Microbial Enhanced Oil Recovery Research Articles

Research on the Functional Microbe Activation System in a Post-Polymer Flooded Reservoir

Further exploitation of the residual oil underground in post-polymer flooded reservoirs is attractive and challenging. Microbial-enhanced oil recovery (MEOR) is a promising strategy to enhance the recovery of residual oil in post-polymer flooded reservoirs. Identifying and selectively activating indigenous microorganisms with oil displacement capabilities is an urgent requirement in the current design of efficient microbial-enhanced oil recovery technologies. This study combines high-throughput sequencing with functional network analysis to identify the core functional microbes within the reservoirs. Concurrently, it devises targeted activation strategies tailored to oligotrophic conditions through an analysis of environmental factor influences. The feasibility of these strategies is then validated through physical simulation experiments. With nutrient stimulation, the overall diversity of microorganisms decreases while the abundance of functional microorganisms increases. The core displacement results showed that the oil recovery factor increased by 3.82% on the basis of polymer flooding. In summary, this research has established a system for the efficient activation of functional microorganisms under oligotrophic conditions by utilizing bioinformatics, network analysis, and indoor simulation systems. This achievement will undoubtedly lay a solid foundation for the practical implementation of microbial enhancement techniques in the field.

Production, characterization, and application of Pseudoxanthomonas taiwanensis biosurfactant: a green chemical for microbial enhanced oil recovery (MEOR)

Biosurfactants, as microbial bioproducts, have significant potential in the field of microbial enhanced oil recovery (MEOR). Biosurfactants are microbial bioproducts with the potential to reduce the interfacial tension (IFT) between crude oil and water, thus enhancing oil recovery. This study aims to investigate the production and characterization of biosurfactants and evaluate their effectiveness in increasing oil recovery. Pseudoxanthomonas taiwanensis was cultured on SMSS medium to produce biosurfactants. Crude oil was found to be the most effective carbon source for biosurfactant production. The biosurfactants exhibited comparable activity to sodium dodecyl sulfate (SDS) at a concentration of 400 ppm in reducing IFT. It was characterized as glycolipids, showing stability in emulsions at high temperatures (up to 120 °C), pH levels ranging from 3 to 9, and NaCl concentrations up to 10% (w/v). Response surface methodology revealed the optimized conditions for the most stable biosurfactants (pH 7, temperature of 40 °C, and salinity of 2%), resulting in an EI24 value of 64.45%. Experimental evaluations included sand pack column and core flooding studies, which demonstrated additional oil recovery of 36.04% and 12.92%, respectively. These results indicate the potential application of P. taiwanensis biosurfactants as sustainable and environmentally friendly approaches to enhance oil recovery in MEOR processes.

Degradation and enhanced oil recovery potential of Alcanivorax borkumensis through production of bio-enzyme and bio-surfactant

Microbial enhanced oil recovery (EOR) has become the focus of oilfield research due to its low cost, environmental friendliness and sustainability. The degradation and EOR capacity of A. borkumensis through the production of bio-enzyme and bio-surfactant were first investigated in this study. The total protein concentration, acetylcholinesterase, esterase, lipase, alkane hydroxylase activity, surface tension, and emulsifying activity were determined at different culture times. The bio-surfactant was identified as glycolipid compound, and the yield was 2.6 ± 0.2 g/L. The nC12 and nC13 of crude oil were completely degraded, and more than 40.0 % of nC14–nC24 was degraded by by A. borkumensis. The results of the microscopic etching model displacement and core flooding experiments showed that emulsification was the main mechanism of EOR. A. borkumensis enhanced the recovery rate by 20.2 %. This study offers novel insights for the development of environmentally friendly and efficient oil fields.

Możliwe zastosowanie energii słonecznej do zasilania operacji wydobycia węglowodorów i metod wspomagania wydobycia ropy naftowej na dużych szerokościach geograficznych

As the world enters the renewable revolution, it is crucial for the petroleum industry to remain relevant in the public eye and become environmentally awareness. One potential path to achieve these goals in a progressive and beneficial way is to integrate renewable energy sources into various nodes of the petroleum industrial operations. Different ways of achieving such integration are described in the review section of the article. These include utilizing solar energy to power upstream operations and a variety of enhanced oil recovery projects, such as microbial enhanced oil recovery and others, or using solar energy downstream to supply power to pumps, gas lift apparatus, etc. The article also proposes a novel potential application of solar energy to power operations and provide long-term sustainable energy source to petroleum operations in high latitudes. The potential applicability of solar power in petroleum engineering operations far North has long been neglected due to potential unprofitability and difficulty of construction of solar power grid in such harsh climactic conditions. However, now, as the world transitions to a new reality of co-existence of fossil fuels with alternative energy sources in light of growing concerns over climate change, it is a strategic time to implement the technology in profitable and environmentally conscious way in countries that have a trustworthy environmental record and strong, robust environmental policies, like Canada, as well as in less environmentally achieving countries with milder emission reduction targets such as Russian Federation.

