Crude Oil Components Research Articles

Increasing the Resistance of Wheat to Oil Pollution Using Endophytic Bacteria Bacillus subtilis

The effect of treatment of wheat seeds with a suspension culture of cells of endophytic bacteria of the strain Bacillus subtilis 26D and lines B. subtilis 26D+n, selected for tolerance to crude oil components, on the growth and biochemical characteristics of wheat plants Triticum aestivum L. in conditions of oil pollution of the soil was studied. It has been shown that seed inoculation with the line B. subtilis 26D+n stimulated the growth of seedlings and suppressed the development of oxidative stress under conditions of exposure to oil pollution in plants in comparison with the control and plants inoculated with the strain B. subtilis 26D. Accordingly, bacteria B. subtilis 26D+n contributed to more successful growth of wheat plants on oil-contaminated soils, which can be used to stimulate the growth of plants in such areas and to return some of them to economic circulation.

Study on the mechanism and recoverability of magnetically enhanced ionic liquid microemulsion for oily sludge treatment

Magnetic ionic liquid (MIL) 1-hexadecyl-3-methylimidazolium tetrachloroferrate (III) ([C16mim]FeCl4) with high surface activity and magnetic responsiveness was synthesized and chosen as surfactant for the preparation of MIL-microemulsion, which could be applied to the effective treatment of oily sludge based on its large specific surface area and good solubilization. Under the optimal conditions of MIL concentration of 3.0 wt%, stirring time of 40 min, stirring speed of 500 r/min and temperature of 25 °C, the residual oil rate reached up to 1.36%. Scanning electron microscope (SEM) and fourier infrared spectrometer (FT-IR) measurement proved the successful removal of crude oil. The interaction between [C16mim]FeCl4 and each component in crude oil was explored by interfacial tension (IFT) and quartz crystal microbalance with dissipation (QCM-D). The results demonstrated that MIL exhibited the lowest interfacial tension of 13.48 mN/m and the highest desorption rate of 28.18% with asphaltene. In addition, based on the magnetic responsiveness of MIL, the application of magnetic field made it possible for the recovery of MIL, which could be reused for the preparation of microemulsion. Even after 5 cycles, the residual oil content in the oily sludge remained below 1.92%. The controllable recovery and reuse of [C16mim]FeCl4 by external magnetic field expanded the application of MIL-microemulsion in the field of oily sludge treatment.

Do oil droplets and chemical dispersants contribute to uptake of oil compounds and toxicity of crude oil dispersions in cold-water copepods?

ABSTRACT Accidental crude oil spills to the marine environment cause dispersion of oil into the water column through the actions of breaking waves, a process that can be facilitated using chemical dispersants. Oil dispersions contain dispersed micron-sized oil droplets and dissolved oil components, and the toxicity of oil dispersions has been assumed to be associated primarily with the latter. However, most hydrophobic, bioaccumulative and toxic crude oil components are retained within the droplets which may interact with marine filter-feeders. We here summarize the findings of 15 years of research using a unique methodology to generate controlled concentrations and droplet size distributions of dispersed crude oil to study effects on the filter-feeding cold-water copepod Calanus finmarchicus. We focus primarily on the contribution of chemical dispersants and micron-sized oil droplets to uptake and toxicity of oil compounds. Oil dispersion exposures cause PAH uptake and oil droplet accumulation on copepod body surfaces and inside their gastrointestinal tract, and exposures to high exposure (mg/L range) reduce feeding activity, causes reproductive impairments and mortality. These effects were slightly higher in the presence of chemical dispersants, possibly due to higher filtration of chemically dispersed droplets. For C. finmarchicus, dispersions containing oil droplets caused more severe toxic effects than filtered dispersions, thus, oil droplets contribute to the observed toxicity. The methodology for generating crude oil dispersion is a valuable tool to isolate impacts of crude oil microdroplets and can facilitate future research on oil dispersion toxicity and produce data to improve oil spill models.

