The correlation of vitrinite reflectance with maximum temperature in humic organic matter

2005 ◽  
pp. 79-93 ◽  
Author(s):  
Ch. E. Barker ◽  
M. J. Pawlewicz
Keyword(s):  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Maximum Temperature

scholarly journals The Role of Organic Matter on Uranium Precipitation in Zoovch Ovoo, Mongolia

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 310 ◽  
Author(s):  
Dimitrios Rallakis ◽  
Raymond Michels ◽  
Marc Brouand ◽  
Olivier Parize ◽  
Michel Cathelineau
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Late Cretaceous ◽  
Uranium Deposit ◽  
Vitrinite Reflectance ◽  
Driven Systems ◽  
Sem Observation ◽  
Organic Matter Type ◽  
Clay Layers

The Zoovch Ovoo uranium deposit is located in East Gobi Basin in Mongolia. It is hosted in the Sainshand Formation, a Late Cretaceous siliciclastic reservoir, in the lower part of the post-rift infilling of the Mesozoic East Gobi Basin. The Sainshand Formation corresponds to poorly consolidated medium-grained sandy intervals and clay layers deposited in fluvial-lacustrine settings. The uranium deposit is confined within a 60- to 80-m-thick siliciclastic reservoir inside aquifer driven systems, assimilated to roll-fronts. As assessed by vitrinite reflectance (%Rr < 0.4) and molecular geochemistry, the formation has never experienced significant thermal maturation. Detrital organic matter (type III and IV kerogens) is abundant in the Zoovch Ovoo depocenter. In this framework, uranium occurs as: (i) U-rich macerals without any distinguishable U-phase under SEM observation, containing up to 40 wt % U; (ii) U expressed as UO2 at the rims of large (several millimeters) macerals and (iii) U oxides partially to entirely replacing macerals, while preserving the inherited plant texture. Thus, uranium is accumulated gradually in the macerals through an organic carbon–uranium epigenization process, in respect to the maceral’s chemistry and permeability. Most macerals are rich in S and, to a lesser extent, in Fe. Frequently, Fe and S contents do not fit the stoichiometry of pyrite, although pyrite also occurs as small inclusions within the macerals. The organic matter appears thus as a major redox trap for uranium in this kind of geological setting.

Hydrocarbon Generative Properties and Maturity of Cretaceous and Eocene Sediments in the Middle Kura Depression, Azerbaijan

2021 ◽  
Author(s):  
Shahin Khosrov Akhundov ◽  
Mushfig Farhad Tagiyev ◽  
Arastun Ismail Khuduzade ◽  
Natig Namig Aliyev
Keyword(s):  
Organic Matter ◽  
Brown Coal ◽  
Lower Cretaceous ◽  
Vitrinite Reflectance ◽  
Sedimentary Cover ◽  
Hard Coal ◽  
Marine Origin ◽  
Formation Conditions ◽  
Lesser Caucasus ◽  
Reflectance Data

Abstract Meso-Cenozoic sedimentary cover in the Middle Kura depression located between the Greater and Lesser Caucasus mountain structures contains numerous oil accumulations. According to studies in the Cretaceous and Paleogene strata, sedimentary organic matter is of mixed clastic-marine origin. Moderate amounts of organic matter have been recorded in the Eocene sediments (on average 0.70%), in the Upper and Lower Cretaceous average values made up 0.39% и 0.42%, respectively. Analysis of bitumoid composition suggests that in a number of areas bitumoids have experienced a widespread movement across the sedimentary strata. The results of measurements on isolated samples indicate that the Cretaceous strata have only advanced to the initial hard-coal stage of organic transformation (0.48-0.55%Ro). On vitrinite reflectance data the Eocene deposits in studied areas of the Middle Kura depression have reached initial (brown-coal) stage of catagenetic transformation (±0.48Ro%; est. paleotemperature of 85°C). Nonetheless, analysis of formation conditions of commercial HC accumulations found earlier in the Eocene strata allows considering them the most prospective in the Middle Kura depression.

Accumulation Factors Analysis of Coal-Bearing Strata Shale Gas in Qinshui Basin

2013 ◽  
Vol 868 ◽  
pp. 121-124 ◽  
Author(s):  
Jun Yuan ◽  
Yan Bin Wang ◽  
Xin Zhang ◽  
Jing Jing Fan ◽  
Pei Xue
Keyword(s):  
Organic Matter ◽  
Mineral Composition ◽  
Shale Gas ◽  
Vitrinite Reflectance ◽  
Qinshui Basin ◽  
Factors Analysis ◽  
Upper Paleozoic ◽  
Organic Matter Type ◽  
Organic Matter Abundance

The Shanxi and Taiyuan formations in Permo-Carboniferous of upper Paleozoic Erathem of Qinshui Basin, not only has abundant coal and CBM resources, also has a lot of shales. By analyzing the shale thickness, organic matter type, organic matter abundance, vitrinite reflectance, mineral composition of the Permo-Carboniferous coal-bearing strata, considered that the shale thickness of coal-bearing strata in the Qinshui Basin is larger, the organic matter abundance is general, but maturity is high and full of rich brittle mineral. It is in favor of late fracturing.

