Hydrocarbon Type Research Articles

Exposure to benzo[α]pyrene causes oxidative stress and cell damage in bay scallop Argopecten irradians

In the present study, bay scallop antioxidant response to acute exposure to the benzo[α]pyrene (BaP; a type of polycyclic aromatic hydrocarbon) was investigated. Scallops were exposed to doses of 0.5 and 1.0 µg/L (low-dose group) and 10 and 50 µg/L (high-dose group) for 72 h. The following oxidative stress indicators were measured in the digestive diverticula tissues or hemolymph: superoxide dismutase, catalase, hydrogen peroxide, and lipid peroxidation. The apoptotic response in the high dose group was assessed using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. The stress indicators in each group increased significantly with time, except in the 0.5 µg/L group. The TUNEL assay revealed that more apoptotic cells were detected after exposure to BaP over time. These results suggest that exposure to BaP induces oxidative stress and causes tissue damage in bivalves. These findings also revealed that high concentrations of BaP exposure can have potential adverse effects (apoptosis and cell damage) in bivalves. Additionally, these results might shed some new light on the ecotoxicological effects of BaP on marine bivalves.

Characterizing the Semi-Volatile Organic Compounds in Runoff from Roads and Other Impervious Surfaces in a Suburban Area of Beijing.

Stormwater runoff samples were collected from five different land use sites (gas station, city road, campus, park, and residential) in a precipitation event on May 22nd, 2017, from a small suburban area (5km × 2km) of the city of Beijing, China. There were 72 types of semi-volatile organic compounds (SVOCs) found in these runoff samples, including 33 types of monocyclic aromatic hydrocarbons (MAHs), 22 types of polycyclic aromatic hydrocarbons (PAHs), 6 types of phthalate esters (PAEs), 9 types of pesticides and 2 types of polychlorinated biphenyls (PCBs). Especially, 26 types of SVOCs (7 MAHs, 9 PAHs, 5 PAEs, and 5 pesticides) were detected in all water samples. SVOCs concentrations were higher in the samples from gas station and city road, and lower in runoff from campus, park and residential sites. The change in the ratio of anthracene to anthracene plus phenanthrene (ANT/(ANT + PHE)) in this study, reflected the importance of PAH source and land use. Di-2-ethylhexyl phthalate (DEHP) and di-n-butyl phthalate, are two of the phthalate esters 100% detected in the runoff samples. The city road runoff DEHP concentrations recorded the highest values (> 6000ng/L), however, were still less than those wastewater DEHP pollutants measured in developed countries (e.g. UK, Canada, Finland, etc.). One-way ANOVA analysis in this study, showed that land use could significantly influence 23 SVOCs in the runoff samples, whereas the runoff SVOCs in different precipitation period showed no statistical changes in the five sites, and presented a general temporal trends "high (beginning)-low (middle period)-little raising (ending)". The findings in this study could be used in municipal management of wastewater collection and treatment.

Spectral and Growth Characteristics of Willows and Maize in Soil Contaminated with a Layer of Crude or Refined Oil

Remote sensing holds great potential for detecting stress in vegetation caused by hydrocarbons, but we need to better understand the effects of hydrocarbons on plant growth and specific spectral expression. Willow (Salix viminalis var. Tora) cuttings and maize (Zea mays var. Lapriora) seedlings were grown in pots of loam soil containing a hydrocarbon-contaminated layer at the base of the pot (crude or refined oil) at concentrations of 0.5, 5, or 50 g·kg−1. Chlorophyll concentration, biomass, and growth of plants were determined through destructive and nondestructive sampling, whilst reflectance measurements were made using portable hyperspectral spectrometers. All biophysical (chlorophyll concentration and growth) variables decreased in the presence of high concentrations of hydrocarbons, but at lower concentrations an increase in growth and chlorophyll were often observed with respect to nonpolluted plants, suggesting a biphasic response to hydrocarbon presence. Absorption features were identified that related strongly to pigment concentration and biomass. Variations in absorption feature characteristics (band depth, band area, and band width) were dependent upon the hydrocarbon concentration and type, and showed the same biphasic pattern noted in the biophysical measurements. This study demonstrates that the response of plants to hydrocarbon pollution varies according to hydrocarbon concentration and that remote sensing has the potential to both detect and monitor the variable impacts of pollution in the landscape.

