Individual Hydrocarbons Research Articles

Neutron Response Modeling to Track Lean Gas Plume in Recycled Gas Cap Reservoir in Concurrent Gas Cap-Oil Rim Development: A Step Forward

Summary Gas cap pressure maintenance while developing the associated oil rim is a critical aspect for optimum recovery. Preventing gas cap pressure dropping below dewpoint by injecting lean gas is essential for concurrent gas cap-oil rim development. Reservoir heterogeneity aggravates lean gas override causing preferential movement of lean gas plume. Thus, it is important to track lean gas plume while recycling and understanding the breakthrough potential of lean gas. This paper demonstrates a new workflow to track lean gas plume by estimating phase saturations with a case study from one of the giant oil and gas fields, Onshore, Abu Dhabi. Pulsed neutron capture (PNC) tools are used for reservoir monitoring and surveillance. However, sigma log evaluation is insufficient to derive individual hydrocarbon phase saturations to monitor lean gas plume. Neutron response modeling (NRM) is devised to differentiate between lean and rich gas. NRM is a probabilistic solver with input of mineral and fluid phase parameters into tool response functions in petrophysical evaluation. To distinguish with discrete neutron fluid response between lean and rich gas, pressure/volume/temperature (PVT) data are utilized to derive hydrogen index, capture cross section, thermal decay length, and neutron macro parameters, such as neutron slowing down length and migration length. Neutron response is investigated for lean and rich gas with sensitivity of invasion effects on neutron log by calibrating to core porosity. The response for each phase under thermal neutron and capture modes with corresponding raw neutron log statistics is reviewed in both openhole and casedhole environments in known lean/rich gas intervals. Thirty-five wells spread across gas cap and oil leg with quality neutron log data are modeled and individual phase saturations are estimated. The target reservoir is under development with over three decades of lean gas injection to support oil production. NRM results and phase saturations are validated with recent formation sampling, which enhanced the confidence in the overall workflow. Later, the results are verified to be in excellent agreement with lean gas injection and production history of the target reservoir. The identified movement of lean gas highlights nonuniform geology and gravity segregation of injected lean gas into upper members of the target reservoir. The results also emphasized the need for better injection support to lower members of the target reservoir where gas cap development is ongoing. The solution presented is unique, particularly for lean gas injection projects by utilizing PVT for NRM based on neutron transport mechanism in pore fluids. Existing workflows require a special nuclear modeling platform with computationally expensive processing on data sets acquired using advanced logging technology. In spite of these prerequisites, existing workflows are not able to distinguish lean gas over rich gas. This paper effectively demonstrates NRM workflow distinguishing lean gas plume from rich gas using neutron logs and reveals compelling reservoir management insights. The sensitivity studies and practicality of this workflow highlight the fundamental importance of neutron logs in mature fields.

Physiological and biochemical characterization and genome analysis of Rhodococcus qingshengii strain 7B capable of crude oil degradation and plant stimulation

Rhodococci are typical soil inhabitants which take part in remediation of soil polluted with hydrocarbons. In this paper, we describe a new strain, Rhodococcus qingshengii 7B, which is capable of growth and hydrocarbon degradation at 45°C and in the presence of up to 10% NaCl in the medium. The genome of the 7B strain consists of a 6,278,280 bp chromosome and two plasmids. The circular plasmid is 103,992 bp in length. The linear plasmid is 416,450 bp in length. Genome analysis revealed the genes of degradation of various hydrocarbons, resistance to salt stress and plant growth promoting activity. This strain is promising for use in remediation of oil-contaminated soils, because it has a pronounced ability to utilize crude oil, oil sludge and individual hydrocarbons in a wide temperature range. Over 15 days of the experiment, the strain utilized 51% of crude oil at 28°C and 24% at 45 °С.