Uses of Microorganisms in The Recovery of Oil and Gas

Microscopic organisms are the only single-celled organisms proposed for the advancement of techniques for Estimation of Oil Recovery (EOR) because they have numerous desirable properties, including a simple structure and an unsustainable growth rate when supplied with vital nutrients, resulting in the release of metabolic chemicals like Aerosols, acids, minimum lubricants, surfactants, and polymers. Clostridium acetobutylicum was isolated from intensive rice cultivation soil and has the ability to use polysaccharides such as starch and carboxylmethyl cellulose to produce biobutanol, while Desulfovibrio hydrocarbonoclasticus was isolated from marine sediment in Iraq and grows in anaerobic synthetic seawater medium with the addition of a trace element solution. These bacteria can also withstand difficult conditions High salinity, high pressure, and high temperature play roles and contribute to underground geological formations. An aqueous mixture of nutrients, Clostridium acetobutylicum, Desulfovibrio hydrocarbonoclasticus, and molasses with nutrient and bacterial spore injection into a reservoir. As a result, these microorganisms are capable of considerable catalytic reactions. production of a diverse spectrum of products (biosolvents, bioacids, biogases, and biosurfactants) from relatively simple nutritional compounds, multiply vigorously under favourable conditions, and have resulted in increased oil release from reservoir rock. The well began producing 70 days after the medication was started. 80 to 90 days after the injection began, relatively brief polyunsaturated fats, Carbon dioxide, and residues of ethanol, 1-butanol, and acetone were detected. Because of their highly resistant endospores, Clostridium are the most ideal of the several microbes used in MEOR (Microbial enhanced oil recovery). Desulfovibrio strains capable of producing biosurfactants in situ, which are beneficial to the MEOR process, are also valuable. Nutrients are often supplied as fermentable carbs to promote microbial metabolism.

Revolutionizing Oil Extraction: Lechinysin's Potential in Microbial Enhanced Oil Recovery as a Biosurfactant

As conventional oil recovery techniques have numerous deficiencies in oil recovery rate (up to 40% OOIP), process safety, financial aspects, sustainability and environmental impacts other efficient techniques like MEOR had been invented that utilize microbes or their metabolites like biosurfactants to enhance oil recovery process from depleted reservoirs and increase the recovery rate up to 50% of remained oil in the reservoirs. Biosurfactants are the interesting chemicals that encompass a large group of compounds with unique properties to play crucial role in improving oil recovery. Among biosurfactants, lichenysin produced by B. lichenoformis or B. mojavensis Jf-2 and it has several different variants based on the producing strains. It is an alternative candidate with amazing features like stability in extremely high temperature up to 140 °C, saving its optimal activity in a wide range of pH values from 6 up to 10 pH, high salinity up to 10% NaCl concentration, and a significant CMC from 10 to 20 mg/L that is the lowest CMC among studied biosurfactants suitable for MEOR. All these characteristics indicate its signifance as a biosurfactant that has the capability to revolutionize the MEOR technique in the future. 

Identification of exopolysaccharide synthesizing genes in bacteria isolated from Bonny River in Rivers State, Nigeria

