophilized powder of the biofilm is dissolved into a biofilm solution and then stirred with the ion solution at 25° C. and 200-300 rpm for 30-60 min for cross-linking reaction;

[0013] When the ion solution is a CaCl2 solution, the volume ratio of the ion membrane solution to the CaCl2 solution is 1:1 to 1:5;

[0014] When the ion solution is a MgCl2 solution, the volume ratio of the ion membrane solution to the MgCl2 solution is 1:1 to 1:7;

[0015] When the ion solution is a NaCl solution, the volume ratio of the ion membrane solution to the NaCl solution is 1:10 to 1:15.

[0016] Optionally, the freeze-dried powder of the biofilm is prepared by expanding the culture of Pseudomonas aeruginosa, separating the biofilm and bacterial cells in the culture medium, and collecting the supernatant; then mixing the supernatant with an equal volume of ethanol, standing, centrifuging, and collecting the precipitate; resuspending the precipitate with deionized water, dialyzing, and freeze-drying the dialysate to obtain the freeze-dried powder of the biofilm.

[0017] Optionally, a long-chain fatty acid or a long-chain fatty acid salt is dissolved to prepare a hydrophobic modification solution, which is then added to a cross-linking reaction system, and then placed in a constant temperature water bath at 50°C for reaction for 30 to 40 minutes to obtain a "pinning" structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa; wherein the volume ratio of the hydrophobic modification solution to the cross-linking reaction system is (1:5) to (1:10), and the concentration of the hydrophobic modification solution is 0.1% to 1% w / v.

[0018] The present invention also provides application of the hydrophobic modified ion membrane in preparing an oil well throughput enhancer.

[0019] The invention also provides an oil well throughput enhancer, which contains the hydrophobic modified ion membrane.

[0020] The present invention also provides the use of the hydrophobically modified ion membrane or the oil well throughput enhancer in any of the following:

[0021] (1) Application in improving oil well throughput efficiency;

[0022] (2) Application in improving oil well displacement efficiency and oil recovery effect;

[0023] (3) Application in improving the water control and oil production increase effect of oil wells;

[0024] (4) Application in improving oil well recovery;

[0025] (5) Application in increasing oil well production.

[0026] The present invention also provides a method for improving oil well recovery, which is characterized by comprising the step of applying the hydrophobic modified ion membrane as an oil well throughput enhancer to the oil well to improve the oil well recovery.

[0027] The present invention discloses the following technical effects:

[0028] The present invention provides a method for preparing an oil well throughput enhancer with a biofilm secreted by Pseudomonas aeruginosa as a basic unit. Through the hydrophobic modification technology and the functional groups in the ion membrane, a hydrophobic membrane with a stable "pinning" structure of roughness is formed. The ion membrane has high activity, can reduce interfacial tension and significantly reduce the relative permeability of the water phase and increase the relative permeability of the oil phase, thereby optimizing the reservoir fluid displacement efficiency and reducing water channeling. The system has excellent stability under medium and high temperature environments, not only significantly improves the oil well throughput efficiency, but also achieves continuous improvement in production under low-cost conditions, showing good economic benefits. Compared with traditional chemical throughput agents (such as surfactants and polymers), the biological ion membrane technology of the present invention has the ability to work stably for a long time in a high-temperature and high-salt environment, with low cost and excellent environmental protection. The biodegradable characteristics of the throughput agent effectively avoid the secondary pollution that may be caused by traditional chemical agents. At the same time, it is simple to operate, mild and continuous in action, and can provide a long-term and efficient production increase solution in oil well development, which meets the comprehensive needs of modern petroleum industry for environmental protection, high efficiency and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 The SEM morphological characterization of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 2;

[0031] Figure 2 The SEM morphological characterization of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 3;

[0032] Figure 3 The SEM morphological characterization of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 4;

[0033] Figure 4 SEM structure of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 2;

[0034] Figure 5 SEM structure of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 3;

[0035] Figure 6 SEM structure of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 4;

[0036] Figure 7 The interfacial tension of different Pseudomonas aeruginosa hydrophobic ion membranes prepared in Examples 2-4 varies with temperature;

[0037] Figure 8 Schematic diagram of contact angle (CA) measurement. DETAILED DESCRIPTION

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0040] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0041] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0042] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0043] The traditional surfactant-based oil well chemical injection agents used in the prior art have the following defects: ① Under high temperature conditions, many surfactants will undergo thermal degradation, resulting in a rapid attenuation of the oil recovery effect. In high-salt reservoirs, salt ions will interact with surfactants, causing the surfactants to fail or precipitate, and unable to maintain the ideal oil-water interface properties; ② The reservoir conditions are complex. Due to the adsorption of surfactants, the rock permeability is easily reduced, and the concentration and velocity of the front flow are reduced. The regulation efficiency is low in high-permeability reservoirs and heterogeneous reservoirs. There may also be problems such as incompatibility between chemicals and fracturing fluid additives; ③ Poor economic efficiency. The price of surfactants themselves is relatively high, especially special formulas with high temperature resistance and salt resistance, which are even more expensive.

