Ratios Of Hydrocarbons Research Articles

Geochemical Parameters of Oil and Rock Samples from Murzuq Basin, Libya: An Application for Paleoenvironment Description

Seven sedimentary rocks and seven crude oils undertook a geochemical analysis to describe their organic matter type and then tag the Paleoenvironments based on the organic matter. The samples were collected from B1-NC151, A1-NC58, P1- NC1, E1-NC174, D1-NC151, H29-NC115, and D1-NC174 boreholes, located in Murzuq Basin. The study was established to understand life forms in the ecosystem based on biomarkers that biochemical techniques recognized. Microscopy was used for kerogen typing and Spore Color Index reference. Organic matter (EOM) was extracted from cutting samples. Furthermore, hydrocarbons were saturated and aromatic fractionated from the samples to investigate using Gas chromatograph system. Spore color index (SCI), range between 1.5-3.5, Amorphous organic matter (AOM) from 42 to 95 percentage, Phytoclasts % were 4-15.5, and Palynomorphs % range 0.5 to 7.5. The percentage of Carbon 85.66-86.29, Hydrogen 13.16-13.73, Nitrogen 0.06 -0.27, and Sulfur 0.31-0.70, besides wax were measured, ranging among 1.3 to 6.0 %. Pristine/n-C17, Phytane/n-C18, Pristine/Phytane, carbon preference index measurements (CPI) and DBT/P as saturated hydrocarbon ratios from whole oil chromatographs were established. Tricyclic terpanes, hopanes and n-alkanes were distinguishing as the most important oil biomarkers that reserved the characteristics in the Paleoenvironments.

Effect of Immersion Temperature on Reburning Characteristics of Coal with Different Preoxidation Degrees

ABSTRACT In light of the phenomenon where water immersion and high ground temperatures impact coal oxidation, this study conducted temperature-programmed heating and FTIR experiments to investigate the effect of water immersion temperature on the reignition characteristics of coal with varying preoxidation levels. The results show that the overall oxygen consumption capacity of coal reburning is strong with the increase in water immersion temperature at 180°C and 230°C. When the water immersion temperature is 50°C, the -CH3/-CH2- value of coal is higher than that of water immersion at 30°C and 40°C, and the maximum difference in aliphatic hydrocarbon ratio before and after reburning is 1.64%. When the temperature of pre-oxidation and immersion is 180°C and 50°C, respectively, the hydroxyl content decreases by 17.73% before and after reburning. The carbonyl content in coal after reburning exhibits varying decreasing trends under different treatment conditions. When immersed in water at 40°C, the carbonyl content in coal decreases more rapidly before and after reburning.

Diagnostic ratios of polyaromatic hydrocarbons for the identification of pollution sources in clams from Okwagbe, Delta State Nigeria

Diagnostic ratios of polyaromatic hydrocarbons for the identification of pollution sources in clams from Okwagbe, Delta State Nigeria

Effect of polyethylene terephthalate plastics on nitrogen, sulphur and chlorine contaminants via sludge pyrolysis and Pb/Cu adsorption properties of biochar

ABSTRACT Pyrolysis is an effective process for disposing of municipal sewage sludge (SS). Plastics can affect the SS pyrolysis behaviour and pyrolysis products due to their low ash and high hydrocarbon ratio. The secondary pollutants from the pyrolysis process may also be affected. Therefore, polyethylene terephthalate (PET), a typical plastic, was chosen to investigate the release characteristics of pollutants containing nitrogen, sulphur, and chlorine via SS pyrolysis, and the changes of biochar to adsorb two typical heavy metals, Pb and Cu. The pyrolysis of PET plastics facilitates the migration of N toward solid and liquid-phase products, S and Cl to the gas-phase products via pyrolysis. Oxygenated compounds of pyrolytic volatiles decreased from 38.18% to 28.43%, concurrently promoting the formation of phenolic compounds. The co-pyrolysis improved the quality of biochar and the ability to adsorb Pb and Cu. This systematic study can provide some support for the further improvement of SS pyrolysis technology, and will also be beneficial for subsequent applications.

