Search

Petroleum hydrocarbons (PHCs) can be biodegraded into CO 2 , and PHC-contaminated aquifers are always deemed as carbon sources. Fortunately, some carbon fixation microorganisms have been found in PHC-contaminated sites. However, most of the studies are related to volatile short-chain PHC, and few studies focus on long-chain PHC-contaminated sites. To reveal the carbon fixation microorganisms in these sites, in the study, a long-chain PHC polluted site in North China was selected. Through hydrochemical and metagenomics analysis, the structure and capacity of carbon fixing microorganisms in the site were revealed. Results showed that there were many kinds of carbon fixed microorganisms that were identified such as Flavobacterium, Pseudomonas. HP/4HB, rTCA, and DC/4HB cycles were dominated carbon fixation pathways. The long-chain PHC were weakly correlated with carbon fixation microorganisms, but it may stimulate the growth of some carbon fixation microorganisms, such as microorganisms involved in rTCA cycle. PRACTITIONER POINTS: The microorganisms with carbon fixation gene exist in the aquifer contaminated by long-chain petroleum hydrocarbon. Microorganisms that have the ability to degrade petroleum also have the ability to carbon fixation. Long-chain petroleum hydrocarbon may promote the growth of carbon fixation microorganisms., (© 2024 Water Environment Federation.)

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%-95.70% and 13.32%-97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO 3 - indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The source of oil and gas in the Tarim Basin's platform has always been controversial. The Lower Cambrian Yurtusi Formation and the Xidashan Formation–Xishanbulak Formation argillaceous source rocks are an important set of oil source series in the basin. Based on the principle of conservation of matter, this paper calculates the hydrocarbon expulsion amount of the source rock. Using a phase state hydrocarbon expulsion amount characterization model, the paper reconstructs the evolution process of the hydrocarbon expulsion phase state of the source rock. According to the characterization model of hydrocarbon expulsion dynamics, the relative contribution of each force to hydrocarbon expulsion is evaluated. The hydrocarbon expulsion geologic model of argillaceous source rocks in the Lower Cambrian in the Tarim Basin is established. The results show that this set of source rocks can serve the main source rocks in the basin. The hydrocarbon expulsion of the Lower Cambrian argillaceous source rocks in the Tarim Basin can be divided into three stages. In the first stage, the hydrocarbon expulsion phase is dominated by the water‐soluble and diffusion phases. The conversion of clay minerals into dehydration and diffusion forces is the main driving force for the hydrocarbon expulsion. In the second stage, the oil and gas expulsion present the characteristics of multiphase and multidynamic coexistence. In the third stage, the phase state of oil and gas expulsion is mainly free phase. The capillary force difference and the thermal expansion force of the fluid rock are the main driving forces for oil and gas expulsion. The research results of this paper can deepen the understanding of the hydrocarbon expulsion mechanism of the set of source rocks, and then guide oil and gas exploration. [ABSTRACT FROM AUTHOR]

The mass fraction of total organic carbon (TOC) is one of the key indicators for evaluating the hydrocarbon generation potential of shale source rocks. Experimental measurements to evaluate the TOC content require significant cost and time. Furthermore, the experimental data are often fragmented and may not provide an accurate depiction of the source rocks throughout the entire block. To solve the above problems, this paper proposes to use the combination of conventional logging data and experimental data after an in-depth study of the geophysical characteristics of hydrocarbon source rocks in the Ordos Basin. A quantitative model between logging data and source rocks is established, and then the continuous distribution value of the TOC content in the hydrocarbon source rock interval is calculated. Firstly, the mud shale formation of the Permian–Shanxi Formation in the Upper Paleozoic, located in the Jingbian area of the Ordos Basin, is selected as the research target using the "Jinqiang method". The model is constructed by selecting appropriate logging curves (acoustic time difference logging, resistivity logging, and density logging) and experimental results based on the response relationship between logging data and TOC data. This method provides more accurate and comprehensive data for source rock studies, combining experimental sampling to contribute to a better evaluation of TOC in source rock. The shale hydrocarbon source rock logging data from 10 wells are selected, and the model is used to realize the full-well section of the logging data to find the hydrocarbon source rock TOC, which is compared with the TOC data from the experimental core tested at a sampling point. The results demonstrate that the model is highly effective and accurate, with a mere 2.7% percentage error observed across 185 sample data points. This method greatly improves the accuracy and completeness of TOC evaluation compared with the results of previous studies and provides a guide for subsequent TOC logging evaluation of source rocks in other areas. With the study in this paper, continuous TOC values of source rocks are obtained, discarding the TOC values representing the whole set of hydrocarbon source rocks with a limited number of sample averages. This method can reflect the contribution of the layers with high and low organic matter abundance, and the calculated reserves are more accurate. By utilizing the measured TOC values of the study area to invert the model to find the parameters, this study contributes to the decision-making of hydrocarbon exploration in domestic and international basins. [ABSTRACT FROM AUTHOR]

It is well known that the existing horizontal-well-drilling and hydraulic fracturing technology used to achieve large-scale, cost-effective production from immature to low–moderate-maturity continental shale in China, where the organic matter mainly exists in solid form, is fairly ineffective. To overcome the obstacles, in situ conversion technology seems feasible, while implementing it in the target layer along with estimating the amount of expected recoverable hydrocarbon in such shale formations seems difficult. This is because there are no guidelines for choosing the most appropriate method and selecting relevant key parameters for this purpose. Hence, based on thermal simulation experiments during the in situ conversion of crude oil from the Triassic Chang 73 Formation in the Ordos Basin and the Cretaceous Nenjiang Formation in the Songliao Basin, this deficiency in knowledge was addressed. First, relationships between the in situ-converted total organic carbon (TOC) content and the vitrinite reflectance (Ro) of the shales and between the residual oil volume and the hydrocarbon yield were established. Second, the yields of residual oil and in situ-converted hydrocarbon were measured, revealing their sensitivity to fluid pressure and crude oil density. In addition, a model was proposed to estimate the amount of in situ-converted hydrocarbon based on TOC, hydrocarbon generation potential, Ro, residual oil volume, fluid pressure, and crude oil density. Finally, a method was established to determine key parameters of the final hydrocarbon yield from immature to low–moderate-maturity organic material during in situ conversion in shales. Following the procedure outlined in this paper, the estimated recoverable in situ-converted oil in the shales of the Nenjiang Formation in the Songliao Basin was estimated to be approximately 292 × 108 tons, along with 18.5 × 1012 cubic meters of natural gas, in an area of approximately 8 × 104 square kilometers. Collectively, the method developed in this study is independent of the organic matter type and other geological and/or petrophysical properties of the formation and can be applied to other areas globally where there are no available in situ conversion thermal simulation experimental data. [ABSTRACT FROM AUTHOR]

Low-to-medium maturity lacustrine shale oil resources have enormous potential and are projected to play a crucial role in the massive scale-up of crude oil production in China in the near future. The in-situ conversion process is currently the only effective means of utilizing this resource. Nevertheless, significant scientific challenges and technological bottlenecks still exist. Under this circumstance, the National Natural Science Foundation of China approved an integrated project of the Enterprise Innovation and Development Joint Fund titled "The Mechanism of Low-to-medium Maturity Lacustrine Shale Oil Resource Formation and its in-situ Conversion and Exploitation". This project aims to systematically investigate the entire process of in-situ conversion for low-to-medium maturity shale oil resources and lay a solid scientific and technological foundation for advancing the smooth implementation of on-site pilot trials. This paper presents the latest progress in this field and summarizes the existing scientific and technological challenges that need to be addressed. With the foundational support of the above project, our research team has made significant progress in several fields, including the formation mechanisms of organic matter superrich shale, low-to-medium maturity shale oil enrichment area evaluation, heat and mass transfer dynamics, coupled fluid field and hydrocarbon expulsion efficiency, exploitation methods, among others. Despite these theoretical advances, several major challenges were identified, which help to further focus on the critical scientific issues, determine the in-situ conversion technique-developing direction, and formulate a feasible implementation plan for future resource utilization. [ABSTRACT FROM AUTHOR]

Affected by Tianshan uplift, the southern Junggar Basin has experienced multi-stage tectonic movements and formed many large-scale anticlines with zonal distribution. The key to hydrocarbon exploration is to accurately implement anticline traps. This paper is guided by the fault-related folds theory to tectonically interpret several seismic profiles in the southern Junggar Basin and then summarize the anticline types and their hydrocarbon accumulation characteristics. This paper showed that the southern Junggar Basin has a tectonic assemblage pattern of "multi-detachment layers and multi-phase superposition". According to the superimposed shape of the anticlines, they could be divided into overthrust anticlines, compound anticlines and multiple superimposed anticlines, and the horizontal and vertical positions of the different types of anticlines are different. The hydrocarbon accumulating characteristics of the different types of anticlines are shown to be different. The highs of the overthrust anticlines and compound anticlines are stable, and the degree of exploration is relatively high. Although the degree of exploration of multiple overlapping anticlines is low, multiple layers can be exploited simultaneously in the process of oil development, with great hydrocarbon potential. The characteristics of hydrocarbon accumulation in the southern Junggar Basin are discussed in order to provide guidance for efficient hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