Modificări clinice și radiologice în intoxicațiile acute cu hidrocarburi la copil

Acute chemical poisoning is an important cause of morbidity and mortality for the pediatric population, with hydrocarbon exposure accounting for a significant share. The route of exposure but especially the type of hydrocarbons are responsible for the effect that these substances exert on the body and implicitly the clinical picture and an understanding of them is used in the care of the patient exposed to hydrocarbons. Objectives. Outlining the clinical and radiological profile of accidental acute hydrocarbon poisoning in children. Material and method. Medical documents of patients hospitalized in the Pediatric Antitoxic Center with a diagnosis of acute hydrocarbon intoxication over a period of 2 years were retrospectively analyzed, taking into consideration demographic characteristics, type of hydrocarbons, clinical manifestations and radiological changes. Results. 25 cases of acute hydrocarbon poisoning were identified in children. Exposure was only accidental by ingestion, with males and the 1-5 age group occupying the largest share. The main clinical manifestations were respiratory, gastrointestinal and nervous system and radiological changes were associated in only 20% of cases. Conclusions. Acute hydrocarbon poisoning in children are frequently asymptomatic or causes mild symptoms, dominated by gastrointestinal, respiratory and neurological manifestations. Pulmonary radiography is mandatory in paraclinical diagnoses but there is no correlation between the severity of the clinical picture and the radiological aspects. There may be situations in which symptomatic patients do not have radiological changes or situations with pathological radiological aspects in asymptomatic patients.

Source Rock Characteristic of Sargelu and Kurrachine Formations from the Selected Wells in Northern Iraq

A total of 56 cuttings samples of Sargelu and Kurrachine formations from different wells (Ain Zalah, Baiji, and Jabal Kand) in northern Iraq have been investigated in this study. Both the Sargelu and Kurrachine formations were examined using Rock-Eval pyrolysis to assess the richness of organic matter and thermal maturity level. The Sargelu Formation Have Total Organic Carbon wt.% ranged from 0.22–2.52 wt.%, average 1.26 wt.% in Ain Zalah Well, and between 0.57–8.90 wt.%, average 2.95 wt.% in Baiji Well, and between 0.81–11.80 wt.%, average 5.01wt.% in for Kand Well. It is considered a potential source rock based on total organic carbon content. total organic carbon wt. % in Ain Zalah and Kand in the Kurrachine Formation is considered poor source rock with a total organic carbon content of 0.17, 0.39 wt. %, respectively, while in Baiji Well is considered moderate source rock with total organic carbon content 0.53 wt. %. The Rock-Eval data are not always sufficient to define the kind of organic matter through the use of the van Krevelen diagram because HI and OI are affected by both matrix mineralogy and the kerogen mixture. For accurate assessments of the source rocks, gas chromatography has been relied on, which provides a direct indication of the kerogen type as well as the type of hydrocarbons that kerogen can generate during maturity. Gas chromatography analysis indicates that all selected samples contained type II kerogen. The highest value of the TAS/ (MAS+TAS) ratio was found in Ain Zalah samples (Sargelu Formation), and this result indicates the occurrence of an aromatization process with increasing thermal maturation.

