Application In Microbial Enhanced Oil Recovery Research Articles

Numerical modelling of biophysicochemical effects on multispecies reactive transport in porous media involving Pseudomonas putida for potential microbial enhanced oil recovery application

pH and resident time of injected slug plays a critical role in characterizing the reservoir for potential microbial enhanced oil recovery (MEOR) application. To investigate MEOR processes, a multispecies (microbes–nutrients) reactive transport model in porous media was developed by coupling kinetic and transport model. The present work differs from earlier works by explicitly determining parametric values required for kinetic model by experimental investigations using Pseudomonas putida at different pH conditions and subsequently performing sensitivity analysis of pH, resident time and water saturation on concentrations of microbes, nutrients and biosurfactant within reservoir. The results suggest that nutrient utilization and biosurfactant production are found to be maximum at pH 8 and 7.5 respectively. It is also found that the sucrose and biosurfactant concentrations are highly sensitive to pH rather than reservoir microbial concentration, while at larger resident time and water saturation, the microbial and nutrient concentrations were lesser due to enhanced dispersion.

Bioremediation of petroleum based contaminants with biosurfactant produced by a newly isolated petroleum oil degrading bacterial strain

Petroleum based hydrocarbon degrading and biosurfactant producing bacterial strain was isolated from an automobile engine. The strain was identified as Bacillus cereus DRDU1 on the basis of 16S rDNA sequencing analysis. The strain was found to be efficiently degrading 96% of kerosene making it a potential tool for bioremediation of petroleum based contaminants. Production and optimization of the biosurfactant produced by the isolate were also carried out. Surface hydrophobicity trait of isolate was found to be 60.67±1.53% and foaming percentage of the crude biosurfactant was found to be 31.33±0.58%. The presence of amino acids and sugar moieties in the biosurfactant was confirmed by biochemical tests and were further validated by FTIR (the Fourier transform infrared) spectrometric analysis revealing the presence of υOH, υCOO, υCOOH, υCH (stretching), υNH, υCH2, υCH3, and υCH (bending), and υCO (ester) in the surfactant. The decrease in contact angle of hydrocarbon oil from (30.67±1.15)° to (21.3±1.53)° respectively after 3 and 6days of incubation reveals its potential to emulsify petroleum oil. Further, emulsification index (E24) of biosurfactant against kerosene, crude oil, and used engine oil were determined to be 55.33±1.53%, 29.67±1.53%, and 20±1% respectively which attracts its future application in MEOR (microbial enhanced oil recovery) process.

Medium factors on anaerobic production of rhamnolipids by Pseudomonas aeruginosa SG and a simplifying medium for in situ microbial enhanced oil recovery applications.

Aerobic production of rhamnolipid by Pseudomonas aeruginosa was extensively studied. But effect of medium composition on anaerobic production of rhamnolipid by P. aeruginosa was unknown. A simplifying medium facilitating anaerobic production of rhamnolipid is urgently needed for in situ microbial enhanced oil recovery (MEOR). Medium factors affecting anaerobic production of rhamnolipid were investigated using P. aeruginosa SG (Genbank accession number KJ995745). Medium composition for anaerobic production of rhamnolipid by P. aeruginosa is different from that for aerobic production of rhamnolipid. Both hydrophobic substrate and organic nitrogen inhibited rhamnolipid production under anaerobic conditions. Glycerol and nitrate were the best carbon and nitrogen source. The commonly used N limitation under aerobic conditions was not conducive to rhamnolipid production under anaerobic conditions because the initial cell growth demanded enough nitrate for anaerobic respiration. But rhamnolipid was also fast accumulated under nitrogen starvation conditions. Sufficient phosphate was needed for anaerobic production of rhamnolipid. SO4(2-) and Mg(2+) are required for anaerobic production of rhamnolipid. Results will contribute to isolation bacteria strains which can anaerobically produce rhamnolipid and medium optimization for anaerobic production of rhamnolipid. Based on medium optimization by response surface methodology and ions composition of reservoir formation water, a simplifying medium containing 70.3 g/l glycerol, 5.25 g/l NaNO3, 5.49 g/l KH2PO4, 6.9 g/l K2HPO4·3H2O and 0.40 g/l MgSO4 was designed. Using the simplifying medium, 630 mg/l of rhamnolipid was produced by SG, and the anaerobic culture emulsified crude oil to EI24 = 82.5 %. The simplifying medium was promising for in situ MEOR applications.

