Rhamnolipid composite oil displacement agent as well as preparation method and application thereof
By combining rhamnolipin with a specific structure produced by fermentation of Pseudomonas aeruginosa CCTCC NO. 2025023 with additives, a rhamnolipin complex oil displacement agent was formed, which solved the problems of high interfacial tension and high cost of rhamnolipin oil displacement agents alone, and achieved the effect of lower interfacial tension and higher recovery rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- IMINGTAI (SHANDONG) BIOTECHNOLOGY CO LTD
- Filing Date
- 2026-01-19
- Publication Date
- 2026-05-08
AI Technical Summary
When rhamnolipin is used alone as an oil displacement agent, it is difficult to reduce the interfacial tension to an extremely low level, resulting in limited recovery, high production costs, and easy adsorption or degradation, making it difficult to cope with complex reservoir types.
A rhamnolipin complex oil displacement agent was formed by fermenting a specific structure of rhamnolipin produced by Pseudomonas aeruginosa CCTCC NO. M 2025023 and compounding it with additives such as coconut oil fatty acid diacetamide, sodium dodecylbenzene sulfonate, sodium cocoyl glycinate, cocoyl dimethyl betaine, and oleamidopropyl betaine.
It achieves lower interfacial tension and higher oil recovery, reduces operating costs, improves oil displacement activity, adapts to complex reservoirs, and has environmental and economic advantages.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of oilfield enhanced oil recovery (EOR) technology, specifically to a rhamnolipin complex oil displacement agent, its preparation method, and its application. Background Technology
[0002] Petroleum is a core energy source and industrial raw material for modern society, a strategic resource supporting socio-economic operations and ensuring national energy security. Petroleum is the "lifeblood" of the economy; for example, it provides fuel for transportation and raw materials for the chemical and manufacturing industries. Petroleum is also the "ballast" of energy security. my country's dependence on imported crude oil exceeds 70%, and older oilfields account for over 90% of the national output, but their recovery rates are generally low, and extraction difficulties are gradually increasing. Improving oil recovery rates through technological means, enabling more crude oil to be extracted efficiently and economically, can extend the lifespan of oilfields, promote their sustainable development, and enhance their competitiveness and resilience. In short, improving oil recovery rates is crucial for promoting high-quality development of oilfields, effectively alleviating resource replacement pressures, and supporting energy security.
[0003] Currently, oil extraction primarily relies on chemical flooding technologies such as ternary composite flooding. While chemical flooding agents can significantly improve oil recovery rates, long-term use can lead to reservoir damage, increased water treatment difficulties, and environmental harm, resulting in high overall costs. Therefore, developing efficient, environmentally friendly, and economical novel bio-based flooding agents is of significant application value for achieving green and sustainable oilfield development, addressing the need to enhance oil recovery rates.
[0004] Rhamnolipids are glycolipid biosurfactants produced by microbial fermentation. They can reduce interfacial tension between oil and rock, and between oil and water, disperse and emulsify crude oil, and alter rock wettability. Compared to traditional chemical surfactants, rhamnolipids offer advantages such as good environmental compatibility, biodegradability, and high activity. Using rhamnolipids as an enhanced oil recovery (EOR) agent aligns with the green development needs of oilfields.
[0005] However, using rhamnolipin alone as an oil displacement agent has the following limitations: While rhamnolipin can reduce the interfacial tension between oil and water, it is often difficult to reduce the interfacial tension to extremely low levels when used alone, affecting oil displacement and limiting the improvement in oil recovery. The production cost of rhamnolipin is relatively high, requiring a large dosage to achieve a certain oil displacement effect when used alone, which increases usage costs. Rhamnolipin is easily adsorbed or degraded in the formation when used alone, reducing the effective concentration and affecting the oil displacement effect. Rhamnolipin has diverse structural compositions, and different structural types of rhamnolipin exhibit varying oil displacement activities. The emulsifying and interfacial activities of rhamnolipin when used alone are limited, making it difficult to cope with complex reservoir types. Rhamnolipin-based oil displacement systems can synergistically enhance emulsifying and interfacial activities through structural complementarity, while the use of rhamnolipin alone lacks this synergistic effect.
