Higher Hydrocarbons Research Articles

Geospatial analytics of driving mechanism of land subsidence in Gulf Coast of Texas, United States

Land subsidence has been an ongoing issue for over a century along the Gulf Coast of Texas in the United States. This study assesses and models the factors contributing to land subsidence covering fifty-six (56) counties along the Gulf of Mexico coastline from Louisiana to the border of Mexico, approximately 300,000 km2. Geospatial statistical techniques and regression models were employed to investigate and predict the fundamental causes of land subsidence by integrating multiple datasets such as Global Navigation Satellite System (GNSS) (147 stations), groundwater extraction (78,420 wells), hydrocarbon production (84,424 wells), precipitation, and population growth. In the last two decades, the overall population rose by 33 % and the compound annual population growth rate increased from 2.08 to 4.10 % in Montgomery, Waller, Fort Bend, and Chambers counties. Emerging hotspot analysis reveals that the groundwater level is persistently declining and the regression model (R2 = 0.92) tested over Harris County predicts that the population growth significantly contributes to land subsidence in this region. The groundwater withdrawal rate is increased from 23 to 96.6 billion gallons in Harris, Montgomery, and Fort Bend counties in the last two decades. A prolonged drought from 2010 to 2015 due to low precipitation affected all fifty-six counties. Oil production increased eightfold and a high extraction rate of 19.5 to 40.1 million bbl/yr of oil in Karnes County was recorded within the last 20 years. The regression model (R2 = 0.73) over this county suggests that oil extraction is a primary contributing factor to the observed subsidence. Although the gas extraction rates for all counties are decreasing over time, some counties in the southern part of the Gulf Coast Aquifer show relatively higher extraction rates. For the first time, this research determines that all fifty-six counties along the Gulf Coast of Texas are undergoing land subsidence and experiencing high population growth, groundwater withdrawal, and hydrocarbon extraction.

Ignition and Combustion of Synthetic High Molecular Weight Hydrocarbons in High-Enthalpy Air Flow

Ignition and Combustion of Synthetic High Molecular Weight Hydrocarbons in High-Enthalpy Air Flow

Effect of multilayered catalytic bed on temperature profiles and catalytic performance for Fischer–Tropsch synthesis over Co/Al2O3 catalyst in a multitubular fixed-bed reactor

Fischer-Tropsch synthesis (FTS) is a widely recognized process that catalytically converts syngas into higher hydrocarbons and oxygenates, which are ultimately upgraded into transportation fuels and chemicals. Effective temperature control and heat dissipation are crucial considerations due to the exothermic nature of the FT reaction. Underutilization of the catalytic bed is another challenge in fixed-bed reactors. The implementation of a multilayered catalytic bed, with the catalytic activity in an ascending order, has shown positive effects in addressing these issues. It mitigates adiabatic temperature rise, reduces the maximum reactor temperature, and minimizes catalyst deactivation at high temperatures. Moreover, this multilayered bed effectively addresses the underutilization issue by ensuring optimal utilization of the entire bed as the catalytic activity transitions from one layer to another during the reaction. Layers with a higher cobalt loading remain active until the completion of the reaction, resulting in minimal fluctuations in CO conversion. To achieve uniform temperature profiles, catalytic activities, and product distributions in all reactor tubes in a multitubular reactor, it is imperative to maintain consistent reaction conditions, utilize the same catalyst loading in all tubes, employ an appropriate heating system, and implement an efficient cooling system to dissipate the heat generated by the exothermic reaction. Furthermore, investigations into the properties of the used catalysts after the reaction indicate that catalyst deactivation primarily occurs due to the deposition of FT products on the catalyst surface and pores and blockage of active cobalt sites, and sintering of cobalt particles.