[0044] Although polymer oil well chemical throughput enhancers (such as polyacrylamide and its derivatives) are widely used to improve reservoir recovery, they also have the following defects: ① During the polymer flooding process, due to adsorption and mechanical capture, a large amount of polymer is adsorbed and retained in the near-wellbore area, undergoing biochemical cross-linking to form polymer micelles, which are entangled with other blockages, resulting in blockage in the near-wellbore area and a significant decrease in reservoir permeability; ② The polymer is incompatible with the reservoir pore throat size. The pore throat size of unconventional oil reservoirs such as low-permeability reservoirs is at the nanometer level, making it difficult for conventional polymer system throughput enhancers to enter, and there is a problem of poor adaptability to pores of different sizes; ③ The long-term use of chemical agents leads to the risk of formation contamination. Under high temperature and high pressure conditions, degradation or by-products may occur, affecting the formation and the surrounding environment.

[0045] As the environmental protection requirements of oil fields increase, the environmental protection limitations of traditional throughput enhancers become more and more prominent. Therefore, the present invention proposes a "pinning" ion membrane oil well throughput enhancer based on Pseudomonas aeruginosa, and its advantages are analyzed as follows:

[0046] ① Pseudomonas aeruginosa is a Gram-negative, facultative anaerobic bacterium belonging to the genus Pseudomonas. It is widely present in the natural environment of hosts such as soil, water and humans, and has potential applications in oil fields, wastewater treatment and bioremediation.

[0047] ② Aiming at the limitations of existing biological throughput agents, a method for preparing an oil well throughput enhancer with Pseudomonas aeruginosa as the basic unit is provided. The microbial cells can grow in situ under reservoir conditions, and use a series of extracellular accessory structures to sense the presence of the rock surface and adhere to it. The cells are strengthened to adhere to the rock surface by secreting extracellular polymers such as proteins, lipopolysaccharides, lipids, and DNA, forming an insoluble biofilm with a certain degree of roughness, which helps it to form irreversible attachment on the rock surface. The Pseudomonas aeruginosa of the present invention is not specific.

[0048] ③ Pseudomonas aeruginosa fermentation liquid can be transformed from a non-viscous fluid into a multifunctional oil recovery bacterial liquid with surface activity and viscoelasticity under medium-high temperature (60-95℃) reservoir conditions. It also has the function of expanding the swept volume and improving the oil washing efficiency, and can effectively drive the residual oil at the blind end, increase the fluidity of crude oil, and has a strong degradation ability. It can decompose some harmful substances in oil wells (such as organic blockages and paraffin deposits), thereby increasing the production of oil wells.

[0049] ④ In the high-salt, high-temperature reservoir environment, the biofilm secreted by Pseudomonas aeruginosa carries functional groups such as carboxyl and amino groups, which can undergo ion cross-linking reactions with metal ions (such as calcium and magnesium) in the solution to form a "pinning" structure, enhance the stability of the biofilm, and promote it to form a stable ion membrane on the rock surface. Under the conditions of high concentrations of multivalent cations such as calcium ions and magnesium ions, these ions can bridge the negative charges between ion membrane molecules, reduce the exposure of its hydrophilic part, and enhance the hydrophobicity of the overall ion membrane. The hydrophobic membrane can form a covering layer on the rock surface, reduce the flow ability of the water phase in the water channel, and enhance the flow ability of the oil phase, thereby achieving selective water plugging and promoting spontaneous oil drainage in the reservoir.

[0050] ⑤ Compared with traditional chemical flooding agents (such as surfactants and polymers), the biological ion membrane formed by Pseudomonas aeruginosa can work stably for a long time in a high temperature and high salt environment, has a low cost of use, and its biodegradability makes it environmentally friendly. The mechanism of action is relatively mild and continuous, and it can be effective in oil wells for a long time, avoiding the secondary pollution and environmental problems that may be caused by chemical flooding agents.

