Alkane Distribution Research Articles

Geochemical and Organic Petrological Evaluation of Organic Matter from Tertiary Sediments of Baga Field in Chad Basin, Northeast Nigeria

The Upper Cretaceous sediments in Bornu are considered an important regional source rock in the Chad Basin. This study therefore evaluated the geochemical and organic petrological evaluation of organic matter in tertiary sediments of Chad Basin, Northeast Nigeria by collecting 25 cutting samples from these organic-rich shale sediments from four wells drilled in Baga field in the Nigeria sector (Bornu) of the Chad Basin, in order to geochemically assess the type of organic matter, thermal maturity, and palaeoenvironmental conditions. Results reveal that Bornu sediments contain high organic matter more than 2.0 wt% TOC and have an excellent oil-generation potential. This is supported by high bitumen extractions and hydrocarbon yields with values 5827 and 3547 ppm, respectively. The investigated biomarkers indicated that the shale sediments contain a high abundance of C27 regular sterane concentrations, high C27/C29 regular sterane ratios and relatively low value of the biomarker sterane/hopane ratio as well as the presence of tricyclic terpanes. A mainly suboxic to relatively anoxic preservation conditions is inferred from Pr/Ph ratios (1.03–2.53). This is support by normal alkane distributions, which are characterized by dominance of types I/II kerogen and low medium molecular weight n-alkane compounds, respectively. This is further supported by lower amounts of acyclic isoprenoids compared to n-alkanes (e.g., pristane/n-C17 and phytane/n-C18 ratios). This is also supported by a mixture of algal and amorphous organic matter that was deposited in a lacustrine environment identified from kerogen microscopy. Based on the analyzed biomarkers, triterpanes and terpanes thermal maturity indicates that the Bornu sediments organic matters have entered into early mature stage for oil generation. This is also supported by vitrinite reflectance values of 0.57–0.71 % Ro indicate that these organic matters have reached oil window maturity.

Prospects of oil and gas potential of the South Torgai sedimentary basin

One of the main directions for assessing the prospects of oil production is the study of oils. In this regard, modern geochemical studies are widely used in forecasting the oil and gas potential of the subsurface, occupying an important role in the question of the origin and source of hydrocarbons. The study is aimed at a comprehensive analysis of the geochemical characteristics of the South Torgai sedimentary basin in order to identify and assess the prospects for oil and gas potential. Comparing the composition of oils from different deposits makes it possible to determine the oil source strata, zones of oil formation and oil accumulation. The compounds in oils that are most or least susceptible to changes under the influence of factors such as water leaching, biodegradation and thermal transformation are subject to comparison. The relative content of individual classes of compounds in the oils of the Aryskum trough, the geological characteristics of oil samples and the distribution of normal alkanes are presented. In this work, a comparative analysis of previously conducted geochemical studies was carried out to determine the composition and genesis of oils in the Aryskum trough. Biomarkers in oils, which make it possible to restore the genetic properties of oils and determine the conditions of sedimentation of oil-generating organic substances, indicate the presence of suboxidation conditions, redox potential and predominantly oxidative environment in the process of sedimentation of organic substances. The results obtained are important for understanding the processes of oil formation and generation, as well as for further forecasting the oil content of the South Torgai sedimentary basin.

Crude Oils of Domanik Genotype from Middle Devonian Deposits of the Timan–Pechora Oil-and-Gas Province

The composition of biomarker hydrocarbons in crude oil samples from Middle Devonian deposits of the Western Tebuk, Dzh”er, and Michayu oil fields of the Omra–Lyzha saddle in the Timan–Pechora oil-and-gas province was studied. Significant effect of the Upper Devonian Domanik source rocks on the formation of the composition of these crude oils was revealed. The main parameters demonstrating the genetic relationship of the oils from Middle Devonian reservoirs with this source rocks are distribution of steranes С27 : С28 : С29, ratio of isoprenoid to normal alkanes, and distribution of normal alkanes. All these characteristics sharply distinguish the crude oils under consideration from paraffinous oils syngenetic to Middle Devonian deposits, characteristic of deposits in the southern part of the Pechora–Kozhva megarampart.

