The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Ramkrishna Sen - One of the best experts on this subject based on the ideXlab platform.
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performance evaluation of batch and unsteady state fed batch reactor operations for the production of a marine microbial surfactant
Journal of Chemical Technology & Biotechnology, 2013Co-Authors: C Sivapathasekaran, Ramkrishna SenAbstract:BACKGROUND: Biosurfactants are microbially derived surface-active and amphipathic molecules produced by various microorganisms. These versatile biomolecules can find potential applications in food, cosmetics, Petroleum Recovery and biopharmaceutical industries. However, their commercial use is impeded by low yields and productivities in fermentation processes. Thus, an attempt was made to enhance product yield and process productivity by designing a fed-batch mode reactor strategy. RESULTS: Biosurfactant (BS) production by a marine bacterium was performed in batch and fed-batch modes of reactor operation in a 3.7 L fermenter. BS concentration of 4.61 ± 0.07 g L−1 was achieved in batch mode after 22 h with minimum power input of 33.87 × 103 W, resulting in maximum mixing efficiency. The volumetric oxygen flow rate (KLa) of the marine culture was about 0.08 s−1. BS production was growth-associated, as evident from fitting growth kinetics data into the Luedeking-Piret model. An unsteady state fed batch (USFB) strategy was employed to enhance BS production. Glucose feeding was done at different flow rates ranging from 3.7 mL min−1 (USFB-I) to 10 mL min−1 (USFB-II). USFB-I strategy resulted in a maximum biosurfactant yield of 6.2 g l−1 with an increment of 35% of batch data. The kinetic parameters of USFB-I were better than those from batch and USFB-II. CONCLUSION: Comparative performance evaluation of batch and semi-continuous reactor operations was accomplished. USFB-I operation improved biosurfactant production by about 35% over batch mode. USFB-I strategy was more kinetically favorable than batch and USFB-II. © 2012 Society of Chemical Industry
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biotechnology in Petroleum Recovery the microbial eor
Progress in Energy and Combustion Science, 2008Co-Authors: Ramkrishna SenAbstract:Abstract Biotechnology has played a significant role in enhancing crude oil Recovery from the depleted oil reservoirs to solve stagnant Petroleum production, after a three-stage Recovery process employing mechanical, physical and chemical methods. Biotechnologically enhanced oil Recovery processes, known as microbial enhanced oil Recovery (MEOR), involve stimulating indigenous reservoir microbes or injecting specially selected consortia of natural bacteria into the reservoir to produce specific metabolic events that lead to improved oil Recovery. This also involves flooding with oil Recovery agents produced ex situ by industrial or pilot scale fermentation. This paper essentially reviews the operating mechanisms and the progress made in enhanced oil Recovery through the use of microbes and their metabolic products. Improvement in oil Recovery by injecting solvents and gases or by energizing the reservoir microflora to produce them in situ for carbonate rock dissolution and reservoir re-pressurization has been enunciated. The role of biosurfactants in oil mobilization through emulsification and that of biopolymers for selective plugging of oil-depleted zones and for biofilm formation have been delineated. The spoil sport played by sulfate-reducing bacteria (SRB) in MEOR has also been briefly reviewed. The importance of mathematical models used in predicting the applicability of an MEOR strategy and the microbial growth and transport has been qualitatively discussed. The results of some laboratory studies and worldwide field trials applying ex situ and in situ MEOR technologies were compiled and interpreted. However, the potential of the MEOR technologies has not been fully realized due to poor yield of the useful microbial metabolic products, growth inhibition by accumulated toxic metabolites and longer time of incubation. A complete evaluation and assessment of MEOR from an engineering standpoint based on economics, applicability and performance is required to further improve the process efficiency for writing more success stories. Thus, this review attempts to address almost all the issues concerning the MEOR, its past and recent trends and its future prospect and directions.
Pål Østebø Andersen - One of the best experts on this subject based on the ideXlab platform.
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A simplified modelling approach for Petroleum Recovery by spontaneous imbibition in naturally fractured reservoirs
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Pål Østebø AndersenAbstract:Abstract A fracture-matrix model is presented for multiphase flow in fractured porous media where oil is recovered by spontaneous imbibition (SI) of injected water. Our aim is to investigate flow in naturally fractured reservoirs using a model composed of several parallel regions with homogeneous distribution of fracture-matrix properties and fixed cross section. Due to symmetry this allows flow in a region to be described only based on a single fracture and its surrounding matrix. The focus is on how region heterogeneity and fluid viscosities can influence the production of a reservoir. We use Buckley-Leverett flow along individual fractures with SI of water into the surrounding matrix relying on a dual porosity formulation. The source terms account for consistent saturation curves for water-wet media and fluid viscosities. First, we show that flow along a homogeneously fractured formation can be characterized into advection dominated (inefficient Recovery) or SI dominated (efficient Recovery) represented by a dimensionless number, ω. Next, we consider flow through several parallel regions (fracture-matrix systems) with different properties. This is the novel part of the work. The approach bears similarities to the Dykstra-Parsons model (for layered non-fractured media) and streamtube modelling. The model illustrates that heterogeneity in fracture geometry (aperture and spacing) can lead to uneven distribution of the injected water. At equal phase viscosities, regions with many and wide fractures receive more water, and are produced fast, but with high water production. Regions with few and narrow fractures receive less water, are produced more slowly, but more of the injected water stays in the matrix. Porosity and permeability variations in the matrix did not cause flow diversion, but variation in Recovery efficiency. If the oil had high viscosity (compared to water) the heterogeneity effects were enhanced by more flow diversion and higher contrasts in Recovery regimes. If the water had high viscosity (compared to oil, i.e. polymer injection) the flow diversion was reduced, but imbibition time increased with net result to worsen Recovery performance. The methodology shown in this paper is relevant for upscaling injection of reactive components or agents that are coupled to the multiphase flow dynamics.
