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Copyright of Oilfield Chemistry is the property of Sichuan University, Oilfield Chemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

AbstractBicadinanes (C30H52) are a family of non-hopanoid, pentacyclic triterpane biomarkers whose utility in oil spill fingerprinting has, to our knowledge, not been previously explored. Owing to their derivation from Diptocarpaceae tree (dammar) resin, crude oils containing bicadinanes are geographically and temporally limited to Southeast Asian oils sourced from Oligocene or younger strata. Bicadinane-bearing oils produced from Southeast Asia, however, are shipped worldwide and thereby bicadinanes may be present in oils spilled both within and outside of Southeast Asia. Bicadinanes’ relative or absolute concentrations are readily measured using a standard oil spill identification analytical method (GC/MS-SIM) that routinely targets more conventional biomarkers (triterpanes, steranes, and aromatic steroids). In this study, the absolute concentrations of four bicadinane isomers (W, T, T1 and R) were measured in 42 tarballs collected from shorelines along the southern extent of the Straits of Singapore, an area with very high oil tanker and cargo vessel traffic. The tarballs’ specific origins are unknown but safely presumed to be derived from various unknown oil spills and/or oil seeps in the region. GC/FID was used to classify the tarball oils’ level of biodegradation (Levels 1, 4, and 6). The absolute concentration of total bicadinanes ranged from 7.5 to 208 µg/g and varied widely and independent of the level of biodegradation. The relative concentrations among the four bicadinane isomers (T > W>T1∼R; on average, 56% > 20% > 12% each) also showed no obvious or statistically significant trend with biodegradation for the samples studied. Thus, variations in both total and individual isomer concentrations are attributable to the tarballs’ multiple crude oil sources spilled or seeped in the study area. Diagnostic ratios (DRs) are critical components in oil spill identification protocols. A newly proposed DR of (W + T)/hopane varied widely (0.01 to 0.54) and also independently from the more conventionally used DR of 18α(H)-oleanane/hopane (oleanane/hopane; 0.04 to 0.42). Two newly proposed DRs among the four bicadinane isomers, W/T and T/(T1 + R), also varied among the 42 tarball oils studied (0.27 to 0.45 and 1.4 to 3.2, respectively). The variation in the (W + T)/hopane, oleanane/hopane, W/T and T/(T1 + R) ratios was unrelated to the level of biodegradation for the samples studied and exceeded the statistical criteria used in the CEN (2012) oil spill identification protocol (i.e., 95% repeatability limit) and thereby demonstrates these DRs’ utility in comparing and distinguishing among different crude oils containing bicadinanes – and, of course, between crude oils that do and do not contain bicadinanes. The additional specificity offered by bicadinanes argues they should be included as target analytes in oil spill identification studies throughout Southeast Asia or in other areas where Southeast Asian oils are believed to be present (shipped, handled, or used). [ABSTRACT FROM AUTHOR] more...

Sir Douglas Mawson, the eminent geologist-mineralogist and Antarctic explorer, was a professor and prominent researcher from 1921 to 1957 at the University of Adelaide where he began teaching in 1906. His little-known interest in the origins of crude oil is evident in two of his archived items with direct links to the birth places of petroleum exploration in the USA and Australia. The first, a sample of crude oil from Edwin Drake's historic discovery well near Titusville, Pennsylvania, is unique for several reasons. Its saturated and aromatic hydrocarbon signatures, hitherto unreported, reveal it to be of sub-oxic marine origin and expelled from its source rock late in the conventional oil-generation window. Produced from the Upper Devonian Riceville Shale, it is the world's first unconventional crude oil discovery. The second item is one of Mawson's several specimens of coorongite recovered from Alfred Flat, South Australia, near the site of Australia's first exploration well. It is a black rubbery material originally regarded as a product of local oil seepage. Later shown to be the desiccated remains of the freshwater alga Botryococcus braunii, its molecular signatures differ markedly from those of the three modern races of this alga. Coorongite is currently of interest as an intermediate in the production of biofuel. [ABSTRACT FROM AUTHOR] more...

This study outlines the application of the Six Sigma methodology to rectify oil seal leaks in an automobile company's hollow drive shafts. Persistent issues with oil seepage through the shaft's oil seal led to clutch malfunctions, power failures, and subsequent breakdowns, resulting in high warranty costs, which negatively impacted the status of a firm in the market and the level of fulfillment experienced by its clients. Projects are crucial for translating an organization's strategic goals into achievable outcomes, serving as the cornerstone of success. We implemented a quality-driven effort using Six Sigma and the Theory of Inventive Problem Solving (TRIZ) to foster a culture of continuous improvement. Utilizing the procedures-oriented DMADV (Define, Measure, Analyze, Design, and Verify) technique, the oil seal leakage issue was addressed and resolved successfully from the gearbox. The Pugh matrix was used to choose a new design from various alternatives, a KANO model to evaluate customer demands, and a cause-and-effect diagram to analyze possible failure situations. The overall aim was to determine the failure situations that were most likely to occur. Through its deployment, we intended to improve both the product's dependability and the production process's efficiency. Following the design improvements, the defects observed in the assemblies dropped to 58, with no occurrences of oil seal leakage. It is plausible to conclude that these techniques can significantly enhance product quality. The study demonstrates the efficacy of Six Sigma methodologies in tackling intricate situations. [ABSTRACT FROM AUTHOR] more...

As China's demand for imported oil continues to grow, large‐scale oil storage facilities have become increasingly important. Currently, China primarily uses underground salt cavern spaces and newly excavated underground water‐sealed caverns for oil storage, which places high demands on the rock formations. China has abundant and widely distributed gypsum mineral resources, and utilizing abandoned gypsum mines for oil storage could not only turn waste into treasure by controlling underground space but also generate significant economic and social value. This article aims to systematically evaluate the mechanical properties of gypsum rock through long‐term immersion tests in crude oil to assess the impact of crude oil immersion on the mechanical performance of gypsum rock and explore the feasibility of using gypsum mines as long‐term stable oil storage caverns. The results show that oil immersion treatment reduces the uniaxial tensile strength of gypsum samples, but has little effect on their compressive strength and long‐term strength. From a mechanical performance perspective, it is feasible to use gypsum mine voids for crude oil storage. [ABSTRACT FROM AUTHOR] more...

The microbial communities of bottom sediments of the Bolshaya Zelenovskaya oil seepage site (Lake Baikal) were investigated to assess their diversity and potential functional activity in the anaerobic degradation of oil. Microorganisms of the subsurface and deep sediment layers were grown in enrichment cultures supplemented with oil and various electron acceptors for 1 year at 10°C, and it was found that the concentrations of n-alkanes and polyaromatic hydrocarbons decreased by 1.2–2 and 2.2–2.8 times, respectively. Hydrocarbon conversion was accompanied by generation of hydrocarbon gases (methane and ethane). The microbial community of subsurface sediments had a higher bacterial diversity than the community of deep horizons and was composed of microorganisms specialized in degradation of a broad range of substrates, including oil hydrocarbons. The community of the deep sediment layer was dominated by Atribacterota, Caldisericota, and Bathyarchaeia (Thermoproteota), as well as members of the "rare biosphere": Elusimicrobiota and Candidatus Hadarchaeota. Apparently, oil degradation in the bottom sediments of Lake Baikal is primarily mediated by members of the phyla Bacillota, Pseudomonadota, Chloroflexota, Actinomycetota, Desulfobacterota, Atribacterota, Halobacteriota, and Bathyarchaeia (Thermoproteota). [ABSTRACT FROM AUTHOR] more...

