A Performance Evaluation of Glycolipid Biosurfactant Synthesized by the Enzyme-catalyzed Method

The practice of enhanced oil recovery (EOR) technique shows that the study and application of biosurfactant flooding system have a vast potential for future development. The authors challenge the traditional idea that the oil displacement surfactant must have ultra low interfacial tension. By changing the wettability of reservoir rock as main target, the glycolipid biosurfactant compounded system was developed by enzyme-catalyzed method in laboratory, and a series of experiments had been done combining with reservoir physical measurement. The properties of the active system were characterized by interfacial characters, disbonded, seepage characteristics, antibiotic property, and oil displacement efficiency.     

Injection of biosurfactant and chemical surfactant following hot water injection to enhance heavy oil recovery

This study investigates the potential of enhancing oil recovery from a Middle East heavy oil field via hot water injection followed by injection of a chemical surfactant and/or a biosurfactant produced by a Bacillus subtilis strain which was isolated from oil-contaminated soil. The results reveal that the biosurfactant and the chemical surfactant reduced the residual oil saturation after a hot water flood. Moreover, it was found that the performance of the biosurfactant increased by mixing it with the chemical surfactant. It is expected that the structure of the biosurfactant used in this study was changed when mixed with the chemical surfactant as a probable synergetic effect of biosurfactant-chemical surfactants was observed on enhancing oil recovery, when used as a mixture, rather than alone. This work proved that it is more feasible to inject the biosurfactant as a blend with the chemical surfactant, at the tertiary recovery stage. This might be attributed to the fact that in the secondary mode, improvement of the macroscopic sweep efficiency is important, whereas in the tertiary recovery mode, the microscopic sweep efficiency matters mainly and it is improved by the biosurfactant-chemical surfactant mixture. Also as evidenced by this study, the biosurfactant worked better than the chemical surfactant in reducing the residual heavy oil saturation after a hot water flood.     

内酯型槐糖脂生物表面活性剂性能评价

为寻找可应用于三次采油的新型生物表面活性剂,以内酯型槐糖脂生物表面活性剂为驱油剂,系统评价了其临界胶束浓度、表面活性、界面活性、乳化性能及耐温耐盐能力,并通过室内物理模拟驱油实验研究了其驱油效率.结果表明:内酯型槐糖脂生物表面活性剂的临界胶束浓度为100 mg/L,具有良好的表面和界面活性及乳化性能,其乳化性能比石油磺酸盐稳定;具有较强的耐温耐盐能力,适用于高温高盐的油藏环境;内酯型槐糖脂表面活性剂的有效驱油质量浓度为10 mg/L,随着其质量浓度的增加,驱油效率成倍增加,当其质量浓度达到10 000 mg/L时,可提高采收率7.15％,具有良好的驱油性能.通过实验还发现石英砂对内酯型槐糖脂表面活性剂的吸附量较少,说明其是比较经济的生物表面活性剂.     

Functional characterization of a biosurfactant-producing thermo-tolerant bacteria isolated from an oil reservoir

A Bacillus subtilis strain JA-1 isolated from an oil reservoir was studied.This strain is capable of growth and producing biosurfactant at a temperature of 60 oC.In nutrient medium it produced biosurfactant which reduced the surface tension from 68.2 mN/m to 28.3 mN/m,with the critical micelle concentration (CMC) of 48 mg/L.The measured surface tension indicated that the biosurfactant possessed stable surface activity at high temperature and a specific range of pH and salt concentrations.The results of thin layer chromatography (TLC) together with FT-IR showed that the metabolic product of strain JA-1 is a lipopeptide biosurfactant.The ability to growth at high temperature and to produce biosurfactant makes strain JA-1 promising for enhanced oil recovery.     

Production of biosurfactant from Bacillus licheniformis for microbial enhanced oil recovery and inhibition the growth of sulfate reducing bacteria

In this study, the bacterium Bacillus licheniformis has been isolated from oil reservoir; the ability of this bacterium to produce a biosurfactant was detected. Surface properties of the produced biosurfactant were confirmed by determining the emulsification power as well as surface and interfacial tension. The crude biosurfactant has been extracted from supernatant culture growth, and the yield of crude biosurfactant was about 1 g/l. Also, chemical structure of the produced biosurfactant was confirmed using FTIR analysis. Results revealed that, the emulsification power has been increased up to 96% and the surface tension decreased from 72 of distilled water to 36 mN/m after 72 h of incubation. The potential application of this bacterial species in microbial-enhanced oil recovery (MEOR) was investigated. The percent of oil recovery was 16.6% upon application in a sand pack column designed to stimulate an oil recovery. It also showed antimicrobial activity against the growth of different strains of SRB (sulfate reducing bacteria). Results revealed that a complete inhibition of SRB growth using 1.0% crude biosurfactant is achieved after 3 h.     