Isoreticular Metal-Organic Frameworks Confined Mononuclear Ru-Hydrides Enable Highly Efficient Shape-Selective Hydrogenolysis of Polyolefins.

Upcycling nonbiodegradable plastics such as polyolefins is paramount due to their ever-increasing demand and landfills after usage. Catalytic hydrogenolysis is highly appealing to convert polyolefins into targeted value-added products under mild reaction conditions compared with other methods, such as high-temperature incineration and pyrolysis. We have developed three isoreticular zirconium UiO-metal-organic frameworks (UiO-MOFs) node-supported ruthenium dihydrides (UiO-RuH2), which are efficient heterogeneous catalysts for hydrogenolysis of polyethylene at 200 °C, affording liquid hydrocarbons with a narrow distribution and excellent selectivity via shape-selective catalysis. UiO-66-RuH2 catalyzed hydrogenolysis of single-use low-density polyethylene (LDPE) produced a C12 centered narrow bell-shaped distribution of C8-C16 alkanes in >80% yield and 90% selectivity in the liquid phase. By tuning the pore sizes of the isoreticular UiO-RuH2 MOF catalysts, the distribution of the products could be systematically altered, affording different fuel-grade liquid hydrocarbons from LDPE in high yields. Our spectroscopic and theoretical studies and control experiments reveal that UiO-RuH2 catalysts enable highly efficient upcycling of plastic wastes under mild conditions owing to their unique combination of coordinatively unsaturated single-site Ru-active sites, uniform and tunable pores, well-defined porous structure, and superior stability. The kinetics and theoretical calculations also identify the C-C bond scission involving β-alkyl transfer as the turnover-limiting step.

Polycyclic aromatic hydrocarbons in tropical Australian stalagmites: a framework for reconstructing paleofire activity

Human activity and climate change are altering natural rates and intensities of wildfire, but the scale and extent of burning prior to the modern era are poorly understood. Paleofire activity may be reconstructed using a variety of records (e.g., charcoal in lake sediments, burn scars on tree rings), but these are not available in all environmental settings. Here we investigate the utility of a novel paleofire proxy: trace pyrogenic organic compounds in stalagmites. Polycyclic aromatic hydrocarbons (PAHs) are linked to burning of biomass and are transported downward through soil and bedrock by infiltrating rainwater and incorporated into stalagmites in underlying caves where they are preserved. In order to test links between the stalagmite PAHs and fire above the cave, we performed a series of experiments using PAH distributions at KNI-51, a shallow cave located in tropical Western Australia, where bushfire is a regular occurrence. First, the possibility of surface contamination was evaluated by measuring PAH abundances and distributions in sequential digestions and by considering other possible additional sources, such as regional oil and gas fields or proximal combustion of fossil fuels. Second, PAHs were measured in soils above the cave and in sediments from the stalagmite chamber floor as possible sources of these organic compounds, and at near annual resolution in three aragonite stalagmites to evaluate the degree of deposition and conservation. Third, possible non-pyrogenic sources of organic compounds were evaluated through alkane distribution and specific m/z ratios. Fourth, signal replication of PAHs was tested in two coeval stalagmites. Fifth, satellite-mapped fire scars were used to examine the relationship between stalagmite PAH abundances and proximity of burning to the cave.The results support the hypothesis that PAHs in KNI-51 stalagmite carbonate reflect paleofire activity within 3 km of the cave, and thus that stalagmites can serve as an important new high resolution proxy for landscape-scale fire activity. Given that karst is present in many fire-prone environments, and that stalagmites can be precisely dated and may grow continuously for millennia, the potential utility of a stalagmite-based paleofire proxy is high.