[0006] In summary, the effect of using rhamnolipin alone as an oil displacement agent on improving oil recovery is limited. This invention develops a rhamnolipin-based composite oil displacement agent based on rhamnolipin with a specific structure produced by microbial fermentation, providing a novel oil recovery agent for oilfield development. Summary of the Invention
[0007] To address the aforementioned problems in the prior art, this invention provides a rhamnolipin complex oil displacement agent, its preparation method, and its application. This invention discloses the oil displacement-related activity parameters of a specific structural rhamnolipin produced by fermentation of *Pseudomonas aeruginosa* CCTCC NO. M 2025023. Further research on the compound system led to the development of a rhamnolipin complex oil displacement agent. This invention's rhamnolipin complex oil displacement agent exhibits high oil displacement activity, is simple to prepare, economical, and environmentally friendly, and can be used to enhance oil recovery.
[0008] To achieve the above objectives, the present invention adopts the following technical solution: A rhamnolipin complex oil displacement agent, characterized in that: the main active ingredient of the complex oil displacement agent is rhamnolipin, wherein the concentration of rhamnolipin is ≥0.02wt%.
[0009] The rhamnolipin was obtained from *Pseudomonas aeruginosa* with accession number CCTCC NO. M 2025023. Pseudomonas aeruginosa The rhamnolipids produced by fermentation account for 63% of the disaccharide diesters, 27% of the monosaccharide diesters, and a total of 10% of the monosaccharide monoesters and disaccharide monoesters.
[0010] The rhamnolipin complex oil displacement agent also contains the following five additives: coconut oil fatty acid diacetamide (CDEA1:2), sodium dodecylbenzene sulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB).
[0011] The rhamnolipin complex oil displacement agent is in liquid form, with a solution pH of 7.0~9.5.
[0012] The rhamnolipin complex oil displacement agent is a liquid obtained by dissolving and mixing coconut oil fatty acid diacetamide (CDEA 1:2), sodium dodecylbenzenesulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB) in the fermentation supernatant of rhamnolipin-producing bacteria; or a liquid obtained by dissolving and mixing rhamnolipin, coconut oil fatty acid diacetamide (CDEA 1:2), sodium dodecylbenzenesulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB) in water; or a diluted solution of the above liquids.
[0013] The rhamnolipin complex oil displacement agent contains rhamnolipin at a final concentration of 0.03-0.3 wt%, coconut oil fatty acid diacetamide (CDEA 1:2) at a final concentration of 0.05-0.25 wt%, sodium dodecylbenzenesulfonate (SDBS) at a final concentration of 0.05-0.25 wt%, sodium cocoyl glycinate (GCS) at a final concentration of 0.03-0.15 wt%, cocoyl dimethyl betaine (BS-814) at a final concentration of 0.05-0.25 wt%, and oleamidopropyl betaine (OAB) at a final concentration of 0.03-0.15 wt%.
[0014] The preparation method of the rhamnolipin complex oil displacement agent includes the following steps: (1) aerobic fermentation of Pseudomonas aeruginosa CCTCCNO. M 2025023 to produce rhamnolipin, and obtain rhamnolipin fermentation broth; (2) centrifuge or filter the fermentation broth to remove bacteria and other insoluble matter, and obtain rhamnolipin fermentation supernatant; or remove bacteria and other insoluble matter from the fermentation broth and further extract the product to obtain rhamnolipin extract; (3) dilute the rhamnolipin fermentation supernatant and add 5 additives in the prescribed amount, or add rhamnolipin extract and 5 additives in the prescribed amount to water, stir to dissolve and mix, and adjust the pH value to 7.0~9.5 to obtain rhamnolipin complex oil displacement agent; (4) pack the rhamnolipin complex oil displacement agent into barrels.
[0015] The surface tension of the rhamnolipin composite oil displacement agent is ≤30 mN / m and the interfacial tension is ≤0.5 mN / m.
[0016] The rhamnolipin complex oil displacement agent has an emulsifying activity index (EI) for crude oil. 24 ≥65%.