Dry Methane Reforming in a Piston Engine for Chemical Energy Storage and Carbon Dioxide Utilization: Kinetic Modeling and Thermodynamic Evaluation

The flexible energy conversion in piston engines offers one possibility for storing energy from renewable sources. This work theoretically explores the engine‐based dry methane reforming converting mechanical energy into chemical energy. The endothermic, endergonic reforming process is activated by the temperature increase during the compression stroke, assisted by a reduction of the heat capacity through dilution with argon. This leads to an increase in chemical exergy, as higher‐exergy species are produced with small exergy losses while simultaneously consuming CO2. The engine‐based homogenous dry reforming serves as a flexible power‐to‐gas process and energy storage solution, presenting an alternative to catalytic processes. The piston engine is simulated using a time‐dependent single‐zone model with detailed chemical kinetics, followed by an analysis of thermodynamics and kinetics. With inlet temperatures ranging from 423–473 K and argon dilutions of 91–94 mol%, CH4 and CO2 conversion are between 50%–90% and 30%–80%, respectively, resulting in synthesis gas yields of 45–55%. Additionally, higher hydrocarbons such as C2H2, C2H4, and C6H6 are produced with yields of up to 20%, 10%, and 10%. So, this power‐to‐gas process allows for exergy storage of up to 3.35 kW L−1 per cycle with an efficiency of up to 75%.

Anaerobic biodegradation of pyrene and benzo[a]pyrene by a new sulfate-reducing Desulforamulus aquiferis strain DSA

The study of anaerobic high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) biodegradation under sulfate-reducing conditions by microorganisms, including microbial species responsible for biodegradation and relative metabolic processes, remains in its infancy. Here, we found that a new sulfate-reducer, designated as Desulforamulus aquiferis strain DSA, could biodegrade pyrene and benzo[a]pyrene (two kinds of HMW-PAHs) coupled with the reduction of sulfate to sulfide. Interestingly, strain DSA could simultaneously biodegrade pyrene and benzo[a]pyrene when they co-existed in culture. Additionally, the metabolic processes for anaerobic pyrene and benzo[a]pyrene biodegradation by strain DSA were newly proposed in this study based on the detection of intermediates, quantum chemical calculations and analyses of the genome and RTqPCR. The initial activation step for anaerobic pyrene and benzo[a]pyrene biodegradation by strain DSA was identified as the formation of pyrene-2-carboxylic acid and benzo[a]pyrene-11-carboxylic acid by carboxylation Thereafter, CoA ligase, ring reduction through hydrogenation, and ring cracking occurred, and short-chain fatty acids and carbon dioxide were identified as the final products. Additionally, DSA could also utilize benzene, naphthalene, anthracene, phenanthrene, and benz[a]anthracene as carbon sources. Our study can provide new guidance for the anaerobic HMW-PAHs biodegradation under sulfate-reducing conditions.

In Ukrainian

The goal of the research work was the pyrolytic synthesis of straight and spiral carbon nanotubes of approximately the same diameter, as well as their comprehensive analysis. To solve the given problem, a new installation for the pyrolytic synthesis of carbon nanostructures (CNS) with a fusion reactor, which for each fusion process can have its own angle relative to the classical horizontal position of the reactor axis. This reactor made it possible to develop a method for obtaining conglomerates of spiral-shaped multi-walled carbon nanotubes with a diameter of 15–60 nm and to synthesize straight multi-walled carbon nanotubes with a diameter of 5 to 60 nm. The research of pyrolytic synthesis of carbon nanostructures in a vertical reactor allows to work out the technology of purposeful synthesis of nanotubes that have a spiral shape with a certain diameter and pitch of the turn. As part of the work, a new mechanism for the formation of spiral multi-walled carbon nanotubes is also considered and proposed, which is important for their further industrial synthesis and their use in related composites. A scheme is proposed of conditions for the synthesis of carbon nanostructures by the pyrolytic method. Thermal analysis was carried out in the work, which recorded the presence of two different structures with low thermal stability (probably amorphous carbon and higher hydrocarbons). When using scanning and transmission electron microscopy, the formation of spiral nanofibers with a diameter of 15–60 nm in the vertical position of the reactor was recorded, and in the horizontal position of the reactor, the formation of straight and slightly curved MWCTs with a diameter of nanofibers from 5 to 60 nm was found. Raman spectroscopy confirms the presence of multi-layered carbon tubular formation, i.e. MWCT, in both synthesis products.

