Hydrocarbon Source Research Articles

INVESTIGATION ON THE NATURE AND PROVENANCE OF PAH FOUND IN SEDIMENTS OF THE SOLIMÕES RIVER AND SOME ASSOCIATED LAKES

The present work aimed at evaluating indicators of hydrocarbon sources to sediments from the Solimões River region, in the central Amazon. The 16PAH, the alkylated homologs and molecular markers were investigated. The entire series of alkylated PAH were present and, in some cases, with a distribution observed when oil residues dominate. Nevertheless, hopanes characterizing immature environments undergoing diagenetic transformation were identified in samples from the Solimões River and in surface as well as in core sediment samples from Preto Lake, in the Coari-Manaus stretch. Investigation suggests early diagenesis of the organic matter confirmed by identifying biogenic markers produced during organic matter transformation. Some of these markers derive from incomplete combustion of biomass and are contained in particulate matter formed during forest burning. In the sediments of an industrial area near the city of Manaus, the entire series of mature hopanes was present indicating anthropogenic source of hydrocarbons. The results so far obtained point out the complexity of PAH source appraisal.

О некоторых закономерностях развития трещиноватости в терригенных породах острова Сахалин

Within complex studies of properties of hydrocarbons source rocks in Sakhalin Island the first preliminary results on the correlations of relations between the fractures distribution and bed thickness were obtained. Numerous measurements of stratification bedding planes, thicknesses of beds and orientations of orthogonal fracturing systems for the Kholmsk formation were performed. The received relations are described by linear approximation and correspond to the global data obtained for similar types of rocks and bed thicknesses.

Long-lasting ceria-based anti-frosting surfaces

Suppressing condensation frosting using superhydrophobic surfaces can have a substantial impact on improving efficiency and safety in many industrial applications. However, the low surface energy coatings on such surfaces can be easily damaged during various harsh operations, which has limited the application potential of passive anti-frosting approaches. Here, we propose robust ceria-based anti-frosting surfaces, where superhydrophobicity is induced by not surface coating but adsorbed hydrocarbon. We also demonstrate how the incorporation of a hydrocarbon source as a binder to the ceria-based coating allows for the quick recovery of superhydrophobicity. In comparison to untreated aluminum surfaces, the developed coatings decreased the frost propagation speed and the ice adhesion strength by 60% and 89%, respectively. The coatings could maintain a low contact angle hysteresis even after 200 cycles of frosting/de-frosting robustness tests and 15,000 cycles of acidity/salinity exposure tests. Using a scalable one-step dipping process, the created coating was incorporated to a fin-tube type heat exchanger, and provided 210% enhanced heat transfer rate and 60% decreased pressure drop. The coatings also provided substantially improved robustness compared to the silane-treated superhydrophobic coating. These findings suggest that the developed ceria-based coatings can be helpful in creating scalable and resilient anti-frosting surfaces for real-world applications.

Oriented sp2 bonded carbon structure of hydrogenated amorphous carbon films

Hydrogenated amorphous carbon films consist of sp 2 or sp 3 bonded carbon networks and hydrogen terminations, and their structure are often determined in terms of sp 2 / sp 3 ratio and the hydrogen contents. Although sp 3 bonded carbon structure is isotropic, sp 2 bonded carbon structure has structural anisotropy. To detect the orientation of extremely small the sp 2 bonded carbon network structure in hydrogenated amorphous carbon film, X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) measurements using synchrotron radiation X-rays with different incident angles were performed. On all prepared films from three types of hydrocarbon source, and the oriented sp 2 bonded carbon networks were detected from their incident angle dependence on XAS and XES spectra. The continuity of these oriented sp 2 carbon bonded structures was small and formed extremely small clusters, and the orientation distribution and direction of the sp 2 carbon structure depended on the source material. Some films have different sp 2 orientations on the surface and inside the film. The orientation of this sp 2 bonded carbon structure in the film was also an important factor and may affect several other film properties. • There is hydrogenated amorphous carbon films with sp 2 oriented structure. • The sp 2 oriented structure could be estimated by angle dependence of XAS and XES. • The sp 2 orientation angle is depend on deposition condition of the films. • The orientation of sp 2 bonded carbon structure affects film properties.