Experimental and Modeling Investigation on the Pyrolysis of n-C10H22 Initiated by C2H5NO2

ABSTRACT To investigate the mechanism of the nitro-alkanes initiation effect on the pyrolysis of hydrocarbons, pyrolysis experiments were conducted on n-C10H22, C2H5NO2, and a binary mixture of both compounds using synchronous vacuum ultraviolet photoionization mass spectrometry. These experiments were performed within a heated flow tube under varying pressure conditions of 30 and 760 Torr. Identifying and measuring pyrolysis species, comprising stable species and radicals, provides insights into the mechanism underlying the pyrolysis and the interaction of n-C10H22 and C2H5NO2. The findings demonstrate that C2H5NO2 can reduce the initial decomposition temperature of n-C10H22, and the acceleration effect on pyrolysis becomes more pronounced with an increase in experimental pressure. The addition of C2H5NO2 also affects the distribution of alkanes, alkenes, dienes, and alkynes. A detailed elementary reaction-dynamics model comprising 223 species and 1730 reactions was established and used to simulate the distribution of C2H5NO2, n-C10H22, major species, and significant intermediates observed in the experiments. The results prove that the developed model exhibits good accuracy in predicting experimental results and enables a detailed analysis of the initiation mechanism of C2H5NO2 on n-C10H22. The impact of C2H5NO2 on the conversion rate and selectivity of pyrolysis products of n-C10H22 is highlighted and elucidated.

Geochemical features of organic matter in the Lower Cretaceous deposits of the Ozhoginskaya Suite (Indigiro-Zyryansky basin)

Limited available data on molecular geochemistry indicate the predominance of terragenous organic matter in the source material of the Lower Cretaceous deposits of the Ozhoginskaya suite, which allows it to be considered gasgenerating. However, based on the mixed nature of the source material, this suite could possess potential for liquid hydrocarbon generation. The geochemical features of the organic matter were studied using classical bituminology, Fourier transform infrared spectroscopy, gas chromatography, and mass spectrometry. The results showed a regular distribution of alkanes with a predominance of low-molecular-weight homologues with a maximum at nC15-19 and low values of ∑n.c.-nC20/∑nC21-c.c., vanadylporphyrin complexes. Thus, the contribution of algal material could be significant to the composition of the fossil organic matter of the Lower Cretaceous Ozhoginsky suite with different ratios of terrigenous and aquatic components in the section. Our results on the Ozhoginskaya suite showed the similarity of geochemical parameters with the Upper Bastakh suite of the Upper Jurassic, the features of bitumoid composition, which were mainly due to the predominance of planktonic-algal material capable of generating a large amount of liquid hydrocarbons. This established similarity raises the estimate of the oil generation potential of the organic matter of the Lower Cretaceous deposits of the Ozhoginskaya suite, along with the high gas generation potential inherent in terragenous organic matter.

ORGANIC MATTER IN THE PARATUNKA GEOTHERMAL FIELD (KAMCHATKA) THERMAL WATERS

Link for citation: Poturay V.A. Organic matter in the Paratunka geothermal field (Kamchatka) thermal waters. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 98-109. In Rus. The relevance of the research is determined by the need to obtain actual data on the composition of organic compounds in thermal mineral waters. Hydrothermal systems contain different classes of organic matter, its composition in the Far East thermal waters being poorly investigated. The organic matter study is primarily aimed at elucidating the mechanisms of organic components transformation under high temperatures and pressure. This study contributes to deeper understanding of the processes occurring in the system «water–rock–organic matter». The main aim of the research is to determine the organic compounds composition and genesis in the Paratunka geothermal area (Northern and Karymshin sites) thermal waters; estimation of the hydrocarbons molecular weight distribution; compare the obtained data with that for other hydrothermal systems of Kamchatka. Objects: the Paratunka hydrothermal system (thermal water from deep wells in the Northern and Karymshin areas), the Mutnovka and Uzon hydrothermal systems (steam-water mixture from deep wells in the Dachnoe and North Mutnovskaya thermal fields, and thermal water from shallow wells in the Eastern thermal field). Methods: field routes, solid-phase extraction, capillary gas chromatography-mass spectrometry, calculation of geochemical hydrocarbon distribution indices. Results. In the Paratunka geothermal area thermal waters 40 organic compounds are found, which belong to 11 homological series. Aromatic and aliphatic hydrocarbons of thermogenic (formed as a result of thermocatalytic transformation of organic residues) and bacterial origin reach their maximum distribution. The specific molecular-weight distribution of normal alkanes showing only even low-molecular-weight homologues is characteristic of the Karymshin thermal waters. Comparison of the data with the results of the study of organic matter in Kamchatka (the Paratunka, Mutnovka, and Uzon geothermal areas) demonstrates a great similarity of main organic components composition, all of them showing a sharp predominance of aliphatic and aromatic hydrocarbons.