[0051] More specifically, the scheme of the present invention is: by culturing a Pseudomonas aeruginosa, obtaining its biofilm and then cross-linking it to ensure that it can form a stable ion membrane ion cross-linking network, the ion cross-linking solution can be a calcium chloride solution (CaCl2), a magnesium chloride solution (MgCl2) and a sodium chloride solution (NaCl) solution, and by adding a long-chain fatty acid salt hydrophobic modifier to ensure that the membrane has good hydrophobicity, but does not affect the adhesion and structural stability of the ion membrane, the long-chain fatty acid salt hydrophobic modifier can be stearic acid (C 18 H 36 O2), palmitic acid (C 16 H 32 O2) and lauric acid (C 12 H 24 O2) and one or more of them, the ion membranes of different embodiments obtained by modification are used for oil well throughput efficiency enhancement. The microscopic morphology and stability analysis of the biofilm are observed, the interfacial tension and hydrophobic effect tests are carried out, the permeability adjustment effect is evaluated, the oil displacement experiment is carried out, and the oil enhancement effect is evaluated. The following is further described with specific embodiments.

[0052] Example 1

[0053] 1. Pseudomonas aeruginosa culture

[0054] (1) Preparation of LB solid medium: Dissolve 10g of tryptone, 5g of yeast extract, and 10g of sodium chloride in 1L of deionized water, adjust the pH to 7.0 (use NaOH solution or HCl for adjustment), add 1.5% agar (15g of agar powder dissolved in 1L of liquid medium), and sterilize the mixed medium by high pressure (121℃, 15-20min). After sterilization, wait for the medium to cool slightly (about 50℃), pour it into a sterile culture dish, and use it after solidification.

[0055] (2) Inoculation and culture of bacterial strains: The standard Pseudomonas aeruginosa PAO1 strain was purchased from the China General Microbiological Culture Collection Center (CGMCC); the PAO1 strain was inoculated on the surface of the LB solid culture medium, cultured at 37°C for 24-48 hours, and the colony growth was observed. The LB solid culture medium used was an agar medium containing sitomycin, which contained sitomycin and could inhibit the growth of non-Pseudomonas aeruginosa. A small piece of colony was taken from the pure culture colony using a sterile inoculation loop or inoculation needle, and streaked on the LB solid culture medium and spread evenly. The inoculated solid culture medium was placed in an incubator, cultured at 37°C for 24-48 hours, and the colony growth was observed. Pseudomonas aeruginosa generally enters the logarithmic growth phase within 24 hours, and the culture time can be appropriately extended to secrete biofilm (generally not more than 48 hours). Pseudomonas aeruginosa often secretes more biofilm when cultured under low carbon source (such as glycerol or glucose) and nitrogen source conditions.

[0056] (3) To improve the salt tolerance of Pseudomonas aeruginosa, NaCl (1%-3%) can be added to the culture medium for high-salt culture to increase the salt tolerance of the biofilm.

[0057] (4) Strain harvesting: Pseudomonas aeruginosa is generally short rod-shaped or rod-shaped and can form typical green or blue-green colonies on LB culture medium. Use a sterile inoculation loop to pick green or blue-green colonies from the surface of the solid culture medium. Make sure to pick a single colony to avoid mixing. Inoculate the picked colony onto a new LB solid culture medium, streak it again, and culture it for 48 hours to obtain a purified strain. Use a sterile scraper to scrape the colony from the surface of the culture medium, transfer it into sterile LB liquid culture medium, and shake it gently to obtain the bacteria. Examine the colony morphology and 16S rDNA gene sequence analysis under a microscope and identify it as Pseudomonas aeruginosa, a Gram-negative bacillus.

[0058] 2. Pseudomonas aeruginosa biofilm extraction

[0059] (1) Collecting bacteria: After the culture is completed, the culture medium contains a large amount of biofilm and bacterial cells. The culture medium is centrifuged at 8000 rpm for 20 min at 4°C, and the supernatant is collected for later use.

[0060] (2) Precipitation and collection: Add an equal volume of cold ethanol (100%) to the supernatant to precipitate the biofilm. The concentration of ethanol is generally 60% to 80% (v / v). Let the mixture stand at 4°C for 12 hours to promote biofilm precipitation. Use high-speed centrifugation (4°C, 10,000 rpm, 30 min) to recover the biofilm precipitate and remove the ethanol solvent. Dissolve the precipitate in an appropriate amount of distilled water and centrifuge again to remove impurities.