Transitional shale gas, rich in resources, is expected to be a practical contributor to the increase in shale gas reserves and production in China. Its exploration prospect has been demonstrated by several wells in the Daning-Jixian block on the eastern margin of the Ordos Basin. In this paper, the Lower Permian Shanxi Formation (P1s) and Taiyuan Formation (P1t) in the eastern margin of Ordos Basin were compared for organic geochemical parameters, revealing that the overflow fan + lagoon combination (OLC) of the third sub-member of the second member of Shanxi Formation (P1s23) and the marine + lagoon combination (MLC) of the first member of Taiyuan Formation (P1t1) are the most favorable shale gas intervals. The two intervals were comparatively analyzed with respect to mineral composition, brittleness, caprocks, and preservation conditions. It is found that the OLC of P1s23 has a similar porosity to and much lower permeability than the MLC of P1t1 (or MLC1) and a BET surface area of 10–15 m2/g, which is smaller than the MLC1 (15–20 m2/g). Moreover, OLC has a brittle mineral content equivalent to MLC1 but a brittleness index of 33.73–62.36 (avg. 49.86), smaller than MLC1 (53.34–58.27, or avg. 55.85). OLC contains sandstones at both the roof and floor, with a higher permeability than shale in the interval, which cannot serve as good physical seals. In contrast, MLC1 contains limestones with lower permeability at the roof and floor, which, together with the overlying coal seams, have hydrocarbon generation capacity and can physically seal the MLC1 shale but also fill it with hydrocarbons, making MLC1 have higher gas content and superior for shale gas exploration than the OLC shale. Due to the multi-lithologies developed in transitional facies, besides the organic matter enrichment, and reservoir characteristics, it is necessary to find a suitable lithological combination to ensure the gas in shale can be better preserved and retained. [ABSTRACT FROM AUTHOR]

Unraveling the complex relationship between orogenesis and hydrocarbon formation and accumulation is challenging and is often hampered by physical and chemical overprints of younger events. The Permian reservoir in the Longmen Shan orogen, South China, is such an example, and its evolution has been hotly debated. In this study, we use a new combination of paleomagnetic dating analysis and Re–Os isotope dating to try to resolve this. Paleomagnetic dating of the hydrocarbon‐host carbonate indicates two remagnetization events during: (a) the Late Triassic, and (b) the Middle Jurassic–Cretaceous. These two remagnetization events are shown to represent two distinct stages of hydrocarbon accumulation. The paleomagnetic estimates are supported by Re–Os dating of bitumen (∼264 Ma) and oil (∼94 Ma). The two different Re–Os ages are associated with two periods of oil generation. We interpret these data in terms of known geological processes: (a) the ∼260 Ma Dongwu large igneous province caused oil generation, and the Indosinian tectonic event caused the migration and accumulation; and (b) the Late Cretaceous Yanshan orogenic events promoted another generation and entrapment of oil in the same reservoir. This combined approach reliably tracks the sequence of oil generation and accumulation, even when the source rock is uncertain, and multi‐phase accumulation and complex tectonism has occurred. Given that paleomagnetic and Re–Os dating are independent methods which can constrain multiple geological processes, when used together they have the potential to be universally applied. Plain Language Summary: Key to understanding complex geological processes is the dates and sequence of each event. The timing of hydrocarbon formation and accumulation is one such complex geological process that can be difficult to unravel, but critical to evaluate the complex orogenesis and hydrocarbon explorations. In this paper, we combine for the first time two independent dating methods to study hydrocarbon reservoirs of Longmen Shan orogen: (a) paleomagnetic and (b) rhenium‐osmium isotope dating. The two methods identified two periods of hydrocarbon formation, followed by two extended periods of hydrocarbon migration. This combined method is particularly powerful as it is independent of the hydrocarbon source rock and complex geological settings. Moreover, the two methods can provide additional tests for each dating technique. The new combined methods can, therefore, be applied in complex hydrocarbon‐bearing regions worldwide. Key Points: Paleomagnetic and Re–Os isotope data were collected for a hydrocarbon carbonate reservoir to determine the hydrocarbon evolution processesOil accumulations are found to have remagnetized the reservoir carbonates during the Late Triassic and CretaceousTiming of oil generation is constrained by Re‐Os dates of bitumen and oil hosted in carbonates at ∼264 and ∼94 Ma, respectively [ABSTRACT FROM AUTHOR]

In the process of diagenesis and burial of sedimentary basins, basin fluid activities participate in the process of hydrocarbon accumulation and metal mineralization. Understanding the evolution of basin fluid is of great significance in revealing the related hydrocarbon accumulation and mineralization. Paleo-reservoirs are closely associated with Carlin-type gold deposits in the Nanpanjiang-Youjiang Basin, South China. Calcite, the fluid activity product, is closely related to bitumen and gold-bearing pyrite. By integrating petrographic, cathode luminescence, and fluid inclusion analysis, as well as the relevant chronological results of predecessors, this paper attempts to establish the relationship between fluid evolution, hydrocarbon accumulation, and gold mineralization. Two types of calcite (black/gray and white) developed in the Banqi-Yata-Laizishan area, the Nanpanjiang-Youjiang Basin. Black/gray calcite is symbiotic with bitumen and features dark red colors in cathode luminescence. Many hydrocarbon inclusions developed along with fluid inclusion analysis at low homogenization temperatures (65.7~173.1 °C). Combining the previously reported U-Pb ages (~250–230 Ma) of this kind of calcite with some geochemistry data on the associated reservoir and gold deposit, this calcite records the consecutive hydrocarbon accumulation and Carlin-type gold mineralization from the Late Permian to the Late Triassic periods controlled by Indosinian tectonic movement. The white calcite featuring bright red in cathodoluminescence is symbiotic with gold-bearing pyrite and realgar, and the associated fluid inclusions have high homogenization temperatures (128.2~299.9 °C). Combined with regional tectonic background and isotopic chronology (~140–106 Ma), it seems to record the early Cretaceous Carlin-type gold mineralization controlled by the subduction of the paleo-Pacific plate in the late Yanshanian period. [ABSTRACT FROM AUTHOR]

The possibilities offered by the use of variational mode decomposition–based Hilbert marginal spectrum and the differential cepstrum for gas‐bearing detection are studied in this paper. We propose a novel variational mode decomposition–based Hilbert marginal differential cepstrum for hydrocarbon detection. Variational mode decomposition–based Hilbert marginal spectrum is first computed. Then discrete cosine transform is carried out to the differential logarithmic variational mode decomposition–based Hilbert marginal spectrum to obtain the variational mode decomposition–based Hilbert marginal differential cepstrum. For hydrocarbon detection, the seismic amplitude anomaly section is generated by extracting the first and second common quefrency sections. Compared with the traditional Fourier‐based cepstrum, the wavelet‐based cepstrum and the Berthil cepstrum, it has the ability to effectively reveal more detailed frequency‐dependent amplitude anomalies with high accuracy and resolution. Model tests and field data applications from a carbonate reservoir in China show that the variational mode decomposition‐based Hilbert marginal differential cepstrum can provide a better gas‐prone interpretation. The proposed method can be a complementary approach to current cepstrum‐based hydrocarbon detection methods and the spectrum decomposition methods. [ABSTRACT FROM AUTHOR]

INTRODUCTION The study focused on the influence of tar concentrations, smoking regimen, and smoking behavior, on benzo[a]pyrene (B[a]P) emission from cigarette mainstream smoke and related health hazards to determine the key factors influencing B[a]P reduction and protection of the smoker's health. METHODS A locally popular brand of cigarettes in Beijing was selected with tar concentrations of 1, 3, 5, 8, 10, and 11 mg/cigarette. Two different machine smoking regimens, the Canada Intense (HCI) regimen and the International Organization for Standardization (ISO) regimen, were adopted to collect the cigarette mainstream smoke. The B[a]P emission concentrations were then measured by gas chromatography and mass spectrum. RESULTS The average B[a]P emission was 8.14--17.6 ng/cigarette for the HCI regimen and 0.92--3.46 ng/cigarette for the ISO regimen. As expected, the tar concentrations and B[a]P emissions exhibited a positive relation in both the HCI and ISO regimens, the cancer risk and non-cancer risk increased with an increase in tar concentrations for both the ISO and HCI regimens, and the smoking behavior also affected the B[a]P emissions with a tendency of VB (ventilation blocking) > HVB (half ventilation blocking) > DP (deep puff), under the same smoking regimen. Under the same conditions, the cancer risk and non-cancer risk in men were 1.19 and 1.11 times, respectively, higher than in women. CONCLUSIONS The smoking regimen influences the B[a]P emission relatively more than the cigarette tar concentration and smoking behavior. The cancer risk and non-cancer risk are higher in men than in women that possibly due to longer smoking duration and greater smoking intensity. [ABSTRACT FROM AUTHOR]

The Qiangtang Basin is one of the largest Mesozoic petroliferous basins in China that is still unexploited for the petroleum industry. The basic geological issues and synthesis of the Qiangtang Basin related to the Tethyan evolution are still poorly understood. This volume presents 20 research papers to address the tectonic settings, basin evolution, and sedimentary environments of the Qiangtang Basin, which are key factors for a better understanding of the overall petroleum system. The Qiangtang Basin holds a Precambrian base developed in response to the Paleo-Tethys Hol Xil-Jinshajiang Ocean evolution, with enhanced sedimentary basin infilling during the opening and expansion of the Neo-Tethys Bangong-Nujiang Ocean in the Mesozoic. The Paleozoic basin framework of the Qiangtang demised as the Paleo-Tethys Ocean closed at the latest Permian, while the Early-Middle Triassic foreland basin underwent a negative basin inversion during the Late Triassic. The latter initiated a new sedimentary filling cycle of the Qiangtang Basin, which was triggered by the active extensional rifting and the onset of the bimodal volcanic eruption. Recent scientific exploratory drilling (QK-1 well) found that the Qiangtang Basin is characterized by multiple source rocks, of which the upper Triassic Bagong Formation and the lower Quse Formation exhibit the most hydrocarbon generation potential. The development of high quality and quantity source rocks in the Qiangtang Basin is ensured by regional to global-scale bottom-water anoxia and high primary productivity in the eastern Tethys realm in the Late Triassic and the Early Jurassic. The main reservoirs in the Qiangtang Basin include the Middle Jurassic reef-beach facies, the Upper Triassic carbonates, and the Lower Jurassic terrestrial clastic rocks. Two very-thick caprocks of gypsum in the Lower Jurassic and gypsum mudstones in the Middle Jurassic strata are found during the scientific drilling, which is interpreted as favorable regional-scale seals for petroleum entrapment in the Qiangtang Basin. [ABSTRACT FROM AUTHOR]

