Application In Microbial Enhanced Oil Recovery Research Articles

Appropriate characterization of reservoir properties and investigation of their effect on microbial enhanced oil recovery through simulated laboratory studies

Appropriate characterization of reservoir properties and investigation of the effect of these properties on microbial metabolism and oil recovery under simulated reservoir conditions can aid in development of a sustainable microbial enhanced oil recovery (MEOR) process. Our present study has unveiled the promising potential of the hyperthermophilic archaeon, identified as Thermococcus petroboostus sp. nov. 101C5, to positively influence the microenvironment within simulated oil reservoirs, by producing significant amounts of metabolites, such as biosurfactants, biopolymers, biomass, acids, solvents, gases. These MEOR desired metabolites were found to cause a series of desirable changes in the physicochemical properties of crude oil and reservoir rocks, thereby enhancing oil recovery. Furthermore, our study demonstrated that the microbial activity of 101C5 led to the mobilization of crude oil, consequently resulting in enhanced production rates and increased efficiency in simulated sand pack trials. 101C5 exhibited considerable potential as a versatile microorganism for MEOR applications across diverse reservoir conditions, mediating significant light as well as heavy oil recovery from Berea/carbonaceous nature of rock bearing intergranular/vugular/fracture porosity at extreme reservoir conditions characterized by high temperature (80–101 °C) and high pressure (700–1300 psi). Core flood study, which truly mimicked the reservoir conditions demonstrated 29.5% incremental oil recovery by 101C5 action from Berea sandstone at 900 psi and 96 °C, underscoring the potential of strain 101C5 for application in the depleted high temperature oil wells.

Genetically modified indigenous Pseudomonas aeruginosa drove bacterial community to change positively toward microbial enhanced oil recovery applications.

Microbial enhanced oil recovery (MEOR) is cost-effective and eco-friendly for oil exploitation. Genetically modified biosurfactants-producing high-yield strains are promising for ex-situ MEOR. However, can they survive and produce biosurfactants in petroleum reservoirs for in-situ MEOR? What is their effect on the native bacterial community? A genetically modified indigenous biosurfactants-producing strain Pseudomonas aeruginosa PrhlAB was bioaugmented in simulated reservoir environments. Pseudomonas aeruginosa PrhlAB could stably colonize in simulated reservoirs. Biosurfactants (200mg l-1) were produced in simulated reservoirs after bio-augmenting strain PrhlAB. The surface tension of fluid was reduced to 32.1 mN m-1. Crude oil was emulsified with an emulsification index of 60.1%. Bio-augmenting strain PrhlAB stimulated the MEOR-related microbial activities. Hydrocarbon-degrading bacteria and biosurfactants-producing bacteria were activated, while the hydrogen sulfide-producing bacteria were inhibited. Bio-augmenting P. aeruginosa PrhlAB reduced the diversity of bacterial community, and gradually simplified the species composition. Bacteria with oil displacement potential became dominant genera, such as Shewanella, Pseudomonas, and Arcobacter. Culture-based and sequence-based analyses reveal that genetically modified biosurfactants-producing strain P. aeruginosa PrhlAB are promising for in-situ MEOR as well.

Horizontal and Vertical Comparison of Microbial Community Structures in a Low Permeability Reservoir at the Local Scale.

Petroleum microorganisms play a crucial role in the application of microbial-enhanced oil recovery, and the community structures of petroleum microorganisms have been widely studied. Due to variations in reservoir geological conditions, reservoir microbial communities exhibit unique characteristics. However, previous studies have primarily focused on microbial community changes within a single well, a single block, and before and after water flooding, and thus, cross-horizon and cross-regional comparative studies of in situ microbial communities are lacking. In this study, the 16S rRNA full-length sequencing method was adopted to study bacterial communities in crude oil samples taken from two wells at the same depths (depths of 2425 m and 2412 m) but approximately 20 km apart in the Hujianshan oilfield, located in the Ordos Basin. At the same time, the results were combined with another layer of research data from another article (from a depth of 2140 m). The aim was to compare the differences in the microbial community structures between the oil wells on a horizontal scale and a vertical scale. The results revealed that there were minimal differences in the microbial community structures that were influenced by the horizontal distances within a small range (<20 km), while differences were observed at a larger spatial scale. However, the dominant bacteria (Proteobacteria and Bacteroidetes) in the different oilfields were similar. Vertical depth variations (>300 m) had significant impacts on the communities, and this was mainly controlled by temperature. The greater the depth, the higher formation temperature, leading to an increase in thermophilic and anaerobic bacteria within a community.