[0061] (3) Purification and preservation: Dissolve the precipitate in deionized water and remove low molecular weight impurities by dialysis. Use a dialysis bag (molecular weight cutoff value 10kDa) for 48 hours and change the water 3 to 4 times. The dialyzed biofilm solution is freeze-dried to obtain purified EPS powder. The freeze-dried sample can be stored for a long time and used in subsequent application experiments.

[0062] During the entire culture and extraction process, exogenous contamination should be avoided to ensure the purity of the biofilm. According to different culture scales and cell densities, the centrifugation conditions should be adjusted to ensure that the bacteria and the supernatant are completely separated. During the dialysis process, attention should be paid to the frequency of water replacement to ensure the purity and solubility of the biofilm. The freeze-dried biofilm can be stored for a long time, but it should be kept away from direct sunlight and high temperature and kept dry.

[0063] Example 2

[0064] (1) Formation of Pseudomonas aeruginosa ion membrane cross-linking solution

[0065] Select CaCl2 solution as the cross-linking agent and prepare a solution with a concentration of 0.5M. According to the charge characteristics of the biofilm, adjust the pH value of the cross-linking solution to 7 to optimize the cross-linking reaction effect (use 0.1M NaOH solution or HCl solution to adjust the pH of the solution). Mix the biofilm solution with the pre-prepared CaCl2 solution at a ratio of 1:5 (v / v), and the concentration of the biofilm solution is 2g / L. During mixing, use a magnetic stirrer to stir at a low speed of 200~300rpm (300rpm was selected in this experiment) to ensure that the cross-linking solution is evenly distributed. Keep the mixed solution at room temperature (25℃) and continue to stir the mixed solution for 30~60min (30min was selected in this experiment) to ensure that the ionic cross-linking occurs sufficiently to obtain an ion membrane-cross-linking solution. At this time, the Ca in the cross-linking solution 2+ It will react with negative charges (such as carboxyl groups) in the biofilm to form a stable ion membrane structure. After the reaction is completed, the mixed solution is allowed to stand and observed to see whether a visible gel-like ion membrane structure is formed. Take out a certain volume of ion membrane-crosslinking solution, pour it into a plate, dry it, and observe and analyze the surface of the dried membrane.

[0066] (2) Hydrophobic modification of Pseudomonas aeruginosa ion membrane

[0067] Prepare a stearic acid solution with a concentration of 0.3% (w / v). Heat the water to 50°C during dissolution to help ensure complete dissolution. Add the prepared stearic acid solution to the ion membrane-crosslinking solution at a ratio of 1:7 (v / v), and gently stir the mixed solution to ensure that the stearic acid solution is evenly dispersed in the ion membrane-crosslinking solution. At this time, the stearic acid molecules will interact with the functional groups such as carboxyl in the ion membrane through their long-chain fatty acid groups to improve the hydrophobicity of the membrane. Place the mixed solution in a 50°C constant temperature water bath and continue the reaction for 30 minutes. At this temperature, the stearic acid molecules can better react with the functional groups in the ion membrane to form a stable hydrophobic ion membrane. During the reaction, you can gently stir it at the right time to ensure uniform modification. Let it stand for more than 12 hours until the stable structure of the membrane is finally formed. Use a scanning electron microscope (SEM) to observe the surface morphology of the modified membrane and check the uniformity and hydrophobicity of the membrane.

[0068] Example 3

[0069] (1) Formation of Pseudomonas aeruginosa ion membrane cross-linking solution

[0070] Select MgCl2 solution as the cross-linking agent and prepare a solution with a concentration of 0.5M. According to the charge characteristics of the biofilm, adjust the pH value of the cross-linking solution to 7 to optimize the cross-linking reaction effect (use 0.1M NaOH solution or HCl solution to adjust the pH of the solution). Mix the biofilm solution with the pre-prepared MgCl2 solution in a ratio of 1:7 (v / v), and the concentration of the biofilm solution is 2g / L. During mixing, use a magnetic stirrer to stir at a low speed of 200~300 rpm (250rpm was selected in this experiment) to ensure that the cross-linking solution is evenly distributed. Keep the mixed solution at room temperature (25°C) and continue to stir the mixed solution for 30~60min (40min was selected in this experiment) to ensure that ionic cross-linking occurs sufficiently. At this time, the Mg in the cross-linking solution 2+ It will react with negative charges (such as carboxyl groups) in the biofilm to form a stable ion membrane structure and obtain an ion membrane-crosslinking solution. After the reaction is completed, the mixed solution is allowed to stand and observe whether a visible gel-like ion membrane structure is formed. Take out a certain volume of the ion membrane-crosslinking solution, pour it into a plate, dry it, and observe and analyze the surface of the dried membrane.

