Dispersed Crude Oil Research Articles

Significant advancement in geological theories and new discoveries of natural gas in China since the 11th Five-Year Plan

The development of geologic theories and exploration findings of natural gas in China supplement each other. Since the 11th Five-Year Plan in 2006–2010, geologic theories of natural gas in China has achieved notable advancement in many aspects, of which, are mainly reflected in the following seven aspects. Among them, there are two research progresses in the basic geological theory enumerated as follows. (1) The formation mechanisms of three types of natural gas that have been studied broadly including highly evolved coal-based source rocks, crude oil pyrolysis gas, and biogas. The cracked gas mode of coal-based source rocks, whole process hydrocarbon-generating mode of humus-type organic matter, and continuous biogas generation mode have been thoroughly advanced. (2) The theory of genetic identification between crude oil pyrolysis gas and kerogen pyrolysis gas, aggregated crude oil pyrolysis gas and dispersed crude oil pyrolysis gas, organic and inorganic gases, coal-type gas and oil origin gas, has been enriched extensively. There are five theoretical advances in the field of hydrocarbon accumulation in large gas fields: (1) the theory of hydrocarbon accumulation in ancient carbonate rock, “five paleo-structures control accumulation”, has been proposed innovatively; (2) the accumulation theory of tight sandstone gas in craton basins, foreland basins, and rift basins have been well-established; (3) the accumulation mode of “three-micro conveying, near-source enrichment, and sustained preservation” for ultra-deep and weak deformation zones has been established; (4) the accumulation theory of volcanic gas reserves in rift basins with basic elements of hydrocarbon generation troughs has been established and improved; (5) lastly, the accumulation theory of offshore high-temperature, overpressure, and deepwater gas were methodically deepened. The development of geologic theories of natural gas has promoted many new exploration discoveries. The accumulation theory in ancient carbonate reservoirs paved the way for the exploration of Anyue gas field in the Sichuan Basin, the largest single reserve in China. The new understanding of tight sandstone gas accumulation in the foreland thrust belt helped the first gas field discovery in the size 1 × 1012 m3 in an ultra-deep layer in the Kuqa Depression. The accumulation theory of ultra-deep reef reservoirs has guided the exploration of Yuanba gas field, the deepest-buried reef gas field in China. The theory of offshore hydrocarbon accumulation has led to remarkable discoveries in the South China Sea. Some of the said discoveries are the Dongfang 13-2 gas field, the largest gas field in China located in self-supported areas, and the Lingshui 17-2 gas field, which is a hundred billion cubic meters in size and is located in the deepwater exploration field.

Microbial degradation of four dispersed crude oils by Rhodococcus sp. evaluated using carbon stable isotope analysis

AbstractBACKGROUNDThe high frequency and wide distribution of oil spills pose serious threats to the marine environmental ecosystem and human health. Microbial degradation is considered to be the most applicable means to process oil spills. Carbon isotope fractionation was employed as a crucial tool for evaluating the biodegradation of four crude oils by Rhodococcus sp. with Corexit 9500A as oil dispersant.RESULTSFollowing biodegradation, carbon isotope fractionation of n‐alkanes in four dispersed crude oil samples was measured by gas chromatography–isotope ratio mass spectrometry. A relationship between the carbon isotope ratios and residual concentrations of n‐alkanes was established based upon the Rayleigh equation, with a correlation coefficient, R2, ranging from 0.67 to 0.83. The carbon isotope enrichment factors for n‐alkanes of the four crude oil samples tended to be 0.04–0.25‰ in the residuals. The biodegradation level of n‐alkanes calculated from the Rayleigh equation agreed with the biodegradation results analyzed by gas chromatography–mass spectrometry.CONCLUSIONSThe degree of microbial degradation was positively correlated to the carbon isotope fractionation in n‐alkanes. Compound‐specific stable isotope analysis is capable of quantifying the biodegradation level of crude oil or oil spills. © 2019 Society of Chemical Industry

Partitioning of PAHs between Crude Oil Microdroplets, Water, and Copepod Biomass in Oil-in-Seawater Dispersions of Different Crude Oils.