Porous oil storage media is the core of selflubricating rolling functional components. The internal pore directivity of porous oil storage media is different and it reduces the utilization rate of lubricating oil. In this paper, a new fabrication method of porous oil storage media with directional pores is carried out, and the properties of the porous media, such as hardness, density, porosity, oil storage rate and oil retention rate are evaluated. The experimental results show that the fabrication pressure has a linear positive effect relationship with the hardness of the porous media, and has no significant effect on the density, porosity, oil storage rate and oil retention rate. The mass fraction of pore former has a linear negative effect relationship with the hardness and density of the porous media, and a linear positive effect relationship with the porosity the greater the mass fraction of pore former, the greater the initial oil seepage rate of oil rejection. The internal pores of the porous media have a fibrous structure of the cave type, and the internal pores are interconnected and have good orientation. This study aims to provide a lubricating theoretical reference for the fabrication of porous oil storage media. [ABSTRACT FROM AUTHOR] more...

Oil spillages on a sea's or an ocean's surface are a threat to marine and coastal ecosystems. They are mainly caused by ship accidents, illegal discharge of oil from ships during cleaning and oil seepage from natural reservoirs. Synthetic-Aperture Radar (SAR) has proved to be a useful tool for analyzing oil spills, because it operates in all-day, all-weather conditions. An oil spill can typically be seen as a dark stretch in SAR images and can often be detected through visual inspection. The major challenge is to differentiate oil spills from look-alikes, i.e., low-wind areas, algae blooms and grease ice, etc., that have a dark signature similar to that of an oil spill. It has been noted over time that oil spill events in Pakistan's territorial waters often remain undetected until the oil reaches the coastal regions or it is located by concerned authorities during patrolling. A formal remote sensing-based operational framework for oil spills detection in Pakistan's Exclusive Economic Zone (EEZ) in the Arabian Sea is urgently needed. In this paper, we report the use of an encoder–decoder-based convolutional neural network trained on an annotated dataset comprising selected oil spill events verified by the European Maritime Safety Agency (EMSA). The dataset encompasses multiple classes, viz., sea surface, oil spill, look-alikes, ships and land. We processed Sentinel-1 acquisitions over the EEZ from January 2017 to December 2023, and we thereby prepared a repository of SAR images for the aforementioned duration. This repository contained images that had been vetted by SAR experts, to trace and confirm oil spills. We tested the repository using the trained model, and, to our surprise, we detected 92 previously unreported oil spill events within those seven years. In 2020, our model detected 26 oil spills in the EEZ, which corresponds to the highest number of spills detected in a single year; whereas in 2023, our model detected 10 oil spill events. In terms of the total surface area covered by the spills, the worst year was 2021, with a cumulative 395 sq. km covered in oil or an oil-like substance. On the whole, these are alarming figures. [ABSTRACT FROM AUTHOR] more...

Yemeni coasts are subjected to several oil spills incidents since 2013 such as the Champion vessel disaster in Mukallah-Arabian Sea, and the massive oil slicks along the coast of Aden in 2021 caused by the leaks abandoned tanker, DIA and sink. This paper aimed to study the environmental impacts of the floating oil storage (FSO Safer) loaded by 1.14 million barrels oil and has been left exposed to humidity, corrosion and lack of maintenance since 2015. The field data were collected during the period 2010 and 2015 through various population surveys, biodiversity monitoring and conducting water analysis in the Ras Issa region, as well as monitoring and follow-up the status of FSO_SAFER during 2018-2022. The results revealed deterioration in environmental biodiversity especially in the coral reefs, while sea water characteristics are changed by oil contamination. In Ras Issa locality, high concentration of petroleum hydrocarbons were recorded i. 12.8 ppm in sample 1 and 3. Verities of heavy elements i.e. As, Cd, Fe, and Ni are exceeding the permissible levels. The present study is highlighted the subsequences scenarios for leaks oil from FSO_SAFER's and expected pollution, while the estimated tackle cost of compensation and damage to environment, clean up, technical work and contingency is reaching up to $26.1 billion. [ABSTRACT FROM AUTHOR] more...

Oil spills and natural oil seeps are sources of petrogenic hydrocarbons in soils and sediments. To determine the source of hydrocarbon contamination in the environment the geochemical signature of the contaminant needs to be characterised. Here, we present biomarker and other molecular marker diagnostic ratios of Alberta Oil Sands using gas chromatography-mass spectrometry to characterise the deposits and detect their incorporation in surficial sediments. Diagnostic ratios of steranes, terpanes, and aromatic steroids (e.g. C27, C28, and C29 regular sterane abundance, Gammacerane Index, Ts/Tm, TAS/(TAS + MAS), and MPI-2) were measured in samples of Alberta Oil Sands providing a set of criteria for their identification. Seven surficial sediment samples from central and southeast Alberta were then analysed using these criteria to detect Alberta Oil Sands contamination and other petrogenic and pyrogenic source inputs. Geochemical signatures consistent with Alberta Oil Sands hydrocarbons were identified in surficial sediments in Lamont County and glacial sediments from a moraine in Beaver County. Both sites are in Central Alberta, ∼300 km south of any oil sands extraction sites and natural exposures in northern Alberta, indicating long-distance sediment transport processes mobilised the deposits. These results show that the oil sands have been eroded and transported beyond the boundaries of their current known limits. This is important for understanding sediment transport processes as well as for remediation and reclamation purposes. [ABSTRACT FROM AUTHOR] more...

We discovered seafloor features such as bacterial mats and carbonate crusts typical for active methane seeps on the continental slope southwest of Svalbard. These features are associated with two main northwest-southeast trending morphological structures that are oriented parallel to the regional continental slope. Both structures occur at c. 800 m water depth, at the boundary between the Storfjorden trough mouth fan to the south and the Hornsund trough mouth fan to the north, which suggests a loading related fluid seepage. The main structure displays depressions and ridges forming a crater in its center. Other occurring features include small sediment mounds, domes often covered by bacterial mats, and hummocky seafloor colonized by siboglinid tubeworms. Free gas bubbles were spotted close to the centre and plumes along the rims of the structure. Thick carbonate crusts indicate a long seepage history in the center of the structure and on top of the ridges. The sources of the seeps are likely to be Miocene old organic-rich deposits, or Paleocene hydrocarbon reservoirs. [ABSTRACT FROM AUTHOR] more...