[0071] (2) Hydrophobic modification of Pseudomonas aeruginosa ion membrane

[0072] Prepare palmitic acid solution with a concentration of 0.3% (w / v). Heat water to 50°C during dissolution to help ensure complete dissolution. Add the prepared stearic acid solution to the ion membrane-crosslinking solution at a ratio of 1:10 (v / v), and gently stir the mixed solution to ensure that the stearic acid solution is evenly dispersed in the ion membrane crosslinking solution. At this time, the palmitic acid molecules will interact with functional groups such as carboxyl groups in the ion membrane through their long-chain fatty acid groups to improve the hydrophobicity of the membrane. Place the mixed solution in a 50°C constant temperature water bath and continue the reaction for 30 minutes. At this temperature, the palmitic acid molecules can better react with the functional groups in the ion membrane molecules to form a stable hydrophobic ion membrane. During the reaction, you can gently stir it at the right time to ensure uniform modification. Let it stand for more than 12 hours until the stable structure of the membrane is finally formed. Use a scanning electron microscope to observe the surface morphology of the modified membrane and check the uniformity and hydrophobicity of the membrane.

[0073] Example 4

[0074] (1) Formation of Pseudomonas aeruginosa ion membrane cross-linking solution

[0075] Select NaCl solution as the cross-linking agent and prepare a solution with a concentration of 0.5M. According to the charge characteristics of the biofilm, adjust the pH value of the cross-linking solution to 7 to optimize the cross-linking reaction effect (use 0.1M NaOH solution or HCl solution to adjust the pH of the solution). Mix the biofilm solution with the pre-prepared NaCl solution in a ratio of 1:10 (v / v), and the concentration of the biofilm solution is 2g / L. During mixing, use a magnetic stirrer to stir at a low speed of 200~300rpm for 60min (300rpm was selected in this experiment) to ensure that the cross-linking solution is evenly distributed. Keep the mixed solution at room temperature (25℃) and continue to stir the mixed solution for 30~60min (60min was selected in this experiment) to ensure that ionic cross-linking occurs sufficiently. At this time, the Na + It will react with negative charges (such as carboxyl groups) in the biofilm to form a stable ion membrane structure and obtain an ion membrane-crosslinking solution. After the reaction is completed, the mixed solution is allowed to stand and observe whether a visible gel-like ion membrane structure is formed. A certain volume of solution is taken out and poured into a plate for drying. The dried membrane is then observed and analyzed on the surface.

[0076] (2) Hydrophobic modification of Pseudomonas aeruginosa ion membrane

[0077] Prepare a lauric acid solution with a concentration of 0.3% (w / v). Heat the water to 50°C during dissolution to help ensure complete dissolution. Add the prepared lauric acid solution to the ion membrane cross-linking solution at a ratio of 1:10 (v / v), and gently stir the mixed solution to ensure that the lauric acid solution is evenly dispersed in the ion membrane-cross-linking solution. At this time, the lauric acid molecules will interact with the functional groups such as carboxyl in the ion membrane through their long-chain fatty acid groups to improve the hydrophobicity of the membrane. Place the mixed solution in a 50°C constant temperature water bath and continue the reaction for 30 minutes. At this temperature, the lauric acid molecules can better react with the functional groups in the ion membrane to form a stable hydrophobic ion membrane. During the reaction, you can gently stir it at the right time to ensure uniform modification. Let it stand for more than 12 hours until the stable structure of the membrane is finally formed. Use a scanning electron microscope to observe the surface morphology of the modified membrane and check the uniformity and hydrophobicity of the membrane.

[0078] Experimental Example 1 Characterization of the morphology of hydrophobic ion membranes of Pseudomonas aeruginosa

[0079] (1) Experimental methods

[0080] Take an appropriate amount of the dried Pseudomonas aeruginosa hydrophobic ion membrane sample prepared in Example 2-4, and fix the sample on the SEM sample stage using an aluminum mesh or conductive glue. In order to obtain a better imaging effect, a thin metal layer (such as gold or platinum) can be coated on the surface of the membrane to improve the conductivity of the membrane. The surface microscopic morphology of the membrane is observed using a scanning electron microscope to analyze the uniformity, roughness, pore structure and other characteristics of the "pinned" ion membrane surface.

[0081] (2) Analysis of experimental results

[0082] Overall, the hydrophobic ion membranes of Pseudomonas aeruginosa in different embodiments all possess key features for successful hydrophobic modification, including porous structure, particle distribution and surface continuity, among which the formed morphology of Embodiment 2 is more ideal.