The impact of oil microdroplets on the partitioning of polycyclic aromatic hydrocarbons (PAHs) between water and marine zooplankton was evaluated. The experimental approach allowed direct comparison of crude oil dispersions (containing both micro-oil droplets and water-soluble fraction; WSF) with the corresponding WSF (without oil droplets). Dispersion concentration and oil type have an impact on the PAH composition of WSFs and therefore affect dispersion bioavailability. Higher T-PAH body residues were observed in copepods treated with dispersions compared to the corresponding WSFs. PAHs with log Kow 3-4.5 displayed comparable accumulation factors between treatments; however, accumulation factors for less soluble PAHs (log Kow = 4.5-6) were higher for the WSF than for the dispersions, suggesting low bioavailability for components contained in oil droplets. The higher PAH body residue in dispersion exposures is assumed to result mainly from copepods grazing on oil droplets, which offers an alternative uptake route to passive diffusion. To a large degree this route is controlled by the filtration rates of the copepods, which may be inversely related to droplet concentration.

Response of natural phytoplankton communities exposed to crude oil and chemical dispersants during a mesocosm experiment

During the 2010 Deepwater Horizon oil spill, the chemical dispersant Corexit was applied over vast areas of the Gulf of Mexico. Marine phytoplankton play a key role in aggregate formation through the production of extracellular polymeric materials (EPS), an important step in the biological carbon pump. This study examined the impacts of oil and dispersants on the composition and physiology of natural marine phytoplankton communities from the Gulf of Mexico during a 72-hour mesocosm experiment and consequences to carbon export. The communities were treated using the water accommodated fraction (WAF) of oil, which was produced by adding Macondo surrogate oil to natural seawater and mixed for 24 h in the dark. A chemically enhanced WAF (CEWAF) was made in a similar manner, but using a mixture of oil and the dispersant Corexit in a 20:1 ratio as well as a diluted CEWAF (DCEWAF). Phytoplankton communities exposed to WAF showed no significant changes in PSII quantum yield (Fv/Fm) or electron transfer rates (ETRmax) compared to Control communities. In contrast, both Fv/Fm and ETRmax declined rapidly in communities treated with either CEWAF or DCEWAF. Analysis of other photophysiological parameters showed that photosystem II (PSII) antenna size and PSII connectivity factor were not altered by exposure to DCEWAF, suggesting that processes downstream of PSII were affected. The eukaryote community composition in each experimental tank was characterized at the end of the 72 h exposure time using 18S rRNA sequencing. Diatoms dominated the communities in both the control and WAF treatments (52 and 56% relative abundance respectively), while in CEWAF and DCEWAF treatments were dominated by heterotrophic Euglenozoa (51 and 84% respectively). Diatoms made up the largest relative contribution to the autotrophic eukaryote community in all treatments. EPS concentration was four times higher in CEWAF tanks compared to other treatments. Changes in particle size distributions (a proxy for aggregates) over time indicated that a higher degree of particle aggregation occurred in both the CEWAF and DCEWAF treatments than the WAF or Controls. Our results demonstrate that chemically dispersed oil has more negative impacts on photophysiology, phytoplankton community structure and aggregation dynamics than oil alone, with potential implications for export processes that affect the distribution and turnover of carbon and oil in the water column.

Comparison of microbial community dynamics induced by distinct crude oil dispersions reveals compositional differences

To understand the impact of oil contamination on marine microbial communities, numerous studies have been conducted following microbial dynamics after oil spills and concerning the effects of different environmental parameters on oil biodegradation potential. Nevertheless, there is a lack of understanding of how distinct oil crude types might influence the dynamics of microbial communities of identical origin. Here we show that different crude oils affect the community composition by shaping it distinctly over the course of incubation. We have used chemical dispersion of three crudes with different properties (paraffinic, paraffinic-asphaltenic and naphthenic). Oceanospirillaceae, Colwelliaceae, Porticocacceae, Flavobacteriaceae and Piscirikettsiaceae were highly abundant in all three oil dispersions. However, comparing group distances of the communities at each time point, as well as pairwise fold comparison of OTUs, has revealed significant differences in microbial composition between the oils (p < 0.05), but also between the major families related to biodegradation (p < 0.01). Furthermore, the PAH degradation rates proved to be significantly higher in naphthenic oil (p < 0.05), while the n-alkane degradation was slower, however not significant (p > 0.05). We conclude that different crude oils can shape microbial community distinctively over exposure time, therefore altering community biotransformation potential and causing different degradation rates of targeted oil compounds.