Treatment of water contaminated with petroleum hydrocarbons using a biochar derived from seagrass biomass as low-cost adsorbent: isotherm, kinetics and reusability studies

ABSTRACT Petroleum hydrocarbons, including alkanes ranging from C10 to C32, have been recognized as priority organic water contaminants with a toxic impact on ecosystems. Therefore, the removal of these contaminants is of utmost importance to protect humans, plants and animals. In this work, biochar derived from the dead leaves of the widely-distributed seagrass Halodule uninervis (SGC) was prepared through biomass pyrolysis at 800°C and characterized using SEM, FTIR, TGA and surface area analysis. The prepared SGC was investigated for adsorptive removal of total petroleum hydrocarbons (TPHs) and individual alkane hydrocarbons (C10 to C32) from water contaminated with crude oil. The SGC displayed good removal efficiency, adsorption capacity and recyclability toward these hydrocarbons. Using the SGC, 98.8% of the TPHs were removed within 300 minutes with an adsorption capacity of 23.5 mg/g. The adsorption results were tested with the most commonly used isotherm and kinetics models. The hydrocarbon adsorption data for the SGC fit the Langmuir and Freundlich isotherms, which indicates non-uniformity of the adsorbent and a predominance of multilayer adsorption of the hydrocarbons onto the prepared SGC adsorbent. The performance and reusability of the prepared SGC adsorbent were promising, losing only 22% of its hydrocarbon removal efficiency after the 3rd cycle.

Mass Concentration, Source and Health Risk Assessment of Volatile Organic Compounds in Nine Cities of Northeast China.

From April 2008 to July 2009, ambient measurements of 58 volatile organic compounds (VOCs), including alkanes, alkenes, and aromatics, were conducted in nine industrial cities (Shenyang, Fushun, Changchun, Jilin, Harbin, Daqing, Huludao, Anshan and Tianjin) of the Northeast Region, China (NRC). Daqing had the highest concentration of VOCs (519.68 ± 309.88 μg/m3), followed by Changchun (345.01 ± 170.52 μg/m3), Harbin (231.14 ± 46.69 μg/m3), Jilin (221.63 ± 34.32 μg/m3), Huludao (195.92 ± 103.26 μg/m3), Fushun (135.43 ± 46.01 μg/m3), Anshan (109.68 ± 23.27 μg/m3), Tianjin (104.31 ± 46.04 μg/m3), Shenyang (75.2 ± 40.09 μg/m3). Alkanes constituted the largest percentage (>40%) in concentrations of the quantified VOCs in NRC, and the exception was Tianjin dominated by aromatics (about 52.34%). Although alkanes were the most abundant VOCs at the cities, the most important VOCs contributing to ozone formation potential (OFP) were alkenes and aromatics. Changchun had the highest OFP (537.3 μg/m3), Tianjin had the lowest OFP (111.7 μg/m3). The main active species contributing to OFP in the nine cities were C2~C6 alkanes, C7~C8 aromatic hydrocarbons, individual cities (Daqing) contained n-hexane, propane and other alkane species. Correlation between individual hydrocarbons, B/T ratio and principal component analysis model (PCA) were deployed to explore the source contributions. The results showed that the source of vehicle exhausts was one of the primary sources of VOCs in all nine cities. Additionally, individual cities, such as Daqing, petrochemical industry was founded to be an important source of VOCs. The results gained from this study provided a large of useful information for better understanding the characteristics and sources of ambient VOCs incities of NRC. The non-carcinogenic risk values of the nine cities were within the safe range recognized by the U.S. Environmental Protection Agency (HQ < 1), and the lifetime carcinogenic risk values of benzene were 3.82 × 10−5~1.28 × 10−4, which were higher than the safety range specified by the US Environmental Protection Agency (R < 1.00 × 10−6). The results of risk values indicated that there was a risk of cancer in these cities.

Current research on simultaneous oxidation of aliphatic and aromatic hydrocarbons by bacteria of genus Pseudomonas.

One of the most frequently used methods for elimination of oil pollution is the use of biological preparations based on oil-degrading microorganisms. Such microorganisms often relate to bacteria of the genus Pseudomonas. Pseudomonads are ubiquitous microorganisms that often have the ability to oxidize various pollutants, including oil hydrocarbons. To date, individual biochemical pathways of hydrocarbon degradation and the organization of the corresponding genes have been studied in detail. Almost all studies of this kind have been performed on degraders of individual hydrocarbons belonging to a single particular class. Microorganisms capable of simultaneous degradation of aliphatic and aromatic hydrocarbons are very poorly studied. Most of the works on such objects have been devoted only to phenotype characteristic and some to genetic studies. To identify the patterns of interaction of several metabolic systems depending on the growth conditions, the most promising are such approaches as transcriptomics and proteomics, which make it possible to obtain a comprehensive assessment of changes in the expression of hundreds of genes and proteins at the same time. This review summarizes the existing data on bacteria of the genus Pseudomonas capable of the simultaneous oxidation of hydrocarbons of different classes (alkanes, monoaromatics, and polyaromatics) and presents the most important results obtained in the studies on the biodegradation of hydrocarbons by representatives of this genus using methods of transcriptomic and proteomic analyses.