In the central Tarim Basin, numerous hydrocarbon deposits were found along ultra-deep strike-slip faults, and its evolving progress and formation mechanism are research hotspots. The Paleozoic small-angle X-type strike-slip fault in the Tabei Uplift is the research subject in this article. Based on high-precision three-dimensional seismic data, three structural deformation layers were revealed: the rift system, weak strike-slip deformation and salt tectonics in the deep structural layer (Sinian-Middle Cambrian), the strong strike-slip deformation and karst-dissolution structure in the middle structural layer (Upper Cambrian-Middle Ordovician), and echelon normal faults in the shallow structural layer (Upper Ordovician-Carboniferous). The formation and evolution of strike-slip faults is jointly controlled by the distribution pattern of basement rift and the activities of surrounding orogenic belts, which can be divided into three stages. In the Middle to Late Cambrian, the initial subduction of the Paleo-Asian and Proto-Tethyan oceans precipitated the emergence of two sets of small-angle X-type strike-slip faults, striking NW and NE above the grooves of Precambrian rifts, influenced by local weak compressive stress. Affected by the closure of peripheral paleo-ocean, strike-slip faults deformed considerably in the Middle-Late Ordovician and were reactivated in the Silurian-Carboniferous, forming en-echelon normal faults in the shallow layer. The layered deformation structure of the strike-slip faults significantly affects the accumulation of hydrocarbons. The differential hydrocarbon enrichment of faults in the Tabei Uplift is collectively influenced by the distribution of source rocks and the migration of oil and gas. The topographical features of the Tabei Uplift, along with the distribution of strike-slip faults across tectonic units, have rendered the NE direction the preferential pathway for hydrocarbon migration. Additionally, impacted by the development of en echelon faults, the NE-trending faults offer superior conditions for hydrocarbon preservation and charging condition, compared to the NW-trending faults. [ABSTRACT FROM AUTHOR]

Recent advances in hydrocarbon exploration have been made in the Member Deng-2 marginal microbial mound-bank complex reservoirs of the Dengying Formation in the western Sichuan Basin, SW China, where the depositional process is regarded confusing. The microfacies, construction types, and depositional model of the Member Deng-2 marginal microbial mound-bank complex have been investigated using unmanned aerial vehicle photography, outcrop section investigation, thin section identification, and seismic reflections in the southwestern Sichuan Basin. The microbialite lithologic textures in this region include thrombolite, dendrolite, stromatolite, fenestral stromatolite, spongiostromata stone, oncolite, aggregated grainstone, and botryoidal grapestone. Based on the comprehensive analysis of "depositional fabricselithologyemicrofacies", an association between a fore mound, mound framework, and back mound subfacies has been proposed based on water depth, current direction, energy level and lithologic assemblages. The microfacies of the mound base, mound core, mound flank, mound cap, and mound flat could be recognized among the mound framework subfacies. Two construction types of marginal microbial mound-bank complex have been determined based on deposition location, mound scale, migration direction, and sedimentary facies association. Type Jinkouhe microbial mound constructions (TJMMCs) develop along the windward margin owing to their proximity to the seaward subfacies fore mound, with a northeastwardly migrated microbial mound on top of the mud mound, exhibiting the characteristics of large-sized mounds and small-sized banks in the surrounding area. Type E'bian microbial mound constructions (TEMMCs) primarily occur on the leeward margin, resulting from the presence of onshore back mound subfacies, with the smaller southwestward migrated microbial mounds existing on a thicker microbial flat. The platform margin microbial mound depositional model can be correlated with certain lateral comparison profile and seismic reflection structures in the 2D seismic section, which can provide references for future worldwide exploration. Microbial mounds with larger buildups and thicker vertical reservoirs are typically targeted on the windward margin, while small-sized microbial mounds and flats with better lateral connections are typically focused on the leeward margin. [ABSTRACT FROM AUTHOR]

The distribution characteristics and main controlling factors of hydrocarbon phases in deep strata from petroliferous basins are important for the evaluation of oil–gas resources and decision-making regarding exploration. The distribution characteristics and controlling factors of the Ordovician hydrocarbon phases are systematically analyzed in the Tazhong I block, Tarim Basin, NW China. The results show that the Ordovician reservoirs in the Tazhong I block are characterized as multi-phase reservoirs with a lateral co-existence of condensates, normal oil reservoirs, and heavy oil reservoirs. From east to west, gas-rich in the fault belt and oil-rich in the platform area are presented. Meanwhile, there are regular variations in the geochemical characteristics of the Ordovician hydrocarbon, showing decreasing trends in the gas/oil ratio (GOR), wax contents, dryness coefficients, methane contents, and methane carbonate isotope values (δ13C1) and an increasing trend in oil densities. Because the same Cambrian–Lower Ordovician source for the Ordovician hydrocarbon is observed in the Tazhong I block, the regular variations in the hydrocarbon phases and geochemical characteristics can be interpreted as records of gas invasion, biodegradation, multi-stage filling, thermal cracking, and thermochemical sulfate reduction (TSR) rather than controlled by the source rock organofacies. This indicated that different kinds of secondary processes for a diversity of the hydrocarbon phase can appear in one region. Our re-construction of the Ordovician hydrocarbon accumulation model in the Tazhong I block encourages future exploration to target gas reservoirs in the fault belt and oil reservoirs in the platform area. [ABSTRACT FROM AUTHOR]

Continental shale in China is a key exploration target with regard to unconventional hydrocarbons. Systematic research on the mineral composition, organic geochemistry, and hydrocarbon mobility has been performed in the Da'anzhai (J1dn) lacustrine shale oil reservoirs, clarifying the factors controlling shale oil accumulation. The results suggest that J1dn consists of three sub-members, with an organic-rich interval developed within the second sub-member. Three types of lithological associations have developed within the organic-rich interval: Type 1 represents the interbedding relationship between shale and shell limestone and Type 2 represents shale with intercalated limestone, followed by Type 3. The brittleness index of the J1dn continental organic-rich shale is relatively low. The porosity of the Da'anzhai lacustrine shale ranges between 0.5% and 10.5% (average value of 5.89%). The porosity is predominantly due to inorganic pores, with a small amount being attributable to nanoscale microfractures and organic pores. The average porosity of the shell limestone is only 1.2%, but fractures at the micron and centimeter scales are well developed. The organic matter in the J1dn continental shale is mainly II1–II2, with maturity in the oil generation stage. The average oil saturation of the J1dn continental shale is 3.15%, with most samples having oil saturation of less than 4%. The J1dn continental shale has great exploration potential with regard to shale oil. Type 1 shale oil is affected by multiscale fractures, including bedding fractures, and has the best mobility. The high hydrocarbon generation capacity of lacustrine shale, coupled with the multiscale fractures within shell limestone and shale, is the principal controlling factor for hydrocarbon enrichment. Based on exploration practices, the Type 1 shale association may represent the optimal interval for future shale oil exploration in the Da'anzhai Member. [ABSTRACT FROM AUTHOR]

Recently, with the ongoing development of the express industry, the consumption of waste plastic express bags has been increasing year by year, which has brought considerable pressure on municipal waste management. At the same time, in China, where coal is the main energy resource, the upgrading of low-rank coal is a more reliable and prospective way. An effective method for waste treatment and resource upgrading by synergistic co-liquefaction of waste plastic express bags and low-rank coal in a supercritical water-ethanol system has been developed. The effects of different experimental factors (temperature, residence time, plastic-coal ratio, water-ethanol ratio) on the conversion ratio and synergistic effect of co-liquefaction were investigated. The results showed that elevated temperature, lower water-ethanol ratio as well as suitable residence time, and plastic-coal ratio of 1:1 were conducive to the conversion ratio. Temperature ≥375 °C and suitable plastic-coal ratio (1:1) had a significant positive synergistic effect on the conversion ratio, whereas the other conditions exhibited no or negative synergistic effect on the conversion ratio. The maximum conversion ratio and positive synergistic efficiency were 85.11% and 12.25% at 425 °C, 60 min, water-ethanol ratio of 1:1, and plastic-coal ratio of 1:1, respectively. It was observed after FT-IR and elemental analysis based on the solid residue that the oxygen-containing functional groups in the residue disappeared, the oxygen content decreased, the carbon content increased, and the higher heating value (HHV) increased significantly, and the residue could be further used (such as gasification or pyrolysis) without the need for landfill. The GC-MS results of the oil products suggested that the oil products contained high content of hydrocarbons and phenols, as well as esters, alcohols, and other compounds. The hydrocarbons and phenols mainly derived from the decomposition of long chains in plastics and the decomposition of aromatic structures in coal, and the hydrocarbon and phenolic contents produced at 400 °C were 27.74% and 32.62%, respectively. Thus, the oil product can be used further as a chemical raw material. It cannot be ignored that the ethanol medium after reaction can also be further recycled by rotary evaporation. The synergistic co-liquefaction of waste plastic express bags and low-rank coal based on supercritical water-ethanol system is a promising method for waste treatment and resource upgrading. [Display omitted] • A synergistic co-liquefaction for waste express bags and low-rank coal was developed. • Ethanol can improve the synergistic efficiency of co-liquefaction. • The maximum conversion ratio of co-liquefaction reached 85.11% at 425 °C, 60 min. • Oil products from co-liquefaction contained hydrocarbons and phenolic compounds. [ABSTRACT FROM AUTHOR]