[0017] The core model of the rhamnolipin composite oil displacement agent enhances oil recovery by ≥10%.
[0018] The rhamnolipin complex oil displacement agent has application value in enhancing oil recovery.
[0019] The beneficial effects of this invention are as follows: Compared to single rhamnolipin-based oil displacement systems, the rhamnolipin composite oil displacement agent of this invention can reduce interfacial tension to a lower level and can also reduce the amount of rhamnolipin used through synergistic effects, thereby lowering usage costs. Furthermore, the components in this rhamnolipin composite oil displacement agent synergistically enhance oil recovery. This invention develops a rhamnolipin composite oil displacement agent based on rhamnolipins with specific structures produced by microbial fermentation, providing a novel oil recovery agent for oil extraction.
[0020] The rhamnolipin used in this invention is produced by fermentation using high-yield rhamnolipin strains, and industrial-scale fermentation production has been achieved, resulting in low overall production costs. This gives the development of compound oil displacement agents based on this rhamnolipin advantages such as low usage costs and high economic benefits.
[0021] Compared with other technical methods, the rhamnolipin composite oil displacement agent of the present invention has high oil displacement activity, is simple to prepare, economical and environmentally friendly, and provides a new oil displacement agent for oil extraction. Attached Figure Description
[0022] Picture 1 Comparison of activity indicators between rhamnolipin-based oil displacement agents and rhamnolipin-based compound oil displacement agents. Detailed Implementation
[0023] The present invention will be described in detail below with reference to specific embodiments to enable those skilled in the art to more fully understand the invention, but this does not limit the invention in any way. In the following embodiments, unless otherwise specified, the materials and reagents used can be purchased from biochemical reagent material companies.
[0024] Example 1: Fermentation production of rhamnolipids The rhamnolipid-producing bacterium used in this embodiment is *Pseudomonas aeruginosa*. Pseudomonas aeruginosa )CCTCC NO. M 2025023.
[0025] Weigh the required reagents and prepare liquid LB medium. The LB medium formula is as follows: 10.0 g / L tryptone, 5.0 g / L yeast extract, 10.0 g / L sodium chloride, and the balance is water; adjust the pH to 7.0.
[0026] Weigh the required reagents and prepare the culture medium for fermentation production of rhamnolipids. The fermentation medium formula is as follows: soybean oil 60.0 g / L, glycerol 60.0 g / L, sodium nitrate 6.0 g / L, yeast extract 2.0 g / L, potassium dihydrogen phosphate 4.0 g / L, dipotassium hydrogen phosphate trihydrate 5.0 g / L, sodium chloride 1.0 g / L, magnesium sulfate heptahydrate 1.2 g / L, potassium chloride 1.0 g / L, calcium chloride 0.1 g / L; adjust the pH to 6.8.
[0027] The dispensed LB medium and fermentation medium were sterilized under high pressure steam at 121°C for 20 min. After the medium cooled to below 30°C, inoculum was introduced.
[0028] Pseudomonas aeruginosa ( Pseudomonas aeruginosa CCTCC NO. M 2025023 strain was inoculated into LB medium and cultured at 35℃ and 180 rpm for 12 hours to prepare a seed culture of *Pseudomonas aeruginosa* CCTCC NO. M 2025023. The *P. aeruginosa* CCTCC NO. M 2025023 seed culture was inoculated at a rate of 5% (v / v) into a 6-liter fermenter containing 2.5 L of fermentation medium. Fermentation conditions were 35℃, 390 rpm, and aeration 1.1 vvm. On days 3 and 4 of fermentation, soybean oil (15 g / L), glycerol (15 g / L), and sodium nitrate (3.0 g / L) were added, respectively. Fermentation was continued for a total of 6 days to produce rhamnolipin. After fermentation, the rhamnolipin fermentation broth was obtained.