Aromatic hydrocarbons from the Middle Jurassic fossil wood of the Polish Jura

2013 ◽  
Vol 2 (1) ◽  
pp. 82-90
Author(s):  
Justyna Smolarek ◽  
Leszek Marynowski
Keyword(s):  
Organic Matter ◽  
Aromatic Hydrocarbons ◽  
Middle Jurassic ◽  
Vitrinite Reflectance ◽  
Fossil Wood ◽  
Terrestrial Organic Matter ◽  
Weathering Processes ◽  
Diagenetic Processes ◽  
Almost All ◽  
Parameter Values

ABSTRACT Aromatic hydrocarbons are present in the fossil wood samples in relatively small amounts. In almost all of the tested samples the dominating aromatic hydrocarbon is perylene and its methyl and dimethyl derivatives. The most important biomarkers present in the aromatic fraction are dehydroabietane, siomonellite and retene, compounds characteristic for conifers. The distribution of discussed compounds is highly variable due to such early diagenetic processes affecting the wood as oxidation and the activity of microorganisms. MPI1 parameter values (methylphenanthrene index) for the majority of the samples are in the range of 0.1 to 0.5, which results in the highly variable values of Rc (converted value of vitrinite reflectance) ranging from 0.45 to 0.70%. Such values suggest that MPI1 parameter is not useful as maturity parameter in case of Middle Jurassic ore-bearing clays, even if measured strictly on terrestrial organic matter (OM). As a result of weathering processes (oxidation) the distribution of aromatic hydrocarbons changes. In the oxidized samples the amount of aromatic hydrocarbons, both polycyclic as well as aromatic biomarkers decreases.

COAL AS A SOURCE OF OIL AND GAS: A CASE STUDY FROM THE BASS BASIN, AUSTRALIA

2003 ◽  
Vol 43 (1) ◽  
pp. 117 ◽  
Author(s):  
C.J. Boreham ◽  
J.E. Blevin ◽  
A.P. Radlinski ◽  
K.R. Trigg
Keyword(s):  
Organic Matter ◽  
Oil And Gas ◽  
Middle Eocene ◽  
Vitrinite Reflectance ◽  
Mineral Resources ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Gas Generation ◽  
Australian Context ◽  
Effective Source

Only a few published geochemical studies have demonstrated that coals have sourced significant volumes of oil, while none have clearly implicated coals in the Australian context. As part of a broader collaborative project with Mineral Resources Tasmania on the petroleum prospectivity of the Bass Basin, this geochemical study has yielded strong evidence that Paleocene–Eocene coals have sourced the oil and gas in the Yolla, Pelican and Cormorant accumulations in the Bass Basin.Potential oil-prone source rocks in the Bass Basin have Hydrogen Indices (HIs) greater than 300 mg HC/g TOC. The coals within the Early–Middle Eocene succession commonly have HIs up to 500 mg HC/g TOC, and are associated with disseminated organic matter in claystones that are more gas-prone with HIs generally less than 300 mg HC/g TOC. Maturity of the coals is sufficient for oil and gas generation, with vitrinite reflectance (VR) up to 1.8 % at the base of Pelican–5. Igneous intrusions, mainly within Paleocene, Oligocene and Miocene sediments, produced locally elevated maturity levels with VR up to 5%.The key events in the process of petroleum generation and migration from the effective coaly source rocks in the Bass Basin are:the onset of oil generation at a VR of 0.65% (e.g. 2,450 m in Pelican–5);the onset of oil expulsion (primary migration) at a VR of 0.75% (e.g. 2,700–3,200 m in the Bass Basin; 2,850 m in Pelican–5);the main oil window between VR of 0.75 and 0.95% (e.g. 2,850–3,300 m in Pelican–5); and;the main gas window at VR >1.2% (e.g. >3,650 m in Pelican–5).Oils in the Bass Basin form a single oil population, although biodegradation of the Cormorant oil has resulted in its statistical placement in a separate oil family from that of the Pelican and Yolla crudes. Oil-to-source correlations show that the Paleocene–Early Eocene coals are effective source rocks in the Bass Basin, in contrast to previous work, which favoured disseminated organic matter in claystone as the sole potential source kerogen. This result represents the first demonstrated case of significant oil from coal in the Australian context. Natural gases at White Ibis–1 and Yolla–2 are associated with the liquid hydrocarbons in their respective fields, although the former gas is generated from a more mature source rock.The application of the methodologies used in this study to other Australian sedimentary basins where commercial oil is thought to be sourced from coaly kerogens (e.g. Bowen, Cooper and Gippsland basins) may further implicate coal as an effective source rock for oil.