To solve the technical problems of safe and efficient exploitation of coal resources by abandoned oil wells in the Ordos Basin, several characteristics of the coal seam need to be fully explored: petroleum seepage pressure, seepage velocity and seepage range. However, these are difficult to determine in situ, and often numerical models are used. A comprehensive analysis method combining COMSOL Multiphysics numerical software and seepage model is proposed here based on the continuous non-linear theory of seepage flow and the constructed seepage channel model of different pores and fissure coal samples. The characteristic parameters are determined by on-site measurement to verify the accuracy of the proposed analysis method. The results show that the characteristic parameters of each seepage flow studied differ from those measured in the field; however, the difference is small. The seepage pressure in time and space can more accurately describe the changes in the tensile parameters. The spatial dimension seepage pressures forms three-stage distribution along the radial direction. The maximum seepage velocity is about 16 m/month, and the radial seepage range is 221 ∼ 235 m. The comprehensive analysis method based on the new seepage model quantitatively reflects the changes in seepage characteristic parameters and enhances the methods of seepage research. [ABSTRACT FROM AUTHOR] more...

This study reveals the heterogeneity, anisotropy, and formation mechanism of nanostructures (pores and throats) for the storage and seepage of tight oil by comprehensively unifying the following techniques: FE–SEM, gas adsorption, EDS, HPMI, MICP, and umbrella deconstruction. The results show that for tight oil reservoirs, 82.8% of the nanoscale pore contributes to oil storage, 50.2% of the nanoscale pore contributes to oil seepage, 76.5% of the nanoscale throat contributes to oil storage, and 38.9% of the nanoscale throat contributes to oil seepage. The nanopores were mainly formed in kaolinite, chlorite, K-feldspar, and illite, with 57%, 21%, 14%, and 7% of the contents, respectively. Among them, 85% are clay minerals. The weathering and dissolution of feldspar contributes a great deal to the formation of nanopores, accounting for about 78%, which a follow-up study should target. The relatively large pores can easily form a relatively large throat, and compaction and diagenesis later have little influence on the density of the nanoscale pores. Simultaneously, the pore radius and throat peak radius are the most robust parameters reflecting the reservoir's storage capacity and infiltration difficulty. The conclusion will provide a crucial scientific basis for tight oil storage and underground flow. • Nanostructures for the storage and seepage of tight oil are revealed comprehensively. • Compaction and diagenesis have little influence on the density of nanopores. • The peak radius could reflect the storage capacity. [ABSTRACT FROM AUTHOR] more...

Cycloalkanes are abundant and toxic compounds in subsurface petroleum reservoirs and their fate is important to ecosystems impacted by natural oil seeps and spills. This study focuses on the microbial metabolism of methylcyclohexane (MCH) and methylcyclopentane (MCP) in the deep Gulf of Mexico. MCH and MCP are often abundant cycloalkanes observed in petroleum and will dissolve into the water column when introduced at the seafloor via a spill or natural seep. We conducted incubations with deep Gulf of Mexico (GOM) seawater amended with MCH and MCP at four stations. Within incubations with active respiration of MCH and MCP, we found that a novel genus of bacteria belonging to the Porticoccaceae family (Candidatus Reddybacter) dominated the microbial community. Using metagenome‐assembled genomes, we reconstructed the central metabolism of Candidatus Reddybacter, identifying a novel clade of the particulate hydrocarbon monooxygenase (pmo) that may play a central role in MCH and MCP metabolism. Through comparative analysis of 174 genomes, we parsed the taxonomy of the Porticoccaceae family and found evidence suggesting the acquisition of pmo and other genes related to the degradation of cyclic and branched hydrophobic compounds were likely key events in the ecology and evolution of this group of organisms. [ABSTRACT FROM AUTHOR] more...

Tight carbonate reservoirs in the Western Qaidam Basin have complex lithologies and pore structures. The oil–water mobility law in reservoirs has not yet been completely determined, restricting the formulation of rational reservoir development methods. To bridge this gap, in this study, we used several test methods, such as casting thin sections, mercury intrusion, and nuclear magnetic resonance, to obtain the pore structure and oil–water displacement characteristics of tight carbonate reservoirs in the Western Qaidam Basin. The pore structures of the reservoirs could be categorized into three types: microfractures + dissolved pores + micropores (MFD), microfractures + micropores (MF), and matrix (M). The characteristics of single‐phase oil seepage and water flooding in reservoirs with various pore structures differed evidently. For the MF‐ and M‐types, the water‐locking effect caused by the strong capillary force affected oil charging in the micropores. The effect of the pressure drop on the MFD‐type algal limestone was less than that on the MF‐type limestone (dolomite) because of the occurrence of a non‐Darcy flow. The MFD‐type, which contained microfractures, had preferential seepage channels, resulting in obvious fluid channeling and low water displacement efficiency. Oil−water displacement mainly occurred in the dissolved pores and microfractures, suggesting that starting oil accumulation in the micropores was crucial. This study will assist in efficient development of tight carbonate reservoirs in the Western Qaidam Basin. [ABSTRACT FROM AUTHOR] more...

A remarkable characteristic of the Bandar Abbas Hinterland is the frequent presence of oil seepages that can serve as an indicator of probable oilfields in the region. The Seeps A and B are located in the main Zagros Suture Zone, 150 km to the northeast of Bandar Abbas and 30 km to the west of the same city, respectively. The presence of well-known Paleozoic source rocks (e.g., Seyahou, Sarchahan, and Gurpi formations) in the vicinity of the mentioned oil seepages shows that the seeping oil is coming from an oil source. The present research is aimed investigating the petroleum system and determining the source of the mentioned oil seepages. Results of the Rock-Eval analyses showed that the samples of the Seyahou Formation are thermally overmatured, making them exhibit inadequate oil generation potential. These samples contain Type-III kerogen and were found to be in the metagenesis stage. However, compared to other formations, Sarchahan and Gurpi exhibited good hydrocarbon generation potentials. On the other hand, based on the PI – Tmax diagram, the Sarchahan Formation was found to be in the early oil and condensate production window (i.e., catagenesis stage) while the Gurpi Formation was seen to be immature. Biomarker analysis results showed that the samples were deposited in a mixed marine environment and contained Type-II and Type II/III kerogen. The reason behind the occurrence of the oil seepages in an oxidative environment could be the sever impact of the biological degradation. The stable carbon isotope composition of the crude samples supported the biomarker data in general. Therefore, it can be concluded that the studied oil seepages were probably sourced from the Sarchahan Formation. more...

The Kalumpang Formation was deposited in a delta plain setting. A Middle to Late Eocene age (Proxapertites operculatus zone) was inferred from palynological analysis, with a paleoenvironment in a coastal plain setting with a strong terrestrial influence. Samples from the Kalumpang Formation indicate a marginal to early mature stage for hydrocarbon generation. It is mostly composed of gas-prone to oil and gas-prone Type III kerogen facies. The biomarker character of both the rock and oil samples suggests a terrestrial origin, with a significant contribution of estuarine or bay organic material. The oil derives from a noncarbonate lithology, while the rock samples are from carbonate/calcareous shale origin. The abundance of oleanane compound and C30 resins suggests higher plant angiosperm input of Late Cretaceous or younger age for both the rock and the oil samples. The oil seep contains more abundant oleananes compared to the carbonaceous mudstone of the Kalumpang Formation. This suggests that the oil originated from more marine facies than the rock samples, which were deposited in a delta plain setting. This study demonstrated the agreement of depositional environment interpretation and age assessment between lithofacies, palynological, and organic geochemistry analysis. [ABSTRACT FROM AUTHOR] more...