Experimental analysis of the recovery and chemical properties of pyrolytic oil derived from medical waste with varying components combined via a systematic combination approach

ABSTRACT Pyrolysis of medical waste components combined via a novel systematic combination approach (sequentially binary, ternary, and quaternary copyrolysis) was conducted at 400°C to investigate the synergy between medical waste components in improving chemical characteristics and yields of pyrolytic oil. Pyrolysis of hydrocarbon-polymer-containing materials such as medical gloves and rubber bands produced more than 30% of liquid products with substantial compositions of saturated aliphatic hydrocarbon polymers. On the other hand, moisture- and carbonyl-rich pyrolytic liquid products with low selectivity were obtained from pyrolysis of lignocellulosic biomass waste such as HVS paper (houtvrij schrijfpapier, meaning “writing paper made from wood pulp”) and garden waste. Binary copyrolysis of lignocellulosic biomass and medical gloves exhibited improvement on pyrolytic liquid yield and selectivity toward saturated aliphatic hydrocarbon polymers due to hydrogen donor as the medical glove fraction became dominant. The addition of rubber band to the mixture of HVS paper and medical face masks enhanced the pyrolytic liquid yield. The pyrolysis of the mixture of HVS paper, medical face masks, medical gloves, and either rubber bands or cotton fabrics with mixture ratio of 60:20:10:10 yielded the most optimum pyrolytic liquid yield with significant distribution of alkanes in the pyrolytic liquid products.

Source rock characteristics and 1D basin modeling of the lower Cretaceous Latrobe Group, Gippsland Basin, Australia

The aim of this study is to perform source rock characterization of the Lower Cretaceous Latrobe Group's formations in the Gippsland Basin. A total of 138 source rock samples with coal and shale lithologies were selected from three formations represented by Chimaera, Curlip and Kipper Shale formations. The geochemical analyses consisting Rock-Eval pyrolysis, total organic carbon (TOC), vitrinite reflectance (% VR), maceral composition, and biomarkers were used for source rock characterization of the studied formations. It can be interpreted that the formations have poor to very good TOC (average of 2.32 wt %) indicating good organic abundance, while the coal samples from Chimaera Formation have higher organic abundance with excellent TOC (average of 45.25 wt %). These indicate good hydrocarbon generative potential. The formations mostly generate type II/III (mixed) to type III (gas prone) kerogens. Maturity parameters including production index (PI), temperature of maximum pyrolysis (Tmax), % VR and carbon preference index (CPI) indicated that the source rocks are immature to late mature (oil to oil/gas windows). Paleodepositional environment of source rocks is evaluated with biomarker data – normal alkane distribution, pristane/phytane (Pr/Ph) and isoprenoid/normal-alkane ratios. The results show that the source rocks are dominantly terrestrial, deposited in oxic setting. The rock samples did not show any sign of hydrocarbon migration, but experienced biodegradation. However, biomarker analyses were only done on the Chimaera Formation and the results do not represent the whole source rocks in this study. 1D basin modeling was done for Kipper wells. The results show that in Kipper-1, the oil and gas generations started in Kipper Shale at depths 1900 m about 24 Ma, and 2510 m about 15.4 Ma, respectively. In Kipper-2, oil and gas generations started in Chimaera Formation at depths 2540 m about 8 Ma, and 2580 m about 2.5 Ma, respectively. Transformation ratio (TR) plots show that the oil and gas generations have not reached the peak. Petroleum system event (PSE) chart suggested that the main hydrocarbon generation of the Latrobe Group started 26 Ma and is simultaneously being preserved in the Gippsland Basin. This study hopes to give insight of the burial history concept, hydrocarbon generation, and give support in the development of the hydrocarbon fields in the Gippsland Basin.