Microbial polysaccharide is the most important biopolymer secreted either by bacteria, fungi, or yeast as natural non-toxic, biodegradable and renewable sugar monomers. Microbial EPS owing to their interesting physicochemical and rheological properties has a wide range of industrial application such as in pharmaceuticals, cosmetics, food and Microbial enhanced oil recovery. This study was aimed to identify exopolysaccharide synthesizing genes in three bacterial isolates from Bonny River in Rivers State, Nigeria. The bacterial isolates were identified using the 16S rRNA gene sequence of the strains which carefully studied by making reference to the GenBank database using a BLAST search as Bacillus xiamensis, Bacillus safensis and Exiguobacterium aurantiacum using 16S rRNA PCR technique. Two priming Gylcosyltranferase genes (pGT) rfbp and cpsD were probed in the genome of the isolates after identification of the isolates. Two isolates Bacillus safensis and Exiguobacterium aurantiacum had both rfbp and cpsD genes while Bacillus xiamensis had only rfbp gene but no cpsD gene. The three isolates were examined for the Exopolysaccharide production on a minimal medium that contained g/l: KH2PO4 0.2, K2HPO4 1.5, MgSO4.7H2O 0.2, CaSO4.2H2O 0.1, FeCl3 0.002, yeast extract 0.5 and sucrose 20 and all three isolates produced EPS. At Optimum biomass of 0.15g/10 ml, the highest EPS yield of 10.20 g/l was obtained from Bacillus safenis. Exiguobacterium aurantiacum had optimum biomass of 0.11g/10ml with an EPS yield of 6.15g/l. The least biomass of 0.08g/10ml and EPS yield of 3.62 g/10ml was observed in Bacillus xiamensis. The biomass production was determined at Optical Density (OD) of 600nm while the EPS production was quantified by the Phenol Sulphuric acid method using glucose as a standard.

Bio‐enhanced oil recovery (BEOR) methods: All‐important review of the occasions and challenges

AbstractBio‐enhanced oil recovery (BEOR) is an advanced and innovative approach in the oil industry that could be a potential solution to increase oil production from existing reservoirs using technologies based on biological methods. Nevertheless, there has been a lack of comprehensive reviews that elucidate the various aspects and potential of different BEOR methods and processes. This review summarizes the recent progress of various methods employed in BEOR, exploring their applications and highlighting their distinct advantages. BEOR employs different techniques, including microorganisms and biomicrobes microbial enhanced oil recovery (MEOR), enzymes, biopolymers, bionanomaterials, alkaline, and biosurfactants to increase oil recovery. Microorganisms contribute significantly to BEOR through metabolic processes that result in the production of gases and acids. The role of enzymes is to enhance the fluid flow and thereby facilitate oil production. Biosurfactants reduce the interfacial tension (IFT) between oil and water and mobilize the trapped oil. Biopolymers are obtained from biological sources such as plants, microorganisms, and algae. Biopolymers can interact with oil, which is well‐used in the process of EOR. Bionano processes represent a fusion of biology and nanotechnology, integrate the advantages of both microorganisms and nanoparticles, and provide a synergic effect for EOR. The BEOR revealed an attractive potential to be an effective approach to maximizing the oil recovery considering environmental, economic productivity, and sustainability issues. Also, this review encourages further studies and development in this field for fully exploiting BEOR's capacity and meeting the ever‐increasing needs of energy resources with a sustainable viewpoint.

High mono-rhamnolipids production by a novel isolate Pseudomonas aeruginosa LP20 from oily sludge: characterization, optimization, and potential application.

This study aims to isolate microbial strains for producing mono-rhamnolipids with high proportion. Oily sludge is rich in petroleum and contains diverse biosurfactant-producing strains. A biosurfactant-producing strain LP20 was isolated from oily sludge, identified as Pseudomonas aeruginosa based on phylogenetic analysis of 16S rRNA. High-performance liquid chromatography-mass spectrometry results indicated that biosurfactants produced from LP20 were rhamnolipids, mainly containing Rha-C8-C10, Rha-C10-C10, Rha-Rha-C8-C10, Rha-Rha-C10-C10, Rha-C10-C12:1, and Rha-C10-C12. Interestingly, more mono-rhamnolipids were produced by strain LP20 with a relative abundance of 64.5%. Pseudomonas aeruginosa LP20 optimally produced rhamnolipids at a pH of 7.0 and a salinity of 0.1% using glycerol and nitrate. The culture medium for rhamnolipids by strain LP20 was optimized by response surface methodology. LP20 produced rhamnolipids up to 6.9 g L-1, increased by 116%. Rhamnolipids produced from LP20 decreased the water surface tension to 28.1 mN m-1 with a critical micelle concentration of 60 mg L-1. The produced rhamnolipids emulsified many hydrocarbons with EI24 values higher than 56% and showed antimicrobial activity against Staphylococcus aureus and Cladosporium sp. with inhibition rates 48.5% and 17.9%, respectively. Pseudomonas aeruginosa LP20 produced more proportion of mono-rhamnolipids, and the LP20 rhamnolipids exhibited favorable activities and promising potential in microbial-enhanced oil recovery, bioremediation, and agricultural biocontrol.

