The influence of pyrolysis conditions on hydrocarbons composition of the shale oil (Aleksinac oil shale, Serbia)

The amount and the composition of liquid hydrocarbons (HCs) obtained by pyrolysis of oil shale depend on kerogen type, as well as pyrolytic system and conditions [1]. The aim of this study was to compare HCs composition of bitumen isolated from raw oil shale samples (osh) and shale oils obtained by pyrolysis of oil shales in an open system (os) and close system (cs) (Table 1). Investigation has been made on immature outcrop oil shale samples (vitrinite reflectance of 0.41 % Rr) from the Aleksinac deposit (Serbia). Pyrolysis experiments were performed on the two selected samples, which have shown the highest quantity of total organic carbon (TOC > 13 %) and high HCs generation potential (Hydrogen Index, HI > 615 mg HCs/g TOC) in the studied sample set [2]. The HCs composition of the shale oils obtained by open system pyrolysis indicates low maturity. They are similar to distributions of HCs in bitumens isolated from raw (initial) oil shales (Table 1). Therefore open system pyrolysis can be useful for assessment of source and depositional environment of organic matter. On the other head, shale oils obtained by pyrolysis in the close system have distributions of HCs which correspond to higher maturity and they are similar to composition of HCs in crude oil, generated in early stage of “oil window” (Table 1). Therefore, for artificial generation of shale oil (from immature oil shale), having composition comparable to crude oil, the close system pyrolysis is required. CPI – Carbon Preference Index, calculated from distributions of n-alkanes; Rc – calculated vitrinite reflectance = 0.49 x C29ααα20S/20R + 0.33; / – Not determined due to the absence of C29 αββ 20Rsterane in these samples

LES CARACTERISTIQUES FONDAMENTALES DE LA LANGUE SERBO-CROATE

Rezime rukopisa »Les caracteristiques fondamentales de la langue serbo-croate« U prostoru i vremenu, srpskohrvatski jezik se nalazi na sredini izrneđu istočnih i zapadnih indoevropskih jezika, krijući u sebi obilježja statičkog Istoka i dinamičnog Zapada. Stvoren je pod uticajem tri osnovna zakona: homofonije (konsonancije nominalnih nastavaka jednorodnih sklopova), heteromorfije (logičkog razlikovanja izborom diferenciranih nastavaka) i homotetije (ekvivalencije nominalne i verbalne distribucije). Isti jezik se razgrađuje, odnosno trpi promjene, pod utjecajem zakona reakcije: heterofonije (disonancije nominalnih nastavaka jednorodnih sklopova, kao posljedice samoindukcije, odnosno otpora materijalne jezične sredine), homomorfije (formalne podudarnosti raznih logičkih obilježja) i heterotetije (razlučivanja analogije između nominalnih i verbalnih ekvivalencija). Procesi su reverzibilni, pa zato i oscilatorni, a naknada guhitka jezgrovite jezične forme ogleda se u stvaranju novih fonetskih odgovarajućih cjelina. Heteromorfiju održava logika kojoj se suprotstavlja materijalna jezična inercija kao homomorfna težnja za svođenjem nominalnih i verbalnih gradacija na osnovna tri razlikovanja (nominativ, genitiv, dativ -sadašnje, prošlo,buduće vrijeme). Osnovno obilježje srpskohrvatskog jezika je njegov položaj u zajednici indoevropskih jezika koji mu osigurava homotetiju u punoj mjeri

The review of some novel biomarkers in sedimentary organic matter

A series of novel C33-C35 hexacyclic benzohopanes have been identified in coals and crude oils of different ages from all over the world [1]. They differ from regular benzohopanes by the presence of methyl group in position C-31. These compounds are more abundant in coals and terrestrial oils. The investigation also showed that mature samples have distributions of benzohopanes distinct from immature ones, which are characterised by a greater number of benzohopane isomers. Although exact structures of the additional isomers were not determined, it seems they were formed by an isomerisation of alkyl groups attached to the aromatic ring. Two novel monoaromatic hydrocarbons (MW = 270; basic fragment ions m/z 255 and 146) were identified in coals, mudstones and crude oils. Their structures were determined as cis- and transicetexa-8,11,13-trienes (or dehydroicetexanes) using NMR spectroscopy. Dehydroicetexanes are potential biomarkers of Cupressaceae (cypress conifers). Benzo[b]naphtho[d]furans (BNFs) have been identified in oils, condensates, source-rocks, coals and coaly shales, being more abundant in the latter. We detected BNFs (m/z 218) in relatively high amounts in the aromatic fractions of pyrolysates of brown coals which attained the maturity corresponding to vitrinite reflectance of 1.80 %Rr [2]. This result suggests that BNFs can be attractive for investigations of mature fluids that originate from gas/condensate prone sources, rich in type III kerogen, which are usually depleted in biomarkers. Recently, it was observed that [2,1]/[1,2]BNF ratio can be used to describe lithofacies [3]. This ratio is much lower in sediments from fluvial-deltaic systems than in clay-depleted sediments from marine environments. 1-Chloro-n-alkanes (m/z 91) have been identified in saltmarsh vegetation, recent sediments from estuarine setting and freshwater lake sediments [4]. Despite their absence in the investigated crude oils, we identified a series of 1-chloro-n-alkanes in pyrolysates of the corresponding asphaltenes, obtained at 250 oC. This result indicates very good preservation of biomarkers occluded inside asphaltenes and announces a possible application of 1-chloro-n-alkanes in correlation studies.Invited Lectur