With the global expansion of shale oil and gas exploration, analyzing the geochemical characteristics of different types of shale has seized extensive attention. Taking the Chang 7 Member and Shanxi Formation in the Ordos Basin as examples, this study investigated the geochemical and hydrocarbon expulsion characteristics of different types of shale. The results show that the Chang 7 shale is mainly type I. The total organic carbon (TOC) distribution of the Chang 7 shale in the study area was between 0.72% and 27.5%, with an average of 7.46%, and the vitrinite reflectance (Ro) ranged from 0.45% to 1.28%. It is a good source rock in immature to mature stages. The Shanxi shale is mainly type III. The TOC distribution of the Shanxi shale was between 0.6% and 58.5%, with an average of 8.92%, and the Ro distribution was between 0.42% and 2.39%, indicating good immaturity over mature source rock. The average hydrocarbon expulsion efficiencies of the Chang 7 shale calculated using the hydrocarbon generation potential method and the original hydrocarbon generation potential method were 82.49% and 94.81%, respectively. Simultaneously, a correlation analysis of hydrocarbon expulsion efficiency with organic matter abundance, maturity, and type found that when TOC was less than 5%, hydrocarbon expulsion efficiency increased with increased organic matter abundance and maturity. When the TOC exceeds 5%, the hydrocarbon expulsion efficiency is mainly related to maturity. The hydrocarbon expulsion efficiency of the sapropelic shale was much higher than that of the humic shale. This study is significant for evaluating shale gas and shale oil resources in similar areas. [ABSTRACT FROM AUTHOR]

In order to study the distribution pattern of hydrocarbons in the shallow layer of the slope area outside of the source in the hydrocarbon-bearing basin, we built a method to predict the favorable site of the fault that adjusts hydrocarbon to the shallow layer in the slope area outside of the source based on the investigation of the mechanism of hydrocarbon adjustment along a conduit fault to a shallow layer. The predicted favorable site is found to be the overlapping area of three sites: the locations of the sand carrier with a lateral supply of hydrocarbon, the transport sites of conduit faults, and the hydrocarbon leakage parts of overlying regional mudstone seal rock. We applied the method in a case study of the favorable sites of the Zhaobei Fault that adjust the hydrocarbon from the lower sub-member within the first member of Shahejie Formation (Es1L) to the shallow Guantao Formation in the Qikou Sag of Bohai Bay Basin. Our prediction shows that the favorable sites are mostly located in the middle part of the Zhaobei Fault with very limited distribution in the east, which are conducive to the oil and gas supplied by the underlying sand carrier in the Es1L Formation to convergence and accumulation in the shallow Guantao Formation. This result is consistent with the distribution of the hydrocarbon in the Guantao Formation located in the middle parts of the Zhaobei Fault, proving that this method is feasible for the prediction of the favorable sites of the fault that adjust hydrocarbon to the shallow layer in the slope area outside of source. [ABSTRACT FROM AUTHOR]

Bozhong Sag, the largest hydrocarbon generation sag in the Bohai Bay Basin, is characterized by presence of the third member of the Shahejie Formation (E2s ³ ), which serves as a significant source rock. While previous studies have provided insights into the source material, sedimentary environment, and thermal maturity of the E2s ³ source rocks, further investigation is required to deepen our understanding of sedimentary events and biological sources. In this research, nine mudstone core samples from the southwestern Bozhong Sag were thoroughly analyzed using organicinorganic geochemistry and organic petrology. The results reveal the following key findings: (1) The middle and lower sections of the third member of the Shahejie Formation are characterized by high-quality source rocks, with the lower section exhibiting superior quality. The increase in water salinity during warm and humid climates, and the detection of 24-n-propylcholestane compounds reflected the occurrence of transgression events in the E2s ³ . These transgressions gradually increased from the lower sections to the middle sections of the E2s ³ . (2) The studied samples exhibit abundant presence of 4α-methyl-24-ethylcholestanes, 24-n-propylcholestanes, 2α-methylhopanes, oleananeabundant algainite, and a small amount of vitrinite. This diversity of hydrocarbon-forming organisms in the E2s ³ source rocks is evident. (3) The moderate marine incursion in the lower part of the E2s ³ results in nutrient elements that promote the flourishing of bacteria and algae, providing an abundant material basis for the formation of high-quality source rocks. However, the large-scale marine incursion in the middle of the E2s 3 weakens water eutrophication, resulting in a decrease in the quality of source rocks compared to the lower part of the E2s 3 . [ABSTRACT FROM AUTHOR]

Fluid inclusion signal strength and visual inclusion abundance are generally lower along migration pathways than in charged reservoirs from the same area. A zone that displays strong fluid inclusion stratigraphy (FIS) hydrocarbon indications and high visualized petroleum inclusion abundance, indicates paleo-charge or in some cases a migration pathway, e.g, where inclusion abundance is enhanced by extensive microfracturing. In this study, fluid inclusion data are interpreted in seven offshore wells of the Lamu Basin to enhance the understanding of hydrocarbon generation, migration and migration pathways. The study also examines the interrelationship among rock texture, rock composition and trapped fluid distribution in the study area. The studies were based on FIS analyzed data courtesy of Fluid Inclusion Technologies (FIT) Inc. in USA laboratories. FIT conducted analysis on 391 samples from the Paleocene to Upper Jurassic (Kiboko-1 well), 249 from the Paleoecene to Campanian (Kubwa-1 well), 106 from the Maastrichtian to Turonian (Mbawa-1 well), 59 from the Eocene to Campanian (Pomboo-1 well), 26 form the Lower Eocene to Maastrichtian (Simba-1 well), 16 from the Eocene toMaastrichtian (Kipini-1 well) and 11 from the Maastrichtian to Campanian (Kofia-1 well). It also made analysis on sidewall core sample plates, with 44 from the Maastrichtian to Campanian (Kubwa-1 well), 108 from the Campanian to Upper Jurassic (Kiboko-1 well) and 8 from the Campanian (Pomboo-1 well) for petrographic evaluation. For photomicroscopy, thin sections were examined under a petrographic microscope using Ultra Violet (UV) fluorescence and microthermometry, in order to verify the presence of petroleum bearing inclusions in the rock samples and to explore textural relationships that may yield additional information on the timing of hydrocarbon migration or generation. Gas shows in Mbawa-1 well is a result of generated hydrocarbons from the carbonate interbeds in the Upper Cretaceous. Gas shows are pockets trapped in the thin carbonate rich beds. There is low abundance of upper-low, moderate and uppermoderate gravity liquid petroleum inclusions in Kubwa-1 well (central deep offshore). The low abundance suggests migration events rather than paleo-accumulations, possibly involving several discrete charges. Despite sufficient vitrinite reflectance and total organic carbon (TOC) content, the temperatures are still insufficient for hydrocarbon generation in the southern deep offshore in the region where Kiboko-1 well is located. There is no sufficient evidence for access to mature source rocks in the deep offshore basin. [ABSTRACT FROM AUTHOR]

The Bohai Bay Basin is a Meso-Cenozoic rifted basin where the Paleozoic buried hills with great hydrocarbon potentials are well developed. The reservoir space types are complex and diverse due to tectonic activities, making fracture distribution highly heterogeneous. Reservoir identification and mapping is challenging due to their large burial depth and poor resolution of seismic data. An integration of well-logging, seismic data interpretation and core observation is applied to identify three structural unit types in the study area, that is, fault breccia zone, fault cataclastic zone, and fault massive rock zone. A comprehensive well-logging identification template and a comprehensive discriminant function M for the reservoir are established based on the well-logging response characteristics. A M value greater than 0.12 indicates a fault breccia zone, that between 0.04 and 0.12 marks a fault cataclastic zone, and that in the range from 0.02 to 0.04 represents a fault massive rock zone. A seismic prediction method with multi-parameter fusion is proposed in the study. The large-scale fractures are mapped by coherenceclutter parameters, while small fractures are predicted via waveform indication inversion. The spatial distribution of "fault-fracture reservoirs" is precisely mapped by frequency fusion technology. It is found that the fault breccia zones usually occur close to the fault planes, while the fault cataclastic zones are slightly away from the fault planes. The hydrocarbon abundance of the breccia zones is greater than that of the fault cataclastic and fault massive rock zones. [ABSTRACT FROM AUTHOR]