Strategies for Large Oil and Gas Companies Operating to Support Sustainable Development and Environmental Safety in the Russian Arctic

IAs conventional oil and gas sources become less productive, unconventional hydrocarbon sources become more attractive due to new technologies and become the target of expanded exploration. Oil and gas development in the Arctic is challenging but promising, the largest reserves of Oil and Gas in the Arctic are on the Arctic Shelf in Russia. Most Arctic communities, especially indigenous communities, depend on fishing, hunting, and gathering, this requires the preservation of environmental health. In this article we tried to delineate a strategy for large oil and gas companies to diversify risk by proposing a form of social entrepreneurship that works for environmentally vulnerable regions with low infrastructure or skilled labor. With this framework, large oil and gas companies could effectively and reliably support smaller-scale enterprises preserving environmental health and creating an innovative business ecosystem that promotes a Arctic. Our model could also lead to local and indigenous entrepreneurship and a more equitable distribution of wealth in the Arctic.

Paleodepositional environment and salt lake organic matter enrichment model of the Paleogene Linhe Formation in the Linhe Sag of the Hetao Basin

The well-developed mudstone and gypsum mudstone in Oligocene Linhe Formation (E3l) in the Hetao Basin are the main source rocks. However, the sedimentary environment and organic matter (OM) enrichment factors of E3l are not clear, which inhibit the prediction of hydrocarbon source rock distribution and resource calculation. The major and trace elements, X-ray diffraction (XRD), scanning electron microscopy, total organic carbon (TOC), Rock-Eval pyrolysis, saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS) experiments were analyzed.

Thermal effect of igneous intrusions on organic-rich Irati Formation and the implications for petroleum systems: a case study in the Paraná Basin, Brazil

The organic geochemistry of organic-rich facies including shales, marls, and carbonates (Assistência Member) of the Irati Formation, Paraná Basin, Brazil, were analyzed to evaluate the thermal effects of igneous intrusions upon the kerogen present in these facies. Total organic carbon (TOC) content and hydrocarbon source potential (S2) of the Irati source rocks range from 0.03 to 20.4% and 0.01 to 112.1 mg HC/g rock, respectively, indicating excellent potential as a source for hydrocarbon generation. Hydrogen index (HI) values reveal that the kerogen is predominantly type I (HI: up to 892.6 mg HC/g TOC) and, therefore, an oil source, except for samples having low TOC content due to severe maturation caused by the heat from diabase intrusions. The thickness of igneous intrusions in the 64 wells investigated in this study ranged from 2 to 231 m. They clearly had a major impact on TOC, HI, and S2 values, which decrease in the vicinity of intrusions, indicating a gradual increase in maturation toward the igneous body. In wells without the influence of igneous intrusions, Tmax values of Rock-Eval pyrolysis and %Ro indicate that the organic matter is immature for the generation of hydrocarbons.

Source rock and reservoir qualities of middle Jurassic Lianggaoshan lacustrine shale at fuxing area, Sichuan Basin: Implication for shale-oil enrichment