[0083] The hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 2 is shown in Figure 1 , it can be clearly seen in the figure that large and small pores are evenly distributed, indicating that the ion membrane has a porous characteristic, which provides a channel for the migration and distribution of fluids in the reservoir and helps to improve the adaptability of the membrane. Many Ca 2+ The crystal particles formed during the cross-linking reaction with the ion membrane, the uniform distribution of the particles helps to enhance the mechanical strength and stability of the membrane, and there is almost no impurity deposition. The fine fibrous structure visible in some areas is a network structure formed after the cross-linking of the molecular chains of the ion membrane. This fibrous structure gives the membrane better flexibility and fracture resistance. The combination of surface roughness and pore structure can enhance the hydrophobic effect.

[0084] Example 3: The hydrophobic ion membrane of Pseudomonas aeruginosa prepared Figure 2 The distribution of large and small pores can be clearly seen in the figure, indicating that the membrane has a porous characteristic, which helps to increase the surface area and functionality of the membrane. The diameter and distribution of the pores are relatively uneven, and there may be local differences in interaction during the cross-linking process. There are a large number of particles "pinned" on the membrane surface, which are Mg 2+ The uniformity of the particles is closely related to the hydrophobic modification effect of the membrane, and the surface of the membrane shows a typical uneven morphology, which is related to the distribution of palmitic acid and the cross-linking effect of the molecular structure of the ion membrane. The formation and stability of the pores indicate that the cross-linking reaction is successful, but the distribution of the particles indicates that the reaction system still needs to be optimized to reduce impurity deposition.

[0085] Example 4: The hydrophobic ion membrane of Pseudomonas aeruginosa prepared Figure 3 The distribution of large and small pores can be clearly seen in the figure, indicating that the membrane has porous characteristics, and the diameter and distribution of the pores are relatively uniform. This structure helps to improve its adsorption capacity and fluid transmission performance during oil recovery. The granular substances "pinned" on the membrane surface are Na + The complex formed during the cross-linking reaction with the ion membrane enhances the structural stability of the membrane. The overall membrane surface appears to be relatively continuous, but a small amount of uneven areas can still be seen, and impurity deposition exists in local areas. This may be related to the conditions of the cross-linking and hydrophobic modification reactions (such as stirring intensity or temperature control), and further optimization of the reaction conditions may improve it. The three-dimensional pore structure and particle distribution of the membrane may provide hydrophobic interaction sites, which help to form an effective barrier at the oil-water interface, thereby improving its oil-water separation ability and interface stability.

[0086] Experimental Example 2 Structural Stability Analysis

[0087] (1) Experimental methods

[0088] The membrane microstructure, crack size, thickness and its adhesion to the core surface were analyzed by scanning electron microscopy.

[0089] (2) Analysis of experimental results

[0090] The hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 2 is shown in Figure 4 , showing that there are larger crystal particles "pinned" on the membrane surface, these particles have clear geometric boundaries, indicating that the ion deposition during the cross-linking process forms a stable crystal structure, the embedding characteristics enhance the mechanical strength and stability of the membrane, the crack size is small, will not seriously damage the integrity of the membrane, the membrane surface is smooth and uniform. The hydrophobic ion membrane of Pseudomonas aeruginosa prepared in Example 2 has the best effect.

[0091] Example 3: The hydrophobic ion membrane of Pseudomonas aeruginosa prepared Figure 5, showing that a complex microstructure with a "pinning" effect is formed on the surface of the hydrophobic ion membrane, but the crack size is large, indicating that the stability of the membrane in the local area may be limited, and the overall integrity of the membrane is mainly maintained by the interweaving of filamentous fibrous substances. This structural characteristic may cause the hydrophobic membrane to be slightly less effective than the uniform and dense membrane of Example 2 in dealing with high permeability channel blocking, and may also reduce the suppression of water phase permeability. Despite this, its super-hydrophobic properties and micro-morphology still retain the effect of improving oil displacement efficiency to a certain extent, but the formation conditions of the membrane still need to be optimized to improve the structural integrity.

[0092] Example 4: The hydrophobic ion membrane of Pseudomonas aeruginosa prepared Figure 6 The Pseudomonas aeruginosa hydrophobic ion membrane shows good integrity and uniformity in microstructure. There are few cracks on the membrane surface, and the width and depth of the cracks are relatively limited, reflecting the continuity and stability of the membrane structure, which can play a stable synergistic role in the process of oil well throughput.