• The sedimentary environment transitioned from clastic shore-shelf of the lower Ediacaran to carbonate platform to mixed shelf of the upper Ediacaran except for the glaciogenic Hangelchaok Formation. • The Ediacaran slop break belt was first identified along the west and south margins of the Manjar sag. • High-quality source rocks and karstic dolostone in Ediacaran indicate great potential for hydrocarbon exploration. The Late Neoproterozoic was an important period for the breakup of Rodinia and the assembly of Gondwana. The Neoproterozoic succession developed under the extensional setting is critical for understanding the early tectono-sedimentary evolution of the Tarim Basin and possibly exhibits considerable hydrocarbon potential. In this paper, the stratigraphic correlation of the Ediacaran is conducted across the whole Tarim Basin, based on the latest wells, seismic data and field investigations. The paleogeographic distribution and hydrocarbon potential of the Ediacaran are thoroughly discussed. The Lower Ediacaran succession is mainly distributed in northern and southwestern Tarim Basin and marginal outcrop areas, but absent in the whole Central Rise. With sea level rising, the Upper Ediacaran succession gradually moved toward Central Rise with the exception of the Tazhong Uplift and the eastern Bachu Uplift. During Early Ediacaran, depositional environment in the Tarim Basin was mainly clastic shore-shelf, with a large denuded region extending from Bachu-Tazhong Uplift to Tadong Uplift. The range of the erosional area gradually diminished during Late Ediacaran. Accordingly, the Tarim Basin was dominated by carbonate platform and mixed shelf. Slope break belt between carbonate platform and mixed shelf was identified around the Manjar sag for the first time. The Ediacaran black mudstone and shale in northeastern and southwestern Tarim, which formed in deep-water environment and have relatively high values of TOC (mostly ranging from 0.3% to 1.2%), can serve as high-quality source rocks. The Upper Ediacaran dolostones altered by paleokarst could be potential reservoir rocks. Our research findings, combining with previous geological results, suggest that the Ediacaran succession in Tarim Basin has great potential for hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

Cuticular hydrocarbons of Cerambycidae species can function as signals for sex recognition. Little is known about the copulatory signals of the juniper bark borer Semanotus bifasciatus, a major economic threat to Platycladus orientalis Franco in China. Here, we investigated the cuticular hydrocarbons of both sexes of S. bifasciatus to determine the chemically mediated mating signals using the solid‐phase microextraction (SPME) technique with carbowax/divinylbenzene fibers (CAR/DVB) and then analyzed by coupled gas chromatography‐mass spectrometry (GC‐MS). A series of aliphatic saturated straight‐chain n‐alkanes (n‐C23 to n‐C28), internally branched monomethylalkanes at carbons 3, 11, or 13, and dimethylalkanes were identified, which showed no qualitative differences in either sex and were similar in the samples with SPME fiber extraction and those with hexane extraction. The bioassay showed that 11‐methylpentacosane (11‐MeC25), 11‐methylhexacosane (11‐MeC26), and 11‐methylheptacosane (11‐MeC27) have sex‐specific recognition functions that triggered more mating attempts at a female‐specific ratio of 100:4:60 than at a male‐specific ratio of 100:85:50. In addition, the female‐specific ratio of 11‐methylalkanes can elicit about 70% of male mating attempts within about 60 s, whereas live females elicit about 98% of male mating attempts within 25 s. The discrepancy in the initiation of mating attempts by synthetic mixtures and live females suggests that the methyl isomers 3‐MeC25, 3‐MeC27, and/or 11,15‐diMeC27 may also be involved in the mating behavior of S. bifasciatus. These results suggest that 11‐MeC25, 11‐MeC26, and 11‐MeC27 constitute the contact sex pheromone of S. bifasciatus, with the presence or absence of 11‐MeC26 in particular playing an important role in mate recognition by males. [ABSTRACT FROM AUTHOR]

Evaluating the hydrocarbon generation potential of highly mature organic matter is a key and critically challenging area of research in petroleum geochemistry. To explore this issue, we used negative ion electrospray ionization-Fourier transform-ion cyclotron resonance-mass spectrometry to investigate the molecular evolution of N-containing compounds in Carboniferous-lower Permian source rocks with a range of maturities in the northwestern Junggar Basin, China. The N1 compounds formed from on-fluorescent chlorophyll catabolites (NCCs), which record the characteristics of the residual soluble organic matter. These components remain in the source rocks after hydrocarbon generation and expulsion, and enable evaluation of the hydrocarbon generation potential. The newly defined indexes of molecular evolution, which are the polymerization index P1 ([DBE 18+DBE 15]/[DBE 12+DBE 9]_N1) and alkylation index R1 (RC6–35/RC0–5), combined with the vitrinite reflectance (VRo) and paleo-salinity index (β-carotane/nCmax), can identify the factors that control the evolution of highly mature organic matter. The main factor for source rocks deposited in a weakly saline environment is the maturity, but for a highly saline environment both the maturity and salinity are key factors. The high salinity inhibits the molecular polymerization of organic matter and extends the oil generation peak. Given the differences in the bio-precursors in saline source rocks, we propose a new model for hydrocarbon generation that can be used to determine the oil generation potential of highly mature organic matter. [ABSTRACT FROM AUTHOR]

A sample from the Jurassic Tamulangou Fm. and two comparison samples from the Cretaceous Fm. were used to document the hydrocarbon generation kinetics and phase behaviors at two heating rates using the confined gold tube system. The results show that the different heating rates affect the reaction rates, paths and levels of organic matter evolution. The average activation energy and dominant frequency activation energy of liquid hydrocarbon are significantly lower than those of gaseous. Moreover, igneous intrusion had a positive effect on the blooming, enrichment and preservation of organic matter, promoting a Ro increase of 0.09%–1.07% in the Jurassic Tamulangou Fm. Two models were used to simulate the normal and abnormal evolution caused by thermal events combined hydrocarbon generation kinetic parameters. Thermal simulation analysis shows that oil generation was initially slow and then increased rapidly until a burial depth of 1500 m was reached at ~128 Ma. The largest hydrocarbon expulsion began at ~120 Ma, corresponding to a burial depth of 2450 m. The maximum cumulative yield is 510 mg/g TOC, and it is still in the peak period of hydrocarbon generation, which demonstrates a favorable potential for hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

To understand hydrocarbon migration in terms of the mechanisms, accumulations and exploration targets, it is essential to correctly identify and characterize the carrier systems that control fluid-migration history and oil/gas reservoir formation. The Yinggehai Basin in China is an important area for natural gas exploration and production. However, due to the argillaceous sand sedimentary environment and the absence of faults from the Neogene thermal subsidence period, traditional migration pathways are absent in the Yinggehai Basin, posing significant challenges to target evaluation in this area. Exploration shows that most of the existing gas reservoirs are associated with vertical migration. In this work, coherence cube and curvature seismic techniques are used in the central diapir zone of the Yinggehai Basin to identify diapir-associated fractures and regional stress. Together with geological analysis, two categories of carrier system are discussed in detail to explain the complex migration and accumulation patterns that have puzzled the area. Diapirs have five evolutionary phases, i.e., pressurization, piercing, equilibrium, release and collapse, which have different fracture development patterns, leading to different mechanisms of hydrocarbon migration and accumulation. The carbon isotopes of gaseous hydrocarbons in DF shallow layers and mid-deep layers have an inverted order distribution, indicating mixed accumulation with different maturity, whereas in the mid-deep layers of the diapir-affected areas, there is a single accumulation with low maturity. Early diapiric activity allowed the natural gas produced from deep source rocks to migrate upward along the diapiric carrier system and accumulate in suitable traps to form gas reservoirs. For regional-stress related fractures, the gradual loss of overpressure and fluids from deep to shallow in high-pressure fractures results in the gas accumulation time of deep traps in the regional stress-related carrier system being relatively late and the gas accumulation time of shallow traps being relatively early. [ABSTRACT FROM AUTHOR]

The Middle Permian Lucaogou Formation in Northwestern China mainly contains typical saline lacustrine oil shale. To study the differences in geochemistry and hydrocarbon generation of source-rock samples in Lucaogou Formation in Jimusaer Sag, 57 core samples from two boreholes were analyzed herein by performing total organic carbon (TOC) analysis, RockeEval pyrolysis, and gas chromatographicemass spectrometry experiments on saturated hydrocarbons. The kinetics of oil generation were studied using two samples comprising typical maceral components. The results showed that the hydrocarbons produced by telalginite are relatively rich in pristane (Pr), phytane (Ph), b-carotane, high-carbon normal alkanes, and C29 regular steranes. Hydrocarbons produced by lamalginite contain a significantly higher content of C20 tricyclic terpanes (TT), C21TT, C24 tetracyclic terpanes (TeT), C29 norhopane, and C28 regular sterane. Based on the pyrolysis and biomarker compound parameters, telalginite has a higher conversion rate for hydrocarbons than lamalginite in the low-mature to mature stage, which is consistent with their kinetic analysis. Lamalginite source rock displays a much narrower distribution of activation energies than telalginite source rocks. Such narrower activation energy distribution effectively narrows the main stage of hydrocarbon generation. In addition, the activation energy distribution of lamalginite concentrated in the high-value interval, indicating the characteristics of the relatively lagging hydrocarbon generation of lamalginite. [ABSTRACT FROM AUTHOR]

The Lower Cretaceous Bayingebi Formation at the Hari sag, Northern China is a significant bearing oil-gas tight reservoir in the Yin'E Basin. In order to understand petrophysical properties of the reservoirs, the diagenesis and hydrocarbon accumulation phases were investigated using casting thin sections, scanning electron microscopy (SEM), X-ray diffraction and fluid inclusion analysis. Additionally, the histories of burial evolution, organic matter thermal evolution and hydrocarbon charge are investigated. The results showed that the pore types include primary pore, intergranular pore and dissolution intragranular pore. The diagenesis of sandstone reservoirs in the process of burial and diagenesis mainly includes compaction, fracture, cementation, metasomatism and dissolution. The comprehensive analysis of various diagenetic stage indexes shows that Bayingebi Formation is in the middle diagenetic stage A-B. The homogenization temperature and salinity of fluid inclusions are low temperature and low salinity (120 °C ∼ 130 °C, 0% ∼ 9%), medium temperature and high salinity (140 °C ∼ 150 °C, 10% ∼ 17%) and high temperature and medium salinity (160 °C ∼ 170 °C, 9% ∼ 11%) respectively. According to the homogenization temperature of the inclusions and the history of burial evolution, the Bayingebi Formation has mainly three phases of hydrocarbon accumulation (100 ∼ 97Ma, 93 ∼ 87Ma, 84 ∼ 81Ma). [ABSTRACT FROM AUTHOR]