Molecular dynamics study of fluid-fluid and solid-fluid interactions in mixed-wet shale pores

Mixed wet pores are abundant in shales, yet there is little to no information on the behavior of fluids confined within pores characterized by one hydrophilic and one hydrophobic surface. This mixed wettability can impact fluid storage, distribution, capillary pressures and transport. In this study, we use molecular dynamics simulations to describe the initial distribution of reservoir fluids, such as multicomponent hydrocarbon mixtures and water, in mixed-wet pores. This is an essential pre-requisite to additional studies documenting fluid transport in such pores. The molecular model of the mixed wet pore used consists of kerogen separated by some distance from two clay surfaces. We evaluate spatial distribution of water and individual hydrocarbon species, at varying values of water concentration. Throughout the entire study, the results from the equilibrated system indicate a high affinity between the heavy components, such as the asphaltene/resin fraction and the kerogen surfaces. The more surprising result is the hydrogen bonding observed between the polar constituents in the asphaltene/resin fraction and water. This creates a situation where the asphaltene/resin fraction shows an affinity towards water. When this happens, the hydrophilic clay surface effectively becomes hydrophobic. A pore bounded by an asphaltene layer on one side and kerogen on the other is more oil-wetting than mixed-wet. The presence of asphaltenes can therefore expect to create conditions of modified wettability that will impact oil recovery, oil transport and distribution. Another surprising result in this work is that water forms structures that bridge between opposing surfaces of the model. These water bridges are seen to happen for water concentration values larger than 20%. In other words, water is not merely just adsorbed on to the clay surfaces, but also forms these bridge-like structures. Nevertheless, we still observe a strong affinity between the asphaltene/resin fraction and water leading to a lesser degree of mixed wettability. This study is the first, to the best of our knowledge, that considers water and multicomponent hydrocarbon mixtures in mixed-wet pores with realistic surface chemistry and constitutes a necessary first step towards additional studies related to water and hydrocarbon transport and EOR processes in shale nanopores.

Evolution of unregulated hydrocarbons distribution with different post injection strategies in a common-rail diesel engine

The experiments were carried out to investigate the influence of different post injection timing and post injection rate on the performance of combustion and unregulated hydrocarbons species emissions from a common-rail diesel engine. Fourier transform infrared spectroscopy was used to measure and analyze the unregulated hydrocarbons emissions which include light hydrocarbons (HCs), aromatic hydrocarbon (AHC), and n-octane (NC8). The results showed that the emissions of individual hydrocarbon species were the similar to that of single injection when the post injection time was at 20 °CA and 40 °CA. In the measured hydrocarbons components, CH4 and C4H6 species maintained a low level and weak sensitivity to the different post injection conditions. The overall variation of NC8 species emission was similar to that of THC emission and accounted for most of the THC, which indicated that most of the fuel had no chemical change and entered the exhaust directly under different post injection conditions. It should be noticed that the olefin species decreased and the alkane species increased gradually as the HCs species raised from C1 to C4. Furthermore, the distribution of HC species at 60 °CA was less changed than that of 40 °CA under different post injection rates and was closer to the required after-treatment gas atmosphere due to its larger proportion of highly reactive components.

Characterization of compositional variability in petroleum substances

In the process of registration of substances of Unknown or Variable Composition, Complex Reaction Products or Biological Materials (UVCBs), information sufficient to enable substance identification must be provided. Substance identification for UVCBs formed through petroleum refining is particularly challenging due to their chemical complexity, as well as variability in refining process conditions and composition of the feedstocks. This study aimed to characterize compositional variability of petroleum UVCBs both within and across product categories. We utilized ion mobility spectrometry (IMS)-MS as a technique to evaluate detailed chemical composition of independent production cycle-derived samples of 6 petroleum products from 3 manufacturing categories (heavy aromatic, hydrotreated light paraffinic, and hydrotreated heavy paraffinic). Atmospheric pressure photoionization and drift tube IMS-MS were used to identify structurally related compounds and quantify between- and within-product variability. In addition, we determined both individual molecules and hydrocarbon blocks that were most variable in samples from different production cycles. We found that detailed chemical compositional data on petroleum UVCBs obtained from IMS-MS can provide the information necessary for hazard and risk characterization in terms of quantifying the variability of the products in a manufacturing category, as well as in subsequent production cycles of the same product.