PH-switchable hydrophobic deep eutectic solvents for sustainable recycling extraction of high oily waste

The accumulation of oily waste increases annually with the growth in crude oil demand. Its toxicity and high heating value present both opportunities and challenges for treatment technologies. In recent years, the emergence of hydrophobic deep eutectic solvents (HDES) has promoted advancements in low-toxicity extraction processes. Leveraging the advantages of HDES and addressing the challenges posed by real oily sawdust (with a 67.9 % oil content), this study presents a novel green HDES solvent composed of ethyl maltol and fatty acids, accompanied by a corresponding extraction process. At a low temperature of 60 °C, the process achieved impressive results: an oil extraction efficiency close to 86.3 %, a dehydration rate exceeding 92.2 %, and a heavy metal removal rate ranging from 15 % to 75 %. In the exploration of solvents recycling, pH-switching facilitated the deprotonation and protonation of phenol-fatty acid HDES, promoting effective recovery of the oil phase. Even after 5 cycles, the oil extraction rate could still be maintained above 75 %. It is worth noting that the regenerated HDES exhibited greater selectivity for extracting light oil after multiple uses. The total ratio of saturated and aromatic hydrocarbons reached approximately 81.7 %, significantly enhancing the value of the recovered oil. Integrating systematic characterization with the extraction performance, as well as the variation in recovered oil phase components, highlighted the multifaceted effects of introducing ethyl maltol. Specifically, this effect is demonstrated in its ability to enhance the oil phase’s solubility by regulating the intermolecular spacing of HDES, and to impede the dissolution of heavy oil into its gaps by optimizing the local zone through the formation of complexes with HDES and heavy metals.

A Novel Method to Calculate Water Influx Parameters and Geologic Reserves for Fractured-Vuggy Reservoirs with Bottom/Edge Water

In practical oilfield production, the phenomenon of water influx typically shortens the water-free recovery period of wells, leading to water flooding and causing a sharp decline in the production well yields, bringing great harm to production. Water invasion usually occurs as a result of the elastic expansion of the water as well as the compaction of the aquifer pore space. However, it can be due to the special characteristics of fractured-vuggy reservoirs such as non-homogeneity and the discrete distribution of the pore spaces. It is challenging to use traditional seepage flow theories to analyze the characteristics of water influx. Also, reservoir numerical simulation methods require numerous parameters which are difficult to obtain, which significantly reduces the accuracy of the results. In this study, considering the driving energy for water influx, a water influx characteristic model was obtained by fitting a graph plate. Subsequently, an iterative calculation method was used to simultaneously obtain water influx volume and OOIP. The aquifer to hydrocarbon ratio was determined by fitting the water influx curve with the graphic plate. Results show that the calculation method is sensitive to the values of reservoir pressure and the crude oil formation volume factor. After applying the method to one field case, it was discovered that water influx performance can be characterized into two types, i.e., linear water influx and logarithmic water influx. In the early stages, the water influx rate of logarithmic water influx is greater compared to linear water influx. However, the volume and energy of waterbody are limited, and the water invasion phenomenon occurs almost exclusively within a short period after the invasion. On the other hand, the volume of waterbody invaded by linear water influx is larger, and it can maintain a stable rate of water influx. The results of the study can provide theoretical support for the waterbody energy evaluation and dynamic analysis of water influx, as well as the control and management of water in these types of reservoirs.

Simulation of DME-O2 Combustion in a Hollow Cone Impinging Jet Combustor for Direct-Fired Supercritical CO2 Power Cycle

ABSTRACT Combustion is critical in the direct-fired supercritical CO2 power cycle. A hollow cone impinging jet combustor is designed. Instead of methane, dimethyl ether is used as the fuel for the direct-fired supercritical CO2 cycle, with a higher hydrocarbon ratio and oxygen. The dimethyl ether combustion process is simulated by Fluent, based on the k-ε turbulence model and Eddy-Dissipation Concept combustion model, combined with the dimethyl ether combustion mechanism. The effects of the CO2 recycling ratio, the excess oxygen coefficient, and in-combustor pressure are investigated to support improving combustion performance. The results indicate that the recycled CO2 intensifies the movement of the mixture in the combustor, reduces the peak temperature, and makes temperature distribution more uniform. As the excess oxygen coefficient increases, the peak temperature is enhanced, and the combustion is more sufficient. The effect of in-combustor pressure is complex. On the one hand, increasing in-combustor pressure reduces the jet penetration and inhibits the contact between dimethyl ether and O2, leading to a lower peak temperature. On the other hand, it prolongs the residence time of the high-temperature exhaust, making the reaction between dimethyl ether and O2 more sufficient. The optimal operating condition of the combustor is a CO2 recycling ratio of 0.95, an excess oxygen coefficient of 1.20, and an in-combustor pressure of 30 MPa. Moreover, the obtained combustion products parameters, such as temperature, component concentration, and mass flow rate, can guide the performance analysis for the direct-fired supercritical CO2 power cycle.