Bacterial degradation of crude oil using solid formulations of bacillus strains isolated from oil-contaminated soil towards microbial enhanced oil recovery application

Microbial enhanced oil recovery has played a major role in enhancing crude oil recovery from depleted oil reservoirs to solve stagnant petroleum production.

Bacillus amyloliquefaciens TSBSO 3.8, a biosurfactant-producing strain with biotechnological potential for microbial enhanced oil recovery

A screening for biosurfactant-producing bacteria was conducted with 217 strains that were isolated from environmental samples contaminated with crude oil and/or petroleum derivatives. Although 19 promising biosurfactant producers were detected, strain TSBSO 3.8, which was identified by molecular methods as Bacillus amyloliquefaciens, drew attention for its production of a high-activity compound that presented an emulsification activity of 63% and considerably decreased surface (28.5mN/m) and interfacial (11.4mN/m) tensions in Trypticase Soy Broth culture medium. TSBSO 3.8 growth and biosurfactant production were tested under different physical and chemical conditions to evaluate its biotechnological potential. Biosurfactant production occurred between 0.5% and 7% NaCl, at pH values varying from 6 to 9 and temperatures ranging from 28 to 50°C. Moreover, biosurfactant properties remained the same after autoclaving at 121°C for 15min. The biosurfactant was also successful in a test to simulate microbial enhanced oil recovery (MEOR). Mass spectrometry analysis showed that the surface active compound was a surfactin, known as a powerful biosurfactant that is commonly produced by Bacillus species. The production of a high-efficiency biosurfactant, under some physical and chemical conditions that resemble those experienced in an oil production reservoir, such as high salinities and temperatures, makes TSBSO 3.8 an excellent candidate and creates good expectations for its application in MEOR.

The Application of Microbial Enhanced Oil Recovery Technology in Shengli Oilfield

For the last 20 years Shengli oilfield has done research into the application of microbial enhanced oil recovery (MEOR). The authors summarize and analyze MEOR progress in mechanism research and field application in Shengli oilfield. The results indicate MEOR could improve oil recovery after water flooding and polymer flooding with multiple mechanisms. Cumulative oil increment of MEOR application on seven blocks was 212,366 t. The research and application of MEOR should concentrate on air assisted microbial flooding and indigenous microbial flooding in the future.

Microbial diversity and abundance in the Xinjiang Luliang long-term water-flooding petroleum reservoir.

Microbial populations associated with microbial enhanced oil recovery (MEOR) and their abundance in the Xinjiang Luliang water-flooding petroleum reservoir were investigated using 16S rRNA, nitrate reductases, dissimilatory sulfate reductase, and methyl coenzyme-M reductase-encoded genes to provide ecological information for the potential application of MEOR. 16S rRNA gene miseq sequencing revealed that this reservoir harbored large amounts of taxa, including 155 bacterial and 7 archeal genera. Among them, Arcobacter, Halomonas, Marinobacterium, Marinobacter, Sphingomonas, Rhodococcus, Pseudomonas, Dietzia, Ochrobactrum, Hyphomonas, Acinetobacter, and Shewanella were dominant, and have the potential to grow using hydrocarbons as carbon sources. Metabolic gene clone libraries indicated that the nitrate-reducing bacteria (NRB) mainly belonged to Pseudomonas, Azospirillum, Bradyrhizobium, Thauera, Magnetospirillum, Sinorhizobium, Azoarcus, and Rhodobacter; the sulfate-reducing bacteria (SRB) were Desulfarculus, Desulfomonile, Desulfosarcina, Desulfotignum, Desulfacinum, Desulfatibacillum, Desulfatibacillum, Desulfomicrobium, and Desulfovibrio; while the methanogens were archaea and belonged to Methanomethylovorans, Methanosaeta, Methanococcus, Methanolobus, and Methanobacterium. Real-time quantitative PCR analysis indicated that the number of bacterial 16S rRNA reached 106 copies/mL, while the metabolic genes of NRB, SRB, and methanogens reached 104 copies/mL. These results show that the Luliang reservoir has abundant microbial populations associated with oil recovery, suggesting that the reservoir has potential for MEOR.