THE USE OF COALS AS INDICATORS OF THE OCCURRENCE OF OIL AND GAS

1970 ◽  
Vol 10 (1) ◽  
pp. 35 ◽  
Author(s):  
J. D. Brooks
Keyword(s):  
Organic Matter ◽  
Carbon Content ◽  
Oil And Gas ◽  
Sedimentary Basin ◽  
Total Carbon ◽  
Maximum Temperature ◽  
Mineral Matter ◽  
Hydrocarbon Generation ◽  
Oil Companies ◽  
Upper Limit

Petroleum hydrocarbons are not normal constituents of recent sediments but only appear when a certain stage of diagenesis is reached, through deeper burial. An investigation of the mechanism of formation of oil and gas has shown that an indication of the generation of oil in a sedimentary basin can be obtained by an examination of coals or coaly material encountered during drilling.Coals form a continuous diagenetic and metamorphic series beginning with peat and ending with graphite. Peat and brown coal contain the same type of hydrocarbons as are present in land plants but the composition of coal hydrocarbons changes abruptly in the sub-bituminous to high-volatile bituminous coal range. This is because petroleum-type hydrocarbons are formed at this stage from precursors which are components of waxy leaf cuticles, pollen and spore coatings, by chemical reactions in which oxygen groups are removed from long-chain acids, alcohols and ester waxes. Most Australian oil occurrences are associated with coal-bearing sediments and it appears likely that they are formed at the same stage of alteration, from such land plant residues, finely disseminated in shales and siltstones.The diagenetic changes in coal composition are caused by the increasing temperature accompanying deeper burial, and the composition of a coal, whatever its present depth, is an indication of the maximum temperature to which it has been subjected. The determination of carbon content, reflectivity and other properties of coal samples provided by a number of oil companies, together with laboratory experiments in which petroleum-type hydrocarbons were generated by artificial diagenesis of coal components, indicated that hydrocarbon generation takes place only when the carbon content of the coals approaches 80 percent. In sedimentary basins in Australia the petroleum generation zone occurs at depths varying from 5,500 to greater than 11,000ft., depending upon present or past geothermal gradient.In addition to this lower limit of diagenesis, it has long been maintained that a relation exists (the Carbon Ratio theory) between the likely occurrence of oil and gas reservoirs in a sedimentary basin and the degree of metamorphism of coal if present. The theory sets an upper limit of alteration of organic matter, and states that oil reservoirs are unlikely to occur in areas or at depths in a basin where the 'fixed-carbon' of the coals is greater than about 65 percent (equivalent to a coal of about 85 percent total carbon — dry, mineral-matter free). The Gid-gealpa-Moomba area appears to be a part of the Cooper Basin in which the organic matter is close to this upper limit of metamorphism. The carbon content of the coal at Gidgealpa, associated with gas and light hydrocarbons, is 85-86 percent whereas that at Moomba, associated with dry gas, is higher at approximately 89 percent.Ihus the properties of coal samples encountered during drilling can provide valuable clues for the petroleum geologist in the search for further oil and gas reserves.

scholarly journals Organic geochemical and palynological studies of the Maastrichtian source rock intervals in Bida Basin, Nigeria: implications for hydrocarbon prospectivity

2020 ◽  
Vol 10 (8) ◽  
pp. 3191-3206
Author(s):  
Olusola J. Ojo ◽  
Ayoola Y. Jimoh ◽  
Juliet C. Umelo ◽  
Samuel O. Akande
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Vitrinite Reflectance ◽  
Source Rocks ◽  
High Yield ◽  
Thermal Maturity ◽  
Hydrocarbon Source Rock ◽  
Moderate Amount ◽  
Oxic Condition ◽  
Freshwater Swamp

Abstract The Patti Formation which consists of sandstone and shale offers the best potential source beds in the Bida Basin. This inland basin is one of the basins currently being tested for hydrocarbon prospectivity in Nigeria. Fresh samples of shale from Agbaja borehole, Ahoko quarry and Geheku road cut were analysed using organic geochemical and palynological techniques to unravel their age, paleoecology, palynofacies and source bed hydrocarbon potential. Palynological data suggest Maastrichtian age for the sediments based on the abundance of microfloral assemblage; Retidiporites magdalenensis, Echitriporites trianguliformis and Buttinia andreevi. Dinocysts belonging to the Spiniferites, Deflandrea and Dinogymnium genera from some of the analysed intervals are indicative of freshwater swamp and normal sea conditions. Palynological evidence further suggests mangrove paleovegetation and humid climate. Relatively high total organic carbon TOC (0.77–8.95 wt%) was obtained for the shales which implies substantial concentration of organic matter in the source beds. Hydrocarbon source rock potential ranges from 0.19 to 0.70 mgHC/g.rock except for a certain source rock interval in the Agbaja borehole with high yield of 25.18 mgHC/g.rock. This interval also presents exceptionally high HI of 274 mgHC/g.TOC and moderate amount of amorphous organic matter. The data suggests that in spite of the favourable organic matter quantity, the thermal maturity is low as indicated by vitrinite reflectance and Tmax (0.46 to 0.48 Ro% and 413 to 475 °C, respectively). The hydrocarbon extracts show abundance of odd number alkanes C27–C33, low sterane/hopane ratio and Pr/Ph > 2. We conclude that the source rocks were terrestrially derived under oxic condition and dominated by type III kerogen. Type II organic matter with oil and gas potential is a possibility in Agbaja area of Bida Basin. Thermal maturity is low and little, or no hydrocarbon has been generated from the source rocks.

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