TY  - JOUR
AU  - Saheed, Ramadan Musbah M.
AU  - Knudsen, Tatjana Šolević
AU  - Faraj, Musbah Abduljalil M.
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
PY  - 2023
UR  - http://cherry.chem.bg.ac.rs/handle/123456789/5795
AB  - Crude oil samples from the Sharara-C oil field (Concession NC-115, Murzuq Basin, SW Libya) were analysed by organic geochemical methods in order to infer the geochemical characteristics of their respective source rocks. Aromatic hydrocarbons were analysed by gas chromatography – mass spectrometry (GC-MS), and gas chromatography – tandem mass spectrometry (GC-MS-MS) was used to analyse saturated biomarkers. The Sharara-C oils are interpreted to have been generated by marine shales containing mixed terrigenous and marine organic materials deposited in an intermediate (suboxic) environment. Age-specific biomarker ratios indicated that the oils are older than Cretaceous, and maturation-related parameters pointed to their high thermal maturity. Consistent with previous studies, source rocks are inferred to be “hot” shales in the Lower Silurian Tanezzuft Formation. Almost all the parameter ratios calculated varied over a very narrow range, indicating that the investigated oils were compositionally similar. The only significant difference that was noted concerned the sterane/hopane ratios whose variation suggested that there was some variability in the composition of the source organic material. The organic geochemical parameters determined for the Sharara-C crude oils were compared with published data on other crude oils from Concession NC-115. Almost all the parameters agreed well with previously published data on oils from this part of the Murzuq Basin. The greatest deviation concerned the values of some of the maturity parameters. This tended to confirm the conclusions of previous studies concerning the presence of a number of distinct oil families and sub-families in the Sharara oil field area which are genetically related but which have different maturities.
T2  - Journal of Petroleum Geology
T1  - Geochemical Characteristics of Crude Oils from the Sharara-C Oil Field, Murzuq Basin, Southwestern Libya
VL  - 46
IS  - 1
SP  - 103
EP  - 123
DO  - 10.1111/jpg.12832
ER  - 

@article{
author = "Saheed, Ramadan Musbah M. and Knudsen, Tatjana Šolević and Faraj, Musbah Abduljalil M. and Nytoft, Hans Peter and Jovančićević, Branimir",
year = "2023",
abstract = "Crude oil samples from the Sharara-C oil field (Concession NC-115, Murzuq Basin, SW Libya) were analysed by organic geochemical methods in order to infer the geochemical characteristics of their respective source rocks. Aromatic hydrocarbons were analysed by gas chromatography – mass spectrometry (GC-MS), and gas chromatography – tandem mass spectrometry (GC-MS-MS) was used to analyse saturated biomarkers. The Sharara-C oils are interpreted to have been generated by marine shales containing mixed terrigenous and marine organic materials deposited in an intermediate (suboxic) environment. Age-specific biomarker ratios indicated that the oils are older than Cretaceous, and maturation-related parameters pointed to their high thermal maturity. Consistent with previous studies, source rocks are inferred to be “hot” shales in the Lower Silurian Tanezzuft Formation. Almost all the parameter ratios calculated varied over a very narrow range, indicating that the investigated oils were compositionally similar. The only significant difference that was noted concerned the sterane/hopane ratios whose variation suggested that there was some variability in the composition of the source organic material. The organic geochemical parameters determined for the Sharara-C crude oils were compared with published data on other crude oils from Concession NC-115. Almost all the parameters agreed well with previously published data on oils from this part of the Murzuq Basin. The greatest deviation concerned the values of some of the maturity parameters. This tended to confirm the conclusions of previous studies concerning the presence of a number of distinct oil families and sub-families in the Sharara oil field area which are genetically related but which have different maturities.",
journal = "Journal of Petroleum Geology",
title = "Geochemical Characteristics of Crude Oils from the Sharara-C Oil Field, Murzuq Basin, Southwestern Libya",
volume = "46",
number = "1",
pages = "103-123",
doi = "10.1111/jpg.12832"
}

Saheed, R. M. M., Knudsen, T. Š., Faraj, M. A. M., Nytoft, H. P.,& Jovančićević, B.. (2023). Geochemical Characteristics of Crude Oils from the Sharara-C Oil Field, Murzuq Basin, Southwestern Libya. in Journal of Petroleum Geology, 46(1), 103-123.
https://doi.org/10.1111/jpg.12832

Saheed RMM, Knudsen TŠ, Faraj MAM, Nytoft HP, Jovančićević B. Geochemical Characteristics of Crude Oils from the Sharara-C Oil Field, Murzuq Basin, Southwestern Libya. in Journal of Petroleum Geology. 2023;46(1):103-123.
doi:10.1111/jpg.12832 .

Saheed, Ramadan Musbah M., Knudsen, Tatjana Šolević, Faraj, Musbah Abduljalil M., Nytoft, Hans Peter, Jovančićević, Branimir, "Geochemical Characteristics of Crude Oils from the Sharara-C Oil Field, Murzuq Basin, Southwestern Libya" in Journal of Petroleum Geology, 46, no. 1 (2023):103-123,
https://doi.org/10.1111/jpg.12832 . .

TY  - JOUR
AU  - Saheed, Ramadan Musbah M.
AU  - Šolević-Knudsen, Tatjana
AU  - Faraj, Musbah Abduljalil M.
AU  - Nikolovski, Zlatko
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
PY  - 2020
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/4303
AB  - Seven crude oils from four oil fields in the Sirte and Murzuq Basins in Libya were investigated in order to estimate their organic geochemical homogeneity. Saturated biomarkers (n-alkanes and isoprenoids) were analyzed using gas chromatography–mass spectrometry (GC–MS). The parameters calculated from the distributions of n-alkanes and isoprenoid aliphatic alkanes, pristane and phytane were used to interpret the organic geochemical characteristics of the oils. Based on the high relative concentration of lower n-alkane homologues in the C11–C16 range and high API values, the oils were classified as light oils. These results also implied that the oils were not biodegraded. The parameters calculated from the distributions of saturated biomarkers indicated that all investigated oils were generated from source rocks containing organic matter of a similar marine origin but with a contribution of terrestrial organic matter. The results also demonstrated that these source rocks were deposited in an oxic environment. The same source rock or the same type of source rocks for all seven samples were postulated. It was concluded that, if the crude oils from these distant basins originated from the same source rocks, they must have had different lengths of their migration pathways.
T2  - Journal of the Serbian Chemical Society
T1  - Saturated biomarkers in the estimation of organic geochemical homogeneity of crude oils from four oil fields in Libya
VL  - 85
IS  - 11
SP  - 1489
EP  - 1499
DO  - 10.2298/JSC200501055S
ER  - 