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

The incessant natural gas flare and oil seepages triggered the source rock potential palynofacies exposé, depositional environment and lateral facies changes as well as sedimentary structures trapping synthesis of the Enugu Formation to unravel the structural trap style, hydrocarbon production potential and pathway for reserves of the formation for hydrocarbon generation. Opaque particles, yellow and dark-brown amorphous organic matter, marine taxa with few dark-brown structured phytoclasts and terrestrial microflora denote the visual palynofacies attributes of the study. Kerogen essential shows thermally mature type II–III kerogen indicative of oil- and gas-prone materials. The natural gas flare are products of kerogen type III (gas prone) palynofacies elements while the pronounced oil seepages are the productive result of kerogen type II (oil prone) palynofacies groups. These palynofacies features are deposited in transitional marine settings in the inner neritic zone with outer neritic influences consistent with estuarine, nearshore and fresh water environment based on the normal diverse quality and quantity of palynofacies components and abundance of land-derived microflora over marine dinocysts. Structural hydrocarbon entrapment mechanisms of the Enugu Formation outcrop key structural traps consists of hanging wall closures, footwall closures and half graben along with infilled and open-joint structures within faulted and unfaulted sandstone lenses. Primary and secondary migration petroleum pathway in sandstones pores and fractures are the major principal means in the creation of petroleum accumulations of the formation. The natural gas flare and oil seepages denote these structural style elements as unequivocal petroleum systems architecture for hydrocarbons trap within the Anambra Basin. The highlighted structural complexity, lateral facies changes, alleviates the gas flare prognosis and subsequent oil drilling pathway as well as exploration campaign in the Formation. [ABSTRACT FROM AUTHOR] more...

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

The rapid global growth of plastic production and waste are harbingers of increasing pollution in terrestrial and marine ecosystems for which safe and effective methods of disposal and degradation must be pursued. In the present study, metabarcoding and culture-based studies have been carried out to provide insights into polyethylene terephthalate (PET) biodegradation potential. Post-consumer PET films and powder were exposed to soil samples obtained from an aged oil bitumen spring site in Southwest Iran. To investigate microbial community composition, metagenome was extracted and hypervariable V3-V4 were sequenced (metabarcoding). Comparison of 16S amplicon metagenomic profiles between samples shows that Bacillus spp. and Halomonas spp. were the most abundant among bacterial genera present in soil samples from the vicinity of the oil seep, while Sphingomonas genus was most frequent in sample C collected from a region ~ 0.5 km distant of the oil seep. In the culture-based approach, Brevibacillus and Pseudomonas spp were isolated and analyzed for PET degradation. Field Emission Scanning Electron Microscope (FE-SEM) analysis shows two isolates had been colonized on PET film surface forming biofilm-like structures. PET degradation components were investigated by Gas Chromatography- Mass Spectrometry (GC-MS) which revealed the presence of aliphatic and aromatic compounds in the bacterial media. In addition, X-Ray diffraction (XRD) analysis showed reduction in crystallinity region peaks after 90 days of incubation with bacteria at 32°C. The diversity of the microbial community and the presence of PET degrading bacteria indicate a potential of the native oil seep-contaminated ecosystem for plastic degradation which is acquired following long-term adaptation to petroleum compounds. [ABSTRACT FROM AUTHOR] more...

A remarkable characteristic of the Bandar Abbas Hinterland is the frequent presence of oil seepages that can serve as an indicator of probable oilfields in the region. The Seeps A and B are located in the main Zagros Suture Zone, 150 km to the northeast of Bandar Abbas and 30 km to the west of the same city, respectively. The presence of well-known Paleozoic source rocks (e.g., Seyahou, Sarchahan, and Gurpi formations) in the vicinity of the mentioned oil seepages shows that the seeping oil is coming from an oil source. The present research is aimed investigating the petroleum system and determining the source of the mentioned oil seepages. Results of the Rock-Eval analyses showed that the samples of the Seyahou Formation are thermally overmatured, making them exhibit inadequate oil generation potential. These samples contain Type-III kerogen and were found to be in the metagenesis stage. However, compared to other formations, Sarchahan and Gurpi exhibited good hydrocarbon generation potentials. On the other hand, based on the PI - Tmax diagram, the Sarchahan Formation was found to be in the early oil and condensate production window (i.e., catagenesis stage) while the Gurpi Formation was seen to be immature. Biomarker analysis results showed that the samples were deposited in a mixed marine environment and contained Type-II and Type II/III kerogen. The reason behind the occurrence of the oil seepages in an oxidative environment could be the sever impact of the biological degradation. The stable carbon isotope composition of the crude samples supported the biomarker data in general. Therefore, it can be concluded that the studied oil seepages were probably sourced from the Sarchahan Formation. [ABSTRACT FROM AUTHOR] more...

Subsurface geological reservoirs of natural hydrogen gas (H 2), a clean fuel and energy vector, are currently a target for energy resource exploration. Such reservoirs can be revealed by the presence of H 2 within soil, analogous to hydrocarbon seepage in petroleum systems. Nevertheless, defining the level of soil H 2 that can indicate a potentially economic resource is currently impossible, and identifying geological H 2 within soil-gas is challenging because H 2 concentrations and the isotopic composition (δ2H) may overlap with the in-situ biological signature. In spite of these limitations, analogies to conventional hydrocarbon systems suggest that the presence of surface advective gas flows can reveal (unlike diffusion) a subsoil source and even pressurised gas accumulations of H 2. Here, a massive release of H 2 is reported from a CH 4 –H 2 rich seep in Turkey, known as Chimaera, an emblematic example of H 2 advection. The site represents the first case where a closed-chamber flux method was applied for H 2 seepage. H 2 advection at the site was clearly indicated by numerous gas vents and flames, and by the heterogeneous spatial distribution of pervasive, invisible exhalation (miniseepage), inducing rapid H 2 concentration build-up within the chamber. H 2 emission (∼10 ± 3 kg day−1, with the highest H 2 emission factor reported, thus far, of ∼5000 kg km−2 day−1) is continuous and long lasting (flames have been documented for millennia) and, using an analogy for hydrocarbon seeps, may stem from pressurised accumulations. The Chimaera case is illustrative of how detecting soil H 2 advection may help unravel surface (biological) vs. subsoil (geological) gas origins in cases where, in the absence of significant gas seepage, soil H 2 concentrations are within the range of biological production (100-103 ppmv, e.g., as for "fairy circles" observed in several countries). Interpretations must, however, be supported by additional geochemical data and evaluations of potential biological H 2 production within the surface ecosystem. • First direct measurements of natural H 2 flux from a seep using a closed-chamber technique. • Highest geological H 2 emission factor reported to date. • Soil H 2 advection as a potential proxy of subsurface gas migration and reservoirs. [ABSTRACT FROM AUTHOR] more...