Organic geochemistry of crude oils from the turija oil field (SE Pannonian Basin, Serbia)

The Turija oil field, being an important oil field in Serbia, is located in the Banat Depression of the southeastern part of the Pannonian Basin. Oil samples from the Turija oil field were investigated in order to estimate origin, depositional environment, thermal maturity and age of the corresponding source rocks. For that purpose, a comprehensive analysis of biomarkers and aromatic compounds was performed. n-Alkanes are predominant compounds in the total ion chromatograms of saturated fractions of all samples, showing that Turija oils are not biodegraded. The distributions of n-alkanes, which are characterised by equivalent abundances of long- and short-chain homologues and maximums at C17, C21 and C27, suggest a mixed aquatic-terrestrial origin. The uniform distributions of regular C27-C29 5α(H)14α(H)17α(H) 20(R) steranes support the previous assumption. The presence of oleanane in all samples is indicative for a contribution of angiosperm plants to the precursor organic matter (OM). Furthermore, the presence of this biomarker implies the Upper Cretaceous or younger age of the corresponding source rocks. Isoreniratane and its derivatives have been identified in all samples. Although isorenieratane can originate from β-carotene, which is widespread in algae, bacteria and terrestrial plants, the presence of other catagenetic products of isorenieratene (mass fragmentogram m/z 133 of the aromatic fraction) unambiguously confirms a contribution of green sulphur bacteria Chlorobiaceae to the precursor organic material [1]. The pristane to phytane (Pr/Ph) ratio ranges from 0.64 to 1.17, indicating reducing to dysoxic conditions during the deposition of precursor OM. The presence of the above mentioned isorenieratane derivatives implies the photic zone of anoxia. The stratification of water column is also supported by the presence of gammacerane and values of gammacerane index, GI = gammacerane x 10/(gammacerane + C30 17α(H)21β(H)-hopane) > 1 in almost all the samples. Alkylated 2-methyl-2- (4,8,12-trimethyltridecyl) chromans (MTTCs) were detected in all studied oils. A predominance of 5,7,8-trimethyl-MTTC over 5,8-dimethyl-MTTC, 7,8-dimethyl-MTTC and 8-methyl-MTTC, associated with the values of MTTC ratio (MTTC = 5,7,8-trimethyl-MTTC/ΣMTTCs) in 0.44 to 0.65 range, indicates deposition of OM in a brackish environment [2]. The maturity of Turija oils was determined using typical sterane and hopane isomerisation maturity parameters and methyldibenzothiophene ratio, MDBTR = 4-MDBT/1-MDBT [3]. The obtained results indicate that Turija oils were generated in an early stage of oil window

Determination of inorganic compounds in drinking water on the basis of house water heater scale, part 1: Determination of heavy metals and uranium

The analysis of scale originated from drinking water on the house water heater, showed that scale is basically calcium carbonate that crystallizes hexagonally in the form of calcite. Scale taken as a sample from different spots in Belgrade – upper town of Zemun (sample 1) and Pančevo (sample 2) showed different configuration although it came from the same waterworks. That indicates either that the water flowing through waterworks pipes in different parts of the city is not the same or the waterworks net is not the same (age, maintaining, etc). All the elements which are dominant in drinking water (Ca, Mg, K, and Na), and which could be found in water by natural processes, are by their content far below the values regulated by law. The analysis also showed the presence of many metals: Ti, Pb, Zn, Cu Li, Sr, Cd, and Cr in the first sample, which are not found in the scale taken near Pančevo. The results obtained by calculating the mass concentration in drinking water on the basis of scale content, showed that both waters belonged to the category of low mineral waters. Contents of inorganic substances in these waters (117.85 mg/dm3 for sample 1 or 80.83 mg/dm3 for sample 2) are twice lower than the values predicted by the legislation. Gammaspectrometric analysis indicates the presence of radioactive elements – uranium and strontium which can influence human health

Maceral and biomarker composition of lignite lithotypes - Implications on palaeoenvironment and grindability properties

Maceral and biomarker composition of different lignite lithotypes: matrix-coal, pale yellow xylite-rich coal, dark yellow xylite-rich coal, brown xylite-rich coal, mineral-rich coal and dopplerite originating from the Upper Miocene (“Pontian”) Kostolac Basin, Serbia was studied in detail. The objective was to establish the sources of organic matter and to determine palaeoenvironmental conditions which resulted in formation of different lignite lithotypes. Moreover, the influence of lignite lithotypes on grindability properties has also been assessed. Mineral-rich coal was formed in topogenous fresh water peat mire with open water areas. Formation of matrix coal was performed in reed march. The peatification of pale yellow- and dark yellow xylite proceeded in dry forest swamp. Brown xylite was formed in wet forest swamp, whereas dopplerite could have formed during transition of wet forest swamp into bush mire. Contents of liptinites, inertinites, gelinite, mineral matter, sesquiterpenoids, hopanoids and n-alkanes have positive impact on Hardgrove Grindability Index (HGI), whereas total huminites, telohuminite and total organic carbon content, as well as retene/2-methyl, 1-(4’-methylpentyl), 6-isopropylnaphthalene ratio exhibited negative influence on HGI