@article{
author = "Saheed, Ramadan Musbah M. and Šolević-Knudsen, Tatjana and Faraj, Musbah Abduljalil M. and Nikolovski, Zlatko and Nytoft, Hans Peter and Jovančićević, Branimir",
year = "2020",
abstract = "Seven crude oils from four oil fields in the Sirte and Murzuq Basins in Libya were investigated in order to estimate their organic geochemical homogeneity. Saturated biomarkers (n-alkanes and isoprenoids) were analyzed using gas chromatography–mass spectrometry (GC–MS). The parameters calculated from the distributions of n-alkanes and isoprenoid aliphatic alkanes, pristane and phytane were used to interpret the organic geochemical characteristics of the oils. Based on the high relative concentration of lower n-alkane homologues in the C11–C16 range and high API values, the oils were classified as light oils. These results also implied that the oils were not biodegraded. The parameters calculated from the distributions of saturated biomarkers indicated that all investigated oils were generated from source rocks containing organic matter of a similar marine origin but with a contribution of terrestrial organic matter. The results also demonstrated that these source rocks were deposited in an oxic environment. The same source rock or the same type of source rocks for all seven samples were postulated. It was concluded that, if the crude oils from these distant basins originated from the same source rocks, they must have had different lengths of their migration pathways.",
journal = "Journal of the Serbian Chemical Society",
title = "Saturated biomarkers in the estimation of organic geochemical homogeneity of crude oils from four oil fields in Libya",
volume = "85",
number = "11",
pages = "1489-1499",
doi = "10.2298/JSC200501055S"
}

Saheed, R. M. M., Šolević-Knudsen, T., Faraj, M. A. M., Nikolovski, Z., Nytoft, H. P.,& Jovančićević, B.. (2020). Saturated biomarkers in the estimation of organic geochemical homogeneity of crude oils from four oil fields in Libya. in Journal of the Serbian Chemical Society, 85(11), 1489-1499.
https://doi.org/10.2298/JSC200501055S

Saheed RMM, Šolević-Knudsen T, Faraj MAM, Nikolovski Z, Nytoft HP, Jovančićević B. Saturated biomarkers in the estimation of organic geochemical homogeneity of crude oils from four oil fields in Libya. in Journal of the Serbian Chemical Society. 2020;85(11):1489-1499.
doi:10.2298/JSC200501055S .

Saheed, Ramadan Musbah M., Šolević-Knudsen, Tatjana, Faraj, Musbah Abduljalil M., Nikolovski, Zlatko, Nytoft, Hans Peter, Jovančićević, Branimir, "Saturated biomarkers in the estimation of organic geochemical homogeneity of crude oils from four oil fields in Libya" in Journal of the Serbian Chemical Society, 85, no. 11 (2020):1489-1499,
https://doi.org/10.2298/JSC200501055S . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Kildahl-Andersen, Geir
AU  - Lindström, Sofie
AU  - Rise, Frode
AU  - Bechtel, Achim
AU  - Mitrović, Danica D.
AU  - Đoković, Nataša
AU  - Životić, Dragana R.
AU  - Stojanović, Ksenija A.
PY  - 2019
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2811
AB  - Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian
lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using
NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10→20)-abeo-abietane or
icetexane skeleton consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of
the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging fromTriassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis+ trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%Rr) above 0.5 suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetaxanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.
PB  - Elsevier
T2  - Organic Geochemistry
T1  - Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae
DO  - 10.1016/j.orggeochem.2019.01.001
ER  - 

@article{
author = "Nytoft, Hans Peter and Kildahl-Andersen, Geir and Lindström, Sofie and Rise, Frode and Bechtel, Achim and Mitrović, Danica D. and Đoković, Nataša and Životić, Dragana R. and Stojanović, Ksenija A.",
year = "2019",
abstract = "Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian
lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using
NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10→20)-abeo-abietane or
icetexane skeleton consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of
the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging fromTriassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis+ trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%Rr) above 0.5 suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetaxanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.",
publisher = "Elsevier",
journal = "Organic Geochemistry",
title = "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae",
doi = "10.1016/j.orggeochem.2019.01.001"
}

Nytoft, H. P., Kildahl-Andersen, G., Lindström, S., Rise, F., Bechtel, A., Mitrović, D. D., Đoković, N., Životić, D. R.,& Stojanović, K. A.. (2019). Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry
Elsevier..
https://doi.org/10.1016/j.orggeochem.2019.01.001

Nytoft HP, Kildahl-Andersen G, Lindström S, Rise F, Bechtel A, Mitrović DD, Đoković N, Životić DR, Stojanović KA. Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry. 2019;.
doi:10.1016/j.orggeochem.2019.01.001 .

Nytoft, Hans Peter, Kildahl-Andersen, Geir, Lindström, Sofie, Rise, Frode, Bechtel, Achim, Mitrović, Danica D., Đoković, Nataša, Životić, Dragana R., Stojanović, Ksenija A., "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae" in Organic Geochemistry (2019),
https://doi.org/10.1016/j.orggeochem.2019.01.001 . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Kildahl-Andersen, Geir
AU  - Lindström, Sofie
AU  - Rise, Frode
AU  - Bechtel, Achim
AU  - Mitrović, Danica D.
AU  - Đoković, Nataša
AU  - Životić, Dragana R.
AU  - Stojanović, Ksenija A.
PY  - 2019
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2846
AB  - Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10 → 20)-abeo-abietane or icetexane skeleton, consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging from Triassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis + trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%R r ) above 0.5, suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetexanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.
PB  - Elsevier
T2  - Organic Geochemistry
T1  - Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae
VL  - 129
SP  - 14
EP  - 23
DO  - 10.1016/j.orggeochem.2019.01.001
ER  - 

@article{
author = "Nytoft, Hans Peter and Kildahl-Andersen, Geir and Lindström, Sofie and Rise, Frode and Bechtel, Achim and Mitrović, Danica D. and Đoković, Nataša and Životić, Dragana R. and Stojanović, Ksenija A.",
year = "2019",
abstract = "Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10 → 20)-abeo-abietane or icetexane skeleton, consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging from Triassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis + trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%R r ) above 0.5, suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetexanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.",
publisher = "Elsevier",
journal = "Organic Geochemistry",
title = "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae",
volume = "129",
pages = "14-23",
doi = "10.1016/j.orggeochem.2019.01.001"
}

Nytoft, H. P., Kildahl-Andersen, G., Lindström, S., Rise, F., Bechtel, A., Mitrović, D. D., Đoković, N., Životić, D. R.,& Stojanović, K. A.. (2019). Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry
Elsevier., 129, 14-23.
https://doi.org/10.1016/j.orggeochem.2019.01.001

Nytoft HP, Kildahl-Andersen G, Lindström S, Rise F, Bechtel A, Mitrović DD, Đoković N, Životić DR, Stojanović KA. Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry. 2019;129:14-23.
doi:10.1016/j.orggeochem.2019.01.001 .

