scholarly journals Biomarkers geochemistry of the Alpagut oil shale sequence: an evaluation of dispositional environments and source rock potential from Dodurga-Çorum basin (N-Turkey)

Author(s):  
S. Korkmaz ◽  
R. Kara-Gülbay ◽  
T. Khoitiyn ◽  
M. S. Erdoğan

AbstractThe Cenozoic Çankırı-Çorum basin, with sedimentary facies of varying thickness and distribution, contains raw matters such as coal deposits, oil shales and evaporate. Source rock and sedimentary environment characteristics of the oil shale sequence have been evaluated. The studied oil shales have high organic matter content (from 2.97 to 15.14%) and show excellent source rock characteristics. Oil shales are represented by very high hydrogen index (532–892 mg HC/g TOC) and low oxygen index (8–44 mgCO2/g TOC) values. Pyrolysis data indicate that oil shales contain predominantly Type I and little Type II kerogen. The biomarker data reveal the presence of algal, bacterial organic matter and terrestrial organic matter with high lipid content. These findings show that organic matters in the oil shales can generate hydrocarbon, especially oil. High C26/C25, C24/C23 and low C22/C21 tricyclic terpane, C31R/C30 hopane and DBT/P ratios indicate that the studied oil shales were deposited in a lacustrine environment, and very low Pr/Ph ratio is indicative of anoxic character for the depositional environment. Tmax values from the pyrolysis analysis are in the range of 418–443 °C, and production index ranges from 0.01 to 0.08. On the gas chromatography, high Pr/nC17 and Ph/nC18 ratios and CPI values significantly exceeding 1 were determined. Very low 22S/(22S + 22R) homohopane, 20S/(20S + 20R) sterane, diasterane/sterane and Ts/(Ts + Tm) ratios were calculated from the biomarker data. Results of all these analyses indicate that Alpagut oil shales have not yet matured and have not entered the oil generation window.

GeoArabia ◽  
2011 ◽  
Vol 16 (1) ◽  
pp. 47-64 ◽  
Author(s):  
Mohammed H. Hakimi ◽  
Wan H. Abdullah ◽  
Mohamed R. Shalaby

ABSTRACT In this paper, organic matter content, type and maturity as well as some petrographic characteristics of the Jurassic shales exposed in the Masila Basin were evaluated and their depositional environments were interpreted using organic geochemical and organic petrological studies. The total organic carbon (TOC) contents of shales in the Sunah, Wadi Taribah, and Kharir fields vary between 2.4% and 4.7% with high Hydrogen Index (HI) values. All shale samples display very low Oxygen Index (OI) values. The Sunah and Wadi Taribah shales contain Type II organic matter, while the Kharir shales contain Type II, with minor contributions from Type I organic matter. Tmax values for the shales range from 428 °C to 438 °C and vitrinite reflectance values (%Ro) range from 0.52% to 0.80%. These values reveal that the Sunah and Kharir shales are at peak mature stage while the Wadi Taribah shales are early mature. This is supported by their biomarker maturity parameters. The pristane/phytane (Pr/Ph) ratios range from 1.8 to 2.3. In addition, all shales show a homohopane distribution which is dominated by low carbon numbers, and C35 homohopane index is very low for all shale samples. All these features may indicate that these shales were deposited in a suboxic environment. Sterane distribution was calculated as C27>C29>C28 from the m/z 217 mass chromatogram for all shale samples. The Sunah, Wadi Taribah and Kharir shales are believed to have good oil generating potential. This is supported by high total organic carbon content, hydrogen indices up to 400 mg HC/g TOC and early to peak mature oil window range.


Geosciences ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 337
Author(s):  
Hanane Sghiouri El Idrissi ◽  
Abderrahim Samaouali ◽  
Younes El Rhaffari ◽  
Salah El Alami ◽  
Yves Geraud

In this work, we study the variability of the lithological composition and organic matter content of samples were taken from the different layers M, X and Y of the Timahdit oil shale in Morocco, in order to experimentally analyze the impact of this variability on petrophysical measurements. The objective of this study is to predict the properties of the layers, including their thermal conductivity, thermal diffusivity, porosity and P and S wave velocities. The results of the study of the impact of the organic matter content of the samples on the petrophysical measurements show that, regardless of the organic matter content, thermal conductivity and diffusivity remain insensitive, while P and S wave velocities decrease linearly and porosity increases with increasing organic matter content. On the other hand, the study of the organic matter variability content is consistent with the velocity ratio, so can be used as an organic matter indicator of the layers. Conductivity and thermal diffusivity are almost invariant to the variability of the organic matter.


2017 ◽  
Vol 5 (2) ◽  
pp. SF225-SF242 ◽  
Author(s):  
Xun Sun ◽  
Quansheng Liang ◽  
Chengfu Jiang ◽  
Daniel Enriquez ◽  
Tongwei Zhang ◽  
...  