Deciphering the laminated botryococcus-dominated shales in saline lacustrine basin, Western Qaidam Basin, NW China: Implications for shale oil potential

Given the high lipid content and potentially huge biomass, the explosive occurrence Botryococcus is regarded as a significant marker of high-quality oil source rocks in petroliferous basins. However, they are rarely discovered in saline lacustrine source rocks, and the formation mechanism of these alga-rich shales remains uncertain. In this study, abundant Botryococcus fossils were firstly found, accounting for an average of 43.5% of the total organic debris from the upper Xiaganchaigou Formation in the Yingxiongling and Zhahaquan hydrocarbon-rich sags of the western Qaidam Basin. The Botryococcus-dominated palynofacies assemblages were usually interpreted as derived from a distal oxic shelf environment. These Botryococcus-dominated sediments were characterized by a perfect laminated texture and composed of detrital, carbonate, and clay laminae. The Botryococcus fossils exclusively occur in the detrital laminae with large-grained quartz and feldspar and low carbonate content, possibly reflecting increased river input under relatively heavy precipitation. The cyclothymic deposition between these Botryococcus-rich detrital laminae and other laminae probably indicates that sufficient terrestrial nutrient inputs and lake salinity decreases driven by periodic heavy precipitation result in Botryococcus bloom under fresh or brackish water environments. These Botryococcus-dominated shales in the western Qaidam Basin usually have a high oil-prone hydrocarbon generation potential, as evidenced by their organic geochemistry parameters. These sediments have biomarker features extremely similar to crude oil with a high relative abundance of C20–C24 tricyclic terpanes, phytane, C27ααR sterane, and a unimodal distribution of n-alkanes with the maximum at n-C18. Therefore, these Botryococcus-dominated shales are possibly important oil sources of these prolific oil sags. Additionally, these high-quality source rock sequences can reach a few tens of meters in thickness and evidently have significance for future shale oil resources.

Exploring Reservoir Potential of the "X Field" Offshore, Niger Delta Basin: An Emphasis on Lithofacies, Depositional Environments, and Petrophysical Characteristics

The geological circumstances under which sediments are built throughout time are referred to as depositional environments. The features of the sediment, such as its texture, composition, and permeability, are influenced by these depositional environments, and these qualities ultimately define the reservoir quality. This study focuses on identifying reservoirs in the western offshore region of Nigeria's Niger Delta Basin and evaluating their properties, such as lithofacies, distribution, and petrophysical characteristics like porosity and permeability, using well log analysis. By utilizing relevant and easily accessible well log data, the depositional environment and quality of the reservoir were evaluated. The data analysis involved examining gamma-ray log patterns, spontaneous potential, deep resistivity, neutron, and density. The thickness of the reservoirs varies between 15 and 440 meters, with thicker reservoirs likely being composite structures formed from layered channels. Sands deposited in high-energy settings have higher levels of porosity and permeability. Sands C and D are the most porous and permeable sand units in the field, while the remaining sands have medium permeability. Hydrocarbons are present in sands B, C, D, and E in varying fluid types and column diameters. The reservoir sands C, D, and E have high hydrocarbon saturation and low water saturation, indicating that more oil than water will be produced. On the other hand, irreducible sand B suggests that more water than oil will be produced. Reservoir sands B, C, and D contain only water and oil. This information can aid in locating production platforms and optimizing hydrocarbon recovery, as well as improving reservoir performance estimates. The geological and petrophysical data collected in this study can also guide the analysis of other fields similar to the "X Field" in Nigeria's Niger Delta offshore region.

Recent Advances of Triglyceride Catalytic Pyrolysis via Heterogenous Dolomite Catalyst for Upgrading Biofuel Quality: A Review.

This review provides the recent advances in triglyceride catalytic pyrolysis using heterogeneous dolomite catalysts for upgrading biofuel quality. The production of high-quality renewable biofuels through catalytic cracking pyrolysis has gained significant attention due to their high hydrocarbon and volatile matter content. Unlike conventional applications that require high operational costs, long process times, hazardous material pollution, and enormous energy demand, catalytic cracking pyrolysis has overcome these challenges. The use of CaO, MgO, and activated dolomite catalysts has greatly improved the yield and quality of biofuel, reducing the acid value of bio-oil. Modifications of the activated dolomite surface through bifunctional acid-base properties also positively influenced bio-oil production and quality. Dolomite catalysts have been found to be effective in catalyzing the pyrolysis of triglycerides, which are a major component of vegetable oils and animal fats, to produce biofuels. Recent advances in the field include the use of modified dolomite catalysts to improve the activity and selectivity of the catalytic pyrolysis process. Moreover, there is also research enhancement of the synthesis and modification of dolomite catalysts in improving the performance of biofuel yield conversion. Interestingly, this synergy contribution has significantly improved the physicochemical properties of the catalysts such as the structure, surface area, porosity, stability, and bifunctional acid-base properties, which contribute to the catalytic reaction's performance.