Investigation of wettability alteration through relative permeability measurement during MEOR process: A micromodel study

Abstract Microbial Enhanced Oil Recovery (MEOR) as a tertiary process employs microorganisms and their metabolites to reduce the residual oil saturation of the reservoir mainly through interfacial tension (IFT) reduction and wettability alteration. In spite of its great potential and the mentioned advantages, application of MEOR has been limited because of the lack of practical convincing experimental results. In this study, the effects of MEOR process on wettability changes and the reduction of residual oil saturation have been examined by providing microscopic visualization of two phase flow in transparent glass micromodels. Biosurfactant producing bacterial strain ( Enterobacter cloacae ) was utilized to investigate the impacts of both the biofilm and biosurfactant on wettability of the micromodel pore walls by measuring the relative permeabilities before and after microbial treatment. Results indicated that wettability of the pores was altered towards more water wetness which was also supported by visual observation of the oil/water phase saturations in the glass micromodel. Moreover, the oil recovery was increased up to 24.5% of the original oil in place (OOIP) during the MEOR process. At last, Biofilm formation was found to be more responsible for the wettability alteration process.

Characterization and optimization of biosurfactants produced by Acinetobacter baylyi ZJ2 isolated from crude oil-contaminated soil sample toward microbial enhanced oil recovery applications

The present work aims to investigate the surface activity of the biosurfactant produced by Acinetobacter baylyi ZJ2 isolated from crude oil-contaminated soil sample in China and evaluate its potential application in microbial enhanced oil recovery. The biosurfactant produced by A. baylyi ZJ2 was identified as lipopeptide based on thin-layer chromatography, Fourier transform infrared spectroscopy and nuclear magnetic resonance techniques. This biosurfactant could reduce the surface tension of water from 65mN/m to 35mN/m, and interfacial tension against oil from 45mN/m to 15mN/m. Moreover, surface activity stability results showed that this biosurfactant was effective when the salinity was lower than 8% and the pH value was 4–9, and it was especially stable when the salinity was lower than 4% and pH was 6–7. Based on the result of gas chromatography, there was a decrease in heavy components and an increase in light components, which indicated that A. baylyi ZJ2 exhibited the biodegradability on the heavy components of crude oil. Furthermore, the ability of recovering oil from oil-saturated core showed that nearly 28% additional residual oil was displaced after water flooding. The lipopeptide biosurfactant produced by A. baylyi ZJ2 presented a great potential application in microbial enhanced oil recovery process, owing its good surface activity and satisfying degradation ability to crude oil.

Modelling of microbial enhanced oil recovery application using anaerobic gas-producing bacteria

Microbial enhanced oil recovery (MEOR) methods apply injection of bacteria to depleted oil reservoirs to produce oil, which had remained unrecovered after the conventional methods of production. The ability of thermophilic anaerobic bacteria to produce gas as the main mechanism in potential MEOR in high salinities of 70–100 g/L was investigated in this study. Maximum gas production of up to 350 mL per 700 mL of salty solution was produced at a salinity of 90 g/L stably during 2–4 days of experiment. The experimental results were upscaled to the Snorre Oilfield, Norway, and simulated using ECLIPSE software for 27 months. The best scenarios showed that the increase in oil recovery on average was at 21% and 17.8% respectively. This study demonstrated that anaerobic bacteria used in biogas plants could be an attractive candidate for MEOR implementation due to their ability to withstand high temperature and salinity, and produce gas in large volumes.