Supramolecular Polymerization of C3-Symmetric, Triphenylene-Cored Aza-Polycyclic Aromatic Hydrocarbons with Excellent and Switchable Circularly Polarized Luminescence Performance

A new type of C3-symmetric aza-polycyclic aromatic hydrocarbon (PAH) discs attached with chiral alkoxyl chains is developed and explored as circularly polarized luminescence (CPL)-active materials with selective control and switching of chiroptical properties. Supramolecular polymerization of these PAHs is studied experimentally and theoretically. With the aid of weak hydrogen bonding and CH···π interactions, these chromophores have strong tendency to form anisotropic chiral aggregates both in solutions and films. The well-controlled noncovalent interactions are critical for their excellent CPL performance. The resultant supramolecular polymers display a polarized emission band with the maximum glum value up to 10–2. Benefited from the chiral supramolecular polymerization process and N-doping structure feature of the core, on/off CPL switching from these molecules can be reversibly realized by external stimuli including the change of temperature, solvent, and pH conditions. Our work shows that chiral supramolecular polymers from concise yet highly rigid and planar PAH cores are superbly suitable for exceptional CPL emission both in dilute solutions and bulk materials, with a promising switchable CPL feature, thereby unlocking new design possibilities.

Degradation Prediction and Products of Polycyclic Aromatic Hydrocarbons in Soils by Highly Active Bimetals/AC-Activated Persulfate

In this study, activated carbon (AC)-supported bimetallic materials (Fe–Ni/AC) were synthesized to activate persulfate for the degradation of 19 types of polycyclic aromatic hydrocarbons (PAHs) in ...

Pollution in the interflow from a simple landfill in a mountainous and hilly area in Southwest China

Simple landfills lack pollution prevention measures and therefore continuously release pollutants into the surrounding environment. There are a large number of simple landfills in the mountainous and hilly areas in China, and the interflow accounts for a large proportion of runoff. However, the pollution in the interflow stemming from the simple landfill has not been extensively studied. Here, the pollution of the interflow caused by the simple landfill near the Yunxi Town Landfill in the mountainous and hilly region in Southwest China was studied. The composition and pollution release potential of aged refuse in the landfill were determined, and the water quality of interflow around the landfill was monitored for five months. Seasonal changes in water quality of the interflow were observed, and the concentration of pollutants in the interflow around the simple landfill greatly exceeded the water quality standard for the local water function zoning throughout the sampling period. Specifically, the chemical oxygen demand concentrations of the interflow were 247.90 ± 81.57 mg/L, and more than 50 types of refractory organics were detected, with as many as 10 types of polycyclic aromatic hydrocarbons and Environmental Protection Agency priority pollutants. The total nitrogen concentration of the interflow was 132.45 ± 108.68 mg/L; organic nitrogen (53.27%) was the main component, followed by nitrate nitrogen (32.28%) and nitrous nitrogen and ammonia nitrogen (14.45%). The results highlight the need for the remediation of interflow around simple landfills in mountainous and hilly areas. Generally, the basic data could be used to aid the development of remediation technology.

Multivariate statistics for summarizing diesel feeds for flammability attributes using comprehensive two-dimensional gas chromatography.

Comprehensive 2D gas chromatography has been utilized for analyzing complex mixtures of hydrocarbons of diesel feeds. Here, we evaluated 19 diesel feeds for their paraffinic, naphthenic, and aromatic group compositions dictating their flammability properties. Compositional ranges of feeds were as follows: paraffins: 9.6-57.8%, naphthenes: 7.9-38.5%, and aromatics: 10.5-82.3%. Diesel's flammability performance is estimated by thermodynamic conditions and rates of radical formation of hydrocarbon type in actual engine condition, limiting cetane number. However, limitations are overcome by understanding the relative compositional variations of feeds by simple ranking of feeds based on C15-16 compositions. Due to the multidimensional variability of feeds, a principal component analysis was adopted later for its distinguishing capability. Paraffinic, naphthenic, and aromatic group's principal component analysis clustered up feeds based on the higher concentration of individual hydrocarbon group. We explored hierarchical cluster analysis to organize feeds into classes of mixed C9 to C26 paraffin's composition in the diesel range. Further, for discriminating C15-C16 enriched and depleted feeds in total paraffin composition, a row dendrogram with heat map was drawn. The above multivariate methods have led to a fair distinction of nonadditive feed compositions influencing flammability properties by radical formation rate.