Molecular Indicators of Sources and Biodegradation of Organic Matter in Sediments of Fluid Discharge Zones of Lake Baikal

This paper performs a detailed study of a wide set of organic-geochemical proxies in 15 sediment cores collected from the main basins of Lake Baikal (the northern, the central and the southern) where processes of focused fluid discharge were detected. A variety of studied zones includes sites with gas and hydrothermal seepage, mud volcanoes with or without gas-oil fluid discharge, gas hydrates and authigenic carbonates. The composition of the dispersed organic matter and individual hydrocarbon molecular markers (n-alkanes, dimethyl alkanes, isoprenoids, steranes, terpanes and polycyclic aromatic hydrocarbons) testify to the input from predominantly allochthonous terrestrial and autochthonous microbial and algal sources. The studied sources, maturity and biodegradation parameters of organic matter vary significantly for areas with different fluid discharge. The composition of specific biomarkers including isoprenoids and immature hopanoids reflects the lateral and vertical changes of microbial activity in sediments associated with various environmental conditions. The identified types of terpanes distribution (mature, mixed and immature) correlate well with types of fluid discharge and attest to the development of various methanogenic and methanotrophic microbial communities in sediments. Moreover, the revealed specificity of microbial molecular markers distribution allowed us to suggest the fluid discharge processes in zones where they were not previously detected.

Rock shale mineral composition influence on oil and gas generation process (results from laboratory experiments)

The paper presents the results of the hydrothermal processes of organic matter transformation in the rocks of the Bazhenov Formation and the Domanik horizon laboratory modeling. Shortterm exposure of samples to high temperatures (350 C) and reservoir pressures (300 atm) in the presence of water made it possible to simulate the processes that could take place in the reservoir, and to transform kerogen up to 70% in the rocks initially containing immature kerogen or kerogen in the beginning of the oil window. It was found that the amount of liquid hydrocarbon compounds generated during cracking mainly linearly depends on the content of organic matter in the rocks, while the gas generation is described by a rate function. The mineral composition of rocks does not affect the size of the formed pores, but in some cases it controls the amount of formed hydrocarbon compounds and the composition of the liquid products. It is shown that the increase in the amount of carbonate material in the rocks inhibits oil and gas generation process, there are lower amounts of light components in the products, and some of hopanes are absent. At the same time, high concentrations of siliceous material in the rocks with low amount of other components and, probably, the presence of pyrite can stimulate the generation process, in some cases allowing an increase in the amount of produced “synthetic” oil and gas, to achieve a greater variety of reaction products. The results obtained in general make it possible to examine the processes of individual hydrocarbon compounds formation during hydrothermal processes, to identify catalysts and inhibitors of the generation mechanism, and also, from a practical point of view, to propose conditions for reservoirs stimulation and development of technologies for increasing oil production and generation of oil with a controlled composition in situ.

Effects of pressure on gas generation and pore evolution in thermally matured calcareous mudrock: Insights from gold-tube pyrolysis of the Eagle Ford Shale using miniature core plugs