Exposure to Crude Oil and Chemical Dispersant May Impact Marine Microbial Biofilm Composition and Steel Corrosion

The release of hydrocarbons and chemical dispersant in marine environments may disrupt benthic ecosystems, including artificial reefs, formed by historic steel shipwrecks, and their associated organisms. Experiments were performed to determine the impacts of crude oil, dispersed crude oil, and dispersant on the community structure and function of microorganisms in seawater (SW) and biofilms formed on carbon steel, a common ship hull construction material. Steel corrosion was also monitored to illustrate how oil spills may impact preservation of steel shipwrecks. Microcosms were filled with seawater (SW) and incubated at 4oC. Carbon steel disks (CSDs) were placed in each tank, and tanks were amended with crude oil and/or dispersant or no treatment. SW and CSD biofilms were sampled biweekly for genetic analysis using Illumina sequencing of 16S ribosomal RNA gene amplicons. Predicted and sequenced bacterial metagenomes were analyzed to examine impacts of oil and dispersant on metabolic function. Gammaproteobacteria, Alphaproteobacteria, and Flavobacteriia dominated SW and biofilms. Bacterial community structure differed significantly between treatments for SW and biofilms. OTUs affiliated with known (Pseudomonas) and potential (Marinomonas) hydrocarbon-degraders were roughly twice as abundant in biofilms treated with oil and dispersed oil, and steel corrosion of CSDs in these treatments was higher compared to control and dispersant treatments. OTUs affiliated with the Rhodobacteraceae family (biofilm formers and potential oil degraders) were less abundant in the dispersant treatment compared to other treatments in biofilm and SW samples, but OTUs affiliated with the Pseudoalteromonas genus (biofilm formers and proposed hydrocarbon degraders) were more abundant in dispersant-treated biofilms. Overall, functional gene analyses revealed a decrease in genes (predicted using PICRUSt and observed in sequenced metagenomes) associated with hydrocarbon degradation in dispersant-treated biofilms. This study indicates that exposure to oil and dispersant could disrupt the composition and metabolic function of biofilms colonizing metal hulls, as well as corrosion processes, potentially compromising shipwrecks as ecological and historical resources.

Study of the plasma proteome of Atlantic cod (Gadus morhua): Changes due to crude oil exposure

Oil contamination is an environmental issue of great concern and the necessity for background studies and monitoring programs to continuously evaluate the levels of oil pollution is required. In this study, Atlantic cod (Gadus morhua) were exposed to dispersed crude oil for 1 and 4 weeks to simulate environmental contamination. Fractionated plasma samples were then analysed by tandem mass spectrometry. In total, 717 proteins were identified and 10 new protein biomarker candidates were found. The significant proteome changes were related to the immune response by alterations in the levels of specific immunoglobulins, alpha-2-macroglobulin and galectin-3-binding proteins. After 4 weeks of oil exposure, a lowered level of a NLRC3-like protein was also observed. The results from this study provide insight into the Atlantic cod plasma proteome and into the toxicological effects and potential response mechanisms of short and long-term exposure to crude oil.

Generation of shrimp waste-based dispersant for oil spill response.