Nytoft, Hans Peter, Kildahl-Andersen, Geir, Lindström, Sofie, Rise, Frode, Bechtel, Achim, Mitrović, Danica D., Đoković, Nataša, Životić, Dragana R., Stojanović, Ksenija A., "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae" in Organic Geochemistry, 129 (2019):14-23,
https://doi.org/10.1016/j.orggeochem.2019.01.001 . .

TY  - JOUR
AU  - Gajica, Gordana
AU  - Šajnović, Aleksandra
AU  - Stojanović, Ksenija A.
AU  - Kostić, Aleksandar Ž.
AU  - Slipper, Ian
AU  - Antonijevic, Milan
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
PY  - 2017
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2522
AB  - A detailed evaluation of geochemical properties of oil shale samples,from the outcrops of the Lower Miocene upper layer in the Dubrava area, Aleksinac basin, Serbia, was performed. For that purpose X-ray diffraction (XRD) analysis, Rock Eval pyrolysis, gas chromatography-mass spectrometry (GC-MS) analysis of biomarkers and conventional pyrolysis in an autoclave were used. Most of the samples have similar mineral compositions with predominance of clay and feldspar minerals. Three samples are characterised by an elevated content of carbonates, and among them one sample has a notable prevalence of this mineral group. This sample also demonstrated certain differences in biomarker distribution. In most samples organic matter (OM) consists predominantly of type I and II kerogens, showing high oil generative potential, whereas three samples, which contain type II kerogen with a certain input of type III kerogen, demonstrated potential to produce both, oil and gas. The OM of all samples is immature and corresponds to the vitrinite reflectance of ca. 0.40%. Biomarker patterns along with Rock-Eval data indicated a strong contribution of aquatic organisms such as green and brown algae and bacteria with some influence of higher plants OM. The organic matter was deposited in a reducing lacustrine alkaline brackish to freshwater environment under warm climate conditions. Preservation of OM was governed by stratification of the water column rather than its height. Tectonic movements that caused the regional tilting of an investigated area and supported minor marine ingression and influx of fresh water played an important role in formation of the sediments. Conventional pyrolytic experiments confirmed that these sediments at the catagenetic stage could be a significant source of liquid hydrocarbons.
PB  - Estonian Academy Publishers, Tallinn
T2  - Oil Shale
T1  - Organic Geochemical Study of the Upper Layer of Aleksinac Oil Shale in the Dubrava Block, Serbia
VL  - 34
IS  - 3
SP  - 197
EP  - 218
DO  - 10.3176/oil.2017.3.01
ER  - 

@article{
author = "Gajica, Gordana and Šajnović, Aleksandra and Stojanović, Ksenija A. and Kostić, Aleksandar Ž. and Slipper, Ian and Antonijevic, Milan and Nytoft, Hans Peter and Jovančićević, Branimir",
year = "2017",
abstract = "A detailed evaluation of geochemical properties of oil shale samples,from the outcrops of the Lower Miocene upper layer in the Dubrava area, Aleksinac basin, Serbia, was performed. For that purpose X-ray diffraction (XRD) analysis, Rock Eval pyrolysis, gas chromatography-mass spectrometry (GC-MS) analysis of biomarkers and conventional pyrolysis in an autoclave were used. Most of the samples have similar mineral compositions with predominance of clay and feldspar minerals. Three samples are characterised by an elevated content of carbonates, and among them one sample has a notable prevalence of this mineral group. This sample also demonstrated certain differences in biomarker distribution. In most samples organic matter (OM) consists predominantly of type I and II kerogens, showing high oil generative potential, whereas three samples, which contain type II kerogen with a certain input of type III kerogen, demonstrated potential to produce both, oil and gas. The OM of all samples is immature and corresponds to the vitrinite reflectance of ca. 0.40%. Biomarker patterns along with Rock-Eval data indicated a strong contribution of aquatic organisms such as green and brown algae and bacteria with some influence of higher plants OM. The organic matter was deposited in a reducing lacustrine alkaline brackish to freshwater environment under warm climate conditions. Preservation of OM was governed by stratification of the water column rather than its height. Tectonic movements that caused the regional tilting of an investigated area and supported minor marine ingression and influx of fresh water played an important role in formation of the sediments. Conventional pyrolytic experiments confirmed that these sediments at the catagenetic stage could be a significant source of liquid hydrocarbons.",
publisher = "Estonian Academy Publishers, Tallinn",
journal = "Oil Shale",
title = "Organic Geochemical Study of the Upper Layer of Aleksinac Oil Shale in the Dubrava Block, Serbia",
volume = "34",
number = "3",
pages = "197-218",
doi = "10.3176/oil.2017.3.01"
}

Gajica, G., Šajnović, A., Stojanović, K. A., Kostić, A. Ž., Slipper, I., Antonijevic, M., Nytoft, H. P.,& Jovančićević, B.. (2017). Organic Geochemical Study of the Upper Layer of Aleksinac Oil Shale in the Dubrava Block, Serbia. in Oil Shale
Estonian Academy Publishers, Tallinn., 34(3), 197-218.
https://doi.org/10.3176/oil.2017.3.01

Gajica G, Šajnović A, Stojanović KA, Kostić AŽ, Slipper I, Antonijevic M, Nytoft HP, Jovančićević B. Organic Geochemical Study of the Upper Layer of Aleksinac Oil Shale in the Dubrava Block, Serbia. in Oil Shale. 2017;34(3):197-218.
doi:10.3176/oil.2017.3.01 .

Gajica, Gordana, Šajnović, Aleksandra, Stojanović, Ksenija A., Kostić, Aleksandar Ž., Slipper, Ian, Antonijevic, Milan, Nytoft, Hans Peter, Jovančićević, Branimir, "Organic Geochemical Study of the Upper Layer of Aleksinac Oil Shale in the Dubrava Block, Serbia" in Oil Shale, 34, no. 3 (2017):197-218,
https://doi.org/10.3176/oil.2017.3.01 . .