Together with an increased interest in deep petroleum and shale gas exploration over the last decade, the effects of pressure on gas generation and pore evolution in organic-rich shales have received renewed attention. In this study, miniature core plugs drilled from a thermally matured Eagle Ford Shale sample were pyrolyzed in sealed gold tubes to investigate the effects of pressure on gas generation coupled with pore evolution in the presence of a relatively intact rock fabric. The gold-tube-capsuled samples were isothermally heated at a temperature of 425 °C for 36 h under different confining pressure conditions (10, 25, 35, 50, 68, 80, and 120 MPa), with maturation being induced from the original oil window to the gas window.Experimental results show that increasing the confining pressure from 10 to 120 MPa has initially retards and then promotes the generation of low molecular hydrocarbons (C1–C5 alkanes), whereas gas dryness (C1/C1–5, vol%) increases continuously from 51% to 63% in this pressure range. The inflection pressures that correspond to the maximum retardation of the generation of individual hydrocarbon compounds are shifted to higher values with increasing the molecule carbon number, e.g., 35 MPa for methane, 50 MPa for ethane to butane, and 68 MPa for pentane. Similar pressure effects have also been found for liquid hydrocarbons (C6–14 hydrocarbons and C14+ compounds), with a single inflection pressure of 68 MPa. These observations indicate that high pressure inhibits residual oil cracking but simultaneously favors generation of methane-rich gas. A mechanism for the interaction of retained hydrocarbons and porous matured kerogen (and/or pyrobitumen) is thus suggested to explain the enhanced methane generation. The extent of such interactions is highly dependent on petroleum expulsion efficiency from an intact rock fabric.BET specific surface area and pore volume measured by N2 adsorption decrease significantly for samples matured at 10–35 MPa and then increase at confining pressures above 50 MPa. The simultaneous variations in pore development and methane generation with increasing confining pressure indicate that the observed effect of confining pressure on the evolution of the pore structure of shales depends on both oil retention and gas generation. Our experimental results provide some new insights into gas generation and pore evolution in shale systems, and the retardation effect of pressure on hydrocarbon generation and expulsion as well as pore evolution may provide a mechanism for the Type II kerogen-dominated oil-prone shales to become potential shale gas reservoirs.

Bituminous substances in soils of Baikal Rift zone

Parameters of hydrocarbon complex of the soils of lacustrine-alluvial plain and sandy uplands of the Baikal rift zone within the Barguzin Depression have been studied. Data were obtained on organic (non-carbonate) carbon, chloroform and hexane bitumoids, as well as on individual polycyclic aromatic hydrocarbons. The content, composition and properties of bitumoids vary depending on the intensity of endogenous activity. In soils located in the zone of active unload of hydrothermal waters and hydrocarbon fluids, atypical accumulation of organic carbon was noted; the concentrations of bitumoids do not correlate with its content. High values of the bitumoid coefficient, significant level of polycyclic aromatic compounds and their diversity, in combination with salts accumulation, indicate an additional influx of hydrocarbons and instability of the soil hydrocarbon system. The level of the indicators shifts towards background values in the soils of sandy hills with a complex combination of exogenous and endogenous factors of soil forming. Studied parameters of the soil hydrocarbon system in aggregate can serve as markers of the intensity of endogenous processes.

The developing zebrafish kidney is impaired by Deepwater Horizon crude oil early-life stage exposure: A molecular to whole-organism perspective

Crude oil is known to induce developmental defects in teleost fish exposed during early life stages (ELSs). While most studies in recent years have focused on cardiac endpoints, evidence from whole-animal transcriptomic analyses and studies with individual polycyclic aromatic hydrocarbons (PAHs) indicate that the developing kidney (i.e., pronephros) is also at risk. Considering the role of the pronephros in osmoregulation, and the common observance of edema in oil-exposed ELS fish, surprisingly little is known regarding the effects of oil exposure on pronephros development and function. Using zebrafish (Danio rerio) ELSs, we assessed the transcriptional and morphological responses to two dilutions of high-energy water accommodated fractions (HEWAF) of oil from the Deepwater Horizon oil spill using a combination of qPCR and whole-mount in situ hybridization (WM-ISH) of candidate genes involved in pronephros development and function, and immunohistochemistry (WM-IHC). To assess potential functional impacts on the pronephros, three 24 h osmotic challenges (2 hypo-osmotic, 1 near iso‐osmotic) were implemented at two developmental time points (48 and 96 h post fertilization; hpf) following exposure to HEWAF. Changes in transcript expression level and location specific to different regions of the pronephros were observed by qPCR and WM-ISH. Further, pronephros morphology was altered in crude oil exposed larvae, characterized by failed glomerulus and neck segment formation, and straightening of the pronephric tubules. The osmotic challenges at 96 hpf greatly exacerbated edema in both HEWAF-exposed groups regardless of osmolarity. By contrast, larvae at 48 hpf exhibited no edema prior to the osmotic challenge, but previous HEWAF exposure elicited a concentration-response increase in edema at hypo-osmotic conditions that appeared to have been largely alleviated under near iso‐osmotic conditions. In summary, ELS HEWAF exposure impaired proper pronephros development in zebrafish, which coupled with cardiotoxic effects, most likely reduced or inhibited pronephros fluid clearance capacity and increased edema formation.

