Morphological Variation and Recovery Mechanism of Residual Crude Oil by Biosurfactant from Indigenous Bacteria: Macro- and Pore-Scale Experimental Investigations

Song, Zhiyong; Huang, Han; Zhu, Weiyao

doi:10.4014/jmb.1409.09074

Cited by 12 publications

(21 citation statements)

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“…The two-dimensional microscopic flooding apparatus shown schematically in Figure a was described in our previous paper. , The experimental setup comprised two primary systems: a flooding system and an image capturing system. The flooding system consisted of a syringe pump, accumulators, and a model holder, and the image-capturing system included a microscope, camera, and computer.…”

Section: Methodsmentioning

confidence: 99%

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO₂ Flooding

et al. 2018

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To understand the pore-scale processes of asphaltene deposition during heavy oil recovery by CO2 flooding, a series of microscopic flooding experiments were conducted in two-dimensional models under high-temperature (80 °C) and high-pressure (2, 6, and 10 MPa) conditions. Two different heavy oils, AZ-4 and KD-9 (with viscosities of 7754 and 19 290 mPa·s, respectively, at 80 °C), were used. In these samples, up to 95% and 85% of oil viscosity reduction, respectively, could be achieved by CO2 dissolution. During CO2 flooding in the microscopic models, with increasing fluid pressure (6 and 10 MPa) and CO2 concentrations (60–80 mol %), both the covered area (17–38%) and the sizes of the deposited particles (up to 200 μm) became larger. At 6 MPa, a dynamic between between dissolution and precipitation was observed in large pores (with diameters of >350 μm). According to the solvent dissolution test (heptane and toluene), the deposited solids comprise both asphaltene and alkane components. Between AZ-4 and KD-9, higher resin/asphaltene ratios tend to reduce asphaltene deposition during the dissolution of CO2 by stabilizing the solubility of asphaltene in crude oil. In addition, although permeability decreased (up to 15%) with increasing pressure (2–10 MPa) and CO2 concentrations (25–70 mol %), the oil recovery mostly increased (up to 88.6% with AZ-4). The only decrease in oil recovery occurred with KD-9, which decreased from 64.7% (6 MPa, with a CO2 concentration of 69.7%) to 56.1% under 10 MPa and considerably high CO2 concentrations (79.7 mol %). Compared with the light oil system, the tested heavy oil shows considerably improved recovery and less asphaltene deposition during high-concentration CO2 flooding. Therefore, although CO2 miscibility can hardly be achieved in heavy oil reservoirs, CO2 is of great interest due to its high solubility in heavy oil and significant oil viscosity reduction.

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Section: Methodsmentioning

confidence: 99%

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO₂ Flooding

et al. 2018

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“…After the original images were sharpened, the water, gas, oil, and glass phases were distinguished by given pixel intensity thresholds. The saturation of the given phase was then calculated using the MATLAB program based on the proportion of the area of a given phase to the total pore area …”

Section: Methodsmentioning

confidence: 99%

“…The saturation of the given phase was then calculated using the MATLAB program based on the proportion of the area of a given phase to the total pore area. 30 2.6. Emulsification Tests.…”

Section: Methodsmentioning

confidence: 99%

Pore-Scale Mechanisms of the Synergistic Effects between Microbial Cultures and Chemical Surfactants on Oil Recovery