Production and Optimization of Microbial Surfactin by Bacillus subtilis for Ex Situ Enhanced Oil Recovery

In the research, biosurfactant production and the optimization of biosurfactant production conditions have been examined have been examined using one strain of Bacillus subtilis isolated from agricultural soil. For biosurfactant production, the optimum conditions were sucrose as carbon source, temperature at 37°C and 250 rpm. At 250 rpm, the optimum filling volume of culture media in a 500 mL Erlenmeyer flask was determined as 100 mL. The results show that shaking the flask should increase the oxygen transfer rate from gas phase to liquid phase, but if the filling volume of culture media is more than 100 mL, the oxygen limitation will be governed on the culture medium which results in the reduction of biomass and biosurfactant at 250 rpm. The oxygen limitation causes 23% and 18% reductions of biomass and biosurfactant, respectively. The biosurfactant produced also attained emulsion indexes as 80%, 75%, 68%, and 65% for crude oil, hexadecane, kerosene, and diesel, respectively. Oil displacement experiments in micromodel with kerosene show 25% higher recovery rate in residual oil using the proposed biosurfactant.     

Studies on the Production of Biosurfactant for the Microbial Enhanced Oil Recovery by Using Bacteria Isolated from Oil Contaminated Wet Soil

Abstract

There are obvious advantages of biosurfactants over chemical surfactants. The developing shortage of oil and rapid increase of oil prices is putting pressure on oil companies to recover as much oil as possible from the wells to sustain the oil economy. Therefore, there is a need to research some “super bugs,” which can produce active and stable biosurfactants in good yields. Five bacterial strains presently isolated from the oil-contaminated soil were selected for the screening for biosurfactant production, via three different methods: surface tension measurements, drop-collapsing test, and emulsification index (EI₂₄) test. Two thermophillic isolates coded as SGI and LFA were found to be the suitable candidates for biosurfactant production. In fact, the biosurfactant produced by the isolate SGI led to the reduction of surface tension up to 26 m/N/m; thus, SGI was selected for the further studies. Biosurfactant production by the thermophillic isolate SGI was found to be growth-associated in all conditions tested. Biosurfactant production using different cheaper carbon substrates was studied. The production of biosurfactant was also studied using isolate SGI, under different conditions of high temperature, NaCl concentration, pH, carbon source, and initial nitrogen concentration. The biosurfactant was found to produce a relatively stable emulsion with hydrocarbons at a wide range of pH. It was also found to be stable at various pH ranges (7.0–14.0) for SGI and was also found to be thermostable for 1 hr at 125°C, based on the value of surface tension. There is a wide array of further studies in the area of microbial enhanced oil recovery (MEOR) including further boosting the activity of the isolate by using adaptation, enrichment, and nutrient enrichment techniques.     

The Utilization of Lipid Waste for Biosurfactant Production and Its Application in Enhancing Oil Recovery

Abstract

In this article, biosurfactant production from low-cost and renewable substrate and its application in petroleum industry were studied. Pseudomonas aeruginosa DG30 grew on used vegetable oil and accumulated 15.56 g/L of biosurfactant at 72 hr. The biosurfactant exhibited excellent surface activity and stability. Sand package tests showed an approximately 20% increase of oil recovery by the treatment of bacterial culture broth. Single-well stimulation tests were conducted in a heavy oil reservoir in Dagang Oilfield, Tianjin, China. The blockages in the wellbore areas were removed effectively and more than 616 tons of crude oil was enhanced.     

Pseudomonas sp.LKY-5产生的表面活性剂提取及其稳定性研究

针对二苯并噻吩高效降解菌Pseudomonas sp.LKY-5降解过程中产生表面活性剂的现象,进行碳源优化,将提取分离出的表面活性剂进行化学组分分析和理化性质测定,考察温度、pH、无机离子对其表面活性稳定性的影响。结果表明,花生油为Pseudomonas sp.LKY-5产生表面活性剂的最佳碳源,产生的表面活性剂为鼠李糖脂,产量为0.15g/L,临界胶束浓度(CMC)为180mg/L,亲水亲油平衡值(HLB)为12.3,对柴油24h的乳化能力达61%。该表面活性剂在温度30~80℃、pH 6~13的条件下表面活性稳定,能够耐受200g/L的NaCl或MgCl2以及20g/L的CaCl2,稳定性能良好。     

Use of different methods for detection of thermophilic biosurfactant-producing bacteria from hydrocarbon-contaminated and bioremediated soils