In this study, shrimp waste was enzymatically hydrolyzed to generate a green dispersant and the product was tested for crude oil dispersion in seawater. The hydrolysis process was first optimized based on the dispersant effectiveness (DE) of the product. The functional properties of the product were identified including stability, critical micelle concentration, and emulsification activity. Water was confirmed as a good solvent for dispersant generation when compared with three chemical solvents. The effects of salinity, mixing energy, and temperature on the dispersion of the Alaska North Slope (ANS) crude oil were examined. Microtox acute toxicity test was also conducted to evaluate the toxicity of the produced dispersant. In addition, DE of the product on three different types of crude oil, including ANS crude oil, Prudhoe Bay crude oil (PBC), and Arabian Light crude oil (ALC) was compared with that of the Corexit 9500, respectively. The research output could lead to a promising green solution to the oil spill problem and might result in many other environmental applications.

The deepwater horizon oil spill coast guard cohort study: A cross-sectional study of acute respiratory health symptoms

IntroductionOver 8500 United States Coast Guard (USCG) personnel were deployed in response to the Deepwater Horizon (DWH) oil spill; however, human respiratory effects as a result of spill-related exposures are relatively unknown. MethodsUSCG personnel who responded to the DWH oil spill were queried via survey on exposures to crude oil and oil dispersant, and acute respiratory symptoms experienced during deployment. Adjusted log binomial regressions were used to calculate prevalence ratios (PRs) and 95% confidence intervals (CI), investigating the associations between oil spill exposures and respiratory symptoms. Results4855 USCG personnel completed the survey. More than half (54.6%) and almost one-fourth (22.0%) of responders were exposed to crude oil and oil dispersants, respectively. Coughing was the most prevalent symptom (19.4%), followed by shortness of breath (5.5%), and wheezing (3.6%). Adjusted analyses showed an exposure-response relationship between increasing deployment duration and likelihood of coughing, shortness of breath, and wheezing in the pre-capping period. A similar pattern was observed in the post-capping period for coughing and wheezing. Adjusted analyses revealed increased PRs for coughing (PR=1.92), shortness of breath (PR=2.60), and wheezing (PR=2.68) for any oil exposure. Increasing frequency of inhalation of oil was associated with increased likelihood of all three respiratory symptoms. A similar pattern was observed for contact with oil dispersants for coughing and shortness of breath. The combination of both oil and oil dispersants presented associations that were much greater in magnitude than oil alone for coughing (PR=2.72), shortness of breath (PR=4.65), and wheezing (PR=5.06). ConclusionsResults from the present study suggested strong relationships between oil and oil dispersant exposures and acute respiratory symptoms among disaster responders. Future prospective studies will be needed to confirm these findings.

Study on Atmospheric Distillation of Some Plain and Chemically Dispersed Crude Oils: Comparison of Yields and Fuel Quality of Distillate Fractions

This paper discusses the distillation behavior of the plain (control) and chemically dispersed crude oils. The oils used were paraffinic (denoted as P-RCP-I), naphthenic (denoted as P-RCN-II), and aromatic (denoted as P-RCA-III) crudes. The chemical dispersants used were anionic, cationic, and neutral surfactants including sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and Triton X-100 (a branched p-octylphenol with an average of 9–10 ethylene oxide units). The effect of Dispersant-to-Oil ratio on the yields of distillate fractions (gasoline and diesel) was investigated. Looking at the results, we conclude that using chemically dispersed crudes enabled us to obtain better yields of light distillate fractions (F1 and F2) in comparison with the control. Among the dispersants used, the SDS was more effective in RCA-III crude where the yield of F1 increased significantly to 58% and that of residue decreased to 6%. The CTAB was found to be more effective in RCN-II crude, which gave a sign...

Dispersion of crude oil by choline based ionic liquids

The employment of chemical dispersants for oil spills is a universally accepted response option. However, the toxicity associated with chemical dispersant restricts its usage in marine environments. The toxicity of these dipersants can be minimized by utilizing biodegradable and enviromentally benign surfactants. In addition, the use of water in their formulation further reduces its toxicity. In this study, the ability of choline based Ionic Liquids (choline laurate and choline oleate) solubilized in water to disperse crude oil were analyzed. Results presented in this study showed that an effective dispersant is obtained by combining these two amphiphilies. For maximum dispersion, the optimal choline laurate and choline oleate ratio used is 50:50 (w/w). The dispersion efficiency of 67% was achieved by employing this optimal combination with dispersant to oil ratio (DOR) of 1:10 (v/v). The interfacial activity of the combined system was also investigated and it was observed that the interfacial activity of the combined system is greater than individual components.The results presented in this study suggests that the blend of choline laurate and choline oleate could potentially replace the conventional toxic oil spill dispersants.