Analyzing the microbial factors affecting microbial enhanced oil recovery through numerical simulation study

ABSTRACT Primary and secondary recovery methods are usually not sufficient to maximize the oil recovery. In many cases, more than 40% of the Oil Initially in Place is left in the reservoir after implementing these recovery methods. To resolve the issue at hand, petroleum engineers have at their disposition a plethora of tertiary recovery methods such as chemical flooding, thermal recovery, and microbial enhanced oil recovery (MEOR). In this study, we propose the use of MEOR: a technique that uses naturally occurring microbes in the reservoir or injected microbes to enhance the oil recovery. The MEOR process is governed by several mechanisms such as viscosity reduction, relative permeability alteration, capillary pressure alteration, and other reaction-induced system changes such as pressurization. This study investigates the impact of these mechanisms on the hydrocarbon production by conducting a numerical simulation using our in-house MEOR numerical simulator. In the base case study, the case with MEOR shows the 20% of oil production improvement than the case without MEOR. We conduct a sensitivity analysis to evaluate the impact of microbial factors affecting MEOR to the system responses and production behavior, where the maximum growth rate of microbes is found to be the most influential factor with the scaled sensitivity coefficient of 1.384 × 105. The findings provide the relative impacts of factors affecting the performance of MEOR, which subsequently suggest the factors to be investigated with emphasis for oil production improvement in the MEOR applications.

Application of “oil-phase” microbes to enhance oil recovery in extra heavy oil reservoir with high water-cut: A proof-of-concept study

Microbial enhanced oil recovery (MEOR) is an important tertiary recovery technology to recover oil, especially heavy oil, from reservoirs. However, MEOR often fails to achieve satisfactory oil recovery in the field applications because of utilization of unsuitable microorganisms and nutrients. Recent studies proved the existence of microbes inside oil (“oil-phase” microbes) and their potential for application in MEOR. To validate this concept, we isolated microbes from the “oil-phase” of crude oil samples. With them, a synthetic four-member microbial consortium K, was selected to use in an experiment of core flooding, which showed a beneficial capacity for improving oil recovery. Furthermore, the consortium K and nutrients were applied in a field trial of microbial huff and puff in an extra heavy oil recovery. Results demonstrated the incremental cumulative oil production of two high water-cut (99%) shut-in wells reached 1078.8 t and 791.6 t, respectively, with the effective period of 14 months, while the viscosity of heavy oil had significantly declined decreased by 50%. In conclusion, our findings clearly demonstrate that the great potential of a novel methodology to use indigenous “oil-phase” microbes as seedbanks for improving oil recovery in extremely viscous oil reservoirs with high water-cut.

Predicting performance of in-situ microbial enhanced oil recovery process and screening of suitable microbe-nutrient combination from limited experimental data using physics informed machine learning approach

Screening of suitable microbe-nutrient combination and prediction of oil recovery at the initial stage is essential for the success of Microbial Enhanced Oil Recovery (MEOR) technique. However, experimental and physics-based modelling approaches are expensive and time-consuming. In this study, Physics Informed Machine Learning (PIML) framework was developed to screen and predict oil recovery at a relatively lesser time and cost with limited experimental data. The screening was done by quantifying the influence of parameters on oil recovery from correlation and feature importance studies. Results revealed that microbial kinetic, operational and reservoir parameters influenced the oil recovery by 50%, 32.6% and 17.4%, respectively. Higher oil recovery is attained by selecting a microbe-nutrient combination having a higher ratio of value between biosurfactant yield and microbial yield parameters, as they combinedly influence the oil recovery by 27%. Neural Network is the best ML model for MEOR application to predict oil recovery (R2≈0.99).

Optimization and characterization of biosurfactant produced by indigenous Brevibacillus borstelensis isolated from a low permeability reservoir for application in MEOR.

Biosurfactants are expected to be a key factor for microbial enhanced oil recovery (MEOR). In this study, we described the novel biosurfactant-producing strain Brevibacillus borstelensis YZ-2 isolated from a low permeability oil reservoir. We purified and characterized the biosurfactants produced by this YZ-2 strain via thin-layer chromatography and MALDI-TOF-MS, revealing them to be fengycins. We additionally used a Box–Behnken design approach to optimize fermentation conditions in order to maximize the biosurfactants production. Core flooding experiments showed that biosurfactants produced by YZ-2 can significantly enhance crude oil recovery. Micro-model tests showed that emulsification and IFT reduction was the main EOR mechanism of the YZ biosurfactant in the oil wet model. In summary, these findings highlight the potential of Brevibacillus borstelensis YZ-2 and its metabolites for MEOR.