Modeling the influence of chain length on secondary organic aerosol (SOA) formation via multiphase reactions of alkanes

Abstract. Secondary organic aerosol (SOA) from diesel fuel is known to be significantly sourced from the atmospheric oxidation of aliphatic hydrocarbons. In this study, the formation of linear alkane SOA was predicted using the Unified Partitioning Aerosol Phase Reaction (UNIPAR) model that simulated multiphase reactions of hydrocarbons. In the model, the formation of oxygenated products from the photooxidation of linear alkanes was simulated using a nearly explicit gas kinetic mechanism. Autoxidation paths integrated with alkyl peroxy radicals were added to the Master Chemical Mechanism v3.3.1 to improve the prediction of low-volatility products in the gas phase and SOA mass. The resulting gas products were then lumped into volatility- and reactivity-based groups that are linked to mass-based stoichiometric coefficients. The SOA mass in the UNIPAR model is produced via three major pathways: partitioning of gaseous oxidized products onto both the organic and wet inorganic phases, oligomerization in the organic phase, and reactions in the wet inorganic phase (acid-catalyzed oligomerization and organosulfate formation). The model performance was demonstrated for SOA data that were produced through the photooxidation of a homologous series of linear alkanes ranging from C9–C15 under varying environments (NOx levels and inorganic seed conditions) in a large outdoor photochemical smog chamber. The product distributions of linear alkanes were mathematically predicted as a function of carbon number using an incremental volatility coefficient (IVC) to cover a wide range of alkane lengths. The prediction of alkane SOA using the incremental volatility-based product distributions, which were obtained with C9–C12 alkanes, was evaluated for C13 and C15 chamber data and further extrapolated to predict the SOA from longer-chain alkanes (≥ C15) that can be found in diesel. The model simulation of linear alkanes in diesel fuel suggests that SOA mass is mainly produced by alkanes C15 and higher. Alkane SOA is insignificantly impacted by the reactions of organic species in the wet inorganic phase due to the hydrophobicity of products but significantly influenced by gas–particle partitioning.

Geochemistry and organic petrology of the bituminite shales from the Kapurdi mine, Rajasthan of NW India: implications for waxy oil generation potential

This study examines the geochemical and petrographic characteristics of seven bituminite shales from the Kapurdi mine in the Rajasthan, NW India, in order to assess their organic matter inputs and evaluate the oil-prone potentials. These bituminite shale samples exhibit high total organic carbon (TOC) content (up to 45.11 wt.%). The high TOC contents were correlated with low total sulfur content of less than 1 wt.% and suggest that these bituminite shales were deposited in a fresh lacustrine environment. The dominance of such lacustrine environmental setting was confirmed by the presence of the Botryococcus algae. The analyzed bituminite shales are characterized by a bimodal distribution of normal alkanes and relatively low isoprenoid Pr/Ph, Pr/n-C17 and Ph/n-C18 ratios. These characteristics suggest that these bituminite shales contain a blend of organic matter that was derived primarily from algal lacustrine and other aquatic organic matter, with terrigenous land plants and deposited under suboxic to anoxic environmental conditions. Such findings of the organic matter (OM) input and environmental conditions are consistent with mainly Types I and II kerogen and small amounts of Type II/III kerogen, thus yielding both oil and gas prone to higher concentrations of oil generation potential. The dominance of hydrogen-rich kerogen and oil generation potential is in agreement with the findings of high hydrogen index (HI = 240–425 mg HC/g TOC) and H/C atomic ratio of more than 1.20. The abundance of n-alkene and n-alkane doublets in the pyrolysis–gas chromatography (Py–GC) also indicates that these bituminite shales have potential to generate high concentrations of paraffinic waxy oil. Most of the maturity indicators show that the bituminite shales from the Kapurdi mine have not yet entered the main stage of oil generation window, exhibiting a range of immature stages. Therefore, as highlighted in this study, these bituminite shales can be considered as a good candidate for oil shale reoterting processes to release commercial amounts of oil upon using artificial heating techniques such as hydrothermal conversion.