Organic Matter Source, Fluid Migration, and Geological Significance of Stylolites in Organic-Lean Carbonate Rocks: A Case from the Sichuan Basin

Carbonate rocks exhibit significant heterogeneity as both a source rock and reservoir. Stylolite formation plays a crucial role in the enrichment of organic matter and the migration of geofluids within carbonate rocks. In order to study the enrichment mechanism of organic matter and the geofluid migration mode in the stylolites developed in carbonate rocks, stylolite-bearing core samples from the Dachigan structural belt in the eastern Sichuan Basin were collected. The stylolites and matrix were subjected to the total organic carbon (TOC) test and Rock-Eval pyrolysis, thin-section observation under fluorescent light, whole-rock X-ray diffraction, carbon and oxygen isotope analysis, and scanning electron microscopy. The organic matter occurring in the stylolites is mainly in the form of three types: soluble organic matter, pyrobitumen, and bitumen. This suggests that the organic matter within the stylolites mainly consists of secondary migrated organic matter. The stylolites also exhibit well-developed secondary dolomite and pyrite resulting from late-diagenetic recrystallization. These minerals contribute to the preservation of intercrystalline pore spaces and fractures, providing favorable conditions for oil and gas accumulation and migration. The strong cementation observed at the contact between the stylolites and matrix, along with the presence of secondary minerals nearby, may be attributed to the fractionation of light and heavy oil components during the migration of hydrocarbon fluids from the matrix to the stylolites. The thicknesses of the stylolites vary within the bulk, indicating severe diagenesis in thinner areas. Consequently, this leads to significant fractionation effects. The fractionation of crude oil components by stylolites poses challenges for the study of definitive oil–source correlations. To overcome these challenges, future research could investigate biomarker compounds to attempt oil–source correlations. Additionally, future efforts should take into consideration the spatial variation in the crude oil properties. Understanding the role of stylolites in organic matter enrichment and geofluid migration is crucial for optimizing exploration strategies in the Sichuan Basin, a region of growing importance in the energy industry. Moreover, our findings shed light on the complex interactions within stylolite-bearing rocks, which are not limited to this specific basin. These insights offer valuable contributions to the broader field of geology and reservoir characterization, enhancing our ability to predict and interpret similar geological formations globally.

Unraveling the functional instability of bacterial consortia in crude oil degradation via integrated co-occurrence networks.

Soil ecosystems are threatened by crude oil contamination, requiring effective microbial remediation. However, our understanding of the key microbial taxa within the community, their interactions impacting crude oil degradation, and the stability of microbial functionality in oil degradation remain limited. To better understand these key points, we enriched a crude oil-degrading bacterial consortium generation 1 (G1) from contaminated soil and conducted three successive transfer passages (G2, G3, and G4). Integrated Co-occurrence Networks method was used to analyze microbial species correlation with crude oil components across G1-G4. In this study, G1 achieved a total petroleum hydrocarbon (TPH) degradation rate of 32.29% within 10 days. Through three successive transfer passages, G2-G4 consortia were established, resulting in a gradual decrease in TPH degradation to 23.14% at the same time. Specifically, saturated hydrocarbon degradation rates ranged from 18.32% to 14.17% among G1-G4, and only G1 exhibited significant aromatic hydrocarbon degradation (15.59%). Functional annotation based on PICRUSt2 and FAPROTAX showed that functional potential of hydrocarbons degradation diminished across generations. These results demonstrated the functional instability of the bacterial consortium in crude oil degradation. The relative abundance of the Dietzia genus showed the highest positive correlation with the degradation efficiency of TPH and saturated hydrocarbons (19.48, 18.38, p < 0.05, respectively), Bacillus genus demonstrated the highest positive correlation (21.94, p < 0.05) with the efficiency of aromatic hydrocarbon degradation. The key scores of Dietzia genus decreased in successive generations. A significant positive correlation (16.56, p < 0.05) was observed between the Bacillus and Mycetocola genera exclusively in the G1 generation. The decline in crude oil degradation function during transfers was closely related to changes in the relative abundance of key genera such as Dietzia and Bacillus as well as their interactions with other genera including Mycetocola genus. Our study identified key bacterial genera involved in crude oil remediation microbiome construction, providing a theoretical basis for the next step in the construction of the oil pollution remediation microbiome.