TY  - JOUR
AU  - Faraj, Musbah Abduljalil M.
AU  - Šolević-Knudsen, Tatjana
AU  - Stojanović, Ksenija A.
AU  - Pavlović-Ivković, Sonja
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
PY  - 2017
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2567
AB  - The values of parameters calculated from distribution and abundance of the selected pentacyclic terpanes in crude oils from Libya and Serbia, which were originally derived from gas chromatography-mass spectrometry (GC-MS) were compared with results of quantification based on gas chromatography-mass spectrometry-mass spectrometry (GC-MS-MS). The parameters analyzed are the most often used terpane source and maturity parameters, which were applied to a large sample set of 70 oils, originating from five oil fields. The aim of the paper was to investigate to which extent the measurements of the selected parameters by these two instrumental techniques agree and to determine the influence of differences between parameter values on geochemical interpretation. For that purpose two methods, concordance correlation coefficient and mean-difference plot were used. The obtained results indicate that calculation of C(27)18 alpha(H)-22,29,30-trisnorneohopane/(C(27)18 alpha(H)-22,29,30-trisnorneohopane +C(27)17 alpha(H)-22,29,30-trisnorhopane), C(29)18 alpha(H)-30-norneohopane/C(29)17 alpha(H) 21 beta(H)-30-norhopane and C(29)17 alpha(H)21 beta(H)-30-norhopane/ C(30)17 alpha(H)21 beta(H)-hopane ratios either by GC-MS or GC-MS-MS do not significantly influence interpretation. On the other hand, the determination of C(30)17 beta(H)21 alpha(H)-moretane/C(30)17 alpha(H)21 beta(H)-hopane ratio, gammacerane index and oleanane index by GC-MS vs. GC-MS-MS could notably affect interpretation. These differences can be explained by the co-elution and the peak overlapping in GC-MS but also by better separation, higher precision and better selectivity of the GC-MS-MS. Deviation of the almost all studied parameters from the line of equality was similar for the oils from the same oil field but some differences were observed for the oils from different oil fields. Therefore, when GC-MS-MS results are to be used in organic geochemical interpretations, a regional calibration of GC-MS vs. GC-MS-MS relationship for each petroleum system is highly recommended.
PB  - Serbian Chemical Soc, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - GC-MS vs. GC-MS-MS analysis of pentacyclic terpanes in crude oils from Libya and Serbia - A comparison of two methods
VL  - 82
IS  - 11
SP  - 1315
EP  - 1331
DO  - 10.2298/JSC170419075A
ER  - 

@article{
author = "Faraj, Musbah Abduljalil M. and Šolević-Knudsen, Tatjana and Stojanović, Ksenija A. and Pavlović-Ivković, Sonja and Nytoft, Hans Peter and Jovančićević, Branimir",
year = "2017",
abstract = "The values of parameters calculated from distribution and abundance of the selected pentacyclic terpanes in crude oils from Libya and Serbia, which were originally derived from gas chromatography-mass spectrometry (GC-MS) were compared with results of quantification based on gas chromatography-mass spectrometry-mass spectrometry (GC-MS-MS). The parameters analyzed are the most often used terpane source and maturity parameters, which were applied to a large sample set of 70 oils, originating from five oil fields. The aim of the paper was to investigate to which extent the measurements of the selected parameters by these two instrumental techniques agree and to determine the influence of differences between parameter values on geochemical interpretation. For that purpose two methods, concordance correlation coefficient and mean-difference plot were used. The obtained results indicate that calculation of C(27)18 alpha(H)-22,29,30-trisnorneohopane/(C(27)18 alpha(H)-22,29,30-trisnorneohopane +C(27)17 alpha(H)-22,29,30-trisnorhopane), C(29)18 alpha(H)-30-norneohopane/C(29)17 alpha(H) 21 beta(H)-30-norhopane and C(29)17 alpha(H)21 beta(H)-30-norhopane/ C(30)17 alpha(H)21 beta(H)-hopane ratios either by GC-MS or GC-MS-MS do not significantly influence interpretation. On the other hand, the determination of C(30)17 beta(H)21 alpha(H)-moretane/C(30)17 alpha(H)21 beta(H)-hopane ratio, gammacerane index and oleanane index by GC-MS vs. GC-MS-MS could notably affect interpretation. These differences can be explained by the co-elution and the peak overlapping in GC-MS but also by better separation, higher precision and better selectivity of the GC-MS-MS. Deviation of the almost all studied parameters from the line of equality was similar for the oils from the same oil field but some differences were observed for the oils from different oil fields. Therefore, when GC-MS-MS results are to be used in organic geochemical interpretations, a regional calibration of GC-MS vs. GC-MS-MS relationship for each petroleum system is highly recommended.",
publisher = "Serbian Chemical Soc, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "GC-MS vs. GC-MS-MS analysis of pentacyclic terpanes in crude oils from Libya and Serbia - A comparison of two methods",
volume = "82",
number = "11",
pages = "1315-1331",
doi = "10.2298/JSC170419075A"
}

Faraj, M. A. M., Šolević-Knudsen, T., Stojanović, K. A., Pavlović-Ivković, S., Nytoft, H. P.,& Jovančićević, B.. (2017). GC-MS vs. GC-MS-MS analysis of pentacyclic terpanes in crude oils from Libya and Serbia - A comparison of two methods. in Journal of the Serbian Chemical Society
Serbian Chemical Soc, Belgrade., 82(11), 1315-1331.
https://doi.org/10.2298/JSC170419075A

Faraj MAM, Šolević-Knudsen T, Stojanović KA, Pavlović-Ivković S, Nytoft HP, Jovančićević B. GC-MS vs. GC-MS-MS analysis of pentacyclic terpanes in crude oils from Libya and Serbia - A comparison of two methods. in Journal of the Serbian Chemical Society. 2017;82(11):1315-1331.
doi:10.2298/JSC170419075A .