Optimization of lipopeptide biosurfactant production by Bacillus licheniformis L20 and performance evaluation of biosurfactant mixed system for enhanced oil recovery

Biosurfactant is an important amphiphilic microbial product, which plays an important role in microbial enhanced oil recovery (MEOR) by reducing crude oil-water interfacial tension (IFT), emulsification and wettability alternation. Compared with chemical surfactants, biosurfactants have the advantages of lower toxicity and higher biodegradability, but the relatively low yield also limits their applications. In this study, the influence of hydrocarbon carbon sources on the production of biosurfactants by Bacillus licheniformis L20 was investigated, and the variable of unit biosurfactant concentration was proposed to optimize the biosurfactant production medium. The highest concentration was obtained in LB/MSS-K medium, which was up to 1.225 g/L. The biosurfactant produced by Bacillus licheniformis L20 in that medium was characterized as lipopeptide via using FTIR. This biosurfactant shown stable emulsifying properties for different hydrocarbons and crude oils, but it can not reduce the oil-water IFT significantly. However, after mixed biosurfactant with chemical anionic surfactants (1,3-diacylglycerols-2-sulfate) and nonionic surfactant (fatty alcohol-polyoxyethylene ether), the anionic surfactant/biosurfactant mixed system can reduce the crude oil-water IFT to 0.109 mN/m. In addition, the emulsification stability of the biosurfactant mixed system were determined, the results shown that the emulsion formed by the nonionic surfactant/biosurfactant mixed system or the anionic surfactant/biosurfactant mixed system can remain stable under a wide range of temperature, pH and NaCl concentration, respectively. Furthermore, the performance of chemical surfactant/biosurfactant mixed system were evaluated, the results shown that anionic surfactant/biosurfactant mixed system and nonionic surfactant/biosurfactant mixed system can increase the oil recovery rate by 24.12% and 21.67% respectively after water flooding, while the biosurfactant used alone was only 19.58%. Thus, the results obtained from this work shown that anionic surfactant/biosurfactant mixed system have good prospect of application in ex-situ MEOR. • Effect of hydrocarbon carbon sources on biosurfactants production was investigated. • Interfacial activity of anionic or nonionic/biosurfactant mixed system was studied. • These mixed system led to higher oil recovery rate than biosurfactant used alone.

Optimization of Enrichment and Isolation Media of Thermophilic Hydrocarbonoclastic Bacteria Isolated from Oil Reservoir of West Java for Microbial Enhanced Oil Recovery (MEOR) Application

Microbial enhanced oil recovery (MEOR) is a tertiary oil recovery process which aims to increase the crude oil recovery uptake to 55% from its original oil in place. In its application, indigenous microorganisms are commonly used as the main biological agents, but the isolation processes become more complicated due to environment’s extreme condition. This study aims to determine the optimum formulation for the enrichment and isolation medium, in order to obtain a highly diverse of indigenous hydrocarbonoclastic bacteria. The isolation process was carried out in two stages; the isolation of mild oil fraction degrading bacteria, and isolation of the heavy oil fraction degrading bacteria which confirmed by the SARA (saturated, aromatic, resinic, and asphaltic) fraction chromatography analysis. Four enrichment and five isolation media were formulated based on the distinction in the macro-and micronutrient composition. Overall, a total of 92 isolates were successfully isolated. The highest bacterial diversities were achieved in the enrichment medium B (crude oil used as carbon source which supplemented with sodium lactate) and isolation medium I (nutrient agar with twice agar concentration), each with 37 and 33% of obtained isolates, respectively. The newly formulated medium can be further utilized to isolate various types of indigenous bacteria from the oil well which were able to degrade SARA fraction from crude oil. The result showed that ABG2-7 as the isolate with the highest activity on SARA degradation. The amount of 15% inoculum of ABG2-7 isolate was able to degrade heavy crude oil, thus might serve as potential bacteria for MEOR application.