Biosurfactant and biopolymer producing microorganisms from West Kazakhstan oilfield

Microbiological enhanced oil recovery (MEOR) uses indigenous or exogenous microorganisms and nutrients to enhance oil production through synthesis of metabolites reducing oil viscosity and surface tension. In order to find bacteria suitable for MEOR, we studied 26 isolates from wells in the Akingen oilfield in West Kazakhstan. Six of them were selected for further analysis based on their ability to reduce surface tension to less than 40 mN/m, with the A9 isolate exhibiting tension reduction values of 32.76 ± 0.3 mN/m. Based on the morphological features, biochemical activities, and the 16S rRNA gene, the isolates were classified to the Bacillus subtilis group. In the phylogenetic analysis the isolates grouped into two main clusters. Genes encoding the surfactin synthetase subunits were found in A2, A8, A9, A12, PW2, only the PW2 strain had lchAA encoding lichenysin, while sacB encoding levan was noted in A2, A8, A9, and A12. The expression of srfAB, srfAC, and sacB tested with qPCR varied among strains. Nevertheless, whereas temperature moderately affects the expression level, with the highest level recorded at 40 °C, salinity significantly impacts the expression of the genes encoding biosurfactants. B. subtilis strains isolated in the study, especially A9, are promising for microbial-enhanced oil recovery.

An overview on trehalolipids: a promising eco-friendly bio-surfactant

Abstract Amphiphilic surfactants, which are currently used mainly for cleaning purposes, are produced in large quantities from petroleum, but are often harmful to the environment and poorly biodegradable. Therefore, the importance of environmentally friendly, non-toxic and skin-friendly biosurfactants is increasing. Different types of biosurfactants exist depending on their molecular structure. Trehalolipids belong to the low molecular weight glycolipids. Compared to other microbial glycolipids, they often show different properties and performances, including inhibition and enhancement of biodegradation rates. Optimisation of their production and downstream processing is one of the major obstacles to the potential use of trehaloselipids in a range of applications. This review provides an overview of different substrates and microorganisms used for trehalose lipid production, as well as various applications in bioremediation, biomedicine and microbial enhanced oil recovery.

Bioclogging

Bioclogging or biological clogging refers to the blockage of pore space in soil by microbial biomass, including active cells and their byproducts such as extracellular polymeric substance (EPS). The microbial biomass obstructs pore spaces, creating an impermeable layer in the soil and significantly reducing water infiltration rates. Bioclogging occurs under continuous ponded infiltration at various field conditions such as artificial recharge ponds, percolation trenches, irrigation channels, sewage treatment systems, constructed wetlands, landfill liners and natural systems such as riverbeds and soils. It also affects groundwater flow in the aquifer, such as ground source heat pumps, permeable reactive barriers, and microbial enhanced oil recovery. Bioclogging is a significant problem where water infiltration is hampered and countermeasures such as regular drying of the system can reduce the levels of bioclogging. However, bioclogging can also serve beneficial purposes in specific conditions. For instance, bioclogging can be utilized to make an impermeable layer to minimize the rate of infiltration or to enhance soil mechanic properties.

Investigation of the transport and metabolic patterns of oil-displacing bacterium FY-07-G in the microcosm model using X-CT technology.

Microbially Enhanced Oil Recovery (MEOR) is dedicated to enhancing oil recovery by harnessing microbial metabolic activities and their byproducts within reservoir rocks and fluids. Therefore, the investigation of microbial mobility and their extensive distribution within crude oil is of paramount importance in MEOR. While microscale models have been valuable for studying bacterial strain behavior in reservoirs, they are typically limited to 2D representations of porous media, making them inadequate for simulating actual reservoir conditions. Consequently, there is a critical need for 3D models and dependable visualization methods to observe bacterial transport and metabolism within these complex reservoir environments. Bacterial cellulose (bc) is a water-insoluble polysaccharide produced by bacteria that exhibits biocompatibility and biodegradability. It holds significant potential for applications in the field of MEOR as an effective means for selective plugging and spill prevention during oil displacement processes. Conditionally cellulose-producing strain, FY-07-G, with green fluorescent labeling, was engineered for enhanced oil recovery. 3D micro-visualization model was constructed to directly observe the metabolic activities of the target bacterial strain within porous media and to assess the plugging interactions between cellulose and the medium. Additionally, X-ray computed tomography (X-CT) technology was employed for a comprehensive analysis of the transport patterns of the target strain in oil reservoirs with varying permeabilities. The results indicated that FY-07-G, as a microorganism employing biopolymer-based plugging principles to enhance oil recovery, selectively targets and seals regions characterized by lower permeability and smaller pore spaces. This work provided valuable insights into the transport and metabolic behavior of MEOR strains and tackled the limitation of 2D models in faithfully replicating oil reservoir conditions, offering essential theoretical guidance and insights for the further application of oil-displacing bacterial strains in MEOR processes.