The shale oil exploration, in the Middle Jurassic Lianggaoshan Formation in the Fuxing area of Sichuan Basin, is in preliminary stage, requiring further in-depth study on shale oil and gas enrichment conditions. The lithological, organic geochemical, and reservoir characteristics of the Lianggaoshan Formation shale were analyzed using a suite of tests, including common thin section observation, organic carbon determination, pyrolysis experiment, combined N 2 -high pressure mercury test and argon ion polishing-scanning electron microscope, to elucidate source rock and reservoir qualities and their variation in vertical. Results suggest that the medium-carbon argillaceous shale, medium-carbon shell calcareous-argillaceous shale, and low-carbon argillaceous shale facies were mainly developed in Member 1 and Member 2 of the Lianggaoshan Formation. The medium-carbon argillaceous shale facies in the sub-layer ④ was rich in organic matter, with abundant sapropel, chitinous and secondary organic components, which were considered as a set of medium-quality source rocks. The medium-carbon shell calcareous-argillaceous shale and low-carbon argillaceous shale in the sub-layers ② and ③ have relatively low organic matter abundance, with vitrinite and inertinite as major organic microscopic components, revealing poor hydrocarbon generation potential. The porosity of shale reservoirs in sub-layers ②‒④ was higher than 3.0%, with predominant mesopores, followed by macropores, consisting of mainly clay mineral pores, organic pores, and microfractures related to organic matter. The medium-carbon argillaceous shale facies at the Lianggaoshan Formation is high-quality source rocks and reservoirs and is thus a potential target for lacustrine shale oil exploration in the Fuxing area of the Sichuan Basin. • The medium carbon clayey shale, medium carbon shell calcareous-clayey shale, and low carbon clayey shale were mainly developed in Member 1 and Member 2 of the Lianggaoshan Formation. • The medium carbon clayey shale facies in the sub-layer ④ exhibits adequate potential as hydrocarbon source rock and reservoir. • Sub-layer ④ is thus a potential target for continental shale oil exploration in the Fuxing area of the Sichuan Basin.

Sensitivity of marginal basins in recording global icehouse and regional tectonic controls on sedimentation. Example of the Cergowa Basin, (Oligocene) Outer Carpathians

Global sea-level fall during the late Eocene-Oligocene icehouse, in conjunction with the Alpine orogenesis, resulted in the epicontinental Paratethys Sea formed at the northern margin of the Tethys Ocean. Among the Paratethys sub-basins, the foreland Dukla Basin hosted dark dysoxic Menilite Shales. Within these the lenticular body of deep-marine Cergowa Beds was deposited. Due to its marginal position and orogenic activity, the Cergowa depocenter was sensitive to a broad range of influences reflected by: separation from and re-connection with the Tethys Ocean; reactions to global sea-level change; variations in calcareous nannoplankton palaeoecology and fluctuations in water chemistry; changing sediment gravity flow mechanisms; facies progradation and basin tectonics; palaeotransport direction; and changes in the calcite compensation depth. The proximal north-western part of the Cergowa depocenter consisted of two troughs evolving towards the south-east into an unconfined distal area. This is shown by palaeocurrent patterns changing down current from low-dispersion to fanning out distributions. Sedimentation during the succeeding NP23 nannoplankton zone was controlled by glacio-eustatic shallowing, enhanced by tectonic uplift, both resulting in isolation from the Tethys Ocean, forming a brackish environment affected by fluvial supply. Aggrading sand-rich proximal turbidite facies common at this stage include hyperpycnally-generated sustained turbidites that were sourced from shelf-edge delta, as well as hybrid event beds that reflect erosion of morphologically unbalanced slopes modified by fold-thrust tectonics. Nannoplankton of the succeeding NP24 zone documents normal salinity of an open sea that was reconnected with the Tethys Ocean, which is contrary to the global cooling and related eustatic sea-level lowstand during this time. At this stage, deposits of low-density turbidity currents predominate and form a succession prograding towards the south-east. Therefore, the oceanic reconnection was likely controlled by local subsidence, the rate of which exceeded the rate of deposition, especially in the south-east. The reconnection also influenced the calcite compensation depth level and resulted in an increase in coccolithophore productivity, recorded by laminated pelagic limestone interbeds within the youngest fining-upwards part of the Cergowa Beds succession. This fining-upwards sequence of low-density turbidites reflects retrogradation of the arenaceous material within the distributary system and a transition to mudstone-dominated disoxic facies of the Menilite Beds, being the most productive hydrocarbon and helium source rock unit in the Outer Carpathians. These processes and relationships show that due to the marginal position of the synorogenic basin, the Cergowa Beds record environmental sensitivity to extrabasinal and intrabasinal factors, and a broad range of global, regional, and local influences, thus providing insights applicable to research into the evolution of other basins placed in a similar context.