Efficient solvent- and hydrogen-free upcycling of high-density polyethylene into separable cyclic hydrocarbons.

Plastic pollution is a planetary threat that has been exacerbated by the COVID-19 pandemic due to the surge in medical waste, personal protective equipment and takeaway packaging. A socially sustainable and economically viable method for plastic recycling should not use consumable materials such as co-reactants or solvents. Here we report that Ru nanoparticles on zeolitic HZSM-5 catalyse the solvent- and hydrogen-free upcycling of high-density polyethylene into a separable distribution of linear (C1 to C6) and cyclic (C7 to C15) hydrocarbons. The valuable monocyclic hydrocarbons accounted for 60.3 mol% of the total yield. Based on mechanistic studies, the dehydrogenation of polymer chains to form C=C bonds occurs on both Ru sites and acid sites in HZSM-5, whereas carbenium ions are generated on the acid sites via the protonation of the C=C bonds. Accordingly, optimizing the Ru and acid sites promoted the cyclization process, which requires the simultaneous existence of a C=C bond and a carbenium ion on a molecular chain at an appropriate distance, providing high activity and cyclic hydrocarbon selectivity.

Spatial and molecular variations in forest topsoil dissolved organic matter as revealed by FT-ICR mass spectrometry

Forest soils cover about 30 % of the Earth's land surface and play a fundamental role in the global cycle of organic matter. Dissolved organic matter (DOM), the largest active pool of terrestrial carbon, is essential for soil development, microbial metabolism and nutrient cycling. However, forest soil DOM is a highly complex mixture of tens of thousands of individual compounds, which is largely composed of organic matter from primary producers, residues from microbial process and the corresponding chemical reactions. Therefore, we need a detailed picture of molecular composition in forest soil, especially the pattern of large-scale spatial distribution, which can help us understand the role of DOM in the carbon cycle. To explore the spatial and molecular variations of DOM in forest soil, we choose six major forest reserves located in different latitudes ranging in China, which were investigated by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Results show that aromatic-like molecules are preferentially enriched in DOM at high latitude forest soils, while aliphatic/peptide-like, carbohydrate-like, and unsaturated hydrocarbon molecules are preferentially enriched in DOM at low latitude forest soils, besides, lignin-like compounds account for the highest proportion in all forest soil DOM. High latitude forest soils have higher aromatic equivalents and aromatic indices than low latitude forest soils, which suggest that organic matter at higher latitude forest soils preferentially contain plant-derived ingredients and are refractory to degradation while microbially derived carbon is dominant in organic matter at low latitudes. Besides, we found that CHO and CHON compounds make up the majority in all forest soil samples. Finally, we visualized the complexity and diversity of soil organic matter molecules through network analysis. Our study provides a molecular-level understanding of forest soil organic matter at large scales, which may contribute to the conservation and utilization of forest resources.

Cometabolic degradation of pyrene with phenanthrene as substrate: assisted by halophilic Pseudomonas stutzeri DJP1.

At present, cometabolic degradation is an extensive method for the biological removal of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in the marine environment. However, due to the refractory to degradation and high toxicity, there are few studies on pyrene (PYR) cometabolic degradation with phenanthrene (PHE) as substrate. In this study, a Pseudomonas stutzeri DJP1 strain isolated from sediments was used in the cometabolic system of PHE and PYR. The biomass and the activity of key enzymes such as dehydrogenase and catechol 12 dioxygenase of strain were improved, but the enhancement of biotoxicity resulted in the inhibition of cometabolism simultaneously. Seven metabolites were identified respectively in PYR, PHE degradation cultures. It was speculated that the cometabolism of PHE and PYR had a common phthalic acid pathway, and the degradation pathway of PHE was included in the downstream pathway of PYR. The functional genes such as PhdF, NidD and CatA involved in DJP1 degradation were revealed by Genome analysis. This study provides a reference for the biodegradation of PYR and PHE in real marine environment.