An experimental study of the effects of bacteria on asphaltene adsorption and wettability alteration of dolomite and quartz

The adsorption of asphaltene on the rock surface and the changes in its wettability are very relevant issues in flow assurance and oil recovery studies, and for carbonate reservoirs, they are even more important. During microbial enhanced oil recovery (MEOR) processes, wettability alteration is considered a crucial mechanism leading to improved oil recovery. Therefore, it is essential to understand the mechanisms of surface wettability changes by bacteria and biosurfactants and find new and reliable methods to prevent asphaltene adsorption. Hence, the main aim of this research was to investigate the effect of a mixture of thiobacillus thiooxidans and thiobacillus ferooxidans microorganisms with an optimum effective temperature of around 30 °C (referred to as mesophilic bacteria), as well as a mixture of two moderate thermophiles Sulfobacillus thermosulfidooxidans for operating temperatures around 50 °C (referred to as moderately thermophilic bacteria) on the adsorption of asphaltene samples isolated from two different crude oils onto main reservoir minerals (i.e., quartz and dolomite). The results indicated that after two weeks of mineral aging in moderate thermophilic bacteria, the adsorption of asphaltene on both minerals increased between 180 and 290%. Fourier-transform infrared spectroscopy (FTIR) analysis for quartz and dolomite samples demonstrated that after aging in bacterial solution, bonds related to the adsorption of bacterial cells and biosurfactant production appear, which are the main factors of change in wettability. Alteration in wettability towards hydrophilicity expands hydrogen bonds on the surface, thus improving asphaltene adsorption due to polar interaction. Asphaltene 1 changed the contact angle of dolomite from 53.85° to 90.51° and asphaltene 2 from 53.85° to 100.41°. However, both strains of bacteria caused a strong water-wetting effect on the dolomite rock samples. The influence of moderate thermophilic bacteria on surface wettability is more significant than that of mesophilic bacteria, which may be caused by the high protein content of these bacteria, which expands hydrogen bonding with the surface. Adsorption of asphaltenes on dolomite rocks previously aged with bacteria showed that the wetted rock samples retained their water-wet state. This study highlights the dual impact of the used microorganisms. On one hand, they significantly reduce contact angles and shift wettability towards a strongly water-wet condition, a crucial positive factor for MEOR. On the other hand, these microorganisms can elevate the adsorption of asphaltenes on reservoir rock minerals, posing a potential challenge in the form of formation damage, particularly in low-permeability reservoirs.

Enrichment of microbial consortia for MEOR in crude oil phase of reservoir-produced liquid and their response to environmental disturbance.

Developing microbial consortiums is necessary for microbial enhanced oil recovery (MEOR) in heavy crude oil production. The aqueous phase of produced fluid has long been considered an ideal source of microorganisms for MEOR. However, it is recently found that rich microorganisms (including hydrocarbon-degrading bacteria) are present in the crude oil phase, which is completely different from the aqueous phase of produced fluid. So, in this study, the microbial consortia from the crude oil phase of produced fluids derived from four wells were enriched, respectively. The microbial community structure during passage was dynamically tracked, and the response of enriched consortia to successive disturbance of environmental factors was investigated. The results showed the crude oil phase had high microbial diversity, and the original microbial community structure from four wells was significantly different. After ten generations of consecutive enrichment, different genera were observed in the four enriched microbial consortia, namely, Geobacillus, Bacillus, Brevibacillus, Chelativorans, Ureibacillus, and Ornithinicoccus. In addition, two enriched consortia (eG1614 and eP30) exhibited robustness to temperature and oxygen perturbations. These results further suggested that the crude oil phase of produced fluids can serve as a potential microbial source for MEOR.

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.