Presence and distribution of N - alkanes in the waters of some areas of the Shatt Al-Arab River, southern Iraq

The study dealt with (4) stations distributed along the Shatt Al-Arab, namely Al-Mashab, Al-Ashar, Abu Al-Khasib and Al-Faw. Samples were collected monthly over a whole year, starting from January 2012 until December of the same year to estimate and diagnose the n - alkanes in them using Gas Chromatography (GC) . The highest recorded concentrations were (154.92 , 167.34 , 104.56 , 191.00 ) µg/l in the stations ( Al - Mshab , Al - Ashar , Abu Al - Khasib and Al - Faw ) respectively during the month of December . The lowest recorded concentrations were (4.79, 5.46, 3.34, 5.00) µg/l in the same stations, respectively. In terms of seasonal changes, the results showed that the highest rate of normal alkanes was recorded during the winter months and the lowest during the summer months. As for the results of the evidence of the Carbon Preference Index (CPI )and the ratio of Pr/Ph compounds (Pristan / Phytan) it was more than one in some months and less than one in other months, which indicates the common sources of hydrocarbons in the water.

Seismic interpretation and geological evaluation of hydrocarbon source rocks in volcanic-rich continental lacustrine rift basins: A case study of the Lower Cretaceous Yingcheng Formation from the Changling Fault Depression in the Songliao Basin, NE China

The Lower Cretaceous Yingcheng Formation in the Changling Fault Depression in the Songliao Basin is composed of volcanic-rich continental lacustrine rift basin sediments. Its complex stratigraphic structure and the difficulty in predicting the hydrocarbon source rock distribution restrict the exploration and evaluation of deep hydrocarbons in this region. This paper uses seismic stratigraphy to divide the strata and interpret dark mudstone layers based on logging and seismic. These data are combined with geochemical test data from hydrocarbon source rocks to assess its quality and predict its distribution. This study indicates that the three types of unconformities identified divide the Yingcheng Formation into four sedimentary sequences. In the Yingcheng Formation depositional period, the number of grabens or half-grabens associated with the Changling Fault Depression decreased, the size of the rift basins increased, and the depositional center migrated to the north and west. During the depositional period of the First and Second Members, volcanic rocks were widely developed, and mud sediments were deposited between several small grabens or half-grabens. During the depositional period of the Third and fourth Members, the study area became a unified lacustrine rift basin with clearly defined geological signatures developed in each sedimentary sequence, which can be divided into three systems tracts. Mudstones in the Lake Transgressive Systems Tract are laterally continuous and widely distributed. The organic matter in these mudstones, with fair to good abundance levels, is predominantly type II2 and type III kerogen and all have reached mature to highly mature stage of thermal evolution, which are favorable hydrocarbon source rock layers. In plan view, the favorable hydrocarbon source rock zones are mostly formed in the Changling Sag, Dongling Structural Zone and Longfengshan Sag. This study offers guidance and direction for deep hydrocarbon exploration in the Changling Fault Depression, and also provides a reference for methods and ideas to predict hydrocarbon source rock distribution in other lacustrine rift basins.

Distribution, sources, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in Kaokaowusu river sediments near a coal industrial zone.