[0029] Example 2: Preparation of fermentation supernatant and extraction and analysis of rhamnolipids The rhamnolipin fermentation broth from Example 1 was filtered through filter paper to remove residual oils and other insoluble substances, and the filtrate was collected. Dilute sodium hydroxide solution was added to the filtrate to adjust the pH to 8.0, and the mixture was centrifuged at 10,000 r / min for 10 min to remove bacterial cells, and the supernatant was collected. The supernatant was then heated in a 90℃ water bath for 20 min to denature and precipitate soluble proteins and other substances. After cooling to room temperature, the mixture was centrifuged at 10,000 r / min for 10 min, and the supernatant was collected again to obtain the rhamnolipin fermentation supernatant. The concentration of rhamnolipin in the supernatant was determined to be 100.68 g / L using liquid chromatography.
[0030] Dilute hydrochloric acid solution was added to the fermentation supernatant of rhamnolipin to adjust the pH to 2.0, reducing the solubility of rhamnolipin in the aqueous phase. The acidified solution was centrifuged at 10,000 r / min for 10 min, and most of the supernatant was discarded. An equal volume of ethyl acetate was added to the remaining liquid containing the precipitate, and the rhamnolipin was extracted three times. The extracts were collected. The organic solvent in the extracts was removed using a rotary evaporator to obtain a brownish-yellow viscous substance, i.e., the rhamnolipin extract. Liquid chromatography analysis showed that the rhamnolipin product contained 63% disaccharide diesters, 27% monosaccharide diesters, and a total of 10% monosaccharide and disaccharide monoesters.
[0031] Example 3: Preparation of rhamnolipin complex oil displacement agent The rhamnolipin fermentation supernatant from Example 2 was diluted with water to a rhamnolipin concentration of 0.5 g / L. Five additives were added to the diluted rhamnolipin fermentation supernatant, with final concentrations of 1.5 g / L for coconut oil fatty acid diacetamide (CDEA 1:2), 1.5 g / L for sodium dodecylbenzenesulfonate (SDBS), 1.0 g / L for sodium cocoyl glycinate (GCS), 1.5 g / L for cocoyl dimethyl betaine (BS-814), and 1.0 g / L for oleamidopropyl betaine (OAB). The mixture was stirred to dissolve and mix, and the pH was adjusted to 8.0 to obtain the rhamnolipin complex oil displacement agent SQ.
[0032] Weigh the rhamnolipin extract from Example 2, dissolve it in water, and use a concentration of 0.5 g / L for rhamnolipin. Weigh out 1.5 g / L each of the following additives: 1.5 g / L of coconut oil fatty acid diacetamide (CDEA 1:2), 1.5 g / L of sodium dodecylbenzenesulfonate (SDBS), 1.0 g / L of sodium cocoyl glycinate (GCS), 1.5 g / L of cocoyl dimethyl betaine (BS-814), and 1.0 g / L of oleamidopropyl betaine (OAB). Add these additives to the rhamnolipin solution, stir to dissolve and mix, and adjust the pH to 8.0 to obtain the rhamnolipin complex oil displacement agent TQ.
[0033] Example 4 The supernatant of rhamnolipin fermentation from Example 2 was diluted with water to a rhamnolipin concentration of 1.0 g / L, and the pH was adjusted to 8.0 to prepare the rhamnolipin-only oil displacement agent DSQ.
[0034] Weigh the rhamnolipin extract from Example 2, prepare a 1.0 g / L rhamnolipin solution with water, adjust the pH to 8.0, and obtain the rhamnolipin-only oil displacement agent DTQ.
[0035] Example 5 The test samples used in this embodiment are the two rhamnolipin composite oil displacement agents SQ and TQ prepared in Example 3, as well as the two individual rhamnolipin oil displacement agents DSQ and DTQ prepared in Example 3.
[0036] The surface tension of the samples was determined using a fully automated surface / interfacial tensiometer at 25°C. The platinum plate method was used to determine surface tension, and the platinum ring method was used to determine interfacial tension. The emulsification index (EI) was used to measure the interfacial tension. 24 The emulsifying activity of the sample on crude oil was characterized. 3 mL of sample was added to a 25 mL transparent colorimetric tube, followed by 3 mL of crude oil. The tube was vortexed for 2 min, then allowed to stand at room temperature for 24 hours. The heights (mm) of the oil and water phases were measured and recorded. The emulsification index (EI) was then determined. 24 The value is equal to the oil phase height divided by the total phase height and then multiplied by 100%. The results of this embodiment are shown in Table 1.