Biotechnology Sustainability in Energy Development

The application of biotechnology in the oil and environmental sectors plays a crucial role in promoting sustainability. Biotechnology offers innovative solutions for enhancing oil recovery, reducing environmental impacts, and advancing sustainable practices. In the oil sector, biotechnology enables the development of microbial-enhanced oil recovery techniques that improve oil extraction efficiency while minimizing environmental disturbances. Additionally, biotechnological approaches facilitate the remediation of oil-contaminated environments by harnessing the capabilities of microorganisms to degrade hydrocarbons. In the environmental sector, biotechnology aids in the development of renewable energy sources, such as biofuels, through the efficient conversion of biomass. Moreover, biotechnological advancements contribute to the sustainable management of waste, wastewater treatment, and the preservation of biodiversity. Embracing biotechnology in these sectors fosters a sustainable pathway by reducing reliance on fossil fuels, mitigating pollution, and promoting resource efficiency, ultimately supporting the long-term well-being of both ecosystems and human societies.

Bioremediation of Hydrocarbon-Contaminated Environments: Harnessing the Potential of Biosurfactants – A review

Hydrocarbon contamination from industries like petrochemicals threatens the environment and public health. Benzene, toluene, xylene, and polycyclic aromatic hydrocarbons in petroleum products are highly toxic. Conventional cleanup methods are costly and risk secondary pollution. This review highlights biosurfactants, microbially produced compounds that enhance hydrocarbon degradation by lowering surface tension and increasing bioavailability. Biosurfactants are biodegradable and eco-friendly, making them a sustainable alternative to synthetic surfactants. The review intends to cover the biosurfactant sources, types, mechanisms, and their applications in hydrocarbon-contaminated environments. Recent bioremediation advancements, including microbial-enhanced oil recovery, soil and water cleanup, and heavy metal removal, are discussed. Optimizing biosurfactant production is also explored, offering a green and effective solution to combat hydrocarbon contamination and promote environmental restoration.

Bacterial Cultural Media Containing Lipopeptides for Heavy Oil Recovery Enhancement: The Results of Sand-Packed Column Experiment

Currently, microbial enhanced oil recovery (MEOR) is of great interest because of its potential high efficiency and low environmental impact. Biosurfactants, in the purified form or contained in the bacterial cultural media, are one of the promising directions in MEOR because they are more stable in response to different environmental factors than life microorganisms are. However, the extraction and purification of biosurfactants, as well as their working concentrations and efficacy in real oilfield conditions remain a challenge. In the present work, cultural media of two novel bacterial isolates (Bacillus pumilus and Peribacillus simplex) were used in a model experiment with sand pack columns to enhance the recovery of heavy oil from Romashkino oilfield (Russia). Using FTIR and TLC methods, it was demonstrated that both cultural media contained lipopeptides. In the genome of both bacterial isolates, genes srfAA, fenD and bamC encoding synthesis of surfactin, fengycin, and bacillomycin, respectively, were revealed. The oil recovery efficacy of cell-free cultural media after 24 h of cultivation was 34% higher and 16% lower as compared with synthetic surfactant for B. pumilus and P. simplex, respectively. It can be concluded that the high-cost step of biosurfactants separation and purification may be excluded, and cell free cultural media of the isolates may be directly used in field conditions to enhance the recovery of heavy oils.

Pore- and Core-Scale Recovery Performance of Consortium Bacteria from Low-Permeability Reservoir.

Performance evaluation of microorganisms that have emulsifying and degrading effects on crude oil has been extensively conducted in the laboratory. However, the ultimate goal of microbial enhanced oil recovery is field application, so the pilot simulation experiments are crucial. In this study, a micro-visualization model and the real cores were chosen to investigate the actual recovery efficiency and the mechanism of the consortium bacteria B-ALL, which has been proven to have good emulsification and degradation effects in lab studies in porous media. At the same time, the cast thin sections and rate-controlled porosimetry were combined to analyze the pore throat structure of the displacement core. It was found that the recovery efficiency was positively correlated with the microbial injection volume as well as the incubation time. For the microscopic model with high pores and high permeability, the efficiency of secondary water flooding can be increased by 44.77% after six days of incubation with two pore volume microbes. For the real tight cores, the maximum secondary water flooding efficiency under the same condition was 6.98%. Through visual modeling, microorganisms increase the oil washing efficiency mainly by emulsification and changing the wettability. The generated oil droplets will play a role in plugging and improving the wave efficiency. However, tight reservoirs have the characteristics of large pores and small throats, and curved and necking throats are developed, greatly reducing permeability. The microbial recovery efficiency was lower under shorter cultivation times. This study provides a practical basis for the application of consortium bacteria in tight oil fields to enhance recovery.