Blue TiO2 with tunable oxygen-vacancy defects for enhanced photocatalytic diesel oil degradation

The proliferation of marine petroleum exploitation has culminated in the undesired release of oils into the aquatic ecosystem, causing detrimental environmental effects. Photocatalysis proffers a solution to degrade recalcitrant diesel oil utilizing abundant solar energy, in which TiO2 is the perennial photocatalyst of choice. However, it suffers from the low utilization of the light spectrum and the rapid recombination of photogenerated charge carriers. In this work, oxygen-vacancy-rich blue TiO2 was employed to overcome the shortcomings of TiO2 in diesel oil degradation which has historically not been attempted. These oxygen vacancies induce favourable mid gap states to extend the optical absorption capabilities and enrich the photocatalyst charge density. Additionally, oxygen vacancies enhance the separation of electron hole pairs by acting as trap states, evident from increased trap-mediated capture fluorescence. Consequently, a 1.60-fold enhancement of diesel oil degradation performance compared to pristine TiO2 was observed. Mechanistic insights revealed the restructuring of diesel alkane distribution upon degradation corollary to the cleavage of hydrocarbon chains, illustrating that short alkanes experience a greater susceptibility to degradation compared to long alkanes. GC–MS analysis elucidates that shorter chained alkanes, alkenes, alcohols and cycloalkanes were produced as a product of the degradation.

Origin, transport, and retention of fluvial sedimentary organic matter in South Africa's largest freshwater wetland, Mkhuze Wetland System

Abstract. Sedimentary organic matter (OM) analyses along a 130 km long transect of the Mkhuze River from the Lebombo Mountains to its outlet into Lake St Lucia, Africa's most extensive estuarine system, revealed the present active trapping function of a terminal freshwater wetland. Combining bulk OM analyses, such as Rock-Eval®, and source-specific biomarker analyses of plant-wax n-alkanes and their stable carbon (δ13C) and hydrogen (δD) isotopic composition showed that fluvial sedimentary OM originating from inland areas is mainly deposited in the floodplain and swamp area of the wetland system but not in the downstream lake area. A distinctly less degraded OM signature, i.e., a considerably lower degree of transformation of unstable components (higher I index) and lower contribution of refractory and persistent fractions (lower R index) as well as recognizably higher δD values compared to samples from upstream sub-environments, characterizes surface sediments of Lake St Lucia. The offset in δD indicates that the contributing vegetation, although similar to upstream vegetation inputs in terms of photosynthetic pathway (δ13C) and alkane distribution pattern, experienced different hydrological growth conditions. The results suggest that under current conditions hinterland sedimentary OM is deposited throughout the wetland system up to the Mkhuze Swamps, which ultimately captures the transported OM. Consequently, samples from the downstream located Lake St Lucia show locally derived signals instead of integrated signals encompassing the river catchment. This finding raises important constraints for future environmental studies as the assumption of watershed-integrated signals in sedimentary archives retrieved from downstream lakes or offshore might not hold true in certain settings.