In this study, a variety of test and analysis methods, such as cast thin sections, fluorescent thin sections, scanning electron microscopy, fluid inclusions, etc., were comprehensively used and combined with logging data, sedimentary systems, burial history and other research results, to systematically study the diagenesis characteristics of Middle Permian Lower Wuerhe formation–Lower Triassic Baikouquan formation reservoirs and their control on hydrocarbon accumulation. The coupling relationship between the hydrocarbon accumulation process and reservoir secondary pores was established. The result shows that besides the development of primary intergranular pores, the reservoir develops secondary pores, such as particle dissolution pores, cement dissolution pores and fractures. The development of secondary dissolution pores, such as particle dissolution pores, carbonate and zeolite cement dissolution pores, is mainly controlled by the range and scale of organic acids produced by the thermal evolution of source rocks. It is considered that being located in the updip direction of source rocks, being involved in the development of the unconformity surface and the faults connecting source rocks, and being involved in the development of alkaline cements (such as laumontite) are the three dominant conditions for the development of secondary dissolution pores in the study area. [ABSTRACT FROM AUTHOR]

Organic matter (OM) type critically controls the hydrocarbon generation potential and organic pore development in black shales. However, maceral variation in lacustrine shales and its control on hydrocarbon generation potential and organic pore development are not yet well understood. In this study, 15 Chang 7 Member shale samples of the Yanchang Formation, Ordos Basin, were investigated with organic petrography, Rock-Eval pyrolysis, and a scanning electron microscope to study the maceral composition, hydrocarbon generation potential, and organic pores in this black shale succession. The results show that the studied shales are in the oil window (Ro~0.70%). OM belongs to Type I and Type III kerogen, as demonstrated by Rock-Eval pyrolysis. Macerals in the Chang 7 Member shales are composed of amorphous OM, alginite, sporinite, liptodetrinite, vitrinite, inertinite, and solid bitumen. Amorphous OM and alginite are major hydrocarbon-generating macerals, and their content determines the hydrocarbon potential of shales. Secondary organic pores were not observed in the studied Chang 7 Member shales due to either a low thermal maturity or a dominance of terrigenous OM. Maceral variation can affect the reliability of using Rock-Eval Tmax as a thermal maturity indicator. This study provides important insights into maceral control on hydrocarbon generation and organic pore development in black shales, calling for a critical evaluation of OM in black shale successions with organic petrography. [ABSTRACT FROM AUTHOR]

Three kerogen samples (JJZG-1, JJZG-2 and JJZG-3) isolated from the Permian Lucaogou shales of varying biodegradation levels (BLs z 0, 3 and 7, respectively) were subjected to sequential stepwise pyrolysis combined with on-line detection of gas chromatography-mass spectrometry (GC-MS). Occluded fractions (bitumen II) released at low-temperature steps (-410 °C) show consistent biodegradative signatures with that reported for solvent-extracted fractions (bitumen I) of the original shales, e.g., broad range of abundant n-alkanes, isoprenoids and regular hopanes for the non-biodegraded JJZG-1; trace n-alkanes and abundant hopanes for the moderately biodegraded JJZG-2; and no n-alkanes but still prominent hopanes including the microbially produced 25-nohopanes for the severely biodegraded JJZG-3. This consistency between bitumen II and bitumen I fractions indicates the biodegradability of the kerogenoccluded bitumen II with limited protection from host kerogen. A minor level of protection was suggested by the trace distribution of n-alkanes in the bitumen II of JJZG-2, whereas the bitumen I had no nalkanes. The kerogen itself was more resistant to biodegradation as reflected by the persistence of high abundances of both n-alkanes and hopanes in the high temperature (-460 °C) products of all three kerogen samples. However, the relative abundances of these product groups did show some evidence of biodegradation alteration, e.g., ratios of n-C15 alkene/C27 hop-17(21)-ene at 510 °C pyrolysis decreased by order of magnitude from the non-biodegraded (JJZG-1 - 27.4) to highly biodegraded (0.3 for JJZG-3) samples. The reduced biodegradation impact on the kerogen fraction (Cf. bitumen fractions) was also evident by the absence of 25-norhopanes in the high-temperature analysis of the JJZG-3 kerogen. [ABSTRACT FROM AUTHOR]

With increased exploration in the faulted basins of eastern China, petroleum exploration in this region has been challenged by unclear remaining petroleum resources distribution, complex reservoir and hydrocarbon enrichment patterns, and lacking of suitable exploration techniques. Aiming at resolving these problems, studies on source rocks, reservoirs, hydrocarbon accumulation and geophysical prospection were carried out by laboratory analysis, reservoir anatomy, and seismic analysis. A highlyefficient hydrocarbon generation/expulsion model of source rocks in saline environment was established, which aided in the discovery of a new set of source rocks in the Jiyang Depression. This study also reveals the formation process of high-quality reservoir by alternating acid and alkaline fluids during deposition and diagenesis, and pattern of secondary pores development in deep clastic rocks. Through the fine anatomy of the oil reservoirs, an orderly distribution pattern of the oil reservoirs is established, and the potential exploration targets in the undrilled area are identified. In addition, single-point highdensity seismic acquisition and high-resolution imaging technologies are developed, enabling fine and efficient exploration in areas with high exploration maturity. The research result plays a leading and demonstrative role in the fine and efficient exploration of faulted basins in eastern China. [ABSTRACT FROM AUTHOR]

A series of natural gas fields have been discovered in the deepwater area of the Qiongdongnan Basin (QDNB) of China. However, the natural gas generation process and mechanism still exist controversy. Hence, two semi-open systematic pyrolysis experiments were conducted on a modified apparatus to study the natural gas generation process and mechanism in the deepwater area of the QDNB in this study, including pressured experiments and non-pressure experiments. In the pressured experiments, a stress pressure ranges from 37.6 to 188.2 MPa and fluid pressure ranges from 14.4 to 96.0 MPa based on the thermal evolution model of the QDNB. In non-pressured experiments, only fluid pressure from 2.0 to 5.0 MPa for a hydrous condition was compared with pressured experiments. The experiment results indicate that the pressured experiments could decrease the generated yields, expulsion efficiencies and expulsion process of the liquid hydrocarbons. Moreover, the suppression effect appears to be stronger under high evolution than that of low-maturity stage. Additionally, liptinite preservation exists during the liquid hydrocarbons and natural gas generation at temperature over 420 °C, whereas the liquid hydrocarbon is cracking to gas at temperature over 500 °C as a function of lithostatic stress, fluid pressure, temperature and time. Hence, pressure plays an important role in influencing expulsion efficiencies and expulsion process of the liquid hydrocarbons and natural gas generation in the high maturity stage. [ABSTRACT FROM AUTHOR]

The oil-gas display of early drilling suggests a considerable exploration prospect in the Nangong Sag. Previous researchers have not analyzed the characteristics of hydrocarbon migration and accumulation from the perspective of fluid potential. We use the Hubbert flow potential model to restore the flow potential of the Nangong Sag in the Pliocene, which was a key period of hydrocarbon generation. The results show that the high value area of fluid potential is large and mainly located in the southeastern part of the study area. The southeast subsag provided fluid, and the northwest slope accumulated fluid. The fluid potential gradual decrease from the southeast subsag to the northwest slope. According to the division trough theory, the Nangong Sag is divided into 8 hydrocarbon migration and accumulation units. We suggest that migration and accumulation units III, IV and V are favorable areas for hydrocarbon exploration. The study area has favorable source-reservoir-cap, pool-forming conditions and good time allocation relationship of hydrocarbon. Based on the characteristics of fluid potential, the hydrocarbon generation and accumulation modes of migration and accumulation unit III and IV in Nangong Sag are preliminarily put forward. The research results have guiding significance for future hydrocarbon exploration in the study area. [ABSTRACT FROM AUTHOR]

Shale oil resources are important supplements for the gradually decreasing oil production from conventional reservoirs. Although the exploitation and development of shale oil have achieved considerable progress in the last decade, the commercial extraction of hydrocarbons from shales is still difficult, especially in the lacustrine sedimentary basins of China. One of the key points controlling the successful extraction of hydrocarbons from shale systems is the understanding of the occurrence mechanism of shale oil. This study comprehensively summarizes the theories and techniques to characterize oil occurrence state, occurrence space, oil content, and oil movability in shale systems. Sophisticated instruments, such as high-resolution scanning electron microscopy and high-energy ray imaging, were utilized to qualitatively analyze the pore networks of shales. Advanced physical experiments and numerical simulation techniques, including step-by-step rock pyrolysis, solvent extraction, and NMR, were introduced to characterize shale oil adsorption and movability. By the comparative analysis of the occurrence space, it is found that the image observation technique especially focuses on concentrated pores, such as organic matter-hosted pores. The fluid injection technology yields particular pore size information, which should be calibrated using other information. The 3D digital core, demonstrating the spatial distribution of minerals and pores, is an effective input for shale oil flow simulation. Geological controls analysis about oil retention in organic-rich shales has found that the inorganic matter pores and fractures are probably the "sweet spot" of shale oil, due to the low oil adsorption and high light hydrocarbons content. Many physical experiments measure the total free oil content but neglect the hydrocarbon–rock interaction and the sequential migration of hydrocarbon compounds. Thus, micro-scaled experiments measuring the hydrocarbon adhesion forces are needed to uncover the occurrence mechanism of shale oil in the future. [ABSTRACT FROM AUTHOR]