Oil droplet fouling and differential toxicokinetics of polycyclic aromatic hydrocarbons in embryos of Atlantic haddock and cod.

The impact of crude oil pollution on early life stages (ELS) of fish, including larvae and embryos, has received considerable attention in recent years. Of the organic components present in crude oil, polycyclic aromatic hydrocarbons (PAHs) are considered the main class of compounds responsible for toxic effects in marine organisms. Although evidence suggests that they are more toxic, alkylated PAHs remain much less studied than their unsubstituted congeners. Recently, it was established that embryos of Atlantic haddock (Melanogrammus aeglefinus) are particularly sensitive to dispersed crude oil, and it was hypothesized that this was caused by direct interaction with crude oil droplets, which adhered to the chorion of exposed embryos. Such a phenomenon would increase the potential for uptake of less water-soluble compounds, including alkylated PAHs. In the current study, we compared the uptake of parent and alkylated PAHs in Atlantic cod (Gadus morhua) and haddock embryos exposed to dispersed crude oil at a range of environmentally relevant concentrations (10–600 μg oil/liter seawater). Although the species are biologically very similar, the cod chorion does not become fouled with oil droplets, even when the two species are exposed to dispersions of crude oil droplets under similar conditions. A close correlation between the degree of fouling and toxicological response (heart defects, craniofacial malformation) was observed. Oil droplet fouling in haddock led to both quantitative and qualitative differences in PAH uptake. Finally, kinetic data on a large suite of PAHs showed differential elimination, suggesting differential metabolism of unsubstituted versus alkylated compounds.

TROPICS FIELD STUDY (PANAMA), 32-YEAR SITE VISIT: OBSERVATIONS AND CONCLUSIONS FOR NEAR SHORE DISPERSANT USE NEBA AND TRADEOFFS

ABSTRACT (#2017-141) The Tropical Oil Pollution Investigations in Coastal Systems (TROPICS) experiment initiated in 1984 on the Caribbean coast of Panama has become one of the most comprehensive field experiments examining effects of oil exposure to a combination of tropical marine reef, seagrass, and mangrove communities. The experimental dosage was chosen to simulate a severe but realistic spill scenario so that results could be useful in decisions about the extent to which dispersants reduced or exacerbated the effects of an oil spill on tropical environments of mangroves, seagrasses, and corals. Research has been conducted in the area prior to and 30+ years following exposure to evaluate long term effects. In July 2016, an international research team revisited the TROPICS field sites. In previous data collection visits, visual observations and core samples of the mangrove substrate at the non-treated (Oil only) site revealed the presence of oil. This “trapped” oil also apparently resulted in lower recovery rates for mangroves in that site. Of particular interest in the 2016 revisit was to determine the presence/non-presence of oil in core samples via new petroleum biomarker triple quadrupole mass spectrometry technology. Additionally, data collection and observations of the extent, diversity, and health of the shallow coral reefs, seagrass, and mangroves were conducted at the three sites. The focus was on the initial disruption and recovery of the study ecosystem over 32 years from the original dosing with crude oil or dispersed crude oil. Analysis qualitatively compared the 2016 results to 1984 pre-spill and post-spill conditions of each site. This paper discusses the results of the 2016 TROPICS study site revisit and conclusions for oil spill preparedness and response, particularly as it applies to the trade-offs for the use of dispersants in near shore tropical marine ecosystems.