This study systematically analyzed the contents, compositions, and sources of polycyclic aromatic hydrocarbons (PAHs) in river sediments near an important energy and chemical base in northwest China. In addition, their possible adverse effects on the ecology and human health were assessed. The PAH concentrations in this study area ranged from 2641.28 to 16783.72 (ng/gdw). PAHs of medium molecular weight (3-ring and 4-ring) showed the largest proportion, followed by PAHs of higher molecular weight (5-ring and 6-ring). The results of molecular diagnostic ratios and principal component analysis revealed that PAHs in the region have complex sources, with incomplete combustion of local fossil fuels and traffic exhaust factors being the main sources. The total toxic equivalent concentration of PAHs varied from 10.05 to 760.26ng/g, and according to the sediment quality guidelines, PAHs have high potential ecological risk in the lower reaches of the river. The mean effect range-median quotient for the region was 0.46, and the combined ecological risk was at moderate to high levels (21% probability of toxicity). The lifetime carcinogenic risks for adults and children exposed to PAHs were 2.95 × 10-3 and 1.87 × 10-2, respectively, which are much higher than the limit of 10-4, indicating moderate to high potential cancer risks. Therefore, the local government should consider taking some environmental remediation measures. This study can provide theoretical support for pollution prevention measures and ecological restoration strategies for rivers in resource-rich areas.

Geochemical characteristics of shale gas formation and the potential for carbon storage in Thailand: An example from the Triassic Huai Hin Lat Formation

An evaluation of the potential shale gas play and geological carbon dioxide (CO2) storage from the Triassic Huai Hin Lat Formation in Thailand was performed based on field observations and mineralogical and geochemical data. This study was mainly focused on mudstone samples in some parts of the Huai Hin Lat Formation. The samples can be divided into three groups based on their mineral compositions as follows: coaly mudstone, carbonate-siliceous mudstone, and carbonate mudstone. The brittleness index based on their mineral compositions indicates that the samples show ultra-high carbonate and quartz contents, which suggests a good hydraulic fracture candidate. Total organic carbon and extractable organic matter of the samples represents poor to excellent generation potential for hydrocarbon source rock with type III kerogen. The depositional environment shows that the Huai Hin Lat Formation occurs in anoxic to suboxic conditions in an aquatic depositional environment. The formation is suitable for geological CO2 storage, which may reduce CO2 during petroleum production and increase the production rate. Consequently, results from this study are useful for unconventional shale reservoir exploration and carbon storage technology in Thailand and adjacent countries.

Localization and development of residual oil reserves using geochemical studies based on neural network algorithms

At the late stage of field development, residual oil reserves undergo a significant change from mobile to sedentary and stationary. These reserves are mainly located in technogenically and production altered, watered layers and areas of deposits. Localization and development of such sources of hydrocarbons is an effective method of increasing the final oil recovery factor in mature fields, due to the presence of a ready-made developed infrastructure for production, transportation and refining, as well as the availability of highly qualified personnel. This article considers an approach that allows, based on neural network algorithms, the estimation the volumes and localization of residual oil reserves in multi-layer deposits in combination with the analysis of geochemical studies of reservoir fluids. The use of machine learning algorithms allows a targeted approach to the development of residual reserves by automated selection of wellwork. This approach significantly reduces the manual labor of specialists for data processing and decision-making time.

Simple lignin-based, light-driven shape memory polymers with excellent mechanical properties and wide range of glass transition temperatures

Lignin is the most abundant biomass source of aromatic hydrocarbons but, at present, is not effectively utilized. The development of simple and efficient methods for producing lignin-based polymers to replace petroleum-based products is an important strategy for promoting environmentally friendly and sustainable materials and controlling carbon emissions. In this work, lignin-based, light-driven shape memory polymers (ELIDs) with improved mechanical properties have been prepared from enzymatic hydrolysis lignin, itaconic acid and 1,12-dodecanediol, without any chemical modification of the lignin. The polymers contain large proportions of lignin (20–40 wt%, designated ELID20 to ELID40) and their mechanical properties are dependent on the lignin content. Maximum tensile strength (46.9 MPa) was achieved with ELID30, maximum elongation at break (93.7 %) was achieved with ELID20 and highest fracture energy (10.75 J cm−3) was achieved with ELID25. These excellent mechanical properties are accompanied by good thermal stability and a wide range of glass transition temperatures (21.2–157.3 °C), supporting a broad range of applications. The shape fixation rate (Rf) and shape recovery rate (Rr) were highest for ELID30 (98.7 % and 97.4 %, respectively). Under 1 sun simulated solar irradiation, ELID20 reached a temperature exceeding the glass transition temperature in 15 s and, under 3 sun simulated solar irradiation, ELID30 reached a temperature of 130 °C and shape recovered in 60 s. The excellent mechanical properties and good light-driven shape memory of ELIDs provide inspiration for the development and utilization of lignin-based polymers.