The Tramutola area in the High Agri Valley represents a key for the Southern Apennines fold and thrust belt. There, natural oil seeps from small carbonate reservoirs located at shallow depths that have been historically known since the 19th century, and hypothermal water was discovered during hydrocarbon exploration. From a geological point of view, the study area, extending for about 11 km2, is characterized with the presence of a complete section of the tectonic units of the southern Apennines and a complex structural framework that has not yet been fully clarified. In this work, geological analysis is based on new lithological and structural data, acquired during a detailed geological survey, compared with well logs obtained during exploration for hydrocarbons. Furthermore, a new geophysical investigation down to a 1 km depth (deep electrical resistivity tomography) allowed inference of buried structural and geological characteristics of the studied area. Through combining surface and subsurface data, some preliminary considerations about the structural setting and geofluid presence down to a 1 km depth have been made. Furthermore, geological–structural cross-sections have been constructed with the purpose of depicting the geometries of structures affecting the Apennine nappe pile in the subsurface, possibly favoring early uprising of hydrocarbons as well as circulation of hypothermal fluids and associated gases rising from deeper reservoirs. [ABSTRACT FROM AUTHOR] more...

Hand‐dug oil wells, located in natural crude oil seep sites, are remnants of historical exploitation activities. Hydrocarbon pollution is regarded as the threat to soil ecosystem. On the other hand, there is no common environmental policies regarding these soils. The hypothesis was that natural attenuation processes might occur in seep soils since a diversified and stable bacterial community structure should be a result of its long‐term (thousands of years) adaptation to hydrocarbon exposure and should be associated with eventual utilization of these compounds. To obtained this goal, we compared the structure, composition, and hydrocarbon‐degrading potential of bacterial communities inhabiting soils with different hydrocarbon contents (seep, hydrocarbon‐impacted, pristine soils), which were collected in two habitats (forest, meadow). 16S rRNA sequencing and isolation of hydrocarbon degraders were performed. The contaminant's presence shaped distinct and unique community structure and composition, and it enhanced physiologically and functionally adapted microorganisms. The most abundant community members were bacteria revealing a strong contribution in genetic potential toward aerobic hydrocarbon transformation (i.e., Mycobacterium/Mycolicibacterium and Pseudomonas). The strong hydrocarbon degraders population suggests that natural biodegradation occurs in situ in seeps and mitigates the pollution impact on adjacent soils. Seep and hydrocarbon‐impacted soils are a great source for remedial bacterial populations. Twenty‐four genera of degraders were isolated; however, strains belonging to the Mycobacterium/Mycolicibacterium, Rhodococcus, and Pseudomonas taxa were common. Our results underline the need to include undervalued microbiological aspects in remediation projects' guidelines for chronically polluted environments. The knowledge regarding seep communities should help to evaluate more efficient remediation strategies for anthropogenic spills. [ABSTRACT FROM AUTHOR] more...

Zein and ethyl cellulose (EC) were used as raw materials to prepare a composite coating applied in aqueous systems with mechanical properties, water stability, water solubility (including room-temperature (RT)/high-temperature and neutral/acidic conditions), and oil resistance as evaluation index. Results showed the most suitable conditions were mass ratio of zein/EC at 1:9, 93 % (v /v) aqueous ethanol, oleic acid as the plasticizer with the amount of 0.3 g/g, and curing temperature at 70 °C. Under these conditions, the tensile strength of composite coating was 4.61 MPa and elongation at break was 21.60 % after 4 weeks of soaking in water. Oil seepage was not observed within 1 week. The water solubility of coating in neutral water was 5.13 % at RT for 24 h, and 3.79 % at 80 °C for 2 min; in acidic water (pH = 4) was 4.54 % at RT for 24 h, and 5.44 % at 80 °C for 2 min. SEM results showed swelling occurred in zein coating after soaking, presenting micropores in soaked zein coating; zein microparticles in composite coating partially broke down and fell off after soaking. Water contact angle results revealed surface hydrophobicity by the following order: EC coating > composite coating > zein coating. FTIR results showed composite coating was physically compounding by hydrophobic interactions and hydrogen bonds. [Display omitted] • Zein and ethyl cellulose were compounded for composite coating preparation. • Tensile strength of composite coating was 4.61 MPa after 4 weeks of soaking in water. • Elongation at break of composite coating was 21.60 % after 4 weeks of soaking in water. • The resulting composite coating has good water stability and oil resistance. • Composite coating was compounding mainly by hydrophobic interactions and hydrogen bonds. [ABSTRACT FROM AUTHOR] more...

The greenhouse gas, methane, budget has significant uncertainty for many sources, including natural geological emissions. A major uncertainty of geological methane emissions, including onshore and offshore hydrocarbon seepage from subsurface hydrocarbon reservoirs is the gas emissions' temporal variability. Current atmospheric methane budget models assume seepage is constant; nevertheless, available data and seepage conceptual models suggest gas seepage can vary considerably on timescales from second to century. The assumption of steady-seepage is used because long-term datasets to characterize these variabilities are lacking. A 30-year air quality dataset downwind of the Coal Oil Point seep field, offshore California found methane, CH4, concentrations downwind of the seep field increased from a 1995 minimum to a 2008 peak, decreasing exponentially afterward with a 10.2-year timescale (R2 = 0.91). Atmospheric emissions, EA, were derived by a time-resolved Gaussian plume inversion model of the concentration anomaly using observed winds and gridded sonar source location maps. EA increased from 27,200 to 161,000 m3 day−1 (corresponding to 6.5–38 Gg CH4 year−1 for 91% CH4 content) for 1995–2009, respectively, with 15% uncertainty, then decreased exponentially from 2009 to 2015 before rising above the trend. 2015 corresponded to the cessation of oil and gas production, which affects the western seep field. EA varied sinusoidally with a 26.3-year period (R2 = 0.89) that largely tracked the Pacific Decadal Oscillation (PDO), which is driven on these timescales by an 18.6-year earth-tidal cycle (27.9-year beat). A similar controlling factor may underlie both, specifically varying compressional stresses on migration pathways. This also suggests the seep atmospheric budget may exhibit multi-decadal trends. [ABSTRACT FROM AUTHOR] more...

Abstract—The composition and relative content of C14–C16 bicyclic sesquiterpanes in oil seeps from thermal springs of the Uzon caldera have been studied by GC-MS technique. It is shown that C16 homodrimanes prevail in oil composition, whereas C15 drimane content is insignificant, and C14 nordrimanes are present in trace amounts. Homodrimane with biological configuration 8α(H) was detected. Bicyclic sesquiterpanes of the Uzon oil are probably its derivatives. It has been revealed that the relative content of C15 drimanes increased with increasing thermal maturity of the oil. A sesquiterpane maturity index, which has not been used previously in organic geochemistry, is proposed. [ABSTRACT FROM AUTHOR] more...