De-oiling characteristics and mechanism of oil-bearing sludge cleaned by CGAs

There hasn't been much study on using Colloidal Gas Aphrons (CGAs) to clean oily sludge. In addition, the efficacy and mechanism of CGAs-enhanced surfactant cleaning of oily sludge are not yet clear. Therefore, in this study, CGAs prepared from the compound surfactant solution were used to clean oily sludge in an oil field in Xinjiang. The performance of CGAs in terms of oil removal and particle size was both examined when building the surfactant compounding system. The removal abilities of CGAs from different crude oil components and an analysis of the chemical cleaning process of CGAs were studied. The results demonstrated that the interfacial tension was as low as 3.535 mN/m and the oil removal rate of CGAs was as high as 92.9% when the ideal ratio of sophorolipid (SL) to sodium dodecyl benzene sulfonate (SDBS) was 6: 4. The average particle size of CGAs was 90.57 µm at this ideal ratio. The Zeta potential and turbidity of the supernatant after CGAs cleaning was lower than those of chemical cleaning. Infrared analysis, two-dimensional fluorescence analysis, and thermogravimetric methods were used to characterize the oily sludge after CGAs cleaned. According to the analysis's findings, CGAs' enormous specific surface area allows them to adsorb more petroleum pollutants and improved the ability of those pollutants to migrate between the water phase and other phases of the atmosphere. Also, CGAs are particularly successful in adhering to petroleum-based pollutants in oil sludge for the removal of light constituents like n-alkanes and aromatic hydrocarbons due to the synergistic effects of hydrophobic and electrostatic effects on the functional surface of CGAs. This work provides useful information on the mechanism of the enhanced removal of crude oil from oily sludge by CGAs and provides a new idea for oily sludge cleaning.

Performance Evaluation of Bacterial Consortia from Low-Permeability Reservoir in Ordos Basin

The combination of strains of different species and genera may enhance the effects of single bacteria, surpass the tolerance upper limit, and optimize the viscosity reduction and degradation. In this study, six strains were isolated in low permeability layers of the Ordos Basin and were combined to verify the effect of the consortium strains. The selected single strains have good emulsifying and viscosity-reducing effects, but their degradation components are different. SC4561 (Bacillus cereus), SC4551 (Bacillus sp.), and H-1 (Brevibacillus sp.) form consortium A, and SC4534 (2) (Bacillus sp.), SC4542 (Bacillus licheniformis), and A-3 (Bacillus licheniformis) form consortium B. The performance of the mixed strains was evaluated by the analysis of change in emulsification rate, crude oil composition, viscosity, and the tolerance (temperature, salinity, and pH) through GC-MS, rotational rheometer, and other methods. The results showed that the temperature tolerance of the consortium strains was improved by 5-7°C. Consortium B had higher emulsibility ( E 24 was higher than 40% in average) and viscosity degradation (above 35%), and the crude oil in consortium B has almost no wall adhesion. The components of crude oil that consortia use were still diverse, including both long- and short-chain hydrocarbons. However, the proportion of long-chain n-alkanes is further reduced compared with that of single bacteria, and the highest ratio was reduced by 23.81% (B-ALL). At the same time, they also had effects on aromatic hydrocarbons with complex structures (phenanthrene and phenanthrene). This research confirms the enhanced effect of consortium bacteria on single bacteria, facilitating the implementation of microbial enhanced oil recovery technology in the future.

Ni/Al2O3 waste catalyst loaded with pomegranate peel extract and Ce3+ ions as a sustainable active/barrier pigment for epoxy anti-corrosion coating