Source-rock samples from the Upper Triassic Yanchang Formation in the Ordos Basin of China were geochemically characterized to determine variations in depositional environments, organic-matter (OM) source, and thermal maturity. Total organic carbon (TOC) content varies from 4 wt% to 10 wt% in the Chang 7, Chang 8, and Chang 9 members — the three OM-rich shale intervals. The Chang 7 has the highest TOC and hydrogen index values, and it is considered the best source rock in the formation. Geochemical evidence indicates that the main sources of OM in the Yanchang Formation are freshwater lacustrine phytoplanktons, aquatic macrophytes, aquatic organisms, and land plants deposited under a weakly reducing to suboxic depositional environment. The elevated [Formula: see text] sterane concentration and depleted [Formula: see text] values of OM in the middle of the Chang 7 may indicate the presence of freshwater cyanobacteria blooms that corresponds to a period of maximum lake expansion. The OM deposited in deeper parts of the lake is dominated by oil-prone type I or type II kerogen or a mixture of both. The OM deposited in shallower settings is characterized by increased terrestrial input with a mixture of types II and III kerogen. These source rocks are in the oil window, with maturity increasing with burial depth. The measured solid-bitumen reflectance and calculated vitrinite reflectance from the temperature at maximum release of hydrocarbons occurs during Rock-Eval pyrolysis ([Formula: see text]) and the methylphenanthrene index (MPI-1) chemical maturity parameters range from 0.8 to [Formula: see text]. Because the thermal labilities of OM are associated with the kerogen type, the required thermal stress for oil generation from types I and II mixed kerogen has a higher and narrower range of temperature for hydrocarbon generation than that of OM dominated by type II kerogen or types II and III mixed kerogen deposited in the prodelta and delta front.


1980 ◽  
Vol 20 (1) ◽  
pp. 44 ◽  
Author(s):  
A.C. Hutton ◽  
A.J. Kantsler ◽  
A.C. Cook ◽  
D.M. McKirdy

The Tertiary oil-shale deposits at Rundle in Queensland and of the Green River Formation in the western USA, together with Mesozoic deposits such as those at Julia Creek in Queensland, offer prospects of competitive recovery cost through the use of large-scale mining methods or the use of in situ processing.A framework for the classification of oil shales is proposed, based on the origin and properties of the organic matter. The organic matter in most Palaeozoic oil shales is dominantly large, discretely occurring algal bodies, referred to as alginite A. However, Tertiary oil shales of northeastern Australia are chiefly composed of numerous very thin laminae of organic matter cryptically-interbedded with mineral matter. Because the present maceral nomenclature does not adequately encompass the morphological and optical properties of most organic matter in oil shales, it is proposed to use the term alginite B for finely lamellar alginite, and the term lamosites (laminated oil shales) for oil shales which contain alginite B as their dominant organic constituent. In the Julia Creek oil shale the organic matter is very fine-grained and contains some alginite B but has a higher content of alginite A and accordingly is assigned to a suite of oil shales of mixed origin.Petrological and chemical techniques are both useful in identifying the nature and diversity of organic matter in oil shales and in assessing the environments in which they were formed. Such an understanding is necessary to develop exploration concepts for oil shales.


2020 ◽  
Vol 21 (1) ◽  
pp. 45
Author(s):  
Moh. Heri Hermiyanto Zajuli ◽  
Riecca Oktavitania ◽  
Ollybinar Rizkika

This study focused on the region of Central Sumatra that geologically into the Central and South Sumatra Basin. The subjects were from the Eocene shale in the areas such as the Kasiro, Sinamar, and Kelesa Formation. Shale of Central Sumatra Basin tend to have different characteristics with shale of South Sumatra Basin. Maceral content of vitrinite and liptinit on shale in South Sumatra Basin larger than Central Sumatra Basin shale. Oxic-anoxic conditions affecting to the abundance maceral-maceral in both basins. Shale of the  Kasiro Formation have a tend to indicate kerogen type I, and II, while shale of the Sinamar and Kelesa Formation included into kerogen type I, II and III. Shale from the three formation have the potential as an oil and gas with different characteristics. Shale of the Kasiro Formation shale has the potential source rock which can produce more oil than gas. Meanwhile shale of the Sinamar Formation  tend to be potentially as the source rock either oil or gas, oil shale and shale gas, but more potential as oil shale.  Key word : Liptinite, Vitrinite, Eocene, Central Sumatera Basin, South Sumatera Basin


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Wentian Mi ◽  
Xueyuan Qi ◽  
Yan Shang ◽  
Xu Kong ◽  
Zifu Hu

The mudstone and marl from western Hoh Xil basin, located in Tibet of the west of China, were deposited in Tertiary lacustrine environment. Investigation of organic geochemistry, sedimentary characteristics, and 13C in kerogen was conducted to analyze the sedimentary environment, biomarkers, paleoclimate, and source of organic matter during deposition. The Cenozoic sedimentary facies of the basin included upper lacustrine facies and lower alluvial fan facies, which belong to Miocene Wudaoliang Formation and Oligocene Yaxicuo Group, respectively. The Miocene marl-sandstone-mudstone from Wudaoliang Formation was analyzed. Maceral composition was dominated by amorphous organic matter. T max values indicated that the mudstones were thermally immature-low maturity with mainly type II and III organic matter, while organic matter in marlite belongs mainly to type I-II1 with low maturity-maturity stage. The biomarkers showed the characteristics of odd-over-even predominance of long-chain n-alkanes, higher proportion of C27 sterane in most of the samples, heavy δ13Corg composition, low Pr/Ph ratios (0.11-0.36), and so on. Organic geochemistry indicated that the organic matter originated from bacteria, algae, and higher plants. The rocks were formed in reducing environments with stratified water column and high productivity. The paleoclimate became more humid during depositional stage in the western Hoh Xil basin.