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

In this paper we consider and systematize the main significant parameters of natural oil seeps and the possibility for determining them according to radar and optical satellite data. It is shown that, at present, the analysis of time series of optical and radar images makes it possible to determine the main/characteristic parameters of natural oil seeps, making it possible to estimate the location of their underwater sources; the composition, intensity, and volumes of emissions; the seismical situation; and, to some extent, the prospects for the oil and gas potential of the region. The possibilities, limitations, and prospects for using remote sensing data for the considered problems are summarized and discussed. The survey nature of the paper made it possible to consider all modern methods and results of studies of natural oil seeps using remote sensing. [ABSTRACT FROM AUTHOR] more...

The Russian-Ukrainian conflict has diverted European nations from purchasing Russian oil and correspondingly increased the demand from Arab Gulf countries, increasing the number of tankers transporting oil via the Gulf of Suez and the Suez Canal. Therefore, the shipping route is vulnerable to oil seepage accidents, affecting Egyptian tourist cities like Hurghada. Thus, the purpose of this study was to determine the most susceptible zones to contamination and calculate affecting processes (evaporation, natural dispersion, and emulsification) that may occur as a result of crude oil spill accidents in the strait of Gubal northern of Hurghada using the General National Oceanic and Atmospheric Administration Operational Oil Modeling Environment (GNOME) and Automated Data Inquiry for Oil Spills (ADIOS2) models. For this purpose, two scenarios were simulated in February and August 2021 of 1000 metric tons of Arabian light crude oil. The trajectory maps highlighted that the northern Red Sea islands (Ashrafie, Small Gubal, Geisum, Tawila, Shadwan, and Gifton), which have enormous economic and strategic significance are the most vulnerable areas to pollution. In addition, the estimated results demonstrated that the movement of the spilled oil is affected by the prevailing wind direction and marine currents. The ADIOS2 model results showed that more than a quarter of the amount of the light crude oil was evaporated. At the same time, the percentage of natural dispersion increased slowly and did not exceed 1.3% in both scenarios. Furthermore, the emulsion's water content increased rapidly to 90% by the end of the simulation, with obvious shrinkage in the surface volume of the spill body including the emulsion with time. Therefore, oil spill responders could use this study as a reference or guide to inform the systematic environmental conservation planning process near Hurghada coasts. [ABSTRACT FROM AUTHOR] more...

Purpose: The purpose of this paper is to put forward the lubrication model of oil bearing and enrich the design theory under the condition of mixed lubrication. Design/methodology/approach: A mixed lubrication model of bilayer porous bearing is established. The effects of the working conditions on the lubrication performance and seepage behavior were analyzed. Findings: Results show that the oil film pressure mainly occurs in the bearing convergence zone and contact pressure mainly occurs near the minimum film thickness. The oil infiltrates into the porous matrix in the contact area and precipitates out to the friction surface at the inlet of the contact area. The oil seepage velocity and dynamic pressure effect at the friction interface can be improved by reasonably matching the load and speed. With the decrease of the external load or increase of the rotating speed, the lubrication performance becomes well. Originality/value: This study provides a reference for the design and application of oil bearing under harsh working conditions. [ABSTRACT FROM AUTHOR] more...

Using the remote sensing data obtained by the Sentinel-1A and Sentinel-1B satellites in the years 2016–2021, a local accumulation of oil slicks in the Barents Sea in 53 synthetic aperture radar images is delineated in the area with coordinates 75.2°–75.3° N and 31.5°–31.8° E. The study of an undisturbed core in this area (station 7105, 84th cruise of the R/V Akademik Mstislav Keldysh) has shown an anomalous distribution of polycyclic aromatic hydrocarbons, PAHs, the concentrations of which increased at the lower horizons of the column, and 2-methylnaphthalene, a marker of oil genesis, dominated in their composition; at the same time, the share of light homologs in the composition of alkanes increased. All this points to the natural formation of hydrocarbons in the sea bottom sediments, and it is definite that the group of oil slicks detected from the satellite radar data is a natural oil seep. [ABSTRACT FROM AUTHOR] more...

Due to the unclear seepage mechanism for shale oil, it is hard to establish a reasonable mathematical model to describe the flowing law. In this study, a real shale pore structure was reconstructed with CT scanning and a numerical model of fluid flowing in the real shale pore is developed with COMSOL, based on the boundary slip at the micro-nano pore scale to study the causes of nonlinear seepage. A two-fluid model is employed to establish a simple mathematical model to describe the relationship between the flow rate and the pressure gradient using the effective slip length to account for the influence of pore structure and true slip, and the established model is verified with experimental data coming from Jiyang shale oil. The results indicated that the pore structure greatly affected the shape of the seepage curve. With the increase in displacement pressure, the percentage of fluid involved in the flow increased until it became stable, showing a changing trend from nonlinearity to linearity. The established model can fit the experimental data well and reasonably characterize the nonlinear seepage of shale oil. [ABSTRACT FROM AUTHOR] more...

The present paper deals with a geochemical investigation (TOC, Rock–Eval pyrolysis, and GC–MS) carried out on two potential mid-Cretaceous (Albian lower Fahdene and Cenomanian–Turonian Bahloul) source rocks and natural oil seeps collected from outcrops and mine boreholes located around the three extrusive salt structures of Ech-Cheid, Fej Lahdoum, and Boukhil, belonging to the Triassic domes zone of northern Tunisia. Rock–Eval pyrolysis results indicate the presence of moderate to good and moderate to excellent quantities of organic matter (OM) of oil–gas type II/III (means TOC: 0.90 wt.%, HI: 180 mg HC/g TOC, and PP: 2.00 mg HC/g rock) and oil-prone type II (means TOC: 3.5 wt.%, HI: 458 mg HC/g TOC, and PP: 20 mg HC/g rock) kerogens for the Fahdene and the Bahloul Formations (Fms), respectively. The thermal maturity of the OM preserved in these source rocks varies between late diagenesis and the late oil window depending mainly on the basin architecture marked by the presence of paleohighs (Triassic salt domes and horsts), grabens, half-grabens, and tilted blocks that controlled the varying degrees of subsidence. Gas chromatography-mass spectrometry (GC–MS) analysis of source rock extracts (Bitumen) and oil seeps and correlations with hierarchical cluster analysis (HCA) using biomarkers parameters (Diasteranes C27βαS/C27ααS and Hopanes C29H/C30H ratios) suggest that the collected oil seep samples were sourced by the Fahdene and the Bahloul Fms. The spatio-temporal oil seeps distribution and associated tectonics indicate that several faults of NW–SE, N-S, E-W, and NE-SW trendings have facilitated oil migration from these source rocks to favorable reservoirs of middle-Turonian Bireno, Coniacian Douleb, and Campanian–Maastrichtian Abiod carbonates as well as a Miocene Oum Dhouil sandstone. These mid-Cretaceous source rocks and associated reservoirs, as well as overlaying argillaceous seals and traps (Flanks of diapirs, uplifted paleohighs, and anticlines), as essential elements, in addition to oil migration pathways and accumulation processes attest to the presence of active conventional petroleum systems in northern Tunisia. This could help guide petroleum exploration activities around subsurface diapir structures analogous. [ABSTRACT FROM AUTHOR] more...