Nickel-containing alumina (Ni/Al2O3) is a commercially available catalyst that is widely used for desulfurizing crude oil components. However, the accumulation of carbon and sulfur on the catalyst surface can lead to its deactivation, making its disposal environmentally hazardous. Additionally, extracting nickel from waste catalysts is not economically feasible. The high specific surface area of Ni/Al2O3 waste catalyst (Cat), which can exceed 100 m2/g, makes it a promising material for repurposing as nanocontainers for anti-corrosive coatings. In this study, an intelligent epoxy (EP) anti-corrosion coating incorporating Cat for encapsulating a green hybrid corrosion inhibitor based on pomegranate peel extract (PPE) and Ce3+ ions was developed. Brunauer-Emmett-Teller (BET) analysis revealed that Cat nanopigment possessed a mesoporous structure and a surface area of 127 m2/g, rendering it a suitable candidate for encapsulating corrosion inhibitors. Fourier-transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TGA) were employed to confirm inhibitor loading in the Cat nanopigment. The self-healing and protective properties of the prepared EP-based composite coatings were evaluated using salt spray and electrochemical impedance spectroscopy (EIS) tests. The findings demonstrated a 440% improvement in the overall corrosion resistance (RT) of Ce-PPE@Cat/EP coating compared to blank/EP coatings.

Hydrocarbon generation differences of shales composed of green algal and cyanobacteria: A case study of Mesozoic and Cenozoic saline lacustrine shales in Junggar Basin, NW China

The Mesozoic and Cenozoic strata in the Junggar basin developed two sets of shallow to semi-deep lacustrine shale, namely, the Cretaceous Qingshuihe Formation (K1q) and the Paleogene Anjihaihe Formation (E2-3a). Through organic petrology and scanning electron microscope (SEM) observation, it is found that the primary hydrocarbon-generating organic matter (OM) in the two sets of strata is different. The biological precursor of the E2-3a OM is mainly green algae (Pediastrum), while the precursor of K1q kerogen is mainly cyanobacteria (Oscillatoria). Then, the E2-3a green algae-rich shale and K1q cyanobacteria-rich shale were subjected to hydrous pyrolysis and kinetic analysis, respectively. The results show that the evolution modes of hydrocarbon generation of the typical shales are very different. Green algae have the characteristics of a low oil generation threshold, heavy oil quality, and no prominent oil peak, while cyanobacteria have the characteristics of late oil generation, concentrated hydrocarbon generation, and relatively light oil quality. The characteristics of oil generation can also be well reflected in the composition evolution of the crude oil components. The carbon isotope of gas, kerogen, and extracts of the E2-3a green algae-rich shale are significantly heavier than the K1q cyanobacteria-rich shale, which may be related to the living habits of their biological precursors, carbon source usage, photosynthesis efficiency, and carbon fixation efficiency.

Effect of alkaline microcrystalline cellulose deacidification on chemical composition, antioxidant activity and volatile compounds of camellia oil

The effect of alkaline microcrystalline cellulose (AMC) deacidification and alkali refining on the physicochemical properties, fatty acid profile, active phytochemicals, antioxidant capacity, and volatile flavor components of crude camellia oil (CO) were investigated comparatively. The results showed that the acid value of AMC deacidification camellia oil (ADO) was effectively decreased from 1.50 ± 0.00 mg KOH/g to 0.30 ± 0.01 mg KOH/g. AMC deacidification more effectively retained 60.22% of the polyphenols (12.34 ± 0.38 mg GAE/100g), 74.60% of α-tocopherol (2.82 ± 0.00 mg/kg) and 93.25% of β-Sitosterol (5.30 ± 0.05 mg/100g) in camellia oil compared to alkali refining and showed a stronger overall antioxidant capacity of the oil (P < 0.05). In addition, the volatile flavors of camellia oil were dominated by acids, aldehydes, and alcohols, and AMC deacidification better preserved the acidic flavors than alkali refining. Principal component analysis (PCA) revealed that ADO and CO were positively correlated with PC1 due to the highly in relation to the higher content of 9C, 11 TR-Conjugated linoleic acid and the stronger antioxidant capacity. Overall, AMC deacidification was moderate reaction conditions and zero wastewater production, making it a potentially effective alternative method in camellia oil deacidification.