Geochemical characterization and origin of kerogens from source-rock of Devonian in the Amazonas Basin, Brazil

Thirty-seven devonian shale samples from the Barreirinha Formation were collected from the northern and southern borders of the Amazonas Basin and were geochemically analyzed to evaluate their hydrocarbon source potentials and depositional paleoenvironments and to estimate the thermal effects of igneous intrusions on kerogens. The results showed that samples from the northern border exhibited total organic carbon (TOC) and Rock Eval pyrolysis parameters that indicated excellent hydrocarbon source potential and type III kerogen. These TOC values were residual due to the intense hydrocarbon generation from heat from intrusive rocks present in that area. Samples from the southern border had poor to excellent hydrocarbon source potential and type II and III kerogens. Chromatograms of organic extracts and saturated biomarkers suggested marine anoxic to oxic and suboxic to oxic depositional paleoenvironments in the northern and southern borders, respectively. The saturated biomarkers and stable carbon isotope ratios (δ¹³C) suggested that the original organic matter was marine with some continental contributions. The maximum pyrolysis temperature (Tmax), Spore Color Index (SCI), kerogen color, Pr/n-C17 and Ph/n-C18 ratios, and biomarker data indicated that the northern border shales are at the end of the oil generation window, while those from the southern border are at the beginning of the oil generation window.

Experimental investigation of size of fuel droplets formed by steam jet impact

The process of liquid hydrocarbon fuel disintegration into droplets under the action of a supersonic jet of superheated steam was studied by shadow photography and high-speed visualization. During the measurements operating parameters for the conditions of fuel spraying in a real burner were varied for three types of fuel: diesel, oil, and kerosene. For the first time, the photographs of the process of disintegration of various types of liquid hydrocarbon fuel during interaction with a supersonic gas jet were obtained. When oil flows onto the steam jet, thin threads and films of liquid with a chaotic structure are formed. The regime of droplet disintegration corresponds to the “catastrophic” one. It is shown that the proposed method of fuel spraying provides effective dispersion for high-quality combustion and it can be used in liquid fuel burners, even when burning liquid combustible waste, as well as in low-emission gas turbine engines. Size distributions of fuel droplets in the region of fuel ignition were obtained for different fuel and steam flow rates. The use of a long-focus lens allowed optical magnification of 7:1 and identification of droplets as small as 1 μm. For diesel and oil, the characteristic droplet size is 2 µm, and for kerosene, it is 1 µm.

Application of factor analysis in the determination of vapor lock tendency in aviation gasolines/motor gasoline/blends and the compatibility as alternatives in naturally aspirated aviation engines

The danger of vapour lock, generation of vapor bubbles inside the aircraft fuel system, needs a well-documented understanding to establish safe operating confines at existing fuel temperature and pressures. The aim of the research is specifically to make contributions in the direction of the present scientific studies of UL aviation gasoline initiatives in piston aircrafts, globally specifically aiming on the vapor locking tendencies of aviation fuels, motor fuels and the blends and comparing the results both experimentally and statistically. Chemical and physical properties of the fuels were tested and categorised based on hydrocarbon types and properties. Study considered nine variables for vapor lock. Twenty-three aviation fuels from various literatures were collected, model equations derived, and respective comprehensive factor scores were calculated. The model was applied to the 14 fuels in this study and their respective comprehensive factor scores were calculated and ranked from the best to worst. The temperature of the gasoline as it approaches the carburettor was experimentally derived for comparative analysis with the comprehensive factor scores. Results showed that Kaiser’s Measure of Sampling Adequacy (MSA) measure of sampling adequacy value is 0.728. Four common factors and their cumulative variance proportion of rotation sums of squared loadings has reached 95.530%. Based on the loadings of the rotated components, PC1 has strong significant correlation with VL index of value 0.917. Among the aviation rated fuels, for vapor lock tendency UL 82, UL 87, SWIFT UL 102, SWIFT Binary Blend and 100 SF have the highest factor score. Fuels AVGAS 100LL (D910), AVF1, AVF2, AVF4, AVGAS, Leaded 91/98, and UL 94 exhibited very poor vapor lock tendencies. RON 98 exhibited the best VL protection among all the tested fuels in this study with ccomprehensive factor scores of 0.126166 and the best experimental temperature of the gasoline as it approaches the carburettor was also exhibited by RON 98. The findings showed that RON 98 able to outperform the commercial AVGAS in terms of vapor locking characteristics.