Optimization and characterization of biosurfactant production by Bacillus subtilis isolates towards microbial enhanced oil recovery applications

Biosurfactant production by three Bacillus subtilis strains (#309, #311 and #573) isolated from Brazilian crude oils was optimized based on different carbon and nitrogen sources. The lowest surface tension values were obtained using sucrose containing media for the three isolates. Biosurfactants produced by each strain were characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF). The chemical characterization showed that the three isolates produced very similar mixtures, containing C13-, C14- and C15-surfactin, although in different proportions. The structure of surfactins produced by the three strains was shown to be in good agreement with their surface-activities. The interfacial-activities of the biosurfactants were characterized and compared with chemical surfactants. Furthermore, the application of biosurfactants and chemical surfactants in oil recovery was evaluated. The results obtained showed that biosurfactants have better interfacial-activity and oil recovery efficiency than common chemical surfactants, thus being more attractive to be applied in Microbial Enhanced Oil Recovery.

Production of Microbial Rhamnolipid by Pseudomonas Aeruginosa MM1011 for Ex Situ Enhanced Oil Recovery

Recently, several investigations have been carried out on the in situ bacteria flooding, but the ex situ biosurfactant production and addition to the sand pack as agents for microbial enhanced oil recovery (MEOR) has little been studied. In order to develop suitable technology for ex situ MEOR processes, it is essential to carry out tests about it. Therefore, this work tries to fill the gap. The intention of this study was to investigate whether the rhamnolipid mix could be produced in high enough quantities for enhanced oil recovery in the laboratory scale and prove its potential use as an effective material for field application. In this work, the ability of Pseudomonas aeruginosa MM1011 to grow and produce rhamnolipid on sunflower as sole carbon source under nitrogen limitation was shown. The production of Rha-C10-C10 and Rha2-C10-C10 was confirmed by thin-layer chromatography and high-performance liquid chromatography analysis. The rhamnolipid mixture obtained was able to reduce the surface and interfacial tension of water to 26 and 2 mN/m, respectively. The critical micelle concentration was 120 mg/L. Maximum rhamnolipid production reached to about 0.7 g/L in a shake flask. The yield of rhamnolipid per biomass (Y RL/x ), rhamnolipid per sunflower oil (Y RL/s ), and the biomass per sunflower oil (Y x/s ) for shake flask were obtained about 0.01, 0.0035, and 0.035 g g(-1), respectively. The stability of the rhamnolipid at different salinities, pH and temperature, and also, its emulsifying activity has been investigated. It is an effective surfactant at very low concentrations over a wide range of temperatures, pHs, and salt concentrations, and it also has the ability to emulsify oil, which is essential for enhanced oil recovery. With 120 mg/L rhamnolipid, 27 % of original oil in place was recovered after water flooding from a sand pack. This result not only suggests rhamnolipids as appropriate model biosurfactants for MEOR, but it even shows the potential as a biosurfactant of choice for actual MEOR applications.

Microbial processes in the Athabasca Oil Sands and their potential applications in microbial enhanced oil recovery

The Athabasca Oil Sands are located within the Western Canadian Sedimentary Basin, which covers over 140,200 km(2) of land in Alberta, Canada. The oil sands provide a unique environment for bacteria as a result of the stressors of low water availability and high hydrocarbon concentrations. Understanding the mechanisms bacteria use to tolerate these stresses may aid in our understanding of how hydrocarbon degradation has occurred over geological time, and how these processes and related tolerance mechanisms may be used in biotechnology applications such as microbial enhanced oil recovery (MEOR). The majority of research has focused on microbiology processes in oil reservoirs and oilfields; as such there is a paucity of information specific to oil sands. By studying microbial processes in oil sands there is the potential to use microbes in MEOR applications. This article reviews the microbiology of the Athabasca Oil Sands and the mechanisms bacteria use to tolerate low water and high hydrocarbon availability in oil reservoirs and oilfields, and potential applications in MEOR.