Effect of Equivalent Ratio and Hydrocarbon Ratio on Explosive Characteristics of Synthetic Gas

With the development of society, the importance of energy is increasing day by day, and more and more people realize the importance of energy for social development.Therefore, people began to explore energy utilization, energy exploitation, clean energy and other fields.Therefore, in order to use coal resources cleanly and efficiently and reduce the damage to the environment, the development of clean coal technology is particularly important.As a kind of clean energy, syngas has been paid more and more attention, so people pay more and more attention to the safety application of syngas. This paper explores its influence on syngas explosion by changing the equivalent ratio of syngas and the ratio of hydrogen and hydrogen.The results show that the maximum explosion pressure of syngas occurs near the equivalent ratio 1.2, the maximum explosion pressure rise rate reaches the maximum near the equivalent ratio 1.5, and the maximum explosion pressure time reaches the minimum near the equivalent ratio 1.5.The change of hydrocarbon ratio does not shift the equivalent ratio of the above result, but only changes its value. The prediction equations for predicting the maximum explosion pressure under different equivalent ratios are obtained

Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction. Thus, a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents. Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions. In this study, the composition and content of liquefied solvents were analyzed. As model compounds, hexadecane, toluene, naphthalene, tetrahydronaphthalene, and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic, bicyclic, and tricyclic aromatic hydrocarbons. The solubility of hydrogen X (mol/mol) in pure solvent components and mixed solvents (alkanes and aromatics mixed in proportion to the chain alkanes + bicyclic aromatic hydrocarbons, bicyclic saturated aromatic hydrocarbons + bicyclic aromatic hydrocarbons, and bicyclic aromatic hydrocarbons + compounds containing heteroatoms composed of mixed components) are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa. The results demonstrated that at high temperatures and pressures, the solubility of hydrogen in the solvent increases with the increase in temperature and pressure, with the pressure having a greater impact. Furthermore, the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents, and the solubility of eicosanoids reaches a maximum of 0.296. The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number. The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons. The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents. Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

Optimizing the Preparation Process of Refined Asphalt Based on the Response Surface and Preparation of Needle Coke.

Refined asphalt was prepared by solvent extraction sedimentation based on the response surface design, using washing oil and kerosene as solvents and the coal tar pitch as raw materials. The mathematical models of the refined asphalt yield, quinoline insoluble (QI) content, ash content, solvent-to-oil ratio, aromatic-to-aliphatic hydrocarbon ratio, extraction temperature, and sedimentation time were proposed, analyzing the influence of each factor and their interactions on the response values. Therefore, the optimal combination of preparation process parameters and better operation window was obtained by optimizing the experiment. Meanwhile, refined asphalt with high QI content and low QI content was selected as raw material, and the needle coke was prepared through the process of carbonization and calcination. The influence of QI content on the composition and the structure of green coke and needle coke was investigated by X-ray diffraction (XRD), Raman spectra, and polarizing microscopy characterizations. The results showed that the solvent-to-oil ratio is 1.2, aromatic-to-aliphatic hydrocarbon ratio is 1.1, sedimentation time is 2 h, and extraction temperature is 110 °C, resulting in the yield of refined asphalt being 76%, QI content being less than 0.1%, and ash content being less than 0.05%, which meets the requirement of the high-quality needle coke. Otherwise, refined asphalt with lower QI content easily generates a mesophase with more fibers and a large structure in the thermal conversion process, and the corresponding green coke and needle coke have a relatively regular carbon microcrystalline structure.