Characteristics and health risks of personal exposure to particle-bound PAHs for Hong Kong adult residents: From ambient pollution to indoor exposure.

Research on individual level polycyclic aromatic hydrocarbons (PAHs) exposure is scarce. Moreover, the independent contribution of ambient‐ and indoor‐origin PAHs to personal exposure remains poorly studied. We performed simultaneous ambient, residential indoor, and personal exposure measurements in a panel of healthy adults to investigate particle‐bound PAHs, focusing on their carcinogenic congeners (cPAHs). Average PAH concentrations were much higher in ambient and residential indoor than personal exposure, with distinct seasonal variations. We employed chrysene as a tracer to investigate residential indoor and personal PAHs exposure by origin. Personal cPAH exposure was largely attributable to ambient‐origin exposures (95.8%), whereas a considerable proportion of residential indoor PAHs was likely attributable to indoor emissions (33.8%). Benzo[a]pyrene equivalent (BaPeq) concentrations of cPAH accounted for 95.2%‒95.6% of total carcinogenic potential. Uncertainties in estimated PAHs (and BaPeq) exposure and cancer risks for adults were calculated using the Monte Carlo simulation. Cancer risks attributable to ambient, residential indoor, and personal cPAH inhalation exposures ranged from 4.0 × 10−6 to 1.0 × 10−5. A time‐activity weighted model was employed for personal PAH exposure estimations. Estimated cPAH exposures demonstrate high cancer risks for adults in Hong Kong, suggesting that exposure to indoor‐generated PAHs should be of great concern to the general population.

Compositional analysis of light oil fractions from deep-water Guneshli field

Hydrocarbon composition of the fraction with 150–300 оС boiling point of oil from deep-water Guneshli field has been studied. The oil is characterized with light, oily, low sulphur, low-in-tar, paraffinic structure (3.7 % mass of solid paraffin), without asphaltenes. The fraction with 250–300 оС boiling point has been divided into naphteno-paraffinic and aromatic hydrocarbon groups using the method of liquid elution-adsorption chromatography. The individual hydrocarbon composition of naphteno-paraffinic hydrocarbons has been studied via chromato-mass-spectroscopy and the structure-group composition of the arenes using PMR-spectroscopy, correspondingly. Isoprenoid С13–С15 and С18, as well as 0.54 % mass of pristane biomarkers (С19) and phytane (С20) biomarkers have been revealed in the composition of naphteno-paraffinic hydrocarbons. the nuclear are enriched in the paraffinic structures in the form of substituent.

Concentration of some Polycyclic Aromatic Hydrocarbons in soil samples of Kirkuk province, Iraq

In order to evaluate the quantity of twelve PAHs (Naphthalene, Tetraphan and Acenaphthylene Fluorene, Phenanthrene, Anthracene, Pyrene, Benzo [a] Anthracene, Ovalene, Chrysene, Benzo [a] fluoranthene and DiBenzo [ah] Anthracene) in the soil samples from Kirkuk province, seven sites (Ras El-Gesr, Benja Ali, Wahed Hozeran, North Oil Company (NOC), Lillan, Kubri and Chimen) were selected using Gas Chromatography (GC) during the autumn 2017 and winter 2018. The results showed that the highest concentration of individual hydrocarbons during the autumn season was for the Acenaphthylene compound in the NOC site 131.19 μg/kg, and for Naphthalene compound, was 100.543μg/kg. The NOC recorded the highest concentration of total hydrocarbons 891.65 μg/kg. For the winter season, the highest concentration of polycyclic aromatic hydrocarbons was recorded for the Fluorene compound at the NOC site 79.19 μg/kg. Fluorene and Naphthalene compounds achieved the highest averages for the season (43.24 and 42.984 μg/kg) respectively, and recorded the location of the NOC, the highest summation of total hydrocarbons amounted to 609.77 μg/kg.

Key Factors for Improving the Carcinogenic Risk Assessment of PAH Inhalation Exposure by Monte Carlo Simulation.