2002 ◽  
Vol 42 (1) ◽  
pp. 387 ◽  
Author(s):  
S.C. George ◽  
H. Volk ◽  
T.E. Ruble ◽  
M.P. Brincat

Geochemical evidence is presented for a previously unrecognised oil generative source rock in the Nancar Trough area. This source rock supplements the middle to late Jurassic source rocks, which have previously been shown to have generated most of the oils in the northern Bonaparte Basin and the Vulcan Sub-basin. Fluids with a strong contribution from this new source rock, defined here as the Nancar oil family, have an unusually high abundance of mid-chain substituted monomethylalkanes. In comparison, oils from the Vulcan Sub-basin contain mostly terminally substituted monomethylalkanes and the overall abundance is much lower. Oils from the Laminaria High and some from the northern Vulcan Sub-Basin show intermediate characteristics and may be co-sourced. Evidence from the analysis of fluid inclusion oils was important in establishing the presence of the new oil family because interference from drilling mud contaminants could be excluded. The detailed geochemistry of Ludmilla–1 fluid inclusion oil suggests the source rock for the Nancar oil family was deposited in a marine environment under sub-oxic conditions with limited sulphur content, a low contribution of terrestrial organic matter and a high contribution of organic matter from bacterial activity. Since monomethylalkanes are typical biomarkers of cyanobacteria, the source rock that gave rise to the new oil family may be rich in cyanobacterial organic matter. Further studies on sediment extracts are needed to establish an explicit oil-source rock correlation and to identify the stratigraphic location/palaeo-environment of the source rock. Such information will be valuable in determining the prospectivity of the large and relatively unexplored province draining the Nancar Trough kitchen.


1988 ◽  
Vol 37 (10) ◽  
pp. 530-537
Author(s):  
Mariko ISHIWATARI ◽  
Haru SAKASHITA ◽  
Takashi TATSUMI ◽  
Koichi ADACHI ◽  
Mitushiro ADACHI ◽  
...  

2014 ◽  
Vol 1006-1007 ◽  
pp. 107-111
Author(s):  
Yan Wang ◽  
Wen Biao Huang ◽  
Min Wang

Based on the analysis of source rock geochemical index, with K1qn1 Formation of southern Songliao basin as the research objective layer, it’s concluded that the mean TOC value of shale in K1qn1 Formation is higher, generally more than 1%, which belongs to the best source rock. Most of shale organic matter types are type I and type II1. The thermal evolution degree of organic matter is generally in the mature stage: a stage of large hydrocarbon generation. With logging geochemical method applied, the calculated total resources of shale oil in K1qn1 formation are 15.603 billion tons. The II level of resources are 8.765 billion tons, which is more than 50% of the total resources. The I level of resources are 4.808 billion tons while the III level of resources 2.03 billion tons. Overall, the southern Songliao Basin still has a certain degree of prospecting and mining value.


1914 ◽  
Vol 34 ◽  
pp. 190-201 ◽  
Author(s):  
John B. Robertson

Investigations into the nature of the organic matter in oil-shales began at the time of the famous Torbanehill case in 1854, when experts attempted to settle the question as to whether the substance known as “ Torbanite ” or “ Boghead Mineral” was a coal or an oil-shale. Several witnesses at the trial (Gillespie v. Russel, Session Papers, 1854) maintained that the oilproducing material in the Mineral was of organic origin, while others pronounced it to be bituminous and produced by subaqueous eruptions. T. S. Traill, M.D., proposed for the Boghead Mineral the name “ Bitumenite,” as it seemed to him to “ consist of much bitumen, mingled with earthy matter” (Trans. Roy. 8oc. Edin., 1857, xxi. p. 7). Dr Redfern (Quart. Jonrn. Micros. Soc, 1855, x. pp. 118-119), on the other hand, supposed the round orange-yellow bodies which occur in torbanite to have had their origin in "“ a mass of vegetable cells and tissues which have been disintegrated and otherwise changed by maceration, pressure, and chemical action, and subsequently solidified."” C. E. Bertrand and B. Renault (Bull. Soc. Hist. Nat. Autun, 1892-3) on microscopic examination have classed these bodies as the remains of gelatinous algae which have been altered by bacterial action.


Sign in / Sign up

Export Citation Format

Share Document