An Experimental and Computational Study on Triple Injection Strategies to Reduce Cold Start Diesel Engine Emissions

Abstract The effect of triple injection strategies in a diesel engine to reduce cold start emissions were experimentally and computationally investigated in this work. The experiments were performed using a 1.9 L four-cylinder, turbocharged compression ignition engine with diesel fuel. As a representative of the cold start condition in the diesel engine, a low load condition of 1500 rpm and 2 bar brake mean effective pressure (BMEP) was chosen as the fixed condition for this study. The injection strategy made use of a late post injection to reduce catalyst light-off time. The pilot and main injections are fixed and the post injection timing is swept later into the expansion stroke to increase exhaust enthalpy available to heat the aftertreatment system. To further understand the source of hydrocarbon (HC) emissions from late injections, equivalent experiments were conducted with a mixture of n-heptane and iso-octane that matched the reactivity of the diesel fuel. The mixture of primary reference fuels (i.e., PRF 34) obtained by matching the cetane number (CN) of diesel fuel, showed similar combustion characteristics of diesel, but is much more volatile due to lighter components in the PRF mixture. The increased volatility of PRF 34 suppressed liquid fuel impingement on the cylinder liner, which isolated liner impingement as a possible source of HC emissions. Simulations were also performed for the present engine configuration and operating conditions in a sector mesh using CONVERGE™. The physical properties of diesel fuel were modeled using a five-component surrogate. The chemical kinetics of the diesel fuel were modeled with a reduced n-heptane model. The simulations were able to capture the experimental trends of combustion characteristics and emissions. The HC emissions were observed to increase for both fuels with retarded post injection timings in engine experiments. PRF 34 had comparable HC emissions to diesel experiments, which indicated that the liner impingement is not the main source of the increase in HC emissions. Overmixing of the fuel and air was identified as the major cause of increase in HC emissions. Additionally, exhaust gas recirculation (EGR) also intensified the overmixing phenomenon and thereby increase in HC emissions.

A baseline study of polycyclic aromatic hydrocarbons distribution, source and ecological risk in Zhanjiang mangrove wetlands, South China

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and pose a severe threat to human health. Here, 38 surface sediment samples collected from the Gaoqiao mangrove wetland in Zhanjiang, south China, were analyzed to determine 16 Environmental Protection Agency (EPA) priority PAHs. Total PAHs concentrations ranged from 33.5 µg/kg to 404.8 µg/kg with an average of 147.7 ± 77.7 µg/kg, inferring a moderate pollution level. Three and four-ring compounds dominated the PAHs composition patterns. Significant positive correlations were observed between the PAHs and the physicochemical properties of the sediments. According to the characteristic molecular ratio method, PAHs in sediments were mainly derived from combustion sources, including the incomplete combustion of liquid fossil fuels, grass, wood, and coal. The result based on the PMF model indicates that the primary combustion sources of PAHs are coal combustion, diesel-powered vehicles, biomass combustion and gasoline-powered vehicles, with a share of 39.01%, 25.21%, 12.72% and 10.48%, respectively. The petrogenic source contributes 12.58% PAHs to the sediments. The mean effects range median quotient (m-ERM-Q) and toxic equivalent method (TEQ) indicate a low comprehensive ecological risk of PAHs in the study area. Still, the evaluation results of effects range low (ERL) suggest that PAHs in the sediment would occasionally have adverse biological effects. Therefore, this situation demands attention and calls for protection strategies in the processes of urbanization and industrialization in south China.