Monte Carlo simulation (MCS) is a computational technique widely used in exposure and risk assessment. However, the result of traditional health risk assessment based on the MCS method has always been questioned due to the uncertainty introduced in parameter estimation and the difficulty in result validation. Herein, data from a large-scale investigation of individual polycyclic aromatic hydrocarbon (PAH) exposure was used to explore the key factors for improving the MCS method. Research participants were selected using a statistical sampling method in a typical PAH polluted city. Atmospheric PAH concentrations from 25 sampling sites in the area were detected by GC-MS and exposure parameters of participants were collected by field measurement. The incremental lifetime cancer risk (ILCR) of participants was calculated based on the measured data and considered to be the actual carcinogenic risk of the population. Predicted risks were evaluated by traditional assessment method based on MCS and three improved models including concentration-adjusted, age-stratified, and correlated-parameter-adjusted Monte Carlo methods. The goodness of fit of the models was evaluated quantitatively by comparing with the actual risk. The results showed that the average risk derived by traditional and age-stratified Monte Carlo simulation was 2.6 times higher, and the standard deviation was 3.7 times higher than the actual values. In contrast, the predicted risks of concentration- and correlated-parameter-adjusted models were in good agreement with the actual ILCR. The results of the comparison suggested that accurate simulation of exposure concentration and adjustment of correlated parameters could greatly improve the MCS. The research also reveals that the social factors related to exposure and potential relationship between variables are important issues affecting risk assessment, which require full consideration in assessment and further study in future research.

Characterization and genomic analysis of Exiguobacterium alkaliphilum B-3531D, an efficient crude oil degrading strain

The aim of the work was to carry out the physiological, biochemical and genetic characterization of the Exiguobacterium alkaliphilum B-3531D strain. This strain is promising for use in the field of environmental biotechnology, since it has a pronounced ability to utilize crude oil and individual hydrocarbons in a wide temperature range. The genome of the strain was sequenced and completely assembled, it consists of a 2,903,369 bp circular chromosome and two circular plasmids, namely, pE73 (73,590 bp) and pE52 (52,125 bp). When cultivated in a mineral medium containing 2% of crude oil, the strain utilized 50% within 30 days of the experiment. In simulated seawater with the same oil content, the loss of hydrocarbons was 45% over the same period. For the first time we observed in an E. alkaliphilum strain the ability to efficiently utilize crude oil, including with an increased content of sodium chloride in the cultivation medium.

THC Concentration Estimation Model using FTIR Spectrum

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;A novel total hydrocarbon (THC) emission concentration estimation model is proposed for reduction of engine development cost and simplification of exhaust measurements. The proposed method uses the absorbance spectra of a Fourier transform infrared (FTIR) spectrometer, which contains the information on a wide variety of hydrocarbons, as input. The model is based on machine learning algorithms including the least absolute shrinkage and selection operator (LASSO) regression and bagging techniques. To train the model, we created a dataset containing pairs of a spectrum of engine exhaust gas and the THC concentration. In addition, we incorporate absorbance spectra of individual hydrocarbon components and several inorganic components so that the model learns the contribution of each hydrocarbon to THC concentration and to ignore interferences of irrelevant gas components. Since the intensity of absorbance spectrum is not entirely linear to all over the THC concentration, a piecewise linear model is constructed for THC concentration estimation. The model was evaluated on both exhaust gases before and after catalyst of a gasoline engine. The proposed approach reduces the error of THC estimations to less than 5% in pre-catalyst exhaust gas and less than 14 % in post-catalyst exhaust gas in both steady and transient operating conditions, in comparison to the 20% error for the regression model using only hydrocarbon concentration data. The results show that modeling directly using FTIR spectrum achieves a higher accuracy, moreover, training with individual gas component spectrum data provides further improvement.&lt;/div&gt;&lt;/div&gt;

Increasing the Yield of Light Distillates by Wave Action on Oil Raw Materials

The article presents the results of the electromagnetic activation of petroleum feed in the vortex layer apparatus. It is shown that under the electromagnetic influence, there is a significant increase in the proportion of straight-run gasoline fraction distillate, as well as a change in the physicochemical parameters of the light fractions obtained as a result of the cavitation effect and the low-temperature cracking. It has been established that the processes of wave action on oil occurring in the electromagnetic field zone lead to a change in the individual and group hydrocarbon composition of the distillates obtained. The gasoline fraction produced from activated petroleum, due to an increase in the proportion of aromatic compounds, has a high octane number compared to the original straight-run fraction and low content of alkenes, which allows us to recommend its use as a high-octane component of motor fuels in the compounding and production of commercial gasoline.