Faraj, Musbah Abduljalil M., Šolević-Knudsen, Tatjana, Stojanović, Ksenija A., Pavlović-Ivković, Sonja, Nytoft, Hans Peter, Jovančićević, Branimir, "GC-MS vs. GC-MS-MS analysis of pentacyclic terpanes in crude oils from Libya and Serbia - A comparison of two methods" in Journal of the Serbian Chemical Society, 82, no. 11 (2017):1315-1331,
https://doi.org/10.2298/JSC170419075A . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Vuković, Nikola S.
AU  - Kildahl-Andersen, Geir
AU  - Rise, Frode
AU  - Životić, Dragana R.
AU  - Stojanović, Ksenija A.
PY  - 2016
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2283
AB  - series of novel C-33-C-35 hexacyclic benzohopanes (C(33)b-C(35)b) were identified in 39 samples of coal extracts and 39 crude oils of different ages from all over the world. C(33)b and C(34)b homologues were isolated, and their structures were determined by nuclear magnetic resonance. The structure of C(35)b benzohopane was proposed based on the mass spectrum and its similarity with the mass spectra of structurally defined C(33)b and C(34)b homologues. The structures of the C(33)b-C(35)b hexacyclic benzohopanes are closely related to isohopanes; both groups are typical for terrestrial organic matter and can be useful in the correlation analysis. A possible pathway of formation of these novel benzohopanes and their hopanoid precursors with an additional branch in the aliphatic side chain is proposed. C(33)b-C(35)b hexacyclic benzohopanes are stable up to the maturity level corresponding to random vitrinite reflectance (Rr) of similar to 0.80%, which was demonstrated by analyzing the samples of different maturity and by the maturation simulation experiments: hydrous pyrolysis of two bituminous coals (Rr = 0.55 and 0.59%) and pyrolysis of an extracted bituminous coal (Rr = 0.56%) and its asphaltenes. This represents a confirmation that the formation of these novel benzohopanes is related to specific depositional conditions and microbial activity during diagenesis. Mature samples (Rr = 0.8%) and hydrous pyrolysate of the bituminous coals (Rr  lt  0.60%) obtained at 330 degrees C show a distinct distribution of benzohopanes in comparison to immature and moderately mature samples, which is characterized by a low abundance of the b series benzohopanes and the presence of regular and numerous other benzohopane isomers. The latter most likely represent isomers of regular and novel benzohopanes with different substitution patterns on the aromatic ring. This isomerization of alkyl groups attached to the aromatic ring, leading to the formation of thermodynamically more stable isomers, is a well-known maturation scenario so far reported in the series of alkylated naphthalenes, phenanthrenes, and dibenzothiophenes. Therefore, in the same way, a distribution of benzohopanes can indicate thermal maturity. In addition to the novel benzohopanes, three series (2 alpha, 2 beta, and 3 beta) of their methylated derivatives were identified in numerous samples. Finally, a novel C-35 heptacyclic benzohopane with an additional cyclopentane ring was also observed in the studied samples, and its structure was tentatively identified based on the mass spectrum. Opposite to the hexacyclic C(33)b-C(35)b benzohopanes, the formation of the C-35 heptacyclic benzohopane does not require a specific hopanoid precursor with two branches in the side chain. Therefore, this compound seems to have less geochemical significance than the new hexacyclic benzohopanes.
PB  - Amer Chemical Soc, Washington
T2  - Energy and Fuels
T1  - Identification of a Novel Series of Benzohopanes and Their Geochemical Significance
VL  - 30
IS  - 7
SP  - 5563
EP  - 5575
DO  - 10.1021/acs.energyfuels.6b00799
ER  - 

@article{
author = "Nytoft, Hans Peter and Vuković, Nikola S. and Kildahl-Andersen, Geir and Rise, Frode and Životić, Dragana R. and Stojanović, Ksenija A.",
year = "2016",
abstract = "series of novel C-33-C-35 hexacyclic benzohopanes (C(33)b-C(35)b) were identified in 39 samples of coal extracts and 39 crude oils of different ages from all over the world. C(33)b and C(34)b homologues were isolated, and their structures were determined by nuclear magnetic resonance. The structure of C(35)b benzohopane was proposed based on the mass spectrum and its similarity with the mass spectra of structurally defined C(33)b and C(34)b homologues. The structures of the C(33)b-C(35)b hexacyclic benzohopanes are closely related to isohopanes; both groups are typical for terrestrial organic matter and can be useful in the correlation analysis. A possible pathway of formation of these novel benzohopanes and their hopanoid precursors with an additional branch in the aliphatic side chain is proposed. C(33)b-C(35)b hexacyclic benzohopanes are stable up to the maturity level corresponding to random vitrinite reflectance (Rr) of similar to 0.80%, which was demonstrated by analyzing the samples of different maturity and by the maturation simulation experiments: hydrous pyrolysis of two bituminous coals (Rr = 0.55 and 0.59%) and pyrolysis of an extracted bituminous coal (Rr = 0.56%) and its asphaltenes. This represents a confirmation that the formation of these novel benzohopanes is related to specific depositional conditions and microbial activity during diagenesis. Mature samples (Rr = 0.8%) and hydrous pyrolysate of the bituminous coals (Rr  lt  0.60%) obtained at 330 degrees C show a distinct distribution of benzohopanes in comparison to immature and moderately mature samples, which is characterized by a low abundance of the b series benzohopanes and the presence of regular and numerous other benzohopane isomers. The latter most likely represent isomers of regular and novel benzohopanes with different substitution patterns on the aromatic ring. This isomerization of alkyl groups attached to the aromatic ring, leading to the formation of thermodynamically more stable isomers, is a well-known maturation scenario so far reported in the series of alkylated naphthalenes, phenanthrenes, and dibenzothiophenes. Therefore, in the same way, a distribution of benzohopanes can indicate thermal maturity. In addition to the novel benzohopanes, three series (2 alpha, 2 beta, and 3 beta) of their methylated derivatives were identified in numerous samples. Finally, a novel C-35 heptacyclic benzohopane with an additional cyclopentane ring was also observed in the studied samples, and its structure was tentatively identified based on the mass spectrum. Opposite to the hexacyclic C(33)b-C(35)b benzohopanes, the formation of the C-35 heptacyclic benzohopane does not require a specific hopanoid precursor with two branches in the side chain. Therefore, this compound seems to have less geochemical significance than the new hexacyclic benzohopanes.",
publisher = "Amer Chemical Soc, Washington",
journal = "Energy and Fuels",
title = "Identification of a Novel Series of Benzohopanes and Their Geochemical Significance",
volume = "30",
number = "7",
pages = "5563-5575",
doi = "10.1021/acs.energyfuels.6b00799"
}

Nytoft, H. P., Vuković, N. S., Kildahl-Andersen, G., Rise, F., Životić, D. R.,& Stojanović, K. A.. (2016). Identification of a Novel Series of Benzohopanes and Their Geochemical Significance. in Energy and Fuels
Amer Chemical Soc, Washington., 30(7), 5563-5575.
https://doi.org/10.1021/acs.energyfuels.6b00799

Nytoft HP, Vuković NS, Kildahl-Andersen G, Rise F, Životić DR, Stojanović KA. Identification of a Novel Series of Benzohopanes and Their Geochemical Significance. in Energy and Fuels. 2016;30(7):5563-5575.
doi:10.1021/acs.energyfuels.6b00799 .