[0037] Table 1: Performance parameters of different oil displacement agent samples The data in Table 1 show that the rhamnolipin-based composite oil displacement agent exhibits better interfacial and emulsifying activities compared to single oil displacement agents containing only rhamnolipin. Table 1 also shows that the rhamnolipin-based composite oil displacement agents SQ and TQ, prepared from rhamnolipin fermentation supernatant and rhamnolipin extract respectively, show no significant differences in surface / interfacial activity and crude oil emulsifying activity. Compared to a single rhamnolipin oil displacement system (containing 1.0 g / L rhamnolipin), the rhamnolipin-based composite oil displacement agent of this invention (containing 0.5 g / L rhamnolipin) can also reduce the amount of rhamnolipin used through a synergistic effect, thereby lowering usage costs. The rhamnolipin-based composite oil displacement agent of this invention has low surface / interfacial tension and excellent crude oil emulsifying activity, which helps to improve oil recovery.
[0038] Example 6 To better compare the interfacial and oil displacement activities of a single oil displacement system containing only rhamnolipin and the rhamnolipin composite oil displacement agent of this invention, this embodiment uses a rotating drop interfacial tensiometer to measure the interfacial tension values of the samples and uses core physical simulation oil displacement experiments to evaluate the oil displacement efficiency of the oil displacement agent samples. The oil displacement agent samples compared in this embodiment are the rhamnolipin composite oil displacement agent SQ prepared in Example 3 and the rhamnolipin-only oil displacement agent DSQ prepared in Example 4.
[0039] The method for measuring the interfacial tension of a rotating droplet is based on the industry standard SY / T 5370-2018, "Methods for Measuring Surface and Interfacial Tension," with a rotation speed of 5000 rpm and a temperature of 55℃.
[0040] The core physical simulation oil displacement experiment method is briefly described as follows: Dry the core and weigh its dry weight; vacuum and saturate the core with water; weigh the core wet weight and calculate the core pore volume (PV) based on the weight difference. Saturate the core with oil and record the volume of water flowing out of the core outlet, which is the saturated oil volume. Calculate the core oil saturation (the ratio of saturated oil volume to core pore volume (PV)). Close the valves at both ends of the core and let it sit for 2 days for aging. Connect the core to the water-drive process, open the valves at both ends of the core, and perform a first water drive. Record the oil output, water output, and pressure every hour until no oil is produced for 8 consecutive hours. The water drive is then complete, and the first water drive recovery rate is calculated. Connect an intermediate container containing the oil displacement agent to the process and inject the oil displacement agent into the core; close both ends of the core and let it sit for 3-5 days before performing a second water drive. After the second water drive is complete, calculate the second water drive recovery rate, which is the recovery rate increased by the oil displacement agent.
[0041] The results of this embodiment are as follows: Picture 1 As shown. The interfacial tension of the single oil displacement system containing only rhamnolipin (1 g / L) was 0.556 mN / m, as measured by the rotating drop method, while the interfacial tension of the rhamnolipin composite oil displacement agent of this invention was 0.077 mN / m. Core model experiments showed that the single oil displacement system containing only rhamnolipin increased the oil recovery rate by 5.29% on the basis of a single waterflooding operation, while the rhamnolipin composite oil displacement agent of this invention can increase the oil recovery rate by 14.46% on the basis of a single waterflooding operation.
[0042] Compared with single oil displacement systems containing only rhamnolipin, the rhamnolipin composite oil displacement agent of this invention can reduce the interfacial tension to a lower level, reaching 10. -2 The oil recovery rate can be improved by synergistic effect of various components, increasing the oil recovery rate by more than 10 percentage points on the basis of primary water drive.