Two hundred km of 2D seismic survey was carried out at the Lesser Himalayan Thrust Belts in Dailekh district, western Nepal. The main motivation is to elucidate the geologic relationship between the known oil and gas seeps, subsurface structure, and stratigraphy in the area. This is a challenging task which is from its extreme structural and geological complexity such as thrust faulting, tight folding, steep dip layers, and strong lateral variations in seismic velocity. Seismic data were acquired with SERCEL 428XL system and processed by GEOEAST computer software. In order to increase signal-to-noise ratio (SNR), suppress interference, and search for optimum acquisition parameters, a series of comparative tests on the different charge depth and size, group interval, CDP fold, geophone array, and single high-sensitivity geophone were conducted. We also tested 2S3L (two lines shooting and three lines receiving) wide line profiling. The results indicate that single hole with charge depth of 12 m, 4-16 kg charge size (less charge size for the densely populated areas), single high-sensitivity geophone, and 1S2L wide line profiling with 132 folds are the optimum acquisition parameters. On the basis of comparative process experiment, data processing workflow consisting of data preparation, prestack denoising, amplitude compensation, deconvolution, tomography static correction, velocity analysis, residual static correction, CRS stack, poststack migration, prestack time migration (PSTM), and prestack depth migration (PSDM) was selected. Maybe affected by problem of conflicting dip in complex media, CRS stack section does not show satisfactory geological characteristics. PSTM profile has moderate signal-to-noise (S/N) ratio; the shallow, medium, and deep continuous reflections can be observed in section. More details of the geological structures can be observed in PSDM section, especially in medium and shallow layers (less than 3000 ms or 4000 m), but PSDM method is more expensive and highly time consuming than that of CRS stack and PSTM. So, the PSTM section can be reasonably used for geological interpretation. By reference to field mapping, thrust characteristics, and MT data, the final interpretation to the PSTM section identified the interfaces of 6 geological units (Paleoproterozoic Nabhisthan Fm., Paleoproterozoic Dubidanda Fm., Neogene to Late Cretaceous Surkhet group, Late Carboneferous to Early Cretaeous Gondwana group, Mesoproterozoic Upper Lakharpata group, and Lower Lakharpata group) and delineated Main Boundary Thrust (MBT), Ramgarh Thrust (RMT), Padukasthan Thrust (PT), and Dailekh Thrust (DT). The bottom of Surkhet group which is our top target zone is about 4250 meters deep. [ABSTRACT FROM AUTHOR] more...

In order to overcome the problems including complicated pore throat structure, changeable seepage characteristics, and difficulty to find seepage law in the tight reservoir, this study simulated the water flooding development process of oilfield reservoir, and the water flooding seepage experiment of real sandstone microscopic model was carried out in a laboratory. Thin slice identification, constant velocity mercury injection, physical property analysis, scanning electron microscope, and other test data were combined to study the reservoir microscopic water flooding characteristics. The relationships between physical properties, water displacement efficiency, displacement pressure, pore structure, wettability, and water injection ratio are discussed. The study showed that the tight reservoir fluids were uniform displacement and reticular displacement seepage that occurred more than finger-reticular displacement. Meanwhile, displacement types affected oil displacement efficiency. Specifically, the uniform displacement type displayed the highest oil displacement efficiency, whose average value was 62.15%. The lowest oil displacement efficiency was finger displacement type, which is 26.89%. Additionally, 79% of the residual oil was cluster and film, and the corner and isolated distribution are less; the change of permeability has a greater effect on oil displacement efficiency than porosity. With the increase of water injection ratio, the oil displacement efficiency was improved. The oil displacement efficiency increases greatly and tended to be smooth and stable, when the water injection increased by 3 PV. There is an exponential relationship between throat radius and oil displacement efficiency. [ABSTRACT FROM AUTHOR] more...

The recent discovery of surface oil seeps in the Tamerza area in the west‐central Gafsa Basin (southern Tunisia) has prompted a re‐evaluation of the hydrocarbon potential of the region. In this paper, we report the results of analyses of seep oils by Rock‐Eval pyrolysis (n = 6) and gas chromatography – mass spectrometry (n = 4). The goals of the study were to assess the composition of the seep oils, to investigate the relationship between the seep oils and potential source rocks, and to highlight the significance of the seep oils for oil exploration in the region. In the Tamerza area, surface oil seeps have been recorded in numerous formations ranging between the Upper Cretaceous Abiod Limestone Formation and the lower Miocene Sehib Siltstone Formation. The results of this study showed that all the seep oil samples analysed in general had a similar geochemical fingerprint: for example, Pr/Ph values are lower than 1; a plot of Pr/n‐C17 (0.27‐ 0.36) versus Ph/n‐C18 (0.3‐0.8) indicates a marine source rock deposited under reducing anoxic conditions; and Ts/(Ts+Tm) ratios indicate that the source rock was thermally mature. Correlation studies suggest that the oils originated from Cenomanian‐Turonian shales corresponding to the informally‐named Bahloul equivalent formation. Oil expulsion from this source rock at the seep locations is inferred to have ended by middle Miocene time. However the main phase of folding occurred here in the Pliocene – early Quaternary, and the resulting anticlinal folds are not therefore prospective structural traps for hydrocarbons because they developed after migration had already ceased. Stratigraphic traps and salt structures in the region may be of greater exploration interest. A surface oil seep sample was also recovered from the Quaternary upper Segui Formation at Jebel Orbata in the east of the Gafsa Basin. Analysis of this oil sample showed that it has similar geochemical characteristics to the seep oils from the Tamerza area, but that it appears to have had a much more recent migration history. In the eastern Gafsa Basin, Pliocene – early Quaternary anticlinal structures could therefore constitute effective structural traps charged by the same Bahloul equivalent formation source rock. [ABSTRACT FROM AUTHOR] more...

The Gulf of Guinea is a very active area with respect to maritime traffic as well as oil and gas exploitation. Due to the failure of some actors to comply with environmental standards, this region has been subject to a large number of oil pollution episodes. This anthropogenic oil pollution is in addition to natural oil seepage from the ocean floor. This study aims to detect oil slicks in the Gulf of Guinea and to analyse their spatial distribution using synthetic-aperture radar (SAR) images. Previous works have already locally mapped oil slicks in this area; however, to our knowledge, this study is the first to achieve a global statistical analysis based on 10 years of radar images covering 17 exclusive economic zones (EEZs) in the Gulf of Guinea. The present study is based on a database of 3644 SAR images collected between 2002 and 2012 by the Advanced Synthetic Aperture Radar (ASAR) sensor onboard the European Spatial Agency (ESA) Envisat mission, and these images allowed the identification of 18 063 oil slicks. The spatial distribution of these oil slicks is available from Zenodo: 10.5281/zenodo.6470470 (Najoui, 2022b). The oil slicks detected in this work encompass both oil spills of anthropogenic origin and oil seeps of natural origin (natural oil reservoir leaks). A set of 100 georeferenced oil spills is also available from Zenodo: 10.5281/zenodo.6907743 (Najoui, 2022a). [ABSTRACT FROM AUTHOR] more...