Nytoft, Hans Peter, Vuković, Nikola S., Kildahl-Andersen, Geir, Rise, Frode, Životić, Dragana R., Stojanović, Ksenija A., "Identification of a Novel Series of Benzohopanes and Their Geochemical Significance" in Energy and Fuels, 30, no. 7 (2016):5563-5575,
https://doi.org/10.1021/acs.energyfuels.6b00799 . .

TY  - JOUR
AU  - Faraj, Musbah Abduljalil M.
AU  - Šolević-Knudsen, Tatjana
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
PY  - 2016
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2355
AB  - Four crude oil samples from the oil fields Intisar A, Intisar D and Intisar E (Sirte Basin, Libya) were investigated in order to define depositional environment, lithology, thermal maturity and geologic age of the corresponding source rocks. Saturated biomarkers (n-alkanes, isoprenoids, steranes and triterpanes) were determined using gas chromatography - mass spectrometry (GC MS) and gas chromatography mass spectrometry - mass spectrometry (GC MS MS). Aromatic hydrocarbons (phenanthrene, methylphenanthrenes, methyl-dibenzothiophenes and trimethyl-naphtalenes) were analyzed by GC-MS. The Intisar crude oils were generated from siliciclastic source rocks containing a mixture of marine and terrestrial organic matter. Maturation parameters indicated high level of thermal maturity corresponding to the main phase of oil generation. The analysis of the age-specific biomarker ratios suggested Cretaceous, most probably Lower Cretaceous age for the Intisar oils. Two source rocks for the Intisar oils were identified, similar in the precursor organic matter type, lithology, maturity and geologic age but different in the redox conditions in the environment during their deposition. The oils generated from these different sources probably migrated over different migration pathways. (C) 2016 Elsevier B.V. All rights reserved.
PB  - Elsevier Science Bv, Amsterdam
T2  - Journal of Petroleum Science and Engineering
T1  - Organic geochemistry of crude oils from the Intisar oil field (East Sirte Basin, Libya)
VL  - 147
SP  - 605
EP  - 616
DO  - 10.1016/j.petrol.2016.09.030
ER  - 

@article{
author = "Faraj, Musbah Abduljalil M. and Šolević-Knudsen, Tatjana and Nytoft, Hans Peter and Jovančićević, Branimir",
year = "2016",
abstract = "Four crude oil samples from the oil fields Intisar A, Intisar D and Intisar E (Sirte Basin, Libya) were investigated in order to define depositional environment, lithology, thermal maturity and geologic age of the corresponding source rocks. Saturated biomarkers (n-alkanes, isoprenoids, steranes and triterpanes) were determined using gas chromatography - mass spectrometry (GC MS) and gas chromatography mass spectrometry - mass spectrometry (GC MS MS). Aromatic hydrocarbons (phenanthrene, methylphenanthrenes, methyl-dibenzothiophenes and trimethyl-naphtalenes) were analyzed by GC-MS. The Intisar crude oils were generated from siliciclastic source rocks containing a mixture of marine and terrestrial organic matter. Maturation parameters indicated high level of thermal maturity corresponding to the main phase of oil generation. The analysis of the age-specific biomarker ratios suggested Cretaceous, most probably Lower Cretaceous age for the Intisar oils. Two source rocks for the Intisar oils were identified, similar in the precursor organic matter type, lithology, maturity and geologic age but different in the redox conditions in the environment during their deposition. The oils generated from these different sources probably migrated over different migration pathways. (C) 2016 Elsevier B.V. All rights reserved.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Journal of Petroleum Science and Engineering",
title = "Organic geochemistry of crude oils from the Intisar oil field (East Sirte Basin, Libya)",
volume = "147",
pages = "605-616",
doi = "10.1016/j.petrol.2016.09.030"
}

Faraj, M. A. M., Šolević-Knudsen, T., Nytoft, H. P.,& Jovančićević, B.. (2016). Organic geochemistry of crude oils from the Intisar oil field (East Sirte Basin, Libya). in Journal of Petroleum Science and Engineering
Elsevier Science Bv, Amsterdam., 147, 605-616.
https://doi.org/10.1016/j.petrol.2016.09.030

Faraj MAM, Šolević-Knudsen T, Nytoft HP, Jovančićević B. Organic geochemistry of crude oils from the Intisar oil field (East Sirte Basin, Libya). in Journal of Petroleum Science and Engineering. 2016;147:605-616.
doi:10.1016/j.petrol.2016.09.030 .

Faraj, Musbah Abduljalil M., Šolević-Knudsen, Tatjana, Nytoft, Hans Peter, Jovančićević, Branimir, "Organic geochemistry of crude oils from the Intisar oil field (East Sirte Basin, Libya)" in Journal of Petroleum Science and Engineering, 147 (2016):605-616,
https://doi.org/10.1016/j.petrol.2016.09.030 . .

TY  - JOUR
AU  - Stojadinović, Sanja M.
AU  - Kostić, Aleksandar Ž.
AU  - Nytoft, Hans Peter
AU  - Stojanović, Ksenija A.
PY  - 2015
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1733
AB  - Middle and Upper Miocene petroleum source rocks from the Banat Depression, SE Pannonian Basin (Serbia) were investigated. These rocks contain organic matter (OM) in a relatively wide range of maturity (from early to late stage of liquid hydrocarbons generation). OM consists predominantly of Type II kerogen and was deposited under variable redox conditions. This prolific oil and gas production area, as a part of the hyperthermal Pannonain Basin, is characterized by high geothermal gradients (4.0-7.5A degrees C/100 m) and high heating rates (9-22A degrees C/Ma) of the Miocene sediments. Considering complexity of the vitrinite reflection measurements in the source rocks containing Type I and/or Type II kerogen, in this study the values of the measured vitrinite reflectance were compared to calculated vitrinite reflectance, based on maximal palaeotemperature and numerous geochemical maturity parameters. The objective of the study was to assess the applicability of calculated vitrinite reflectance for the Type II kerogen source rocks from a hyperthermal basin. The correlation analysis was performed according to Spearman and Pearson tests. The obtained results showed that calculation of vitrinite reflectance and determination of thermal maturity of OM of the source rocks in hyperthermal basins with high heating rates is best done when based on geochemical parameters calculated from compositions of steranes and methyldibenzothiophenes, and as expected-on maximal palaeotemperature.
PB  - Maik Nauka/Interperiodica/Springer, New York
T2  - Petroleum Chemistry
T1  - Applicability of Calculated Vitrinite Reflectance for Assessment of Source Rock's Organic Matter Maturity in Hyperthermal Basins (Banat Depression, Serbia)
VL  - 55
IS  - 6
SP  - 444
EP  - 454
DO  - 10.1134/S0965544115060134
ER  - 