Characterising flame-retardant mechanism of phosphorous-containing intumescent coating on polyethylene via ReaxFF MD simulations

Localised flame-retardant (FR) chemistry of polymer composites is complex, versatile and microscopic depending on the combination of polymer matrix and various FR systems. Particularly, the pyrolysis behaviour of the polymers can be varied and reinforced by effective microscopic synergistic effects between coating compositions. However, these atomistic reactions can be difficult to be characterised via experimental approaches. In this study, experimental studies and reactive molecular dynamic (ReaxFF-MD) simulation techniques were utilised to identify the thermal degradation behaviour of flame retarded high-density polyethylene (HDPE), coated with phosphoric acid (PA) and pentaerythritol (PER). The simulations tracked the pyrolysis product distribution under different heating temperatures and elucidated the pyrolysis hindrance offered by the FR system. The atomistic reaction pathways of phosphorus-based FR mechanism were also characterised, including secondary reactions and intermediate species, such as P-O-C and P-O-P cross-linking between FRs and radical capturing effects. These reactions were found to be increasing the C/H ratios of pyrolysed hydrocarbons and the aromaticity of residues. After applying the periodic removal techniques, the simulations can even predict the residue weight percentage of the polymer and exhibit similar degradation behaviour to the experimental results.

Hydrocarbons in bottom sediments of coastal waters of the Kazantip peninsula (Azov Sea)

The aim of the article is to study the bottom sediments of the coastal zone of Kazantip peninsula in the Sea of Azov of complexes of hydrocarbon pollution. This water area is a site with a high level of recreational load, despite the presence of a nature reserve there, and is also characterized by a rugged coastline, which causes the accumulation of pollution in bottom sediments. The material for the study was samples of the upper layer of bottom sediments, which were taken in the summer of 2021 in the coastal waters of Cape Kazantip (Sea of Azov) with a manual sampler from depths of up to 1.5 m both within the protected area and beyond its borders. Determination of hydrocarbons in bottom sediments was carried out by gas and liquid chromatography in accordance with certified methods. The paper presents new original materials on the distribution of hydrocarbons in bottom sediments in the area of Kazantip peninsula, as well as an assessment of the local level of pollution of marine soils in this area. The ratio of hydrocarbons of different origin in bottom sediments is given. In addition, possible ways and sources of pollution are indicated. As a result of the study, it was shown that the bottom sediments of the coastal zone of Kazantip peninsula are not polluted and the concentrations of the main groups of hydrocarbons are within the range of average values for the Sea of Azov. But, despite this, there are traces of fresh inflows of petroleum hydrocarbons, which can be of both anthropogenic and natural origin.

General Methods for the Analysis of Physical Properties of Fuels

This article is another in a series of articles focused on introducing general methods for evaluating conventional and alternative fuels. The text presents an overview of the physical properties determined for liquid and gaseous fuels. Additionally, methods for determining these properties are presented. The significance of individual determinations is also discussed. Emphasis is placed particularly on standardized parameters and tests, but in some cases, tests that are not required by the relevant standards are also discussed. The main goal of the article is to provide a comprehensive overview of which physical properties are monitored for each fuel, why these properties are monitored, and what methods are used for this purpose. The article provides an overview of monitored physical properties for liquid and gaseous alternative fuels. Regarding the physical properties, density at 15 °C is practically monitored for all discussed liquid fuels. Only for E95 fuel, the density at 20 °C is prescribed. Kinematic viscosity at 40 °C is monitored for all diesel engine fuels, while there are no prescribed viscosity limits for gasoline fuels. For Jet A-1 fuel, the relevant ASTM standard pre-scribes the maximum value of kinematic viscosity at -20 °C. Distillation characteristics are prescribed for all fuels except E85, E95, rapeseed oil, and FAME. It should be noted that for FAME and fuels based on vegetable oils, the simulated distillation method is often used as a complementary method. Vapor pressure is monitored for fuels containing volatile components, including E5 and E10 gasoline, E85 fuel, and LPG. Seasonal values for vapor pressure are prescribed for E5, E10, and LPG fuels, representing values for summer and winter periods. The vapor pressure of LPG is regulated by the ratio of C3 and C4 hydrocarbons in the mixture. Flash point characterizes the fuel from a fire safety perspective and is determined for petroleum-type fuels (B7-B30, FAME, SMN 30, and paraffinic diesel), as well as for rapeseed oil and E95 fuel. Except for E95 fuel, which is determined using an open cup method, all other fuels use closed cup methods. Lubricity is determined for aviation kerosene, motor diesel fuels B7 and B10, blended motor diesel fuel SMN 30, and paraffinic diesel. Low-temperature properties are determined for petroleum-type fuels, aviation kerosene, and marine fuels. The crystallization point is determined for aviation kerosene. For fuels B7-B30, FAME, SMN 30, and paraffinic diesel, prescribed values include the temperature of wax precipitation and CFPP (Cold Filter Plugging Point).