Distinct microbial community along the chronic oil pollution continuum of the Persian Gulf converge with oil spill accidents

The Persian Gulf, hosting ca. 48% of the world’s oil reserves, has been chronically exposed to natural oil seepage. Oil spill studies show a shift in microbial community composition in response to oil pollution; however, the influence of chronic oil exposure on the microbial community remains unknown. We performed genome-resolved comparative analyses of the water and sediment samples along Persian Gulf’s pollution continuum (Strait of Hormuz, Asalouyeh, and Khark Island). Continuous exposure to trace amounts of pollution primed the intrinsic and rare marine oil-degrading microbes such as Oceanospirillales, Flavobacteriales, Alteromonadales, and Rhodobacterales to bloom in response to oil pollution in Asalouyeh and Khark samples. Comparative analysis of the Persian Gulf samples with 106 oil-polluted marine samples reveals that the hydrocarbon type, exposure time, and sediment depth are the main determinants of microbial response to pollution. High aliphatic content of the pollution enriched for Oceanospirillales, Alteromonadales, and Pseudomonadales whereas, Alteromonadales, Cellvibrionales, Flavobacteriales, and Rhodobacterales dominate polyaromatic polluted samples. In chronic exposure and oil spill events, the community composition converges towards higher dominance of oil-degrading constituents while promoting the division of labor for successful bioremediation.

The Impact of Lanthanum and Zeolite Structure on Hydrocarbon Storage

Hydrocarbon traps can be used to bridge the temperature gap from the cold start of a vehicle until the exhaust after-treatment catalyst has reached its operating temperature. In this work, we investigate the effect of zeolite structure (ZSM-5, BEA, SSZ-13) and the effect of La addition to H-BEA and H-ZSM-5 on the hydrocarbon storage capacity by temperature-programmed desorption and DRIFT spectroscopy. The results show that the presence of La has a significant effect on the adsorption characteristics of toluene on the BEA-supported La materials. A low loading of La onto zeolite BEA (2% La-BEA) improves not only the toluene adsorption capacity but also the retention of toluene. However, a higher loading of La results in a decrease in the adsorbed amount of toluene, which likely is due to partial blocking of the pore of the support. High loadings of La in BEA result in a contraction of the unit cell of the zeolite as evidenced by XRD. A synergetic effect of having simultaneously different types of hydrocarbons (toluene, propene, and propane) in the feed is found for samples containing ZSM-5, where the desorption temperature of propane increases, and the quantity that desorbed increases by a factor of four. This is found to be due to the interaction between toluene and propane inside the structure of the zeolite.

Bromination Reactivity of Oxygen-Terminated Edges of Graphene.

The bromination reactivity of various types of polycyclic aromatic hydrocarbons (PAHs) with oxygen atoms and graphene with oxygen atoms was estimated by density functional theory calculation and experimentally clarified by analyzing bromination of PAHs using gas chromatography-mass spectrometry. In the experimental and theoretical bromination reactivity of PAHs, the presence of hydroxyl group increased the reactivity of PAHs because of electron-donating nature of the hydroxyl group but the other oxygen-containing functional groups such as lactone, ether, and ketone decreased the reactivity due to the electron-withdrawing nature of those groups. These effects of functional groups on the reactivity were also confirmed in graphene. The tendency of theoretical bromination reactivity of graphene was graphene with hydroxyl group > graphene with no group > graphene with lactone group > graphene with ether group > graphene with ketone group. Our study on the estimation of bromination reactivity of graphene edges provides the groundwork for the bromination of graphene edges.