@article{
author = "Stojadinović, Sanja M. and Kostić, Aleksandar Ž. and Nytoft, Hans Peter and Stojanović, Ksenija A.",
year = "2015",
abstract = "Middle and Upper Miocene petroleum source rocks from the Banat Depression, SE Pannonian Basin (Serbia) were investigated. These rocks contain organic matter (OM) in a relatively wide range of maturity (from early to late stage of liquid hydrocarbons generation). OM consists predominantly of Type II kerogen and was deposited under variable redox conditions. This prolific oil and gas production area, as a part of the hyperthermal Pannonain Basin, is characterized by high geothermal gradients (4.0-7.5A degrees C/100 m) and high heating rates (9-22A degrees C/Ma) of the Miocene sediments. Considering complexity of the vitrinite reflection measurements in the source rocks containing Type I and/or Type II kerogen, in this study the values of the measured vitrinite reflectance were compared to calculated vitrinite reflectance, based on maximal palaeotemperature and numerous geochemical maturity parameters. The objective of the study was to assess the applicability of calculated vitrinite reflectance for the Type II kerogen source rocks from a hyperthermal basin. The correlation analysis was performed according to Spearman and Pearson tests. The obtained results showed that calculation of vitrinite reflectance and determination of thermal maturity of OM of the source rocks in hyperthermal basins with high heating rates is best done when based on geochemical parameters calculated from compositions of steranes and methyldibenzothiophenes, and as expected-on maximal palaeotemperature.",
publisher = "Maik Nauka/Interperiodica/Springer, New York",
journal = "Petroleum Chemistry",
title = "Applicability of Calculated Vitrinite Reflectance for Assessment of Source Rock's Organic Matter Maturity in Hyperthermal Basins (Banat Depression, Serbia)",
volume = "55",
number = "6",
pages = "444-454",
doi = "10.1134/S0965544115060134"
}

Stojadinović, S. M., Kostić, A. Ž., Nytoft, H. P.,& Stojanović, K. A.. (2015). Applicability of Calculated Vitrinite Reflectance for Assessment of Source Rock's Organic Matter Maturity in Hyperthermal Basins (Banat Depression, Serbia). in Petroleum Chemistry
Maik Nauka/Interperiodica/Springer, New York., 55(6), 444-454.
https://doi.org/10.1134/S0965544115060134

Stojadinović SM, Kostić AŽ, Nytoft HP, Stojanović KA. Applicability of Calculated Vitrinite Reflectance for Assessment of Source Rock's Organic Matter Maturity in Hyperthermal Basins (Banat Depression, Serbia). in Petroleum Chemistry. 2015;55(6):444-454.
doi:10.1134/S0965544115060134 .

Stojadinović, Sanja M., Kostić, Aleksandar Ž., Nytoft, Hans Peter, Stojanović, Ksenija A., "Applicability of Calculated Vitrinite Reflectance for Assessment of Source Rock's Organic Matter Maturity in Hyperthermal Basins (Banat Depression, Serbia)" in Petroleum Chemistry, 55, no. 6 (2015):444-454,
https://doi.org/10.1134/S0965544115060134 . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Kildahl-Andersen, Geir
AU  - Šolević-Knudsen, Tatjana
AU  - Stojanović, Ksenija A.
AU  - Rise, Frode
PY  - 2014
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1882
AB  - A C-30 pentacyclic triterpane eluting slightly after 18 alpha(H)-oleanane in the m/z 191 mass chromatograms of Late Cretaceous/Tertiary terrigenous oils (peak "J'' in the early literature) has been isolated from a Niger Delta oil and identified using NMR spectroscopy as 3 beta-methyl-24-nor-18 alpha(H)-oleanane. The previous assignment as 18 beta(H)-oleanane is therefore partly erroneous. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane affords a larger m/z 412 - gt  356 response than the oleananes and the relative contribution of 3 beta-methyl-24-nor-18 alpha(H)-oleanane to the 412 - gt  191 "oleanane peak'' can be roughly estimated from comparison of the 412 - gt  356/412 - gt  191 ratio from the oleanane peak with that of the pure compounds. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane can be as abundant as 18a(H)-oleanane in oils having a high concentration of early eluting rearranged oleananes. 3 beta-Methyl-24-nor-19 alpha(H)-taraxastane was also tentatively assigned in the oils on the basis of its mass spectrum as well as its gas chromatography and high performance liquid chromatography retention times. 3 beta-Methyl-24-nor-gammacerane was tentatively assigned in a similar way in an oil containing gammacerane. All 3 beta-methyl-24-nor-triterpanes could be formed via dehydration, rearrangement and hydrogenation of triterpenoids having an OH group at C-3. (C) 2014 Elsevier Ltd. All rights reserved.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Organic Geochemistry
T1  - Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane
VL  - 77
SP  - 89
EP  - 95
DO  - 10.1016/j.orggeochem.2014.09.010
ER  - 

@article{
author = "Nytoft, Hans Peter and Kildahl-Andersen, Geir and Šolević-Knudsen, Tatjana and Stojanović, Ksenija A. and Rise, Frode",
year = "2014",
abstract = "A C-30 pentacyclic triterpane eluting slightly after 18 alpha(H)-oleanane in the m/z 191 mass chromatograms of Late Cretaceous/Tertiary terrigenous oils (peak "J'' in the early literature) has been isolated from a Niger Delta oil and identified using NMR spectroscopy as 3 beta-methyl-24-nor-18 alpha(H)-oleanane. The previous assignment as 18 beta(H)-oleanane is therefore partly erroneous. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane affords a larger m/z 412 - gt  356 response than the oleananes and the relative contribution of 3 beta-methyl-24-nor-18 alpha(H)-oleanane to the 412 - gt  191 "oleanane peak'' can be roughly estimated from comparison of the 412 - gt  356/412 - gt  191 ratio from the oleanane peak with that of the pure compounds. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane can be as abundant as 18a(H)-oleanane in oils having a high concentration of early eluting rearranged oleananes. 3 beta-Methyl-24-nor-19 alpha(H)-taraxastane was also tentatively assigned in the oils on the basis of its mass spectrum as well as its gas chromatography and high performance liquid chromatography retention times. 3 beta-Methyl-24-nor-gammacerane was tentatively assigned in a similar way in an oil containing gammacerane. All 3 beta-methyl-24-nor-triterpanes could be formed via dehydration, rearrangement and hydrogenation of triterpenoids having an OH group at C-3. (C) 2014 Elsevier Ltd. All rights reserved.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Organic Geochemistry",
title = "Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane",
volume = "77",
pages = "89-95",
doi = "10.1016/j.orggeochem.2014.09.010"
}