Integrative biomarker assessment of the effects of chemically and mechanically dispersed crude oil in Pacific oysters, Crassostrea gigas

The impact of dispersed crude oil and dispersant on adult Pacific oysters, Crassostrea gigas, was evaluated through an integrative biomarker approach including (1) biochemical (plasma catecholase- and laccase-type phenoloxidase and superoxide dismutase), (2) histological (digestive cell lysosomal responses, digestive gland histopathology) and (3) physiological (flesh condition index) endpoints in the haemolymph and digestive gland. Adult oysters were exposed to non-contaminated water (control), chemically-dispersed oil (Brut Arabian Light), mechanically-dispersed oil and dispersant (FINASOL®) alone for 2days, and further depurated in non-contaminated water for 4weeks. After exposure to chemically and mechanically dispersed oil oysters exhibited induction of plasma laccase-type phenoloxidase and superoxide dismutase activities, enlargement of digestive cell lysosomes, lipofuscin accumulation, reduced neutral lipid content and atrophy of digestive gland diverticula; more markedly on exposure to chemically dispersed oil. From the studied biomarkers, only lysosomal biomarkers were significantly affected after exposure to the dispersant alone. This included lysosomal enlargement, neutral lipid depletion and lipofuscin accumulation in the digestive gland epithelium. A recovery of plasma enzyme activities was observed after 4weeks of depuration. The integrative biological response index indicated that chemically dispersed oil caused significantly higher stress to C. gigas than the mechanically-dispersed one or the dispersant alone; nevertheless, the response seems to be reversible after depuration.

The enhanced stability and biodegradation of dispersed crude oil droplets by Xanthan Gum as an additive of chemical dispersant

It is necessary for chemical dispersant to disperse oil effectively and maintain the stability of oil droplets. In this work, Xanthan Gum (XG) was used as an environmentally friendly additive in oil dispersant formulation to enhance the stability and biodegradation of dispersed crude oil droplets. When XG was used together with chemical dispersant 9500A, the dispersion effectiveness of crude oil in artificial sea water (ASW) and the oil droplet stability were both greatly enhanced. In the presence of XG, lower concentration of 9500A was needed to achieve the effective dispersion and stabilization. In addition to the enhancement of dispersion and stabilization, it was found that the biodegradation rate of crude oil by bacteria was dramatically enhanced when a mixture of 9500A and XG was used as a dispersant. Because of the low environmental impact of XG, this would be a potential way to formulate the dispersant with lower toxicity.

Valve gape behaviour of mussels (Mytilus edulis) exposed to dispersed crude oil as an environmental monitoring endpoint

Environmental monitoring requires cost-effective and efficient methods for detecting potential effects of pollution, and valve gape behaviour has been used with this purpose for a range of contaminants in freshwater and marine bivalves. The current study investigated the use of a new method for measuring valve behaviour responses in mussels (Mytilus edulis) exposed to dispersed crude oil (DCO). Results confirmed that valve gape is a sensitive parameter; at the high DCO concentration (0.25mgL−1) the mean valve gape was reduced from 49 to 31%, and mussels increased shell movement (measured as distance travelled) or spent more time closed to avoid contact with the oil. At the low DCO concentration (0.015mgL−1) the distance travelled parameter was the most sensitive endpoint. Results also demonstrated that valve gape behaviour is a valid endpoint when monitoring mussels for exposure to DCO.

Effects of weathering on the dispersion of crude oil through oil-mineral aggregation

Crude oil that is inadvertently spilled in the marine environment can interact with suspended sediment to form oil-mineral aggregates (OMA). Researchers have identified OMA formation as a natural method of oil dispersion, and have sought ways to enhance this process for oil spill remediation. Currently there is a lack of understanding of how the weathering of oil will affect the formation of OMA due to a lack of published data on this relationship. Based on literature, we identified two conflicting hypotheses: OMA formation 1) increases with weathering as a result of increased asphaltene and polar compound content; or 2) decreases with weathering as a result of increased viscosity. While it is indeed true that the viscosity and the relative amount of polar compounds will increase with weathering, their net effects on OMA formation is unclear. Controlled laboratory experiments were carried out to systematically test these two conflicting hypotheses. Experimental results using light, intermediate, and heavy crude oils, each at five weathering stages, show a decrease in OMA formation as oil weathers.