Optimization and Partial Characterization of Biosurfactants Produced by Bacillus Species and Their Potential for Ex-Situ Enhanced Oil Recovery

Summary This study aims to test the potential of microbial enhanced oil recovery (MEOR) as an effective alternative in Omani oil fields. In this study, biosurfactants produced by Bacillus licheniformis and Bacillus subtilis strains isolated from oil-contaminated soils from different parts of the Sultanate of Oman were investigated. Eight different minimal production media using different sugars as carbon sources were tested on three of the strains to select the medium that maximized the production of biosurfactants which were indicated by the interfacial tension (IFT) reduction. All isolates were tested on their potential media to screen for the best biosurfactant producer among the available strains. It was found that Bacillus subtilis Strain W19 gave the maximum IFT reduction (46.6 mN/m to 3.28 mN/m) in 16 hours of incubation when grown in a minimal medium containing glucose. The yield of the biosurfactant produced by B. subtilis W19 was 2.5g/L. Critical micelle concentration (CMC) was measured to be 0.4 g/L. The biosurfactant was partially characterized by FT-IR analysis, in which the peaks obtained imply the presence of aliphatic hydrocarbons as well as a peptide-like moiety in the biosurfactant. The cell-free biosurfactant broth produced from Strain W19 was found to be stable over a pH range from 6 to 10 and was most effective at 7. It also showed no loss in surface activity when subjected to various temperatures (60, 80, and 120°C). The biosurfactant also retained almost 60% of its activity even in a high-saline environment up to 20% NaCl (w/v). Further studies were conducted to test the interaction of biosurfactant produced by B. subtilis W19 with porous media in coreflooding experiments as a tertiary-recovery stage. The results showed high potential of using this bacterium during ex-situ MEOR applications in which a total of 23% of residual oil was produced after biosurfactant and concentrated-biosurfactant injection.

Interactions of Microbial-Enhanced Oil Recovery Processes

Microbial-enhanced oil recovery (MEOR) has been considered as a promising technique to further increase oil recovery from petroleum reservoirs. Although the potential benefits of MEOR applications are considerable, engineering of oil recovery via the manipulation of microbial metabolism still remains an unproven concept rather than a highly desirable reality. One of the main reasons is that there are few tools appropriate to quantify the multiple metabolic and physical processes involved in the oil recovery. This study seeks to address the lack of tools by presenting a computational model for simulating coupled processes in MEOR systems with two mobile, immiscible fluids. The primary goal of MEOR is to reduce the residual oil saturation. The residual saturation changes as a function of the capillary number that defines the relative effect of viscous forces versus surface tension acting across an interface between oil and water. In all previous MEOR studies, no explicit relations between residual oil saturation and capillary number were incorporated into theoretical models although this concept is often used in commercial reservoir simulators to simulate interfacial tension (IFT) modification. In this study, a functional relation between residual oil saturation and capillary number is achieved through solution of a coupled biological (B) and hydrogeological (H) finite element model. The BH model is quite sophisticated and difficult to solve numerically, however, presentation of the model results is simple and straightforward. A robust implicit method that incorporates a number of cross couplings between the BH processes is developed to solve the BH model. The model results are presented as a simple relation between the residual oil saturation and the capillary number and are compared to data from a well-documented core-flooding experiment. The model is applied to perform parametric studies for different microbial flooding scenarios. The BH model incorporates a description of the evolution of porosity and permeability that depends on the combined effects of the interactions between the BH processes. The model is used to predict the enhancement of oil recovery in a simple homogeneous test case. The model results demonstrate that MEOR could enhance the oil recovery significantly if a larger capillary number (between 10−5 and 10−1) is achievable.