Geochemistry of oils and condensates from the lower Eagle Ford Formation, south Texas. Part 5: Light hydrocarbons

There is a rich history of using light hydrocarbon distributions to characterize source and thermal maturity based on observations made on source rocks and petroleum fluids produced from conventional reservoirs. In this study, a suite of lower Eagle Ford oils and condensates was used to determine the accuracy and reliability of established light hydrocarbon parameters in an unconventional petroleum system. These samples have well defined organic source facies, generative temperatures, and extent of thermal cracking. They are largely free of the influence of long-distance migration, multiple charging events, reservoir alteration processes that commonly occur in conventional accumulations and free of contributions from other reservoirs along faults induced by fracturing.All established light hydrocarbon thermal maturity parameters are influenced to varying degrees by source facies. Ratios of i-C4/n-C4 and quaternary/tertiary dimethylpentanes linearly correlate with %Ro (R2 > 0.8) with negligible sensitivity to differences in source facies. The Isoheptane and C6–C7 branched/(branched + cyclic) hydrocarbon ratios correlate with %Ro (R2 > 0.8) but also are influenced by source facies. Some established C7 parameters are affected by thermal cracking: i-C5/n-C5 and toluene/n-C7 are the most sensitive ratios to the onset of intense hydrocarbon cracking (∼1.35 %Ro) and do not appear to be significantly influenced by source facies, C6–C7 branched/(branched + normal) hydrocarbons and methylcyclohexane/n-C7 both increase in response to cracking conditions but are significantly influenced by source facies, which is likely related to the presence of reactive clays. A revised formula for Ctemp is proposed: Ctemp = 161.9 + 29.4•(ln[2,4-DMP/2,3-DMP]). The revised Ctemp formula is applicable for oils/condensates with 2,4-DMP/2,3-DMP >0.25, expanding the practical limit from ∼120 to ∼160 °C, and yields Ctemp values consistent with the maximum exposure temperature with an accuracy of ∼ ±5 °C for most samples, excluding those that have been altered by evaporation. The Mango (1997) Ctemp formula should be used for lower maturity oils having DMP/2,3-DMP values < 0.25. Sample integrity is critical as many of the light hydrocarbon parameters are significantly altered by evaporative loss.

New insights on black carbon in pelagic Atlantic sediments

Black carbon (BC) is ubiquitous in pelagic sediments and presumed to have an older radiocarbon age due to long ocean residence times and pre-aging in terrestrial soils. Here, we analyzed sediments from five regions in the subtropical Atlantic Ocean to quantify the black carbon fraction of the total organic carbon pool. Black carbon, derived from the chemothermal oxidation method, comprised between 17 ± 6% of the sedimentary organic carbon in the Northwest Argentina Basin and 65 ± 18% in the Amazon Delta. Black carbon sediment accumulation rates were six times greater in the Sierra Leone Rise (8.4 ± 4.1 mg cm−2 kyr−1) compared to the remote Northwest Argentina Basin (1.3 ± 0.4 mg cm−2 kyr−1), possibly due to enhanced regional atmospheric deposition from annual African grassland fires. The radiocarbon age for BC from subtropical Atlantic sediments were more modern compared to the bulk total organic carbon, and BC source was apportioned as biomass burning byproducts from their stable carbon isotopic signatures and characteristic ratios of polycyclic aromatic hydrocarbons. This study demonstrated that subtropical Atlantic Ocean sediments serve as an important sink for young BC.