Rapid and accurate estimation of soil petroleum hydrocarbon content is crucial for analyzing the degree of soil pollution and evaluating pollution status. Surface soil samples and hyperspectral measurements in the reservoir area in Lenghu Town, Qinghai Province, China, were viewed as research objects, and the correlation between different spectral forms of original data and petroleum hydrocarbon content in soil was analyzed. To improve the estimation accuracy, we proposed a solution that introduces least absolute shrinkage and selection operator (LASSO) combined with extremely randomized trees (ERT) and gradient boosting decision tree (GBDT) ensemble learning for constructing hyperspectral estimation model. The results show: LASSO algorithm can not only solve the spectral multicollinearity problem effectively but also reduce the number and calculation complexity of soil hyperspectral variables to a great extent. Compared with traditional machine learning, ERT and GBDT perform superior. In particular, the estimation accuracy of the LASSO-GBDT model is the highest. [ABSTRACT FROM AUTHOR]

The present investigation is the first to provide information on the formation, process and influence factors for hydrocarbon generation and expulsion potential of the Cuizhuang Formation source rock in the Yuncheng sub‐basin to decipher the reason why no commercial petroleum resources have been found so far. In this study, data from the Jitan‐1 well in the Yuncheng sub‐basin were applied for the Cuizhuang Formation source rock basin modelling and organic geochemical analyses to reconstruct the burial and thermal evolution history and reveal the timing and process of hydrocarbon generation and expulsion. The modelling results indicate that the peak palaeotemperature of the Cuizhuang Formation source rock reached ~205°C in the Middle Carboniferous (~327 Ma) at a maximum burial depth of ~4000 m, when rapid burial subsidence and thermal events played a significant role in increasing thermal maturity. The Cuizhuang Formation generated and expelled small amounts of hydrocarbons from the Early Ordovician until the Middle Carboniferous, starting with the primary kerogen cracking and conversion to oil from the Early to Middle Ordovician (~476–461 Ma), corresponding to the thermal maturity values of 0.55–0.70 %VRo and transformation ratio (TR) <10%. The expulsion of most generated oil (0.70–1.30 %VRo, TR of 10%–90%) started from the Middle Ordovician to the Early Carboniferous (~461–351 Ma), before reaching the secondary cracking of the retained oil into gas (>1.30 %VRo and TR of 90%–100%) from the Early to Middle Carboniferous (~351–327 Ma). Destruction of the initial formation of hydrocarbon reservoirs in the Yuncheng sub‐basin was primarily controlled by the Middle Carboniferous tectonic event with its major uplift‐erosion, resulting in the absence of potential hydrocarbon reservoirs in recent exploration activities in some parts of the Yuncheng sub‐basin. [ABSTRACT FROM AUTHOR]

Ambient non-methane hydrocarbons (NMHCs) were investigated at Shenhua coal chemical industrial park (SH), and Baofeng coal chemical industrial park (BF) in Ningdong Energy and Chemical Industrial Base (NECIB) in China's Energy Golden Triangle (EGT). Ambient air samples were collected using preevacuated 2-L electro-polished stainless steel canisters at SH and BF from 9: 00 a.m. to 9:30 a.m. (UTC+8) from 22 to 31 December 2016. Fifty-seven NMHCs were analyzed using gas chromatography-mass selective detector/flame ionization detector. The average NMHCs mixing ratios were 49.05 ± 44.37 ppbv in SH, and 39.31 ± 18.77 ppbv in BF. Overall, alkanes took up the largest proportion (>60%), followed by alkenes, acetylene, and aromatics. The propylene-equivalent (Prop-Equiv) concentration and the ozone formation potential (OFP) of NMHCs were calculated to estimate their chemical reactivities. Alkenes played a predominant role in NMHCs reactivity, among which propylene and ethylene were the largest contributors. OFP values show that alkenes and acetylene were the largest contributors (60%) to measured total NMHCs. Ethylene, propylene, m/p-xylene, n-butane, 1-butene, propane and acetylene were the major precursors in ground-level ozone formation in this region, which accounted for 66% and 62% of the total ozone formed by NMHCs at BF and SH, respectively. This study identified that industrial activities were the primary sources of NMHCs, confirmed by the high ratios of benzene to toluene (B/T = 2.23). Therefore, these organic pollutants should be monitored further based on their high toxicities. [ABSTRACT FROM AUTHOR]

The Leikoupo Formation of the Middle Triassic is one of the hot strata of marine natural gas exploration in the western Sichuan Basin in recent years. Petroleum geologists have different opinions on the reservoir-forming conditions and the types of gas pools. The research shows that the 4th member of Leikoupo Formation in the western Sichuan Basin has favorable hydrocarbon accumulation conditions. It not only has a large-scale stable distribution of the tidal flat dolomite reservoirs, but also develops two sets of source rocks: the Permian source rock and the Leikoupo Formation source rock. There are three models of hydrocarbon accumulation in the 4th member of Leikoupo Formation from the east to the west in the Western Sichuan Depression. That is the "lower generation and upper storage" structural gas reservoir transported by cross-layer source faults and fractures, the "lower generation and upper storage" structure-formation gas reservoirs transported by the relay combination of small source faults and intra-layer fractures, and the "self-generating and self-accumulation" lithologic gas reservoir transported by intra-layer fractures. After the proved reserves of 100 x 109 m³ of the structural gas reservoir in the 4th member of Leikoupo Formation in the western Sichuan Basin, it is considered that the area near the pinch-out line of the 4th member of Leikoupo Formation in the eastern depression is a favorable area for exploration of tectonic-stratigraphical gas reservoirs, and the middle and lower part of the eastern slope (Guanghan slope) in the Western Sichuan Depression is a favorable area to explore lithologic gas reservoirs. [ABSTRACT FROM AUTHOR]

Organic-rich black shale and dark-grey mudstone are widespread in the Seventh Member of the Yanchang Formation, Ordos Basin. There are obviously differences in geochemical characteristics and hydrocarbon generation potential between black shale and dark-grey mudstone. Based on the detailed organic geochemical examination, this paper reveals the differences in hydrocarbon generation processes and characteristics (activation energy and conversion rate of hydrocarbon generation) between dark-grey mudstone and black shale and the causes for the differences. Black shale is characterized by moderate to very high total organic carbon (TOC) contents (5.08%–39.39%) and its kerogen type belongs to type II 1 and type I. Dark-grey mudstone has a characteristic of low to moderate TOC contents (0.64%–7.35%) and its kerogen types are mainly composed of type II 2 and type II 1. The hydrocarbon generation activation energy of black shale mainly oscillates around 250–310 KJ/mol, and the corresponding hydrocarbon generation threshold is high (the simulated temperature is 400 °C). The process of hydrocarbon generation is characterized by fast conversion rate and short cycle. By contrast, the hydrocarbon generation activation energy of dark-grey mudstone has a wide range (170–360 KJ/mol), and the corresponding hydrocarbon generation threshold is low (the simulated temperature is 230 °C). The process of hydrocarbon generation is characterized by slow conversion rate and long cycle. The difference of hydrocarbon generation process and characteristics between black shale and dark-grey mudstone is mainly affected by macerals composition and organic matter source. The organic matter of black shale mainly originated from algae, and its macerals was mainly composed of alginite. The organic matter of dark-grey mudstone mainly originated from the mixture of algae and terrestrial higher plants (conifers), and its macerals was mainly composed of vitrinite, liptodetrinite and inertinite. The complex macerals composition and organic matter source make the activation energy distribution of dark-grey mudstone more dispersed than that of black shale. In addition, affected by the macerals (e.g sporinite and resinite) with low activation energy from terrestrial higher plants, the activation energy of dark-grey mudstone containing sporinite and resinite in the macerals is lower than black shale. Therefore, the dark-grey mudstone containing algae and terrestrial higher plants corresponds to low hydrocarbon generation threshold, slow conversion rate and long hydrocarbon generation cycle. The black shale containing a large number of algae corresponds to high hydrocarbon generation threshold, fast conversion rate and short hydrocarbon generation cycle. Moreover, the conversion rate of black shale containing radioactive elements and more clay minerals is higher than that of dark-grey mudstone. • Detailed comparison of hydrocarbon generation characteristics, molecular composition and organic petrology between mudstone and shale in the Chang 7 Member. • The difference of hydrocarbon generation potential between mudstone and shale is mainly affected by paleo-productivity and preservation environment. • The difference of hydrocarbon generation characteristics between mudstone and shale is mainly affected by macerals composition and organic matter source. [ABSTRACT FROM AUTHOR]

The compounds in volatile flavor substances in duck meats of three different body parts (breast, leg, and wing) were extracted by headspace solid‐phase micro‐extraction and determined by gas chromatography‐mass spectrometry. A total of 16 main volatile compounds including 4 hydrocarbons, 4 alcohols, 2 acids, 3 aldehydes, and 3 others (N‐containing, S‐containing) were identified in raw duck meats from three different body parts. The hydrocarbon compounds account for more than 50% of all volatile substances in all three body parts. And the percentage of hydrocarbon compounds in raw duck breast meat reaches 82.76%. A total of 81 volatile compounds including 15 hydrocarbons, 10 alcohols, 7 acids, 12 aldehydes, 4 esters, 19 S‐containing and N‐containing compounds, and 14 others were isolated and identified in 1 hr‐marinated and cooked duck meats. A total of 101 kinds of volatile flavor compounds including 13 hydrocarbons, 14 alcohol, 7 acids, 8 aldehydes, 12 esters, 23 S‐containing and N‐containing compounds, and 24 others were detected in 3 hr‐marinated duck meats of the three body parts. It was proved in this study that under the same conditions, the volatile compounds in duck legs are more than those in duck breasts and wings, and the types of volatile flavor substances increase significantly in duck meats after cooked. Practical applications: Prepared and cooked duck meat, especially wings and legs are popular food in China. The results suggest that Pickling makes duck meat more flavory while proper pickling time is less than 3 hr. Duck wings are better for marinating and cooking compared with duck breasts and legs. The acceptance study of duck meat from different body parts and the analysis of volatile flavor compounds are beneficial for optimizing utilization of whole parts of duck meat. [ABSTRACT FROM AUTHOR]