[0093] Experimental Example 3: Interfacial tension and hydrophobic effect test

[0094] (1) Experimental methods

[0095] The Pseudomonas aeruginosa ion membranes prepared in different embodiments at different temperatures were designed to perform interfacial tension tests, and the interfacial tension values ​​of different solutions were compared. Representative dry reservoir cores were selected and immersed in the Pseudomonas aeruginosa throughput enhancer for a period of time. The contact angle of the treated cores was measured using a contact angle meter (see Figure 8 ). Compare the changes in contact angle of the core before and after treatment.

[0096] (2) Analysis of experimental results

[0097] The results are as follows Figure 7 As shown, the different Pseudomonas aeruginosa hydrophobic ion membrane oil well throughput enhancement systems prepared in Examples 2-4 have a greater effect on the oil-water interfacial tension at different temperatures. As the temperature increases, the interfacial tension between all embodiments and crude oil gradually decreases. When the temperature rises, it can not only reduce the viscosity of crude oil, but also enhance the activity of the Pseudomonas aeruginosa ion membrane, intensify the thermal motion of the molecules on the membrane surface and the liquid molecules, facilitate the diffusion of the ion membrane, and weaken the intermolecular interaction forces (such as van der Waals forces and hydrogen bonding). It is easier for the interface molecules to rearrange and the interfacial tension is reduced. Among them, Example 2 has the best effect in reducing the interfacial tension.

[0098] The hydrophobicity of different Pseudomonas aeruginosa "pinning" hydrophobic ion membrane oil well throughput enhancement systems prepared in Examples 2-4 is shown in Table 1. The tight network structure formed helps to form a better hydrophobic surface, and the uniform microporous structure on the membrane surface makes the distribution of hydrophobic molecules more uniform. The crystals formed by the combination of the hydrophobic component and the ion membrane can increase the hydrophobicity. The more uniform the crystal distribution, the stronger the hydrophobic ability of the membrane. The oil-gas-solid equilibrium contact angle of the core interface was measured. After the water-wet core was soaked in different Pseudomonas aeruginosa "pinning" ion membranes prepared in Examples 2-4 for 24 hours, the contact angle was always greater than 130°, among which the super hydrophobic performance of Example 2 was the best.

[0099] Table 1 Hydrophobicity of Pseudomonas aeruginosa "pinning" hydrophobic ion membrane prepared in Examples 2-4

[0100]

[0101] Experimental Example 4 Determination of permeability adjustment effect

[0102] (1) Experimental methods

[0103] The oil-water permeability experiment of the hydrophobic ion membrane of Pseudomonas aeruginosa prepared in different embodiments was designed, and the effect of the throughput agent concentration on the relative permeability was revealed based on the characteristic point analysis of the permeability curve.

[0104] (2) Analysis of experimental results

[0105] The oil-water relative permeability experiment found that the Pseudomonas aeruginosa hydrophobic ion membranes prepared in different embodiments can effectively reduce the relative permeability of the water phase and increase the relative permeability of the oil phase in the low permeability core, as shown in Table 2, where n is w and n o are the phase permeability shape factors of the water phase and the oil phase, respectively, K rw and K ro are the permeability endpoint values ​​of the water phase and the oil phase, respectively. Due to the formation of a stable hydrophobic ion membrane, the preferential flow ability of the oil phase in the large pores is enhanced, thereby improving the fluid displacement efficiency in the core.

[0106] The water phase shape factor and endpoint value decreased, indicating that the system can effectively reduce the contribution of water phase seepage, reflecting the effect of inhibiting water phase permeability; the oil phase shape factor and endpoint value increased, indicating that it has a good effect in improving the oil phase permeability. As can be seen from Table 2, the Pseudomonas aeruginosa hydrophobic ion membrane prepared in Example 2 performed best in regulating the relative permeability of the water phase and the oil phase, showing a higher oil phase enhancement effect.

[0107] Table 2 Variation of phase permeability parameters in different embodiments

[0108]

[0109] Experimental Example 5 Oil displacement experiment (1) Experimental method

[0110] An oil displacement experiment was carried out using the Pseudomonas aeruginosa hydrophobic ion membrane prepared in different embodiments as a throughput agent in a low permeability (porosity of about 15%, permeability of about 25 mD) core. At a temperature of about 25°C, the core recovery rates of a water flooding and a Pseudomonas aeruginosa "pinning" ion membrane oil well throughput enhancement system were recorded respectively.