I: Biomarker quantification in fish exposed to crude oil as input to species sensitivity distributions and threshold values for environmental monitoring

The aim of this study was to determine a suitable set of biomarker based methods for environmental monitoring in sub-arctic and temperate offshore areas using scientific knowledge on the sensitivity of fish species to dispersed crude oil. Threshold values for environmental monitoring and risk assessment were obtained based on a quantitative comparison of biomarker responses. Turbot, halibut, salmon and sprat were exposed for up to 8 weeks to five different sub-lethal concentrations of dispersed crude oil. Biomarkers assessing PAH metabolites, oxidative stress, detoxification system I activity, genotoxicity, immunotoxicity, endocrine disruption, general cellular stress and histological changes were measured. Results showed that PAH metabolites, CYP1A/EROD, DNA adducts and histopathology rendered the most robust results across the different fish species, both in terms of sensitivity and dose-responsiveness. The reported results contributed to forming links between biomonitoring and risk assessment procedures by using biomarker species sensitivity distributions.

Study on organic alkali-surfactant-polymer flooding for enhanced ordinary heavy oil recovery

With regard to ordinary heavy oil reservoirs which are not suitable for thermal methods, alkaline-surfactant-polymer (ASP) flooding exhibits great potential for enhancing heavy oil recovery. But for the formation water with high content of Ca2+ and Mg2+ ions, conventional ASP flooding always causes precipitation of a large amount of Ca and Mg salts which are damage to reservoirs. In this study, organic alkali-surfactant-polymer (OASP) flooding system is established, which exhibits good compatibility with the brine containing high-valent metal ions. The interfacial tension tests show that the combination of Shengli petroleum sulfonate (SLPS) and ethanolamine exhibits a good synergistic effect, and acquires an ultralow interfacial tension. Based on micromodel flooding tests, the mechanisms of OASP flooding system are studied as follows: the organic alkali in OASP system reacts with the acidic component of heavy oil and promotes the formation of water-in-oil (W/O) emulsion in heavy oil, thus increasing the flow resistance of flooding liquid and improving the sweep efficiency of normal ASP system. The generated surface active materials and surfactant can decrease the interfacial tension to an ultralow level, which could easily initiate the emulsion dispersion of crude oil, form the O/W emulsion, and improve the oil displacement efficiency. The sandpack flood results demonstrate that the oil recovery is increased by about 20%, and the recovery increases with the increase in organic alkali concentration. Therefore, the organic alkali-surfactant-polymer flooding technology can be developed into a new type of economically and technically feasible compound flooding technology suitable for ordinary heavy oil reservoirs with high content of Ca2+ and Mg2+ ions. Moreover, OASP flooding technology shows broad application prospects in improving the recovery of ordinary heavy oil reservoirs in Shengli Oilfield.

Effect of dispersed crude oil on the feeding activity, retention efficiency, and filtration rate of differently sized blue mussels (Mytilus edulis)

ABSTRACTThe use of physiological response endpoints in environmental monitoring represents an opportunity to provide an integrated picture of health status and ecological fitness of individuals, and may provide an indication of potential longer term effects on aquatic organisms in the environment. The feeding behavior response sensitivity of blue mussels (Mytilus edulis) of differing size to dispersed crude oil (DCO) was investigated in a lab exposure experiment. The ability of mussels to recover following a single exposure was also investigated, as well as the response to consecutive exposures, in order to assess the utility of employing the same individuals in chronic environmental monitoring. Feeding physiology was assessed by measuring retention efficiency and filtration rate of individual mussels in a live-algae feeding assay. In addition, the percentage of mussels actively filtering during testing was calculated. The feeding physiology parameters were sensitive and able to discriminate exposed mussels from controls. Further, data indicated that larger mussels appear more suitable in environmental monitoring, as these animals showed both sensitivity and an ability to adapt and recover from exposure while remaining sensitive to subsequent treatments. Smaller mussels were also sensitive to the measured endpoints, even if these animals suffered higher rates of mortality during the exposure. Finally, when exposed to the high concentration of DCO, mussels displayed a tendency to close the valves and terminate filtration.