Synergistic Catalysis of Reservoir Minerals and Exogenous Catalysts on Aquathermolysis of Heavy Oil

In this study, based on existing heavy oil extraction technology, combined with the mineral composition in a reservoir, the synergistic catalytic effect of reservoir minerals and exogenous catalysts under the reaction system of a hydrogen-rich environment not only reduces the viscosity of thick oil but also reduces the extraction cost and further improves the recovery rate of heavy oil. In this study, the impacts of different reservoir minerals and exogenous catalysts on the aquathermolysis of heavy oil were investigated. The research results showed that the sodium montmorillonite within the reservoir minerals exhibited an optimal catalytic effect, and the synergistic catalytic effect of sodium montmorillonite and catalyst C-Fe (catechol iron) resulted in a viscosity reduction rate of 60.47%. Furthermore, the efficiency of different alcohols as hydrogen donors was screened, among which ethanol had the best catalytic effect. Under the optimal reaction conditions, the viscosity reduction rate after the addition of ethanol was 75.25%. Infrared spectroscopy, elemental analysis, thermogravimetry, and differential scanning calorimetry were used to study the changes in heavy oil before and after hydrothermal cracking. Element analysis showed that the synergistic catalytic effect of sodium-based montmorillonite and catalyst C-Fe increased the hydrocarbon ratio from 0.116 to 0.117, and the content of S and N elements decreased. This fully confirms the catalytic effect of sodium-based montmorillonite and C-Fe catalyst for he hydrogenation reaction of the unsaturated carbon in heavy oil.

Organic matter input, paleovegetation and paleoclimate of Upper Cretaceous lignite from Maiganga coalfield, Upper Benue Trough, Nigeria: Insights from biomarkers and stable isotopes

Upper Cretaceous Gombe Formation coals from Maiganga coalfield, Upper Benue Trough, Nigeria were investigated to evaluate the thermal maturity, organic matter input, paleovegetation, paleoclimate, and depositional environment using bulk and molecular geochemical techniques. Vitrinite reflectance (<0.40 %Ro) and biomarker maturity indicators (C31 homohopane 22S/(22S + 22R) < 0.3; 16(H) β/(β+α) phyllocladane <0.5; MPI-1 < 0.5; MPR <2.65) generally signify low thermal maturity. Source-related aliphatic and aromatic hydrocarbon ratios indicate that the coals are derived mainly from terrestrial organic matter but with considerable input from marine algal organic matter. The higher abundance of diterpenoids over triterpenoids and sesquiterpenoids suggests a prevailing contribution of gymnosperms to the Maiganga paleoflora. This is corroborated by the relatively heavier carbon isotopic composition (δ13C = −25.9‰ to −25.0‰) and low angiosperm/gymnosperm ratios. A new proxy, the polycyclic aromatic hydrocarbon ratio (PAHr) which is calculated from PAHr = (phenanthrene + pyrene + fluoranthene + perylene)/(phenanthrene + pyrene + fluoranthene + perylene + retene + cadalene), was proposed to evaluate the abundance and origin of combustion-derived polycyclic aromatic hydrocarbons (PAHs). The mostly high (>0.9) PAHr values for the coals are characteristic of a pyrogenic/combustion origin. Combustion-derived PAHs are abundant in the coals and their ratios indicate a mixed petrogenic/pyrogenic to dominantly pyrogenic origin. However, the high proportion of unburnt organic matter and low abundance of 7-ring PAHs such as coronene indicates limited, high-temperature wildfires. The coronene index values suggest burning temperature in the 700–1000 °C range, which is consistent with the estimated high pO2 of ∼26.5% in the Maastrichtian. n-Alkane proxies (Pwax, Paq, n-C23/n-C29, n-C27/n-C31, etc.) and hydrogen isotope ratios (−117‰ to −112‰) are suggestive of humid paleoclimate with frequent dry periods and lower paleopeat water levels. Moderately high pristane/phytane ratios (2.0–4.8) indicate deposition under sub-oxic to oxic freshwater settings. Additionally, low total sulphur content (0.29–0.90) and dibenzothiophene/phenanthrene ratios (0.05–0.17) imply peat accumulation in lacustrine-swamp to fluvial/deltaic depositional environments with minor post-depositional marine influence.