The Effect of Temperature on the Size and the Deposition of Asphaltene Particles

Summary The deposition of asphaltene as a main component of crude oil is considerably affected by temperature. Despite the studies on influencing factors on deposition and size of asphaltene particles, no experimental research was previously conducted on the simultaneous impact of temperature on asphaltene particle size and deposition. In this study, the asphaltene deposit mass was measured within a Couette device at various temperatures ranging between 20 and 65°C under a constant angular velocity. Furthermore, the asphaltene particle size was simultaneously measured to investigate the relationship between deposition mass and asphaltene particle size and also to validate the concept of critical particle size. A digital microscope was used to measure the size of unstable asphaltene particles in oil. Asphaltene solubility and oil viscosity were measured to understand the deposition mechanisms. The analysis of microscopic images indicated that larger asphaltene particles are produced at higher temperatures. Although the total mass of the deposit was decreased with temperature, the deposition fraction, defined as mass fraction of total unstable asphaltene particles that deposit, was increased. Higher fraction of deposition was found for larger particles that is in contradiction to the previously introduced critical particle size concept. Additionally, the effect of solubility was found to be dominant in comparison with viscosity from the point of view of the total mass of the deposit. For the oil sample investigated in this study, a 45°C increase in temperature reduced the total mass of the deposit by 46.84%.

Study on Interaction Characteristics of Injected Natural Gas and Crude Oil in a High Saturation Pressure and Low-Permeability Reservoir

Natural gas injection is considered for enhanced oil recovery (EOR) in a high saturation pressure reservoir in block B111 of the Dagang oilfield, China. To investigate the interaction characteristics of injected natural gas and crude oil, the ability for dissolution–diffusion and miscibility–extraction of natural gas in crude oil was tested using a piece of high-temperature and high-pressure PVT equipment. The physical properties and minimum miscible pressure (MMP) of the natural gas–crude oil system and their interaction during dynamic displacement were analyzed using the reservoir numerical simulation method. The results show the following: (1) Under static gas–oil contact conditions, natural gas has a significant dissolution–diffusion and miscibility–extraction effect on the crude oil in block B111, especially near the gas–oil interface. The content of condensate oil in gas phase is 10.14–18.53 wt%, while the content of dissolved gas in oil phase reaches 26.17–57.73 wt%; (2) Under the reservoir’s conditions, the saturated solubility of natural gas injected in crude oil is relatively small. The effect of swelling and viscosity reduction on crude oil is limited. As the pressure increases with more natural gas dissolved in crude oil, the phase state of crude oil can change from liquid to gas; accordingly, the density and viscosity of crude oil will be greatly reduced, presenting the characteristics of condensate gas; (3) The MMP of natural gas and crude oil is estimated to be larger than 40 MPa. It mainly forms a forward-contact evaporative gas drive in block B111. The miscible state depends on the maintenance level of formation pressure. The injected natural gas has a significant extraction effect on the medium and light components of crude oil. The content of C2–C15 in the gas phase at the gas drive front, as well as the content of CH4 and C16+ in the residual oil at the gas drive trailing edge, will increase markedly. Accordingly, the residual oil density and viscosity will also increase. These results have certain guiding significance for understanding gas flooding mechanisms and designing gas injection in block B111.

Effect of nonionic surfactants on the synergistic interaction between asphaltene and resin: Emulsion phase inversion and stability

Interaction between surface active components in crude oils and nonionic surfactants plays an important role in phase inversion behavior of crude oil emulsion, while the interaction mechanism is not yet fully explored. Herein, the effects of nonionic surfactants on the synergistic interaction between asphaltene and resin, emulsion stability, and emulsion phase inversion were investigated. It is shown that the addition of Span 80 and Tween 80 promotes the reduction of phase inversion point of water in oil emulsion stabilized by asphaltene and resin, as well as increases the yield strain value of the emulsion. The addition of Tween 80 to the asphaltene and resin mixture reduces the inversion point from 70 % to 30 %. The decrease of phase inversion point is attributed to the difficulty in the formation of multiple emulsions after adding nonionic surfactants. The addition of nonionic surfactants can affect the hydrogen bonding between asphaltene and resin, thereby improving the emulsion stability. Span 80 coexists with asphaltene and resin at oil-water interface, reducing the Turbiscan Stability Index (TSI) of emulsion by 15 and improving the strength of the oil-water interface membrane. In comparison, Tween 80 with stronger hydrophilic ability dissolves asphaltene and resin into bulk phase, which leads to the oil-water interface occupied by a large amount of Tween 80. Its numerous EO groups result in the strong hydrogen bonding on the oil-water interface membrane, effectively increasing the strength of the oil-water interface membrane and reducing the TSI by 19. This work contributes to a better understanding of the phase inversion of crude oil emulsion and improves crude oil recovery.