A CONTEXTUAL ASSESSMENT OF EUROPEAN UNION’S ENERGY SUPPLIES IN MID 2022

Following the pandemic, European Union’s decisions that backfire on its economy appear to be controversial. Bruxelles politicians oscillate between renewable energies and possible new hydrocarbon sources in a bid to eliminate Russian supplies. The study reveals that the EU has actually had problems with energy independence ever since the oil age began. The historical superpower approach on oil and gas adopted by USA and Russian Federation, a still relevant UK, combined with the rise of China as economic leader, leave little room for the EU to gain control over its energy supplies. The study identifies a sinuous relation between USA and the former USSR in terms of energy trade, but not only: while the two countries collaborated on different issues in recent history, their interests were both convergent and divergent and their approaches to international relations as well. Among others, the study identifies France as the single country with a company in top 10 world oil and gas companies by revenue, and the only EU country with a company in top 4 manufacturers of nuclear fuel at global level. The study concludes that unless the energy paradigm will shift significantly, EU’s chances to become energy independent are minimal.

Variations in the concentration, source and flux of polycyclic aromatic hydrocarbons in sediments of the Pearl River Estuary: Implications for anthropogenic impacts

Variations in the distribution, source composition, mass inventory and burial flux of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Pearl River Estuary (PRE) collected in 2011 and 2019 were analyzed to investigate the influence of the anthropogenic activities. Total concentrations of 16 priority PAHs in 2019 (200.40 ± 188.86 ng g−1 dry weight on average) were at the medium level among global bays/estuaries/coastal areas. In 2019, PAH concentrations have decreased by about 50% compared to 2011 and the dominant composition has changed from low- to high-molecular-weight PAHs. The qualitative and quantitative source apportionment analysis indicates that the dominant source of PAHs has shifted from petroleum (40.33%) in 2011 to traffic emission (44.17%) in 2019. The source variation in the PRE can be attributed to the transformation of the energy source structure from petrogenic to pyrogenic in the Pearl River Delta. The estimated PAH mass inventory of the top 5-cm sediment was 38.70 metric tons in 2019, which was about 41 metric tons lower than that in 2011. The average deposition fluxes have dropped from 418.91 ± 261.02 ng cm−2 yr−1 in 2011 to 215.52 ± 246.63 ng cm−2 yr−1 in 2019. The decreasing PAH concentration is related to the sediment coarsening and decline of total organic carbon. These findings in the PRE can be applied to other estuarine environments influenced by anthropogenic activities.

Mathematical Modeling of a Non-Isothermal Flow in a Porous Medium Considering Gas Hydrate Decomposition: A Review

Deposits of natural gas hydrates are some of the most promising sources of hydrocarbons. According to studies, at the current level of natural gas consumption, the traditional reserves will last for about 50 years, and the gas hydrate deposits will last for at least 250 years. Therefore, interest in the study of gas hydrates is associated first of all with gas production from gas hydrate deposits. Additionally, gas hydrates are widely studied for solving practical problems, such as transportation and storage of natural gas, utilization of industrial gases and environmental and technological disasters associated with gas hydrates. When solving practical problems related to gas hydrates, in addition to laboratory and field studies, mathematical modeling is also widely used. This article presents the mathematical models of non-isothermal flow in a porous medium considering the decomposition of gas hydrate. The general forms of the mass conservation equations, Darcy’s law and the energy conservation equation are given. The article also presents derivations of the equations for taking into account the latent heat of phase transitions and non-isothermal filtration parameters for the energy conservation equation. This may be useful for researchers to better understand the construction of the model. For the parameters included in the basic equations, various dependencies are used in different works. In all the articles found, most often there was an emphasis on one or two of the parameters. The main feature of this article is summarizing various dependencies for a large number of parameters. Additionally, graphs of these dependencies are presented so that the reader can independently evaluate the differences between them. The most preferred dependencies for calculations are noted and explained.