Investigation of Biodegradable Bacteria as Bio indicators of the Presence of PAHs Contaminants in Marine Waters in the Marine Tourism Area of Makassar City

The activities of the petroleum processing industry and marine transportation potentially cause of hydrocarbon pollution. It is assumed that every water area exposed to hydrocarbons also found bacterial species that have biodegradation properties against PAH contaminants. This study aims to analyze the relationship between biodegradable bacteria and the status of marine waters exposed to hydrocarbons. The method of analyzing the type of PAH contaminants for each seawater and sponge samples were processed at 4 different points using GC-MS, the same sample was also carried out isolation, characterization and activity test of bacterial isolates against naphthalene and pyrene type PAH. The analysis showed that the four samples of seawater were contaminated with hydrocarbons. The type of hydrocarbons found in each sample is different and the concentration value varies. The types of bacteria identified in seawater and sponge samples also varied. There were 8 types of isolates selected, each one isolate per sample, all of which showed biodegradation activity against hydrocarbon contaminants, while the order of aromatic contamination levels at the four sampling points Sp. 1 > Sp.2 > Sp.3 > Sp.4. These results indicate that the presence of biodegradable bacteria in water areas can be a bio-indicator for the presence of PAH pollutants.

Roles of alkanes, alcohols, and aldehydes for crude oil oxidation during the air injection process

Although the air injection process (AIP) has been applied for enhanced oil recovery purposes for many decades now, the oxidation mechanism behind the exotherm has not yet been widely discussed. Previous methane oxidation studies have stated that hydrocarbon oxidation is a chain reaction. Four types of hydrocarbons have been proposed to significantly affect the hydrocarbon oxidation, namely, alkanes, alkyl peroxides, alcohols, and aldehydes. Therefore, the functional groups of hydrocarbons might be the key to understanding the oxidation behaviors of crude oil during the AIP.This study used an accelerated-rate calorimeter to investigate the self-heating behaviors of three types of hydrocarbons and their corresponding mixtures with crude oil under high pressure. n-Decane, 1-decanol, and 1-decanal were selected for use herein because of their availability to represent the self-heating behaviors of the hydrocarbon types. The oxidation behaviors of hydrocarbons with a longer hydrocarbon chain can be explained by analogy with the results of previous methane oxidation studies; thus, the enthalpy from the low-temperature oxidation mainly comes from the oxidation process from alkanes to alcohols. The negative temperature coefficient region is mainly caused by the reactions that turn alcohols into aldehydes. Aldehydes are the direct fuel for high-temperature oxidation and have the lowest activation energy among the three tested types of hydrocarbons. More aldehydes in the crude oil should be favorable for the AIPs in low-temperature reservoirs.

Cultivation of ‘Botryococcus Braunii’ Microalgae for Hydrocarbons Production and CO2 Bio-fixation

CO2 fixation for climate change mitigation actions through photosynthesis can be carried out by growing intensively managed microalgae. The capability of microalgae in the CO2 fixation is favourable compare to trees or crops, yielding three to five times more biomass per land area than typical plants. Another interesting feature of microalgae is microalgal farms can use arid, semi-arid land or highly saline water, which is practically not suitable for agriculture and other biomass production activities. In addition, algae biomass contains fibre, fatty acid, lipid, protein, polysaccharide, and hydrocarbon. These materials could be extracted for biofuels or biochemicals. Biofuels derived from microalgae are environmentally friendly and carbon neutral. However, microalgal farming seen only for producing biomass as sources of fuels and chemicals probably uneconomical. The yields of microalgal farm to produce fuels/chemicals are also low. Therefore, microalgal farm with the objective of solely producing fuels/chemicals is economically unfeasible. If it is designed for CO2 mitigation measures and all at once for fuels/chemicals production, such endeavour could be economically justifiable. This paper presents results of a research on microalgae cultivation for producing biomass and hydrocarbons for biofuels that simultaneously fixing the CO2 emissions from coal power plant effluent through photosynthesis process, which also for the implementation of circular economy concepts. A strain of ‘Botryococcus Braunii’ microalgae, which known can produce high hydrocarbons and lipids throughout its growth period has been used. The research identified and evaluated the effect of cultivation medium and CO2 concentration to the growth rate, biomass production, lipid and hydrocarbon content and type. The microalgae were cultivated in bioreactor supported with airlift system for supplying CO2/air and for mixing process. Results of the research show that modified Chu13 (MChu13) is appropriate cultivation medium for the growth, hydrocarbon/lipid production, and CO2 fixation from B. braunii. The magnitude of biomass production in MChu13 is 0.145 g/L.9days, while in modified BG11 is 0,118 g/L.9days, Bold Bassal Medium (BBM) is 0.09 g/L.9days, and Bristol is 0.023 g/L.9days. This biomass production rate is in lined with the CO2 fixation rate. In MChu13 the dry weight of B.brauni is 0.268 g/L.7days while in Bristol only 0.229 g/L.7days.