Petroleum Asphaltene-Based Activated Nanoporous Carbon for CO2 Capture and H2 Storage

In the present study, we report on how to prepare activated nanoporous carbon materials based on petroleum asphaltenes, readily available and the heaviest component and by-product of crude oil. A thorough characterization of the carbonized nanoporous materials by spectroscopy and thermogravimetric analysis (TGA) confirmed their synthesis. The nanoporosity of the carbonized materials was displayed by scanning electron microscopy (SEM) imaging. It was confirmed further by Brunauer–Emmett–Teller (BET) surface area analysis showing large surface areas exceeding 2500 and 3000 m2/g. The newly carbonized materials’ architectural rigidity and swelling behavior were tested by the ghost solvent low-field nuclear magnetic resonance (LF-NMR) approach. Finally, the gas adsorption capacity of these materials was tested. The porous carbon structures afforded a hydrogen storage capacity of 2.85 wt % at 1 bar, and the highest uptake of CO2 at 1 bar is 28.95 and 19.15 wt % at 0 and 22 °C, respectively. Nanoporous carbonized asphaltenes are promising materials to be applied in various areas as gas-absorbing and CO2-capturing proxies.

Synthesis and evaluation of multi-aromatic ring copolymer as viscosity reducer for enhancing heavy oil recovery

Functional polymers play an increasingly significant role in oilfield development. Herein, the side-chain functionalized copolymer APVR was fabricated using functional monomer 2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yl-methacrylate (BMP) with similar structure to the heavy components in crude oil and di-hexadecanol maleate (DHM) with long alkyl chain. 1H NMR, FTIR and TGA analyses were employed to characterize the structure of APVR. Simultaneously, viscosity reduction performance and heavy oil displacement performance of APVR were also studied. For comparison, the copolymers P(AAB), P(AAD) and P(AA) containing one functional monomer and without functional monomer were also synthesized. The results showed that when the copolymer concentration is 2000 mg/L, the viscosity reduction rate (VRR) of APVR, P(AAB), P(AAD) and P(AA) is 93.1%, 84.3%, 82.4% and 65.4%, respectively. Furthermore, compared with water flooding, their ultimate recovery of heavy oil increased by 18.34%, 13.78%, 13.18% and 9.93%. The interaction mechanisms between APVR and heavy oil were studied using XRD, SEM, and molecular dynamic simulation. Due to their unique structure, BMP and DHM were able to permeate into the molecule structures of heavy oil, reducing the intermolecular forces between heavy components by forming supramolecular forces with asphaltene. Thus, they led to the loose stacking of asphaltene aggregates, making it easier for APVR to emulsify oil droplets due to its amphiphilic property. The copolymer APVR shows promising potential for reducing heavy oil viscosity and may have broad application prospects in heavy oil exploitation.

Effect of asphaltenes structure on interfacial properties: A dissipative particle dynamics study

Asphaltenes are important components of crude oil that stabilize oil-water emulsions. Due to their complex molecular nature, the connections between molecular structure and interfacial properties of asphaltenes remain unclear. In this work, the effects of polyaromatic cores size, length and the number of aliphatic side chains, and heteroatoms on the structural properties of asphaltenes in oil–water system are investigated by dissipative particle dynamics (DPD). The results show that the asphaltene molecules with larger aromatic cores are better for reducing the interfacial tension (IFT) of the system. The relationship between the interfacial activity of asphaltenes and the length of aliphatic side chains is not monotonic as the concentration increases. Asphaltene molecules with intermediate length and shorter length aliphatic side chains are effective in reducing IFT at lower and higher concentrations, respectively. The asphaltenes with more aliphatic side chains contribute more to the reduction of IFT at lower concentrations, but the side chains can hinder the adsorption of asphaltenes at the interface, which is not conducive to the stability of the system at higher concentrations. In addition, oxygen atoms in the molecular structure of asphaltenes are the key factors that promote the adsorption of asphaltenes to the interface and reduce the IFT. This detailed investigation of the behavior of asphaltenes would be useful to understand the role of asphaltenes in the formation of oil–water emulsions.