The exploration and exploitation of shale oil resources enhance the necessity to characterize the mobility of the occluded oil in shales. Up to now, the understanding of the controlling factors of shale oil mobility has mainly come from molecular dynamics simulation but lacking in-depth research on actual shales. Therefore, in this study, the effects of mineral composition, soluble organic matter (SOM) composition and wettability on the shale oil mobility were studied by X-ray diffraction, N 2 adsorption, mercury intrusion, contact angle, chloroform bitumen and group component detection methods, comprehensively. The results show that: (1) The asphaltene contents and (Asphaltenes × Aromatics)/(Saturates × Resins) negatively and positively correlate with clay and carbonate mineral contents, respectively, while the I/S and illite contents present opposite trend with (Asphaltenes × Aromatics)/(Saturates × Resins). These correlations indicate that the SOM that confined in the pores constructed with carbonate minerals and illite present better flow potential. (2) Both δVt and δSSA negatively correlate with asphaltenes and (Asphaltenes × Aromatics)/(Saturates × Resins). That is, less pores and surfaces can be released by extraction for the shales with more asphaltenes. Therefore, it can be concluded that asphaltene is a negative factor for shale oil seepage. Additionally, the larger pores present better flow condition for shale oil, even for asphaltenes. (3) Pore surface wettability also significantly affects the shale oil mobility. The hydrophobicity of the pore wall greatly inhibits the shale oil flow, especially for the mesopores and macropores. The pattern diagram was established to illustrate the effect of the interactions between pore surfaces and shale oil components on the movable potential. Based on our research, mineral composition, group composition and pore surface wettability are efficient parameters for the shale oil mobility evaluation based on the interfacial interaction theory, and the "sweet spots" for shale oil seepage of the Jiyang Depression are the shales with more illite, carbonate, saturates and relatively low lipophilicity. [Display omitted] • Effects of minerals , SOM composition and wettability on shale oil mobility were analyzed comprehensively. • A conceptual model was established to show the effects of interactions between pore wall and shale oil on its mobility. • Mineral composition, group composition and wettability are efficient parameters for shale oil mobility evaluation. • Based on this study, shales with more illite, carbonate, saturates and low lipophilicity present better flow potential. [ABSTRACT FROM AUTHOR] more...

Monterey formation crude oil spilled from an onshore pipeline and entered the surf zone near Refugio State Beach, Santa Barbara County, CA, USA on 19 May 2015. Exposure to nearshore fish was evaluated by measuring biliary polycyclic aromatic hydrocarbon (PAH) metabolite concentrations in surfperch (Embiotocidae), collected near the release point, at a lesser oiled area, Gaviota State Beach, and near the Coal Oil Point oil seep, Campus Point, at both four days and approximately one year after the oil spill. Three to four weeks after the spill, fish, invertebrates, and kelp were collected near the same three sites for PAH analysis of edible tissues to support the fishery closure assessment. Additionally, thirteen days after the spill, vegetation, and invertebrate tissue samples from the seafloor near Refugio State Beach were analyzed for PAHs. In surfperch bile, mean naphthalene, phenanthrene and benzo(a)pyrene metabolite equivalents were significantly higher at Refugio State Beach, compared to Gaviota State Beach or Campus Point in 2015. One year later, there was no significant difference between the three sites. Spatial and depth zone patterns of PAH tissue concentrations from composited invertebrate, vegetation and fish showed highest concentrations were measured in invertebrates collected near Refugio State Beach. Overall, results show elevated PAH levels in nearshore organisms and provide a useful reference for potential PAH exposures in fish and subtidal invertebrates following a large nearshore oil spill. [ABSTRACT FROM AUTHOR] more...

The Gulf of Mexico is a hydrocarbon-rich region characterized by the presence of floating oil slicks from persistent natural hydrocarbon seeps, which are reliably captured by synthetic aperture radar (SAR) satellite imaging. Improving the state of knowledge of hydrocarbon seepage in the Gulf of Mexico improves the understanding and quantification of natural seepage rates in North America. We used data derived from SAR scenes collected over the Gulf of Mexico from 1978 to 2018 to locate oil slick origins (OSOs), cluster the OSOs into discrete seep zones, estimate the flux of individual seepage events, and calculate seep recurrence rates. In total, 1618 discrete seep zones were identified, primarily concentrated in the northern Gulf of Mexico within the Louann salt formation, with a secondary concentration in the Campeche region. The centerline method was used to estimate flux based on the drift length of the slick (centerline), the slick area, and average current and wind speeds. Flux estimates from the surface area of oil slicks varied geographically and temporally; on average, seep zones exhibited an 11% recurrence rate, suggesting possible intermittent discharge from natural seeps. The estimated average instantaneous flux for natural seeps is 9.8 mL s−1 (1.9 × 103 bbl yr−1), with an annual discharge of 1.73–6.69 × 105 bbl yr−1 (2.75–10.63 × 104 m3 yr−1) for the entire Gulf of Mexico. The temporal variability of average flux suggests a potential decrease following 1995; however, analysis of flux in four lease blocks indicates that flux has not changed substantially over time. It is unlikely that production activities in the Gulf of Mexico impact natural seepage on a human timescale. Of the 1618 identified seep zones, 1401 are located within U.S. waters, with 70 identified as having flux and recurrence rates significantly higher than the average. Seep zones exhibiting high recurrence rates are more likely to be associated with positive seismic anomalies. Many of the methods developed for this study can be applied to SAR-detected oil slicks in other marine settings to better assess the magnitude of global hydrocarbon seepage. [ABSTRACT FROM AUTHOR] more...

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

The characteristic scale of pore flow in tight reservoirs is generally in the range of 0.1 μm to 1 μm, which shows the obvious micro- and nanoscale effect. The traditional oil and gas seepage theory cannot accurately describe the flow law of liquid in the micro- and nanopores. The determination of seepage characteristics is crucial to the development, layout, and prediction of tight oil. Therefore, a non-Newtonian fluid model is established to discuss the flow characteristics of confined liquid in the heterogeneous pores of microtubules and reveal the nonlinear seepage law of water in micro- and nanochannels and tight reservoirs. Based on the characteristics of non-Newtonian fluid of confined fluid in micro- and nanospace, the flow model of non-Newtonian fluid under the action of shear stress was deduced. The flow velocity variation of liquid in micro- and nanochannel and dense core was analyzed, and the flow rate of water was less than that predicted by macro theory. According to the flow experiment of water in micro- and nanochannels, the flow model of power-law non-Newtonian fluid was verified. At the same time, through the flow experiment of water in the dense rock core, the non-Newtonian model was used for nonlinear fitting, and the non-Newtonian power-law parameters and average pore radius were obtained, which verified the effectiveness of the non-Newtonian flow model. [ABSTRACT FROM AUTHOR] more...