Process Optimization of Palm Oil Mill Effluent-Based Biosurfactant of Halomonas meridiana BK-AB4 Originated from Bledug Kuwu Mud Volcano in Central Java for Microbial Enhanced Oil Recovery

Biosurfactants are one of the microbial bioproducts that are in most demand from microbial-enhanced oil recovery (MEOR). The production of biosurfactant is still a relatively high cost. Therefore, this study aims to reduce production costs by utilizing palm oil mill effluent (POME) as the main carbon source. This work examines the optimal conditions of biosurfactant production by Halomonas meridiana BK-AB4 isolated from the Bledug Kuwu mud volcano in Central Java Indonesia and studies it for EOR applications. The biosurfactant production stage was optimized by varying POME concentration, incubation time, NaCl concentration, and pH to obtain the maximum oil displacement area (ODA) values. A response surface methodology (RSM) and a central composite design (CCD) were used to identify the influence of each variable and to trace the relationship between variables. Optimum biosurfactant production was found at a POME concentration (v/v) of 16%, incubation (h) of 112, NaCl concentration (w/v) of 4.7%, pH of 6.5, with an oil displacement area of 3.642 cm. The LC-MS and FTIR analysis revealed the functional groups of carboxylic acid or esters, which indicated that the biosurfactant produced belonged to the fatty acid class. The lowest IFT value was obtained at the second and seventh-day observations at a concentration of 500 mg/L, i.e., 0.03 mN/m and 0.06 mN/m. The critical micelle concentration (CMC) of biosurfactant was about 350 mg/L with a surface tension value of about 54.16 mN/m. The highest emulsification activity (E24 = 76%) in light crude oil (naphthenic–naphthenic) and could reduce the interfacial tension between oil and water up to 0.18 mN/m. The imbibition experiment with biosurfactant results in 23.89% additional oil recovery for 60 h of observation, with the highest increase in oil recovery occurring at the 18th hour, which is 2.72%. Therefore, this bacterium and its biosurfactant show potential, and the bacterium are suitable for use in MEOR applications.

Comparison of mono-rhamnolipids and di-rhamnolipids on microbial enhanced oil recovery (MEOR) applications.

Rhamnolipids (RMLs) have more effectiveness for specific uses according to their homologue proportions. Thus, the novelty of this work was to compare mono-RMLs and di-RMLs physicochemical properties on microbial enhanced oil recovery (MEOR) applications. For this, RML produced by three strains of Pseudomonas aeruginosa containing different homologues proportion were used: a mainly mono-RMLs producer (mono-RMLs); a mainly di-RMLs producer (di-RMLs), and the other one that produces relatively balanced amounts of mono-RML and di-RML homologues (mono/di-RML). For mono-RML, the most abundant molecules were Rha-C10 C10 (m/z 503.3), for di-RML were RhaRha-C10 C10 (m/z 649.4) and for Mono/di-RML were Rha-C10 C10 (m/z 503.3) and RhaRha-C10 C10 (m/z 649.4). All RMLs types presented robustness under high temperature and variation of salinity and pH, and high ability for oil displacement, foam stability, wettability reversal and were classified as safe for environment according to the European Union Directive No. 67/548/EEC. For all these properties, it was observed a highlight for mono-RML. Mono-RML presented the lowest surface tension (26.40 mN/m), interfacial tension (1.14 mN/m), and critical micellar concentration (CMC 27.04 mg/L), the highest emulsification index (EI24 100%) and the best wettability reversal (100% with 25 ppm). In addition, mono-RML showed the best acute toxicity value (454 mg/L), making its application potential even more attractive. Based on the results, it was concluded that all RMLs homologues studied have potential for MEOR applications. However, results showed that mono-RML stood out and have the best mechanism of oil incorporation in micelles due their most effective surface-active physicochemical features.

Stability test of biosurfactant produced by Bacillus licheniformis DS1 using experimental design and its application for MEOR

Microbial enhanced oil recovery (MEOR) is a proven tertiary recovery technique. Biosurfactant is a microbial bioproduct that plays an important role in MEOR applications. This study aimed to test biosurfactant stability using a design experiment based on response surface methodology. First, isolation and screening for potential biosurfactant-producing bacteria from crude oil samples was performed, followed by their characterization. A biosurfactant core flooding experiment was also conducted to examine bacterial activity on MEOR. Thirty-one sequential isolates of bacteria were screened based on qualitative and semi-qualitative parameters. One selected biosurfactant-producing bacterium was identified as Bacillus licheniformis DS1 based on phylogenetic analysis of the 16S rRNA gene. This bacterium had the highest emulsification activity (Ei24 = 65.19%) in light crude oil and could reduce the interfacial tension between oil and water with an effective critical-micelle concentration of 157.5 mg/L. The biosurfactant was observed as a growth-associated metabolite type and the Fourier transform infrared spectrum revealed that the biosurfactant produced belonged to a group of lipopeptides. The biosurfactant has good stability in maintaining emulsification activity at pH 4–10, high temperatures up to 120 °C, and with an NaCl concentration up to 10% (w/v). Based on response surface methodology using the Box–Behnken experimental design, the optimum condition for the most stable biosurfactant is pH 12, a 40 °C temperature and 10% salinity, with an Ei24 value of 94.28%. Core flooding experiments with biosurfactant resulted in 5.4% additional oil recovery. Therefore, this biosurfactant shows a high potential application for MEOR.