CFD analysis of combustion and emission characteristics of biodiesel under conventional and late-injection based premixed combustion conditions

The simultaneous reduction in NOx and smoke emissions can be achieved with biodiesel under a late-injection based low temperature combustion (LTC) strategy. However, this occurs at the expense of a substantial increase in unburned hydrocarbon (HC) and carbon monoxide (CO) emissions. It is worthwhile to understand the reasons behind the formation of these emissions, emphasizing comparison with conventional combustion, which is known to result in significantly low HC and CO emission levels, particularly with oxygenated biodiesel fuel. The present investigation attempts to examine the same with 3D CFD simulation. Experimental data were obtained from a light-duty diesel engine using biodiesel from non-edible Karanja oil. The unmodified engine with OEM low-pressure mechanical fuel injection system was utilized for conventional combustion operation. It is replaced with a modified common rail injection system for a late-injection-based LTC mode of operation. By combining retarded high-pressure injection with EGR, sufficient premixing was sustained to enable late injection-based premixed combustion (LI LTC). The combustion simulation was performed using CONVERGE CFD tool, utilizing a two-component surrogate of methyl butanoate (MB) and n-dodecane to represent biodiesel. A reduced chemical kinetic mechanism, developed and validated in an earlier investigation on biodiesel combustion, was utilized in the current study. The mechanism was solved using the SAGE Detailed CHEMKIN solver in CONVERGE. Validation was conducted at two engine operating conditions defining low and high loads for both combustion modes. The cylinder pressure and heat release rates were predicted with a maximum error of 1.5 and 13%, respectively. The validated CFD tool was employed to compare and analyze the equivalence ratio, in-cylinder gas temperatures, and HC and CO contours between conventional and LI LTC modes. Under LTC mode, the cylinder pressure and heat release rates were predicted with a maximum error of 10 and 15%, respectively. The comparison revealed fuel-rich regions concentrated near the bowl in conventional combustion, while the fuel was spread throughout the combustion chamber in LI LTC mode with over-rich and over-lean regions near the cylinder wall. The cylinder temperature is significantly higher for conventional combustion than LI LTC mode. The O and OH radical concentrations are higher for conventional combustion, corroborating with lower CO emissions, as they aid in CO oxidation. Fuel-rich regions contribute to increased CO emissions, whereas over-lean regions at a low-temperature result in high HC emissions, exhibited by the emission contours. Possible countermeasures to reduce high HC and CO emissions in LI LTC mode include maintaining higher coolant temperatures to enable HC and CO oxidation in the near-wall regions and fuel injection system modification to alter the air–fuel mixing.

Measurement report: Underestimated reactive organic gases from residential combustion – insights from a near-complete speciation

Abstract. Reactive organic gases (ROGs), as important precursors of secondary pollutants, are not well resolved as their chemical complexity has challenged their quantification in many studies. Here, a near-complete speciation of ROG emissions from residential combustion was developed by the combination of proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) with a gas chromatography system equipped with a mass spectrometer and a flame ionization detector (GC-MS/FID), including 1049 species in all. Among them, 125 identified species, ∼ 90 % of the total ROG masses, were applied to evaluate their emission characteristics through real combustion samplings in rural households of China. The study revealed that with 55 species, mainly oxygenated species, higher hydrocarbons with ≥8 carbon atoms, and nitrogen-containing species, previously un- and under-characterized, ROG emissions from residential coal and biomass combustion were underestimated by 44.3 % ± 11.8 % and 22.7 % ± 3.9 %, respectively, which further amplified the underestimation of secondary organic aerosol formation potential (SOAP) as high as 70.3 % ± 1.6 % and 89.2 % ± 1.0 %, respectively. The hydroxyl radical reactivity (OHR) of ROG emissions was also undervalued significantly. The study provided a feasible method for the near-complete speciation of ROGs in the atmosphere and highlighted the importance of acquiring completely speciated measurement of ROGs from residential emissions, as well as other processes.

Bioremediation of polycyclic aromatic hydrocarbons in crude oil by bacterial consortium in soil amended with Eisenia fetida and rhamnolipid.