[0043] This invention utilizes rhamnolipin with a specific structure produced by the fermentation of *Pseudomonas aeruginosa* CCTCC NO. M 2025023 as the main active ingredient, and develops a rhamnolipin composite oil displacement agent through component compounding. Compared with single rhamnolipin oil displacement systems, this invention's rhamnolipin composite oil displacement agent can reduce interfacial tension to a lower level, reduce the amount of rhamnolipin used through synergistic effects, thereby reducing usage costs, and the components synergistically enhance oil recovery. Compared with other technologies, this invention's rhamnolipin composite oil displacement agent has high oil displacement activity, is simple to prepare, economical and environmentally friendly, and has application value in improving oil recovery.
Claims
1. A rhamnolipin complex oil displacement agent, characterized in that: The main active ingredient of the composite oil displacement agent is rhamnolipin, wherein the concentration of rhamnolipin is ≥0.02wt%. The rhamnolipin was obtained from *Pseudomonas aeruginosa* with accession number CCTCC NO. M 2025023. Pseudomonas aeruginosa The rhamnolipids produced by fermentation account for 63% of the disaccharide diesters, 27% of the monosaccharide diesters, and a total of 10% of the monosaccharide monoesters and disaccharide monoesters. The rhamnolipin complex oil displacement agent also contains the following five additives: coconut oil fatty acid diacetamide (CDEA 1:2), sodium dodecylbenzene sulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB).
2. The rhamnolipin complex oil displacement agent according to claim 1, characterized in that: The composite oil displacement agent is in liquid form, with a solution pH of 7.0~9.
5.
3. The rhamnolipin complex oil displacement agent according to claims 1-2, characterized in that: The composite oil displacement agent is a liquid obtained by dissolving and mixing coconut oil fatty acid diacetamide (CDEA 1:2), sodium dodecylbenzenesulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB) in the fermentation supernatant of rhamnolipid-producing bacteria, or a liquid obtained by dissolving and mixing rhamnolipid, coconut oil fatty acid diacetamide (CDEA 1:2), sodium dodecylbenzenesulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB) in water, or a diluted solution of the above liquids.
4. The rhamnolipin complex oil displacement agent according to claim 1, characterized in that: The final concentrations of rhamnolipin, coconut oil fatty acid diacetamide (CDEA 1:2), sodium dodecylbenzenesulfonate (SDBS), sodium cocoyl glycinate (GCS), cocoyl dimethyl betaine (BS-814), and oleamidopropyl betaine (OAB) in the compound oil displacement agent are 0.03-0.3 wt%, 0.05-0.25 wt%, 0.05-0.25 wt%, and 0.03-0.15 wt%, respectively.
5. The preparation method of the rhamnolipin complex oil displacement agent according to claims 1 to 4 includes the following steps: (1) aerobic fermentation of Pseudomonas aeruginosa CCTCC NO. M 2025023 to produce rhamnolipin, and obtain rhamnolipin fermentation broth; (2) centrifuging or filtering the fermentation broth to remove bacteria and other insoluble matter, and obtain rhamnolipin fermentation supernatant; or removing bacteria and other insoluble matter from the fermentation broth and further extracting the product to obtain rhamnolipin extract; (3) diluting the rhamnolipin fermentation supernatant and adding 5 additives in the prescribed amount, or adding rhamnolipin extract and 5 additives in the prescribed amount to water, stirring to dissolve and mix, adjusting the pH value to 7.0 to 9.5, and obtaining rhamnolipin complex oil displacement agent; (4) packing the rhamnolipin complex oil displacement agent into barrels.
6. The rhamnolipin complex oil displacement agent according to claim 4, characterized in that: The surface tension of the composite oil displacement agent is ≤30 mN / m and the interfacial tension is ≤0.5 mN / m.
7. The rhamnolipin complex oil displacement agent according to claim 4, characterized in that: The composite oil displacement agent has an emulsification activity index (EI) of crude oil. 24 ≥65%.
8. The rhamnolipin complex oil displacement agent according to claim 4, characterized in that: The core model of the composite oil displacement agent enhances oil recovery by ≥10%.
9. The application of the rhamnolipin complex oil displacement agent according to claim 1 in enhancing oil recovery.