Sixteen bacterial strains were isolated from petroleum hydrocarbons contaminated soils and screened for biosurfactants/bioemulsifiers production in liquid culture containing crude oil under thermophilic conditions. The bacterial strains grew in wide range of temperature, from 37 °C to 100 °C. Six of them were Gram positive. Their biosurfactant-production was evaluated at 45 °C.Blood agar lysis, drop-collapse method, oil spreading and stalagmometric techniques and surface tension (ST) measurements were used to detect biosurfactant production. Emulsification activity for culture broth was also tested using xylene, toluene, petroleum and diesel oils.All isolates reduced surface tension at varying degrees with strains: T/1 resulting in the highest reduction (35 mN/m). The drop-collapse, oil spreading and stalagmometric and reduction techniques all seem to give clear indicative results for biosurfactant production while blood hemolytic activity did not. The use of both the drop-collapse and oil spreading techniques were easy and quick to screen for biosurfactant producers but were not always conclusive.Although surface tension reduction was a good measure of biosurfactant production, it did not correlate well with emulsion ability. Several of our isolates had good emulsifying abilities with all hydrocarbon tested. The simplicity of the above techniques allows effective screening of biosurfactant-producing microorganisms. Although hemolytic activity have been reported as an initial selection criterion for biosurfactant producers, other more conclusive tests such as surface tension measurements should be carried out for confirmation of the obtained results.     

小井距生物表面活性剂三元复合驱矿场试验

小井距生物表面活性剂三元复合驱先导性矿场试验表明,将生物表面活性剂与磺酸盐类表面活性剂复配所形成的生物表面活性剂三元复合体系与未加入生物表面活性剂的三元复合体系相比,不仅左侧酸盐类表面活性剂的用量减少1/2,注入化学剂的成本降低了30%以上,而且体系与原油间仍能达到10^-3dmN/m超低界面张力值,取得中心井区提高采收率23.24%,全区提高采收率16.64%的好效果。     

生物表面活性剂驱油性能研究

为探讨生物表面活性剂菌种采油性能及矿场应用潜力,在吉林油区广泛取样,采用特定培养基对菌种进行筛选,在建立生物表面活性剂检测方法的基础上,对菌种生长代谢及发酵环境条件进行了分析。采用色谱法对菌种作用原油后组分变化进行了定性分析,在室内物模驱油效率试验的基础上,进行了矿场清防蜡应用试验。原油经生物表面活性剂菌作用后,油水界面张力降低到10～mN／m,原油黏度下降50％;室内物模驱油效率试验提高采收率10％以上,矿场清防蜡有效率〉65％,单井平均增油73．5t;在微生物强化水驱、油井清防蜡及近井解堵等MEOR工艺方面具有良好的应用前景。     

生物表面活性剂产生菌BYS6的产物特性与稳定性研究

从延长油田采油厂的土样中分离出一株不动杆菌BYS6(Acinetobacter sp.),在以甘油为碳源的培养基中发酵可产生生物表面活性剂,红外光谱检测该产物为糖脂类生物表面活性剂,在25℃室温条件下将发酵培养基表面张力从69.8mN/m降低至32.3mN/m左右。对原油的乳化降粘效果良好,9d后乳化相仍可保持86%。经测定其临界胶来浓度CMC值为70mg/L。该产物性能稳定,在不同温度、pH和矿化度条件下表面活性剂性能保持不变。     

生物表面活性剂检测方法研究

针对萨北油田小井距生物表面活性剂三元复合驱矿场试验中存在的生物表面活性剂RH的定量分析检测问题,得出RH定量分析的公式,较好地解决了RH的检测问题,为今后开展生物表面活性剂化学驱中如何检测RH提供了一种较为准确的方法。     

Promotion effect of biosurfactant on heavy-oil biodegradation

Biosurfactants have received considerable attention in the field of heavy-oil remediation processes. Heavy oil was used to isolate biosurfactant-producing and oil-degrading bacteria. According to 16S rRNA, the isolated bacteria was identified as Bacillus amyloliquefaciens. The critical micelle concentration (CMC) of the produced biosurfactant was 100 mg/L. Biosurfactant could greatly improve the properties of heavy oil and significantly improve the biodegradation. The viscosity reduction rate was from 24 to 47% over the temperature range of 30–90°C. Biodegradation rates of saturated hydrocarbon (C₁₃–C₃₃) were from 21 to 85%. The biodegradation accelerating rate of biosurfactant for different aromatic hydrocarbon series was 9.89%, 9.60%, 29.71%, 16.75%, and 10.04%. These findings demonstrate that the produced biosurfactant could be useful in environmental remediation processes.     