The present study investigated the concerted effort of Eisenia fetida and rhamnolipid JBR-425 in combination with a five-member bacterial consortium exhibiting elevated degradation levels of low and high molecular weight polycyclic aromatic hydrocarbons (PAH) from soil contaminated with Digboi crude oil. Application of bacterial consortium (G2) degraded 30-89% of selected PAH from the artificial soil after a 45-day post-exposure, in which chrysene showed the highest level of degradation with 89% and benzo(a)pyrene is the lowest with 30%, respectively. Moreover, an acute exposure study observed that earthworm biomass decreased, and mortality rates increased with increasing crude oil concentrations (0.25 to 2%). Earthworms with a 100% survival rate at 1% crude oil exposure suggest the tolerance potential and its mutual involvement in the bioremediation of crude oil with selected bacterial consortia. Bacterial consortium assisted with E. fetida (G3) showed 98% chrysene degradation with a slight change in benzo(a)pyrene degradation (35%) in crude oil spiked soil. Besides, the most dominant PAH in crude oil found in the current work, fluoranthene, undergoes 93% and 70% degradation in G3 and G5 groups, respectively. However, rhamnolipid JBR-425 coupled with the bacterial consortium (G5) has resulted in 97% degradation of chrysene and 33% for benzo(a)pyrene. Overall, bacterial consortium assisted with earthworm group has shown better degradation of selected PAH than bacterial consortium with biosurfactant. Catalase (CAT), glutathione reductase (GST) activity and MDA content was found to be reduced in earthworms after sub-lethal exposure, suggesting oxidative stress prevalence via reactive oxygen species (ROS). Hence, the findings of the present work suggest that the application of a bacterial consortium, along with earthworm E. fetida, has huge potential for field restoration of contaminated soil with PAH and ecosystem sustainability.

Systematic Pore Characterization of Sub-Bituminous Coal from Sohagpur Coalfield, Central India Using Gas Adsorption Coupled with X-ray Scattering and High-Resolution Imaging

Pore characterization helps to estimate the coalbed methane recovery and carbon storage potential of the reservoir. Earlier research on the characteristics of coal pores has shown that coal has high hydrocarbon storage potential in the adsorbed state, but few studies have shown the influence of chemical heterogeneities and depth on the adsorption potential of the coal. With the objective of studying the effect of chemical variation, depth, and surface roughness on gas adsorption potential, this study combines coal composition analysis and adsorption-based pore characterization of coal and shale samples coupled with high-resolution imaging and X-ray scattering measurements. Variation in pore features is correlated with varying depth and composition. A decrease in the mesopore volume and surface area is observed with an increase in the depth and total organic content and inverse behavior is observed for micropores. Scanning electron microscopy images depict the change in the pore shape from semi-spherical OM pores to elongated pores with depth, and samples with high mineral content show a dominance of inter- and intraparticle pores. Fractal dimension values estimated from SAXS are notably higher than N2-LPGA-derived values (i.e.,─DS > DN) due to the incorporation of inaccessible pores, which reflects an increase of up to 62% in SAXS estimated mesopore volume and surface area. This study will provide a better approach to understand the impact of composition, depth, and surface roughness over the gas storage potential in coal reservoirs.

Response of the soil microbial community to petroleum hydrocarbon stress shows a threshold effect: research on aged realistic contaminated fields.

Microbes play key roles in maintaining soil ecological functions. Petroleum hydrocarbon contamination is expected to affect microbial ecological characteristics and the ecological services they provide. In this study, the multifunctionalities of contaminated and uncontaminated soils in an aged petroleum hydrocarbon-contaminated field and their correlation with soil microbial characteristics were analyzed to explore the effect of petroleum hydrocarbons on soil microbes. Soil physicochemical parameters were determined to calculate soil multifunctionalities. In addition, 16S high-throughput sequencing technology and bioinformation analysis were used to explore microbial characteristics. The results indicated that high concentrations of petroleum hydrocarbons (565-3,613 mg•kg-1, high contamination) reduced soil multifunctionality, while low concentrations of petroleum hydrocarbons (13-408 mg•kg-1, light contamination) might increase soil multifunctionality. In addition, light petroleum hydrocarbon contamination increased the richness and evenness of microbial community (p < 0.01), enhanced the microbial interactions and widened the niche breadth of keystone genus, while high petroleum hydrocarbon contamination reduced the richness of the microbial community (p < 0.05), simplified the microbial co-occurrence network, and increased the niche overlap of keystone genus. Our study demonstrates that light petroleum hydrocarbon contamination has a certain improvement effect on soil multifunctionalities and microbial characteristics. While high contamination shows an inhibitory effect on soil multifunctionalities and microbial characteristics, which has significance for the protection and management of petroleum hydrocarbon-contaminated soil.