Wang

Zhu

et al. 2018

Energy Fuels

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A significant synergistic effect has been reported between microbial cultures and chemical surfactants in crude oil recovery processes. A number of attempts have been made to understand the synergistic mechanism. However, the existing studies only addressed the aspects of wettability alteration and interfacial tension (IFT) reduction, although there are many more contributors to the mechanism, such as emulsification, functional microbial activities, and diverse byproducts. In addition, the previous knowledge on synergistic oil recovery was based on indirect evidence from core-scale flooding and test tube experiments. To fully exploit the synergistic effects in the future, a new experimental system must be introduced (i) to verify the existing mechanisms in situ in porous media during the flooding process and (ii) to address the other potential contributors for a more comprehensive insight into the actual major contributors. Therefore, a visual pore-scale flooding experimental system was introduced in the present study to mimic the pore networks and conditions of a reservoir (55 °C, 10 MPa). This system enabled direct observations of fluid dynamics in pores during flooding. The final oil recovery using indigenous microorganisms (8.3%) and an anionic surfactant [sodium alcohol ether sulphate (AES)] (15.5%) was considerably enhanced (22.4%) when the two solutions were equally mixed, which indicated significant synergistic effects between them, whereas no such effects were observed with a nonionic surfactant [polyoxyethylene nonylphenol ether (OP10)]. The pore-scale and macroscale analyses were combined to reveal the synergistic mechanisms between the microbial culture and AES. The results show that the IFT reduction and wettability alteration, traditionally considered to be synergistic mechanisms, contributed to the oil recovery but were not the major contributors to the synergistic effects. In this case, the synergistic mechanisms include the following aspects: the anionic surfactant promotes microbial metabolism, such as biogas production (significantly enhanced from 0.0018 mL/mL medium to 0.0196 mL/mL medium), and the microbial culture, in turn, reduces the critical micelle concentration of the surfactant and enhances the emulsion effectiveness, including reducing the oil droplet sizes (from D 90 = 217 to 116 μm) and increasing the stability of the emulsion system from several minutes to a few days. The two synergistic mechanisms reflect the mutually positive effects between the chemical surfactant and the microbial system; these mutual effects are especially essential for long-term and long-distance oil migration and final recovery in a real reservoir-scale flooding process.

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“…To date, the isolated hydrocarbon-degrading microorganisms mainly belong to Pseudomonas [15–17], Acinetobacter [5], Bacillus [8, 18], Aeribacillus pallidus [19], Bacillus licheniformis [20], and Geobacillus [21]. These microbial populations were demonstrated to be able to enhance oil recovery in laboratory, and some species were found showing positive responses with incremental oil in laboratory and MEOR field trials [5, 8, 9, 22, 23].…”

Section: Introductionmentioning

confidence: 99%

Low-Abundance Dietzia Inhabiting a Water-Flooding Oil Reservoir and the Application Potential for Oil Recovery

Gao

Wang

et al. 2019

BioMed Research International

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With the development of molecular ecology, increasing low-abundance microbial populations were detected in oil reservoirs. However, our knowledge about the oil recovery potential of these populations is lacking. In this study, the oil recovery potential of low-abundance Dietzia that accounts for less than 0.5% in microbial communities of a water-flooding oil reservoir was investigated. On the one hand, Dietzia sp. strain ZQ-4 was isolated from the water-flooding reservoir, and the oil recovery potential was evaluated from the perspective of metabolisms and oil-displacing test. On the other hand, the strain has alkane hydroxylase genes alkB and P450 CYP153 and can degrade hydrocarbons and produce surfactants. The core-flooding test indicated that displacing fluid with 2% ZQ-4 fermentation broth increased 18.82% oil displacement efficiency, and in situ fermentation of ZQ-4 increased 1.97% oil displacement efficiency. Furthermore, the responses of Dietzia in the reservoir accompanied by the nutrient stimulation process was investigated and showed that Dietzia in some oil production wells significantly increased in the initial phase of nutrient injection and sharply decreased along with the continuous nutrient injection. Overall, this study indicates that Dietzia sp. strain has application potential for enhancing oil recovery through an ex situ way, yet the ability of oil recovery in situ based on nutrient injection is limited.

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Morphological Variation and Recovery Mechanism of Residual Crude Oil by Biosurfactant from Indigenous Bacteria: Macro- and Pore-Scale Experimental Investigations

Cited by 12 publications

References 0 publications

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO₂ Flooding

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO₂ Flooding

Pore-Scale Mechanisms of the Synergistic Effects between Microbial Cultures and Chemical Surfactants on Oil Recovery

Low-Abundance Dietzia Inhabiting a Water-Flooding Oil Reservoir and the Application Potential for Oil Recovery

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Morphological Variation and Recovery Mechanism of Residual Crude Oil by Biosurfactant from Indigenous Bacteria: Macro- and Pore-Scale Experimental Investigations

Cited by 12 publications

References 0 publications

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO2 Flooding

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO2 Flooding

Pore-Scale Mechanisms of the Synergistic Effects between Microbial Cultures and Chemical Surfactants on Oil Recovery

Low-Abundance Dietzia Inhabiting a Water-Flooding Oil Reservoir and the Application Potential for Oil Recovery

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2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO₂ Flooding

2-D Pore-Scale Experimental Investigations of Asphaltene Deposition and Heavy Oil Recovery by CO₂ Flooding