Alexey Ershov - One of the best experts on this subject based on the ideXlab platform.
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the potential application of microorganisms for sustainable Petroleum Recovery from heavy oil reservoirs
Sustainability, 2019Co-Authors: T N Nazina, Diyana S Sokolova, Denis S Grouzdev, E M Semenova, T L Babich, Salimat K Bidzhieva, Dmitriy Serdukov, Dmitriy Volkov, Konstantin Bugaev, Alexey ErshovAbstract:A microbial enhanced oil Recovery (MEOR) technique was tested at low-temperature heavy oil reservoirs (Russia). The bioaugmentation approach used is based on the introduction of hydrocarbon-oxidizing bacteria into the oilfield in combination with an injection of oxygen as a H2O2 solution in order to initiate the first stage of hydrocarbon oxidation and of (NH4)2HPO4 as a source of biogenic elements. Before the pilot trials, the microorganisms of Petroleum reservoirs were investigated by high-throughput sequencing, as well as by culture-base and radioisotope techniques. Molecular studies revealed the differences in microbial composition of the carbonate and terrigenous oil reservoirs and the communities of injection and formation water. Aerobic bacteria Rhodococcus erythropolis HO-KS22 and Gordonia amicalis 6-1 isolated from oilfields oxidized oil and produced biosurfactants. Fermentative enrichment and pure cultures produced considerable amounts of low fatty acids and alcohols from sacchariferous substrates. In core-flooding tests, 43.0–53.5% of additional heavy oil was displaced by aerobic bacteria, producing biosurfactants, and 13.4–45.5% of oil was displaced by fermentative bacteria, producing low fatty acids, alcohols, and gas. A total of 1250 t additional oil was recovered as a result of the application of an MEOR technique at the Cheremukhovskoe heavy oil reservoir and Vostochno-Anzirskoe reservoir with light conventional oil.
Bozhong Mu - One of the best experts on this subject based on the ideXlab platform.
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chemical structure property and potential applications of biosurfactants produced by bacillus subtilis in Petroleum Recovery and spill mitigation
International Journal of Molecular Sciences, 2015Co-Authors: Serge Maurice Mbadinga, Shizhong Yang, Jidong Gu, Bozhong MuAbstract:Lipopeptides produced by microorganisms are one of the five major classes of biosurfactants known and they have received much attention from scientific and industrial communities due to their powerful interfacial and biological activities as well as environmentally friendly characteristics. Microbially produced lipopeptides are a series of chemical structural analogues of different families and, among them, 26 families covering about 90 lipopeptide compounds have been reported in the last two decades. This paper reviews the chemical structural characteristics and molecular behaviors of surfactin, one of the representative lipopeptides of the 26 families. In particular, two novel surfactin molecules isolated from cell-free cultures of Bacillus subtilis HSO121 are presented. Surfactins exhibit strong self-assembly ability to form sphere-like micelles and larger aggregates at very low concentrations. The amphipathic and surface properties of surfactins are related to the existence of the minor polar and major hydrophobic domains in the three 3-D conformations. In addition, the application potential of surfactin in bioremediation of oil spills and oil contaminants, and microbial enhanced oil Recovery are discussed.
John A Pojman - One of the best experts on this subject based on the ideXlab platform.
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the effect of a crosslinking chemical reaction on pattern formation in viscous fingering of miscible fluids in a hele shaw cell
Chaos, 2017Co-Authors: P Bunton, Michael Tullier, Eckart Meiburg, John A PojmanAbstract:Viscous fingering can occur in fluid motion whenever a high mobility fluid displaces a low mobility fluid in a Darcy type flow. When the mobility difference is primarily attributable to viscosity (e.g., flow between the two horizontal plates of a Hele-Shaw cell), viscous fingering (VF) occurs, which is sometimes termed the Saffman-Taylor instability. Alternatively, in the presence of differences in density in a gravity field, buoyancy-driven convection can occur. These instabilities have been studied for decades, in part because of their many applications in pollutant dispersal, ocean currents, enhanced Petroleum Recovery, and so on. More recent interest has emerged regarding the effects of chemical reactions on fingering instabilities. As chemical reactions change the key flow parameters (densities, viscosities, and concentrations), they may have either a destabilizing or stabilizing effect on the flow. Hence, new flow patterns can emerge; moreover, one can then hope to gain some control over flow instabilities through reaction rates, flow rates, and reaction products. We report effects of chemical reactions on VF in a Hele-Shaw cell for a reactive step-growth cross-linking polymerization system. The cross-linked reaction product results in a non-monotonic viscosity profile at the interface, which affects flow stability. Furthermore, three-dimensional internal flows influence the long-term pattern that results.