Effects of nutrient composition on the formation of biofilm and biocorrosion in MEOR biostimulation medium based on response surface methodology

Nutrition addition in Microbial Enhanced Oil Recovery (MEOR) application is one of the methods used to increase oil production. Nutrition injection in MEOR application must be done carefully because the lack of proper nutrition addition can induce biofilm and biocorrosion formation. The composition of biostimulation medium for optimizing beneficial indigenous bacterial growth in Microbial Enhanced Oil Recovery (MEOR) was evaluated using Response Surface Methodology (RSM) with Central Composite Design (CCD). Three main factors for the medium composition were molasses, Diammonium Phosphate (DAP), and NPK. The RSM was used to know the most effective medium composition towards biofilm production and strength that high potential leads to biocorrosion. Molasses, NPK, and diammonium phosphate (DAP) are utilized as carbon, nitrogen, and phosphate supplementary substrate in Brine water as basal medium. Molasses concentration was 0%-10% while DAP and NPK was 0%-0.5%. Both aerobic and anaerobe sessile bacteria, as well as acid producing bacteria, were enumerated by total plate and turbidity methods. Statistical analysis with α=0.05 proves molasses give significance effect to biofilm strength and sessile anaerobic bacteria. DAP gives significance effect to biofilm strength and sessile aerobic and anaerobic bacteria. NPK give significance effect to sessile anaerobic bacteria. Molasses addition decrease brine pH by microbial activity, make the carbon steel coupon ST-37 corrosion rate increased. Meanwhile, the addition of DAP increased the pH of brine medium and decrease the corrosion rate.

Application of rhamnolipid biosurfactant produced by Pseudomonas aeruginosa in microbial-enhanced oil recovery (MEOR)

In this study, the biosurfactant produced by Pseudomonas aeruginosa was evaluated in view of its ability to be used in Microbial-Enhanced Oil Recovery (MEOR). This microorganism was isolated from a soil artificially contaminated with crude oil and used to produce rhamnolipid using glycerol as the carbon source. The biosurfactant efficiently reduced water surface tension from 72 to 35.26 mN/m at its critical micelle concentration of 127 mg/L and emulsification rate (E24) of 69% for the crude oil. Furthermore, it was demonstrated that the rhamnolipid can recover oil, even 2 months after its production, which shows that its biodegradability is not a disadvantage to the application in MEOR. The best result, for a biosurfactant concentration of 100% above the Critical Micelle Concentration (CMC) and petroleum with API gravity of 21.90, showed that the total recovery factor was 50.45 ± 0.79%, of which 11.91 ± 0.39% corresponds to MEOR.

Screening and characterization of biosurfactant produced by Pseudoxanthomonas sp. G3 and its applicability for enhanced oil recovery

Biosurfactants are one of the microbial bioproducts that are in most demand from microbial-enhanced oil recovery (MEOR). We isolated and screened potential biosurfactant-producing bacteria, followed by biosurfactant production and characterization, and a simulation of the MEOR application to biosurfactants in a sand-packed column. Isolate screening was conducted based on qualitative (hemolytic blood assay and oil-spreading test) and semi-qualitative (emulsification assay and interfacial tension measurement) parameters. Bacterial identification was performed using 16S rRNA phylogenetic analysis. Sequential isolation yielded 32 bacterial isolates, where Pseudomonas sp. G3 was able to produce the most biosurfactant. Pseudomonas sp. G3 had the highest emulsification activity (Ei = 72.90%) in light crude oil and could reduce the interfacial tension between oil and water from 12.6 to 9.7 dyne/cm with an effective critical-micelle concentration of 0.73 g/L. The Fourier transform infrared spectrum revealed that the biosurfactant produced was a glycolipid compound. A stable emulsion of crude extract and biosurfactant formed at pH 2–12, up to 100 °C, and with a NaCl concentration of up to 10% (w/v) in the response-surface method, based on the Box–Behnken design model. The sand-packed column experiment with biosurfactant resulted in 20% additional oil recovery. Therefore, this bacterium and its biosurfactant show potential and the bacterium is suitable for use in MEOR applications.