[0111] (2) Analysis of experimental results

[0112] The recovery rates of the throughput agents of different embodiments after injection into the core are shown in Table 3. The recovery rate of the first water drive is only about 26%. The recovery rate is improved after the throughput agent is injected, and the final recovery rate can reach about 38%. The recovery rate of Example 2 is the highest, which is 38.93%. This is because the ion membrane secreted by Pseudomonas aeruginosa forms a stable "pinned" ion membrane with the rock surface under the action of the cross-linking agent, which can maintain hydrophobic properties and structural integrity for a long time. The hydrophobic properties of the membrane surface reduce the adhesion between the oil and the rock surface, enhance the flow ability of the oil phase, and at the same time, the hydrophobic membrane changes the fluid distribution characteristics in the pore network, making the water drive more uniform, avoiding "water channeling", and improving the oil recovery efficiency.

[0113] Table 3 Changes in recovery factor after injection in different embodiments

[0114]

[0115] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A pinning structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa, characterized in that: It is obtained by cross-linking the biofilm secreted by Pseudomonas aeruginosa with an ion solution, and then adding long-chain fatty acids or long-chain fatty acid salts for modification; Wherein, the long-chain fatty acid or long-chain fatty acid salt comprises a fatty acid or fatty acid salt containing an alkyl chain of ≥12 carbons or lauric acid; The ion solution includes CaCl2 solution, MgCl2 solution and NaCl solution.

2. A method for preparing a hydrophobically modified ion membrane based on a pinning structure of Pseudomonas aeruginosa as claimed in claim 1, characterized in that: The method comprises the following steps: after the biofilm secreted by Pseudomonas aeruginosa is cross-linked with an ion solution, long-chain fatty acids or long-chain fatty acid salts are added for modification to obtain a hydrophobically modified ion membrane based on the "pinning" structure of Pseudomonas aeruginosa.

3. The preparation method according to claim 2, characterized in that: The ionic solution includes a CaCl2 solution, a MgCl2 solution and a NaCl solution. The concentration of the ionic solution is 0.1-0.5M and the pH value is 6-8.

4. The preparation method according to claim 3, characterized in that: Dissolving the lyophilized powder of the biofilm into a biofilm solution and then stirring the biofilm solution with the ion solution at 25° C. and 200-300 rpm for 30-60 minutes to perform a cross-linking reaction; When the ion solution is a CaCl2 solution, the volume ratio of the biofilm solution to the CaCl2 solution is 1:1 to 1:5; When the ion solution is a MgCl2 solution, the volume ratio of the biofilm solution to the MgCl2 solution is 1:1 to 1:7; When the ion solution is a NaCl solution, the volume ratio of the biofilm solution to the NaCl solution is 1:10 to 1:

15.

5. The preparation method according to claim 4, characterized in that: The freeze-dried powder of the biofilm is prepared by expanding and culturing Pseudomonas aeruginosa, separating the biofilm and bacterial cells in the culture solution, and collecting the supernatant; then mixing the supernatant with an equal volume of ethanol, standing, centrifuging, and collecting the precipitate; resuspending the precipitate with deionized water, dialyzing, and freeze-drying the dialyzate to obtain the freeze-dried powder of the biofilm.

6. The preparation method according to claim 2, characterized in that: A long-chain fatty acid or a long-chain fatty acid salt is dissolved to prepare a hydrophobic modification solution, and then the hydrophobic modification solution is added to a cross-linking reaction system, and then placed in a constant temperature water bath at 50°C for reaction for 30 to 40 minutes to obtain a pinning structure hydrophobically modified ion membrane based on Pseudomonas aeruginosa; wherein the volume ratio of the hydrophobic modification solution to the cross-linking reaction system is (1:5) to (1:10), and the concentration of the hydrophobic modification solution is 0.1% to 1% w / v.

7. Use of the hydrophobic modified ion membrane according to claim 1 in the preparation of an oil well throughput enhancer.

8. An oil well throughput enhancer, characterized in that: Contains the hydrophobically modified ion membrane according to claim 1.

9. Use of the hydrophobic modified ion membrane according to claim 1 or the oil well throughput enhancer according to claim 8 in any of the following: (1) Application in improving oil well throughput efficiency; (2) Application in improving oil well displacement efficiency and oil recovery effect; (3) Application in improving the water control and oil production increase effect of oil wells; (4) Application in improving oil well recovery; (5) Application in increasing oil well production.

10. A method for improving oil well recovery, characterized in that: The method comprises the steps of applying the hydrophobically modified ion membrane of claim 1 to an oil well as an oil well throughput enhancer to improve the oil well recovery rate.

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