Comparison of in-situ and ex-situ microbial enhanced oil recovery by strain Pseudomonas aeruginosa WJ-1 in laboratory sand-pack columns

Microbial enhanced oil recovery (MEOR) applies biotechnology to improve residual crude oil production from substratum reservoir. MEOR includes in-situ MEOR and ex-situ MEOR. The former utilizes microbial growth and metabolism in the reservoir, and the latter directly injects desired active products produced by microbes on the surface. Taking biosurfactant-producing strain Pseudomonas aeruginosa WJ-1 for research objects, in-situ enhanced oil recovery and ex-situ enhanced oil recovery by biosurfactant-producing strain WJ-1 were comparatively investigated in sand-pack columns.The results showed that P.aeruginosa WJ-1 really proliferated in sand-pack columns, produced 2.66 g/L of biosurfactant, altered wettability, reduced oil-water interfacial tension (IFT) and emulsified crude oil under simulated in-situ process. Results also showed that higher biosurfactant concentration, lower IFT, smaller average diameters of emulsified crude oil were obtained in in-situ enhanced oil recovery experiment than those in ex-situ enhance oil recovery experiment. Similar wettability alteration was observed in both in-situ and ex-situ enhanced oil recovery experiment. The flooding experiments in sand-pack columns revealed that the recovery of in-situ was 7.46%/7.32% OOIP (original oil in place), and the recovery of the ex-situ was 4.64%/4.49% OOIP. Therefore, in-situ approach showed greater potential in enhancing oil recovery in contrast with ex-situ approach. It is recommended that the stimulation of indigenous microorganisms rather than injection of microbial produced active products should be applied when MEOR technologies were employed.     

生物表面活性剂在大庆油田的应用研究

对从大庆油田地层水中分离得到的产生物表面活性剂菌株及其代谢产物进行分析鉴定,确定菌株为枯草芽孢杆菌,代谢产物为脂肽类。将脂肽类生物表面活性剂与化学合成表面活性剂复配并对体系性能进行研究,结果表明,复配体系性能好于或相当于合成表面活性剂体系,复配体系物理模拟驱油实验提高采收率27．35％（OOIP）,比相同注人流程化学驱提高4．35％（OOIP）。由于脂肽表面活性剂替代了部分化学合成表面活性剂,在提高采收率的同时降低了成本,具有良好的应用前景。     

Using biosurfactant producing bacteria isolated from an Iranian oil field for application in microbial enhanced oil recovery

Microbial enhanced oil recovery (MEOR) is a useful technique to improve oil recovery from depleted oil reservoirs beyond primary and secondary recovery operations using bacteria and their metabolites. In the present study, the biosurfactant production potential of Bacillus licheniformis microorganisms that were isolated from oil samples of Zilaei reservoir in the southwest of Iran was explored under extreme conditions. Growth media with different temperatures of 40, 50, 60, and 70°C; salinities of 1, 3, 5, and 7 wt%; and yeast extract concentrations of 0.5, 1, 1.5, and 2 g/L were used to find the optimum growth conditions. The results demonstrated that bacteria grown in a mineral salt solution with temperature of 50°C, salinity of 1 wt% and yeast extract concentration of 1 g/L has the highest growth rate and therefore, these conditions are the optimum conditions for growing the introduced bacterium. This isolate was selected as the higher biosurfactant producer. The obtained biosurfactants by bacteria isolated in a medium with these conditions could reduce the interfacial tension of crude oil/water system from 36.8 to 0.93 mN/m and surface tension of water from 72 to 23.8 mN/m. The results of the core flooding tests showed that the tertiary oil recovery efficiency due to the injection of microorganisms was 13.7% of original oil in place and bacteria could reduce the oil viscosity by 41.242% at optimum conditions. Based on these results, the isolated microorganism is a promising candidate for the development of microbial oil recovery processes.     

Potential application of biosurfactants mixtures in high-temperature and high-salinity reservoirs

In this research, the interfacial behavior and emulsifying ability of biosurfactants mixtures were evaluated to investigate the potential application in high-temperature and high-salinity reservoirs. Results indicated that the mixtures of biosurfactants and betaine 4# gave the lowest interfacial tension values of ～10^?3 mN/m and emulsified crude oil more effectively. Core flooding tests showed that the binary systems gave the highest oil recovery of 11%, which is more efficient than any single biosurfactant or chemical.     

Emulsifying action of Pseudomonas aeruginosa L6-1 and its metabolite with crude oil for oil recovery enhancement

Pseudomonas aeruginosa L6-1 was isolated from formation brine of Xinjiang Oilfield, China. Strain L6-1 showed perfect emulsification activity to crude oil and transformed mixture of crude oil and water into emulsion when crude oil was used as sole carbon source; thus, this method is a promising approach for emulsification and mobilization of residual oil in oil reservoirs and enhancement of its recovery. Average diameters of emulsified crude oil were between 1 and 8 µm. Interfacial tension of crude oil and water was reduced to 0.8 mN m^?1. Strain L6-1 produced 2.2 g L^?1 of rhamnolipid biosurfactant. Core flooding tests were carried out to investigate application potential of strain L6-1 for microbial enhanced oil recovery (MEOR). Enhanced oil recovery efficiencies ranged from 9.23% to 12.58% in both core models, with and without oxygen injection. These results revealed that strain L6-1 is a candidate functional microorganism for MEOR application.