Biosurfactant-Producing Capability and Prediction of Functional Genes Potentially Beneficial to Microbial Enhanced Oil Recovery in Indigenous Bacterial Communities of an Onshore Oil Reservoir.

Microbial enhanced oil recovery (MEOR) is a bio-based technology with economic and environmental benefits. The success of MEOR depends greatly on the types and characteristics of indigenous microbes. The aim of this study was to evaluate the feasibility of applying MEOR at Mae Soon Reservoir, an onshore oil reservoir experiencing a decline in its production rate. We investigated the capability of the reservoir's bacteria to produce biosurfactants, and evaluated the potentials of uncultured indigenous bacteria to support MEOR by means of prediction of MEOR-related functional genes, based on a set of metagenomic 16s rRNA gene data. The biosurfactant-producing bacteria isolated from the oil-bearing sandstones from the reservoir belonged to one species: Bacillus licheniformis, with one having the ability to decrease surface tension from 72 to 32mN/m. Gene sequences responsible for biosurfactant (licA3), lipase (lipP1) and catechol 2,3-dioxygenase (C23O) were detected in these isolates. The latter two, and other genes encoding MEOR-related functional proteins such as enoyl-CoA hydratase and alkane 1-monooxygenase, were predicted in the bacterial communities residing the reservoir's sandstones. Exposure of these sandstones to nutrients, consisting of KNO3 and NaH2PO4, resulted in an increase in the proportions of some predicted functional genes. These results indicated the potentials of MEOR application at Mae Soon site. Using the approaches demonstrated in this study would also assist evaluation of the feasibility of applying MEOR in oil reservoirs, which may be enhanced by an appropriate nutrient treatment.

The biopolymer produced by Rhizobium viscosum CECT 908 is a promising agent for application in microbial enhanced oil recovery

Polymer flooding is one of the most promising techniques used to increase the productivity of mature oil reservoirs. Polymers reduce the mobility ratio of the injected water relative to the crude oil, improving the displacement of the entrapped oil and consequently, increasing oil recovery. Biopolymers such as xanthan gum have emerged as environmentally friendly alternatives to the chemical polymers commonly employed by the oil industry. However, in order to seek more efficient biomolecules, alternative biopolymers must be studied. Here, the applicability of a biopolymer produced by Rhizobium viscosum CECT 908 in Microbial Enhanced Oil Recovery (MEOR) was evaluated. This biopolymer exhibited better rheological properties (including higher viscosity) when compared with xanthan gum. Its stability at high shear rates (up to 300 s−1), temperatures (up to 80 °C) and salinities (up to 200 g/L of NaCl) was also demonstrated. The biopolymer exhibited better performance than xanthan gum in oil recovery assays performed with a heavy crude oil, achieving 25.7 ± 0.5% of additional recovery. Thus the R. viscosum CECT 908 biopolymer is a promising candidate for application in MEOR.

A Review of Microbial Enhanced Oil Recovery Applications Projects

A Review of Microbial Enhanced Oil Recovery Applications Projects

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

ABSTRACTPseudomonas 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.

The application of microbial combination flooding oil recovery technology in heavy oil reservoir with low temperature

HuabeiBaolige Oilfield belongs to the common heavy oil reservoirs with low temperature, which were tapped by the conventional waterflooding. The formation temperature of Baolige Oilfield is 38~58°C, and the oil viscosity of reservoir is 13.7~2000mPa•s. Thanks to the high oil-water viscosity ratio and strong heterogeneity, the small waterflooding swept volume and serious water breakthrough are caused by waterflooding fingering, causing that the workable reserve cannot be used efficiently during the oilfield development. According to the characteristic that the environment of the reservoirs is fit for the growth and reproduction of microorganism, the microbial enhanced oil recovery (MEOR) technology is used to improve oilfield development status. On the basis of continuous and further studies of MEOR, the industrialized application of MEOR has been fulfilled. By the continuous and further study, the efficient system of the combination flooding technology with oil displacement microbial fields was formed, and MEOR technologies have been enriched. All the above researches could provide technical ideas for the comprehensive treatment for similar blocks.