Investigation on the interactions of resinous and asphaltenic synthetic oils and silicon oxide nanoparticles stabilized by different ionic liquid-based surfactants: interfacial tension and wettability alteration studies

The effects of the main components of crude oil, especially resin and asphaltene fractions, are essential concerns for efficient enhanced oil recovery (EOR) processes, especially during chemical injection processes. This importance comes from the nature of these two fractions which can act as surface active agents with undeniable effects on the used chemical for interfacial tension (IFT) reduction and wettability alteration. In this way, the effect of silicon oxide nanoparticles (SiO2-NPs) concomitant with two ionic liquids (ILs), namely 1-dodecyl-3-methyl imidazolium chloride ([C12mim][Cl]) and 1-octadecyl-3-methyl imidazolium chloride ([C18mim][Cl]), is investigated on the wettability alteration and IFT reduction using synthetic oils prepared by dissolving the extracted resin and asphaltene fractions with a concentration of 1–5 wt%. The measurements reveal that the effect of resin fraction is less than the asphaltene fraction for IFT reduction and wettability alteration. The sole presence of resin fraction reduces the IFT from 35.3 to 28.3 mN/m as the concentration is increased from 1 to 5 wt%, while a similar increase in the asphaltene fraction concentration reduces the IFT from 35.5 to 19.1 mN/m. Besides, the results reveal that the presence of [C12mim][Cl] in the range of 0–1000 ppm leads to a reduction in IFT from its maximum value of 35.3 to 0.81 mN/m, while in the case of [C18mim][Cl] with similar concentration variation, IFT is reduced from 35.3 to 0.7 which means the better effect of IL with longer chain length on the IFT reduction. Further analysis revealed that the effect of asphaltene fraction on the IFT is higher than resin fraction since the minimum IFT value was observed for [C18mim][Cl] with the value of 0.58 mN/m, while the contact angle (CA) values revealed revers effect for asphaltene fraction compared with the resin fraction. In general, regardless of the used IL, it seems that ILs leading to better wettability conditions which are crucial for EOR purposes and even better IFT values that can mobilize the trapped oil toward production points. Besides, further measurements revealed a positive effect of SiO2-NPs concomitant with the ILs to move the wettability toward the strongly water-wet condition with CA values of 29.2° and 28.3° for SiO2-NPs concentration of 1000 ppm and 1000 ppm of concentration for [C12mim][Cl] and [C18mim][Cl], respectively, for resinous synthetic oil (RSO) (5 wt%) while no meaningful effect regarding the SiO2-NPs presence at the different concentrations (100–2000 ppm) is found on the IFT reduction. A similar trend is observed for asphaltenic synthetic oil (5 wt%)/aqueous solution (SiO2-NPs with a concentration of 1000 ppm + ILs with a concentration of 1000 ppm) which reduces the CA to 26.3° and 37.8° for [C12mim][Cl] and [C18mim][Cl]), respectively.