Effect of K-promoter use in iron-based plasma-catalytic conversion of CO2 and CH4 into higher value products

In the new field of plasma-catalytic synthesis, iron-based catalysts have been intensively studied but no study was reported on the use of potassium promoter although it is widely used in thermo-catalytic synthesis. In this frame, we study the effect of K-promoter on iron-based plasma-catalytic conversion of CO2 and CH4 into higher value products, through a series of experiments with and without potassium. As expected, K-promoter increases the selectivity of unsaturated hydrocarbons but also that of long-chain oxygenates (C3 + acids and alcohols), by changing the H-adsorption property of the catalyst. Based on this selectivity tuning way, this paper proposes a first process optimization attempt for maximizing at the same time the production of liquid products and the share of unsaturated hydrocarbons. Coproduction of high quality syngas (H2/CO∼2.0), C2 + hydrocarbons and C1 + oxygenates with 5.10% CO2 and 12.65% CH4 conversions, 21.76% liquid selectivity and unsaturated over saturated hydrocarbons ratio close to 1.

Ecological indicators and source diagnostic ratios of aliphatic and polyaromatic hydrocarbons in marine sediments of Qatar

The marine ecosystems surrounding oil and gas production sites are particularly vulnerable to ecological harm that may be affected by its operations. In this study, we examined the composition, contaminant sources, and the potential ecological risk of aliphatic hydrocarbons (AH) and polyaromatic hydrocarbons (PAH) in the marine sediments along the western coast of Qatar. The ΣAHs concentration ranged from <0.10 to 246 ng⋅g−1 (site SD2) while the ΣPAH concentration ranged from <0.10 to 44 ng⋅g−1 (site SD10). Pollution concentration profile was site specific where AH and PAH concentrations were relatively higher within close proximity to the oil and gas production. TOC appeared to be positively correlated with PAH and therefore a good indicator for PAH but not for AH. Low molecular weight even-carbon numbered alkanes (n-C10-18) were more abundant than the higher molecular weight (n-C20-34) AHs. The Σ16PAHs compositional analysis mean concentrations were composed of 2-ring (6%), 3-ring (18%), 4-ring (48%), 5-ring (28%), and 6-ring (0.14%), respectively. Fluoranthene obtained the highest concentration of 11 ng⋅g−1 (site SD10). Diagnostic ratios and hydrocarbon parameters suggested mixed sources of petrogenic, pyrolytic, and biomass except for vehicular traffic. The overall results for AH and PAH indicated low pollution based on pollution criteria and were below the threshold limit set by the National Oceanic and Atmospheric Administration (NOAA) and the Canadian Sediment Quality Guidelines (CSQG). This suggests low probability of a negative toxic effect caused by these contaminants however, continuous long term-monitoring is needed to ensure these pollutants do not exceed the current levels.

Maceral and Organic Geochemical Characteristics of the No. 6 Coal Seam from the Haerwusu Surface Mine, Inner Mongolia, China

Haerwusu Surface Mine of the Jungar Coalfield is a large coal mine. Its coal formation environments have not been reported in detail. In order to reconstruct the paleoenvironment of the peat formation, nine samples were collected, and were analyzed using microscope, column chromatography, gas chromatography (GC), and gas chromatography–mass spectrometry (GC–MS). According to the results of the microscopic analysis, the average random vitrinite reflectance ( Rr) is 0.73%, indicating a low rank bituminous coal. Vitrinite group is the predominant macerals with an average content of 54.54%, followed by inertinite group with an average of 35.99%. The higher inertinite contents indicate widespread wildfire events during the peat formation. The distribution pattern of n-alkanes, the cross plot between Pr/ n-C17 and Ph/ n-C18, the lower saturated/aromatic hydrocarbon ratios (0.22–0.68) and the presence of cadalene, retene, simonellite indicates that the organic matter is predominantly terrestrial higher plants with a small amount of aquatic organisms. The ternary diagram of Pr/Ph, Pr/ n-C17 and Ph/ n-C18 and the relative abundance of fluorene, dibenzofuran and dibenzothiophene indicate a continental–oceanic alternative facies. The higher contents of combustion-derived PAHs are also indicative of widespread wildfire events during peat formation.