Steam reforming of biomass gasification gas for hydrogen production: From thermodynamic analysis to experimental validation

Biomass gasification produces syngas composed mainly of hydrogen, carbon monoxide, carbon dioxide, methane, water, and higher hydrocarbons, till C4, mainly ethane. The hydrocarbon content can be upgraded into richer hydrogen streams through the steam reforming reaction. This study assessed the steam reforming process at the thermodynamic equilibrium of five streams, with different compositions, from the gasification of three different biomass sources (Lignin, Miscanthus, and Eucalyptus). The simulations were performed on Aspen Plus V12 software using the Gibbs energy minimization method. The influence of the operating conditions on the hydrogen yield was assessed: temperature in the range of 200 to 1100 °C, pressures of 1 to 20 bar, and steam-to‑carbon (S/C) molar ratios from 0 (only dry reforming) to 10. It was observed that operating conditions of 725 to 850 °C, 1 bar, and an S/C ratio of 3 enhanced the streams' hydrogen content and led to nearly complete hydrocarbon conversion (>99%). Regarding hydrogen purity, the stream obtained from the gasification of Lignin and followed by a conditioning phase (stream 5) has the highest hydrogen purity, 52.7%, and an hydrogen yield of 48.7%. In contrast, the stream obtained from the gasification of Lignin without any conditioning (stream 1) led to the greatest increase in hydrogen purity, from 19% to 51.2% and a hydrogen yield of 61.8%. Concerning coke formation, it can be mitigated for S/C molar ratios and temperatures >2 and 700 °C, respectively. Experimental tests with stream 1 were carried out, which show a similar trend to the simulation results, particularly at high temperatures (700–800 °C).

Risk prediction for petroleum exploration based on Bayesian network classifier

Effective prediction of petroleum exploration risks is critical for boosting oil and gas extraction efficiency and increasing economic benefits. To improve the accuracy and efficiency of risk prediction, this paper proposes a scalable k-dependence Bayesian network classifier (SKDB) method for solving the risk prediction problem of oil and gas exploration. The effectiveness and efficiency of the SKDB method were illustrated by taking the Jurassic Sangonghe Formation hydrocarbon exploration risk prediction in the Junggar Basin as an example. The model accuracy comparison results showed that SKDB has the highest accuracy compared with the state-of-the-art methods, and the accuracy was improved by 3.55∼7.63%. The oil and gas probability map prediction results indicated that the SKDB method not only showed high hydrocarbon probability in the reservoir areas, but also had better trend inference ability compared with other methods. Based on the SKDB prediction results, the remaining hydrocarbon favorable areas of the Sangonghe Formation reservoir were visualized and three types of favorable hydrocarbon distribution zones were preferentially selected, namely Type I (highly favorable), Type II (moderately favorable) and Type III (low favorable). The application results can provide a decision basis for the next oil and gas exploration and optimization strategy.

HC EMISSION STABLE AND POWER OPTIMATION OF THE MOTORCYCLE LPG ENGINE BY HEAT TRANSFER TO THE INJECTOR

This study was conducted on a motorcycle engine that already has bi-fuel, with liquid phase LPG injection. However, when conducting experiments on the concentration of substances in the exhaust gas, the results show that the concentration of hydrocarbon in the tests has different effects. It is possible to see a sudden high hydrocarbon concentration at some point in time. Over time, the nozzle tip will gradually form ice around the nozzle due to LPG evaporation and heat collection. When forming large lumps, this ice will break off and move into the combustion chamber. A part of ice has not yet mixed with the air to create an explosive mixture, and the combustion process is not completed. The solution proposed is to use the method of heat transfer to the nozzle body by an electronic heating device. The experiment measured brake power at the wheel, fuel consumption, and concentration of pollutants in the exhaust gas according to each controlled temperature to supply to the nozzle body. With this result, a suitable nozzle supply temperature is selected to ensure that the engine achieves the most optimal power and fuel consumption and eliminates the phenomenon of abnormal hydrocarbon concentration. From the test results, 30OC is the most suitable temperature when adjusting the heating device around the nozzle.