Organic biogeochemical study of deeper southeastern Bengal Basin sediments in West Bengal, India

The Bengal Basin is a fluvio-deltaic basin spanning Bangladesh and part of east and northeast India. The evolution of the peripheral foreland basin has been studied, but published literature on depositional conditions, source and maturity of organic matter in the deeper sediments of the Indian section of the basin is rare, despite the fact that natural gas is often encountered during hydrocarbon exploration. Our research assesses the depositional environment and source of the organic matter (OM) in the Pleistocene-Miocene sediments from five wells drilled by Oil and Natural Gas Corporation Limited in the southeastern Bengal Basin, West Bengal, India and aims to understand its maturity and potential to yield natural gas. The total organic carbon/nitrogen ratio and stable isotope (δ13C and δ15N) signature indicate primarily aquatic and C3 terrestrial plant sources of the OM and deposition under tidal flat and marshy environments. The n-alkane and isoprenoid alkane distribution are consistent with an autochthonous source of OM and terrestrial oxic-suboxic shallow-water depositional setting. The Rock-Eval parameters, such as maximal pyrolysis temperature, hydrogen and oxygen indices, indicate the immature nature of Type III and Type IV kerogen. The presence of methanogenic archaea, as indicated by phylogenetic analysis, in two Miocene sediment samples from one well indicates an active microbial activity in Type III immature OM, derived from C3 marsh vegetation and deposited under oxic shallow-water conditions. Our research describes the presence of methanogenic archaea for the first time in Miocene Bengal Basin sediments and is one of the few reports of their presence in deep (> 4000 m) horizons.

Nitrogen–Sulfur–Oxygen compounds in the study of oil migration in Block TW, eastern flank of the Oriente Basin, Ecuador

Nitrogen–Sulfur–Oxygen compounds of crude-oil samples were analyzed to study oil migration in Block TW. The 15 crude-oil samples of the Upper Cretaceous Napo Formation M1ss Member had similar geochemical characteristics; a similar normal alkane distribution mode (forward peak-single peak model); and similar terpane, hopane, and regular sterane distribution characteristics, which are similar to those of the Upper Cretaceous marl in the eastern flank. The nitrogen compounds of the crude oils from the M1ss Member in Block TW show a prominent geochromatographic effect-an obvious decrease in the total absolute abundance of pyrrole (a kind of biomarker), absolute abundance of exposed pyrrolic hydrogen. The ratios of “shielded pyrrolic hydrogen/exposed pyrrolic hydrogen” and “partially shielded pyrrolic hydrogen/exposed pyrrolic hydrogen” increase with oil migration while the ratios of “shielded pyrrolic hydrogen/partially shielded pyrrolic hydrogen” exhibited almost no change. The ratios of 1,8-/2,6-dimethylcarbazole, 1,4-/2,6-dimethylcarbazole, and 1,5-/2,6- dimethylcarbazole were good indicators of oil migration, which greatly decreased in short-distance migration in the Johanna reservoir and Alice West reservoir and could be used to semiquantitatively analyze the oil migration direction within the same reservoir. The main oil migration in Block TW was from southwest to northeast, and the geochromatographic effects between different reservoirs were not obvious, which might be the results of different oil charging points, different migration pathways, or the simultaneous supply of local and far sources. Heteroatomic compounds of oxyfluorene and thiofluorene series have strong biodegradation resistance and can assist in identifying the direction of oil migration. The variation trend of total abundance of oxyfluorene and thiofluorene in Block TW is similar to that of carbazole series compounds, but the migration fractionation effect is not as obvious as that of pyrrole series compounds. A set of parameters should be used in studying oil migration, which can be determined according to most of their variation trends. The ratios of 1,8-/2,6-dimethylcarbazole, 1,4-/2,6-dimethylcarbazole, and 1,5-/2,6-dimethylcarbazole in the M1ss Reservoir of Block TW have similar and obvious geochromatographic effects, which can be used as regional oil and gas migration indicators. The pyrrole compounds (particularly the carbazole series) have obvious geochromatographic effects along with oil migration, which could be used to analyze its direction, particularly in highly explored areas with several wells.

Indexes of tobacco smoke contribution to environmental particulates based on molecular fingerprints of alkanes.