Teknologi Low-Frequency Acoustic untuk Identifikasi Gas Hidrat Berdasarkan Perubahan Karakter Seismik di Perairan Laut Aru

Gas hydrate is a type of hydrocarbon formed like crystals and is formed in the seabed sediment layer. Water temperature and pressure affected the area where gas hydrates are formed; gas hydrates are composed of gas and water elements. Gas hydrates have the potential as an alternative to current uses of oils and gasses. The identification of gas hydrates on the seabed can be detected using low-frequency acoustic, seismic technology. This research aims to identify the presence of gas hydrate in Aru Sea waters based on changes in the seismic character of the gas hydrate. The method used is seismic data processing with ProMAX software. This research uses seismic data for the 3.01 trajectory acquired by the Marine Geology Research and Development Center in 2016 in the Aru Sea. Based on the data processed, gas hydrate was detected on the 3.01 line with a depth of 5,925 meters. Gas hydrate indicator on the seabed is characterized by cutting stratigraphy, reversing its polarity, high amplitude, and shape following the seabed.

A reservoir quality evaluation approach for tight sandstone reservoirs based on the gray correlation algorithm: A case study of the Chang 6 layer in the W area of the as oilfield, Ordos Basin

As an important type of unconventional hydrocarbon, tight sandstone oil has great present and future resource potential. Reservoir quality evaluation is the basis of tight sandstone oil development. A comprehensive evaluation approach based on the gray correlation algorithm is established to effectively assess tight sandstone reservoir quality. Seven tight sandstone samples from the Chang 6 reservoir in the W area of the AS oilfield in the Ordos Basin are employed. First, the petrological and physical characteristics of the study area reservoir are briefly discussed through thin section observations, electron microscopy analysis, core physical property tests, and whole-rock and clay mineral content experiments. Second, the pore type, throat type and pore and throat combination characteristics are described from casting thin sections and scanning electron microscopy. Third, high-pressure mercury injection and nitrogen adsorption experiments are optimized to evaluate the characteristic parameters of pore throat distribution, micro- and nanopore throat frequency, permeability contribution and volume continuous distribution characteristics to quantitatively characterize the reservoir micro- and nanopores and throats. Then, the effective pore throat frequency specific gravity parameter of movable oil and the irreducible oil pore throat volume specific gravity parameter are introduced and combined with the reservoir physical properties, multipoint Brunauer-Emmett-Teller (BET) specific surface area, displacement pressure, maximum mercury saturation and mercury withdrawal efficiency parameters as the basic parameters for evaluation of tight sandstone reservoir quality. Finally, the weight coefficient of each parameter is calculated by the gray correlation method, and a reservoir comprehensive evaluation indicator (RCEI) is designed. The results show that the study area is dominated by types II and III tight sandstone reservoirs. In addition, the research method in this paper can be further extended to the evaluation of shale gas and other unconventional reservoirs after appropriate modification.