MEOR Success in Southern Saskatchewan

Summary A microbial enhanced-oil-recovery (MEOR) process was successfully applied in a mature waterflooded reservoir in Saskatchewan, Canada. A nutrient solution, which was designed specifically for this reservoir to stimulate indigenous microbes to grow, multiply, and help to release oil, was tested and piloted. A significant decrease in water cut and increase in oil production have been realized through the selective stimulation of bacteria using nutrient injection. The field is a mature waterflood averaging more than 95% water cut. To combat the increasing water-cut issue, an in-situ microbial response analysis (ISMRA) was performed on a typical high-water-cut producer in the area. The test well was treated with a nutrient solution and then was shut in for a number of days to allow indigenous microbes to grow and multiply. Upon return to production, the well produced at an average of 200% more oil with a 10% decrease in water cut for a year. Pretreatment rates averaged 1.2 m3/d of oil (8 BOPD) and post-ISMRA treatment daily production peaked at 4.1 m3/d of oil (26 BOPD). The ISMRA provides a direct support of laboratory studies and frequently increases oil production. As a result of the successful ISMRA, a pilot project was initiated and the nutrients were applied in three batch treatments on an injector with three offset production wells. Three weeks after the first batch treatment, a water-cut decrease was seen at one of the offset producers. This well's oil production gradually increased from 1.4 to more than 8 m3/d (9 to 50 B/D). Oil production in another producer doubled from 1.5 to more than 3.0 m3/d (9 to 19 B/D). Subsequent treatments were tried on marginally economic wells and on a reactivated idle producer. The average decrease in water cut in these wells was more than 10%. On the idle well, oil production increased from 0.5 m3/d (3 B/D) pretreatment to an average of 3.0 m3/d (19 B/D) post-treatment. Throughout the world, there remains a huge target for enhanced-oil-recovery (EOR) processes to target (Bryant 1991). This successful MEOR application will have a tremendous impact on ultimate recovery in many of these reservoirs not only through an increase in production, but a decrease in operating costs through associated reduction in lifting costs with less water production.

Growth and Starvation of a Strain of Klebsiella pneumoniae Isolated from a Brazilian Oil Formation

The changes that occur in cell size and shape during experimental starvation and resuscitation of bacteria may find practical application in the biotechnological processes used in microbial enhanced oil-recovery (MEOR), in in situ bioremediation and in the creation of biobarriers. In the work described here, the aim was to observe certain aspects of the response of a strain of Klebsiella pneumoniae, isolated from oil producer wells belonging to PETROBRAS (National Oil Company of Brazil), to starvation and growth under various culture conditions. Cells of K. pneumoniae were taken from an exponentially-growing culture, washed and suspended in phosphate-buffered saline solution, without nutrients, where they remained for 91 days. Aliquots were withdrawn periodically, to perform viable and total cell counts and measure the optical density and cell dimensions. The starved cells were resuspended in sodium citrate medium, where they recuperated and exhibited a typical growth curve. The results indicate that this strain is a viable option for future trials on the transport and growth of microorganisms inside porous media, aimed at possible applications in MEOR.

Mathematical Modeling of the Soaking Period in a Microbial Enhanced Oil Recovery Application

In this study, experimental conditions of the microbial enhanced oil recovery (MEOR) technique applied for Garzan oil (26° API; southeast Turkey) were utilized in a mathematical model that describes the transport of bacteria and its nutrients by convective and dispersive forces, including bacterial decay and growth. From the results of the variation of bacterial concentration with distance, it was observed that the bacterial concentration increased as the nutrients were consumed with time. Although some bacteria died during the experiments, this did not slow down the overall increase in bacterial population significantly at earlier times. However, in the later periods of the soaking process, severe bacterial decay occurred due to the lack of nutrients. The pressure behavior in the model during the shut-in period was also calculated and agreed well with the experimental results.

Selection of Bacteria with Favorable Transport Properties Through Porous Rock for the Application of Microbial-Enhanced Oil Recovery

This paper presents a bench-scale study on the transport in highly permeable porous rock of three bacterial species-Bacillus subtilis, Pseudomonas putida, and Clostridium acetobutylicum-potentially applicable in microbial-enhanced oil recovery processes. The transport of cells during the injection of bacterial suspension and nutrient medium was simulated by a deep bed filtration model. Deep bed filtration coefficients and the maximum capacity of cells in porous rock were measured. Low to intermediate ( approximately 10/ml) injection concentrations of cellular suspensions are recommended because plugging of inlet surface is less likely to occur. In addition to their resistance to adverse environments, spores of clostridia are strongly recommended for use in microbial-enhanced oil recovery processes since they are easiest among the species tested to push through porous rock. After injection, further transport of bacteria during incubation can occur by growth and mobility through the stagnant nutrient medium which fills the porous rock. We have developed an apparatus to study the migration of bacteria through a Berea sandstone core containing nutrient medium.