Influence of surface cleaning on the wettability of calcite/oil/brine systems

Contact angle (θ) is a measurement that characterizes the wettability of solid surfaces. Typically, contact angle measurements are conducted under one of the following conditions; cleaned rock surface, aged rock surface, or native (intact) rock surface. However, conventional cleaning agents such as toluene, acetone, heptane, and methanol may adsorb onto the rock surfaces and influence the wettability of the rock/oil/brine system. The effect of rock surface preparation using solvents prior to wettability assessments on rock/oil/brine systems is not systematically investigated. The influence of surface cleaning using solvents on the wettability of calcite/oil/brine systems was investigated. Calcite surface wettability was estimated via contact angle at high temperature (353 K) and pressures (0.1 to 50 MPa) before and after exposure to formation fluids and solvents. We have also conducted imaging and nanomechanical properties analyses of the rocks’ surfaces to investigate adsorption, change in surface chemistry and roughness, and mechanical properties of the rocks via Scanning Electron Microscopy (SEM), Scanning Probe Microscopy (SPM), nanoindentation, Fourier transform infrared spectroscopy (FTIR) and X-Ray Fluorescence (XRF) analysis before and after exposure. The results showed that these solvents get adsorb onto the rock surfaces and/or fail to completely remove the crude oil components from the rocks surfaces. Consequently, the wettability of the rock/oil/brine system is modified. Moreover, different contact angle values were observed for the same rock surface under different cleaning agents. Therefore, results from this study demonstrate that restoration of the initial rock wettability after fluids exposure was challenging as different rock surface cleaning prior to contact angle measurements results in different rock wettability.

A universal route to deciphering the internal mechanism of crude oil self–emulsification

Crude oil emulsions generated during the life period of crude oil from production and separation comprise a fascinating interdisciplinary topic that is being actively studied in both chemical science and engineering. However, a comprehensive understanding of the emulsification mechanism based on a sound chemicophysical foundation for the natural emulsifiers of crude oil remains challenging and is not well established. In this study, we developed a framework that combines crude oil separation, molecular structure characterization and inference, self–assembly of natural emulsifiers at the oil–water interface, and phase behavior of natural emulsifier emulsions to decipher the self–emulsification of crude oil. Our results revealed that crude oil components have independent and synergistic effects on the formation and stabilization of crude oil emulsions. Asphaltene has the highest molecular weight and the strongest interfacial activity compared to other components, significantly contributing to the formation of crude oil emulsions. As the second highest molecular weight crude oil component, resin is the solvent for asphaltene. Aromatic and saturated hydrocarbons adsorbed at the oil–water interface form an interfacial viscoelastic film that mainly stabilizes the crude oil emulsion. The viscosity of crude oil emulsions is mostly affected by asphaltene and resin, while their phase inversion point is primarily determined by aromatic and saturated hydrocarbons. These results provide a universal insight into the internal emulsification mechanism of crude oil. We expect that these findings will also provide theoretical support for taking advantage of crude oil emulsions for the purpose of efficient oil recovery.

Exposure to volatile hydrocarbons and neurologic function among oil spill workers up to 6 years after the Deepwater Horizon disaster

BackgroundDuring the 2010 Deepwater Horizon (DWH) disaster, oil spill response and cleanup (OSRC) workers were exposed to toxic volatile components of crude oil. Few studies have examined exposure to individual volatile hydrocarbon chemicals below occupational exposure limits in relation to neurologic function among OSRC workers. ObjectivesTo investigate the association of several spill-related chemicals (benzene, toluene, ethylbenzene, xylene, n-hexane, i.e., BTEX-H) and total petroleum hydrocarbons (THC) with neurologic function among DWH spill workers enrolled in the Gulf Long-term Follow-up Study. MethodsCumulative exposure to THC and BTEX-H across the oil spill cleanup period were estimated using a job-exposure matrix that linked air measurement data to detailed self-reported DWH OSRC work histories. We ascertained quantitative neurologic function data via a comprehensive test battery at a clinical examination that occurred 4–6 years after the DWH disaster. We used multivariable linear regression and modified Poisson regression to evaluate relationships of exposures (quartiles (Q)) with 4 neurologic function measures. We examined modification of the associations by age at enrollment (<50 vs. ≥50 years). ResultsWe did not find evidence of adverse neurologic effects from crude oil exposures among the overall study population. However, among workers ≥50 years of age, several individual chemical exposures were associated with poorer vibrotactile acuity of the great toe, with statistically significant effects observed in Q3 or Q4 of exposures (range of log mean difference in Q4 across exposures: 0.13–0.26 μm). We also observed suggestive adverse associations among those ≥ age 50 years for tests of postural stability and single-leg stance, although most effect estimates did not reach thresholds of statistical significance (p < 0.05). ConclusionsHigher exposures to volatile components of crude oil were associated with modest deficits in neurologic function among OSRC workers who were age 50 years or older at study enrollment.