Oil in an unconventional tight reservoir is considered to migrate from a very adjacent reservoir or be impregnated in situ within source rocks, but their large hydrocarbon molecular fractions during short‐distance migration in the tight system are poorly understood. In order to explore the evolution characteristics and differences of the geochemical properties, especially the biomarkers, between expelled oil (just detached from source rock and not undergoing long‐distance migration) and retained oil under different thermal evolution stages of lacustrine marlstone. Semi‐open hydrous pyrolysis was conducted on an immature lacustrine marlstone collected from the third member of the Eocene Shahejie Formation in Shulu Sag, Bohai Bay Basin and the hydrocarbon product expelled from and remained in the rock during pyrolysis were collected and analysed with gas chromatography–mass spectrum instrument. The results indicate that the saturates compositions show expelled oil having commonly lower thermal maturity than retained oil because expelled oil is a mixture of multiple‐term hydrocarbon expulsions, while retained oil is the remained final hydrocarbon product of pyrolysis in semi‐open experimental system. The hydrocarbon migration has a significant effect on the maturity‐related parameters distribution such as 20S/(20S + 20R) and αββ/(αββ + ααα) for C29 steranes. Hydrocarbon expulsion enables Ts/(Ts + Tm) ratio in expelled oil is much greater than that of retained oil at lower matural stage. The saturated hydrocarbon maturity biomarkers in retained oil and expelled oil vary in a subtly different pathways with increasing maturity, comparatively the aromatic hydrocarbon biomarkers, such as triaromatic steroids and methyl‐phenanthrene (MPI1 and MPI2), regularly changed during maturation, which is not obviously affected by migration effects and can be used not only for thermal maturity predications but also for oil–oil or oil–source correlation. C29 20S/(20S + 20R) and C29 αββ/(αββ + ααα) commonly are preferable maturity parameters for shale or mudstone, reflecting that mineral matrix and oil in source rock are not affected by migration and supposed to have an oil thermal maturity corresponding to depth. Combined with some tight reservoir cases in North America and China, the biomarker ratios variation along depth and its abnormal value can be used to predict sweet spots in tight reservoirs. [ABSTRACT FROM AUTHOR]

Commercial diesel consists of hundreds of hydrocarbons such as alkanes, cycloalkanes, and aromatics. The components of the fuel's composition are what determine its physical and ignition properties, and their variations affect engine performance. In this study, n-heptane, n-dodecane, tetralin, and decalin were chosen as typical additives to blend with commercial diesel according to the China VI standard (Heavy Duty Diesel Vehicle Pollutant Emission Limits and Measurement Methods) in 20% and 50% volume fractions, respectively. The physical properties of the fuel blends, such as viscosity, density, cetane number (CN), and distillation range, were measured first. Then, the commercial diesel's lower heat value was measured, and blended fuels were calculated accordingly. The CN of the blended fuel is tested by an Ignition Quality Tester (IQT), which is known as the derived cetane number (DCN). The results show that adding n-dodecane increases the value of DCN, while tetralin reduces the DCN, and n-heptane and decalin have negative effects. This study uses a type of WP12 diesel engine made by Weichai that meets China's emission regulation 6. During the tests, the fuel injection strategy was kept as a pure diesel operation without any modifications. Compared with pure diesel operation, the bench test results show the following characteristics: the maximum torque output increased with increased decalin, followed by tetralin and n-dodecane, while n-heptane has a side effect compared to pure diesel operation. The addition of n-dodecane and n-heptane can reduce fuel consumption, while tetralin will increase it, and decalin has no obvious effect on fuel consumption. It was found that n-heptane increases HC and NOx emissions significantly. Furthermore, n-dodecane slightly increases CO, HC and NOx emissions. Decalin increases CO and HC emissions when mixed in a large proportion. In addition, tetralin causes a substantial increase in HC, CO and NOx emissions at medium and high loads. [ABSTRACT FROM AUTHOR]

The nuclear magnetic resonance (NMR) technique is a crucial means for formation evaluation. It can provide an accurate set of formation parameters in single-phase-flow reservoirs, such as porosity, permeability, and pore structure distribution; however, in most cases, there are hydrocarbon-water two-phase fluids in the reservoirs. The secondary change of the T 2 distribution makes the accuracy of the evaluation a challenge. Hence, it is necessary to clarify the impact of changes in hydrocarbon content on the response of NMR signals before using the traditional evaluation methods. In this paper, we analyzed the response mechanism of NMR T 2 distribution under different saturation conditions. Based on the theoretical derivation, we established a nuclear magnetic model that describes the relation among the T 2 geometric mean value of water signal, hydrocarbon signal, and water saturation. The accuracy of each model part was verified by numerical simulation. In addition, the calculation results in core samples show that the proposed model is more effective and reliable than two existing models (the T2 saturation ratio model and the Xiao empirical model), especially in extreme conditions (irreducible water and hydrocarbon saturated samples). Finally, we applied the proposed model to field application in the Tertiary formation in the Bohai Bay Basin, China, which achieved good effects in the NMR fluid substitution and the NMR saturation evaluation. • The relation among NMR T 2gm of the water, hydrocarbon signal and the water saturation could be expressed mathematically. • A new model was established for characterizing the NMR response in hydrocarbon bearing rocks. • Compared with the traditional model, the new model was proved to be better regional adaptability and stability. • The model could be used for NMR fluid substitution and saturation evaluation in hydrocarbon bearing formation. [ABSTRACT FROM AUTHOR]

The nano-scale pore structure of shale is closely related to the self-generated and self-accumulated shale oil and gas. The Bohai Bay Basin is a crucial oil-bearing basin in eastern China, and the Paleogene Shahejie Formation is the most important source rock section in this area. In order to study the internal relationship between hydrocarbon generation evolution and pore structure characteristics of source rocks, we conducted hydrocarbon generation simulation tests with a closed gold tube system, and heated up original rocks from Shahejie Formation in Laizhou Bay Sag, southern Bohai Bay Basin, from 290 °C to 440°C at different heating rates. Besides, we carried out low-temperature N2 adsorption experiments on sample residues, and measured their pore structure characteristic parameters. The results show that with the increase of simulated temperature, the specific surface area and pore volume of nano-pores below 10 nm (which are mainly organic pores) decrease first and then increase, while those of nano-pores above 10 nm increase all the way. The evolution trend of total specific surface area and pore volume is mainly controlled by pores below 10 nm which are mainly organic pores, especially micropores below 2 nm. There are two main factors affecting the development of inorganic pores: (1) Dissolution of organic acids produced by pyrolysis of organic matter in hydrocarbon-generation evolution; (2) Deformation of crystal structure of mineral components under the combined action of temperature and pressure. The experimental results at different heating rates demonstrate that rapid settlement under geological conditions is not conducive to the development of nano-pores, especially micro-pores composed of organic pores. [ABSTRACT FROM AUTHOR]

This study seeks to understand the ambient levels, gas/particle partitioning, and sources of nonpolar organic molecular makers (OMMs) at a suburban site in Nanjing, China. Particle‐ and gas‐phase OMMs were collected using a medium volume sampler equipped with two quartz filters in series and a polyurethane foam (PUF)/XAD‐4/PUF (PXP) adsorbent sandwich. More than 100 pairs of filter and PXP samples were collected diurnally from September 2018 to September 2019. The concentration profiles of total n‐alkanes and polycyclic aromatic hydrocarbons were peaking at n‐C12–n‐C17 homologs (9.98 ± 5.43–38.4 ± 17.7 ng m−3) and naphthalene (92.5 ± 56.7 ng m−3), respectively, followed by decreasing concentrations with further increases in molecular weight. Three artifact correction methods with different pre‐assumptions on relative contributions of evaporation loss to backup filter measurements were used to separate particle‐ and gas‐phase OMMs. The resulting particle‐phase fractions showed significant differences for OMMs with vapor pressure <10−9 atm at 298.15 K. Absorptive gas/particle partitioning coefficients of OMMs were empirically calculated based on measurements and theoretically predicted for comparison. The results obtained under the three artifact correction methods suggested growing importance of evaporation loss with decreased vapor pressure. Positive matrix factorization (PMF) was performed for source apportionment using total (PMFtotal) and particle‐phase (PMFparticle) OMMs data, respectively. Besides eliminating the influence of gas/particle partitioning, the involvements of more volatile species and gaseous OMMs data improved the identification of specific emission sources, supporting the usage of total OMMs data over a wide vapor pressure range for PMF source apportionment. Key Points: The particulate fractions of organic molecular markers attained their minima in summer, when the total concentrations increasedEvaporation loss might be the main sampling artifact of particulate organics when the vapor pressure is lower than 10−10 atmTotal concentrations of organic molecular markers over a wide vapor pressure range should be used for positive matrix factorization analysis [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing 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.)