Tobacco smoke (TS) is the source of a number of toxicants affecting the atmosphere and poses a threat to smokers and the whole community. Chemical, physical, and toxicological features of smoking products (vapors as well as mainstream, side stream, and third-hand smoke) have been investigated extensively. Special attention is paid to organic compounds (individually or in combination giving rise to peculiar molecular fingerprints), potentially able to act as “chemical signature” of TS. In this regard, the percent distribution of long-chainnormal, iso, and anteiso alkanes was ascertained as typical of TS. Nevertheless, until now no indexes have been identified as suitable for assessing the global TS contribution to environmental pollution, e.g., the TS percentage in carbonaceous aerosol and in deposited dusts, the only exception consisting in the use of nicotelline as tracer. This paper describes the results of an extensive study aimed at chemically characterizing the nonpolar lipid fraction associated to suspended particulates (PMs) and deposition dusts (DDs) collected at indoor and outdoor locations. Based on the iso, anteiso, and normal C29–C34 alkane profile in the samples as well in tobacco smoke- and no-TS-related emissions (literature data), various parameters describing the distribution of compounds were investigated. Finally, a cumulative variable was identified as the tobacco smoke impact index (TS%) suitable for estimating the TS percentage occurring in the particulate matter. The TS% rates were plotted vs. the exceedance of normal C31 alkane with respect to the average of C29 and C33 homologs, which results higher in TS than in most other emissions, revealing a link in the case of suspended particulates but not of deposited dusts. According to back analysis carried out on all particulate matter sets, it was found that traces of TS affect even remote areas, while inside the smokers’ homes the contributions of TS to PM could account for up to ~61% and ~10%, respectively, in PM and DD. This confirms the need of valuing the health risk posed by TS to humans, by means of tools easy to apply in extensive investigations.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-16617-0.

Model of hydrocarbon compounds distribution in pore space of bazhenov horizon

The article provides the results of the hydrocarbon compounds (HCS) molecular composition in open and closed pores of the Bazhenov horizon source rocks studying. Extraction with solvents of different polarity allows to withdraw additional HCS from both open and closed pores of rock samples, and their composition systematically differs both in the distribution of normal alkanes and in the values of biomarker parameters characterizing the maturity and sedimentary conditions. HCS in open pores is more thermally maturated than HCS in closed pores, and in both cases, maturity can decrease in blocked pores, especially in those sealed with soluble in alcohol-benzene resins-asphaltenes. The values of parameters Pr/Ph and dia/(dia+reg)C27 are higher for bitumen in open pores, but the values of C29/C30 and H35S/H34S are much higher for bitumen in closed pores, and can vary in blocked pores with respect to the open ones. As a result, a improved model of HCS distribution in the pore space was proposed, which shows the presence of residual light HCS in open pores, as well as two types of blocked pores, in which HCS are sealed by different resins-asphaltenes in both open and closed pore spaces.

Study on Preparation of Fuel Oil from Three Kinds of Molecular Sieve Catalytic Cracking Waste Lubricating Oil

Three different molecular sieves hy, Rey and self-made Ti-MCM-41 were used as catalysts to produce fuel oil from catalytic cracking waste lubricating oil, the effects of reaction temperature and catalyst dosage on the yield of liquid product were investigated, and the distribution of carbon atoms and the distribution of alkanes, olefins, cycloalkanes and aromatics in liquid products obtained by cracking reaction with different catalysts were analyzed. The results show that, under the condition of adding 0.35g catalyst to 100g waste lubricating oil at 400°C, the catalytic effect of Ti-MCM-41 is the best. The yield of liquid product is 69.6%, which is more suitable for cracking waste lubricating oil than hy and Rey. Different catalysts have different selectivity for the liquid products of cracking reaction, the carbon number in the liquid products obtained from Ti-MCM-41 catalytic cracking is the most widely distributed in the range of light components, in which the contents of alkanes, cycloalkanes and aromatics are relatively high, which is consistent with the main chemical components of gasoline, and does not contain olefins, compared with the liquid products obtained from hy and Rey catalytic cracking, it is more suitable to be used as the blending component of commercial gasoline.

Vertical Distribution of Alkanes in Atmospheric Aerosol in the Russian Arctic in September 2020

Vertical Distribution of Alkanes in Atmospheric Aerosol in the Russian Arctic in September 2020