Nytoft, H. P., Kildahl-Andersen, G., Šolević-Knudsen, T., Stojanović, K. A.,& Rise, F.. (2014). Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane. in Organic Geochemistry
Pergamon-Elsevier Science Ltd, Oxford., 77, 89-95.
https://doi.org/10.1016/j.orggeochem.2014.09.010

Nytoft HP, Kildahl-Andersen G, Šolević-Knudsen T, Stojanović KA, Rise F. Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane. in Organic Geochemistry. 2014;77:89-95.
doi:10.1016/j.orggeochem.2014.09.010 .

Nytoft, Hans Peter, Kildahl-Andersen, Geir, Šolević-Knudsen, Tatjana, Stojanović, Ksenija A., Rise, Frode, "Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane" in Organic Geochemistry, 77 (2014):89-95,
https://doi.org/10.1016/j.orggeochem.2014.09.010 . .

TY  - JOUR
AU  - Stojanović, Ksenija A.
AU  - Životić, Dragana R.
AU  - Šajnović, Aleksandra
AU  - Cvetković, Olga
AU  - Nytoft, Hans Peter
AU  - Scheeder, Georg
PY  - 2012
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1532
AB  - The objective of the study was to determine the origin and to reconstruct the geological evolution of lignites from the Drmno field (Kostolac Basin, Serbia). For this purpose, petrological and organic geochemical analyses were used. Coal from the Drmno field is typical humic coal. Peat-forming vegetation dominated by decay of resistant gymnosperm (coniferous) plants, followed by prokaryotic organisms and angiosperms. The coal forming plants belonged to the gymnosperm families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae and Pinaceae. Peatification was realised in a neutral to slightly acidic, fresh water environment. Considering that the organic matter of the Drmno lignites was deposited at the same time, in a relatively constant climate, it could be supposed that climate probably had only a small impact on peatification. Therefore, variations in compositions of macerals and biomarkers indicate changes in the water level, due to seasonal drying of the mire, which caused vegetation differences in the palaeoplant communities and changes in the redox conditions (from anoxic to slightly oxic) during peatification. Diagenetic transformations of the organic matter were mainly governed by microbial activity, rather than thermal alteration.
AB  - Cilj rada bio je da se utvrdi poreklo i geološka evolucija lignita ležišta Drmno basena Kostolac. Primenjene su petrografske i organsko geohemijske metode. Ligniti ležišta Drmno su tipični humusni ugljevi. Glavni izvor organske supstance bile su gimnosperme (golosemenice), a zatim prokariotski organizmi i angiosperme (skrivenosemenice). Utvrđeno je da prekursorski organski materijal potiče od sledećih familija gimnospermi: Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae i Pinaceae. Taloženje i humifikacija organske supstance lignita odvijali su se u slatkovodnoj, neutralnoj do slabo kiseloj sredini. Uzimajući u obzir da se stvaranje lignita u ležištu Drmno odigravalo u isto vreme, pretpostavljeno je da klimatski faktor nije mogao značajnije uticati na sastav organske supstance. Razlike u sastavu macerala i biomarkera u ispitivanim lignitima posledica su kolebanja nivoa vodenog stuba u sredini taloženja usled sezonskih promena u količini padavina. Ovo kolebanje vodenog stuba uzrokovalo je promene kako u sastavu paleovegetacije, tako i u redoks potencijalu sredine taloženja (od anoksične do blago oksične). Dijagentske promene organske supstance odvijale su se uz intenzivnu mikrobnu aktivnost, dok je termička degradacija bila gotovo beznačajna.
PB  - Serbian Chemical Soc, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - Drmno lignite field (Kostolac Basin, Serbia): origin and palaeoenvironmental implications from petrological and organic geochemical studies
T1  - Ligniti ležišta Drmno (basen Kostolac) - poreklo i paleouslovi stvaranja na osnovu petrografskih i organsko-geohemijskih istraživanja
VL  - 77
IS  - 8
SP  - 1109
EP  - 1127
DO  - 10.2298/JSC111126017S
ER  - 

@article{
author = "Stojanović, Ksenija A. and Životić, Dragana R. and Šajnović, Aleksandra and Cvetković, Olga and Nytoft, Hans Peter and Scheeder, Georg",
year = "2012",
abstract = "The objective of the study was to determine the origin and to reconstruct the geological evolution of lignites from the Drmno field (Kostolac Basin, Serbia). For this purpose, petrological and organic geochemical analyses were used. Coal from the Drmno field is typical humic coal. Peat-forming vegetation dominated by decay of resistant gymnosperm (coniferous) plants, followed by prokaryotic organisms and angiosperms. The coal forming plants belonged to the gymnosperm families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae and Pinaceae. Peatification was realised in a neutral to slightly acidic, fresh water environment. Considering that the organic matter of the Drmno lignites was deposited at the same time, in a relatively constant climate, it could be supposed that climate probably had only a small impact on peatification. Therefore, variations in compositions of macerals and biomarkers indicate changes in the water level, due to seasonal drying of the mire, which caused vegetation differences in the palaeoplant communities and changes in the redox conditions (from anoxic to slightly oxic) during peatification. Diagenetic transformations of the organic matter were mainly governed by microbial activity, rather than thermal alteration., Cilj rada bio je da se utvrdi poreklo i geološka evolucija lignita ležišta Drmno basena Kostolac. Primenjene su petrografske i organsko geohemijske metode. Ligniti ležišta Drmno su tipični humusni ugljevi. Glavni izvor organske supstance bile su gimnosperme (golosemenice), a zatim prokariotski organizmi i angiosperme (skrivenosemenice). Utvrđeno je da prekursorski organski materijal potiče od sledećih familija gimnospermi: Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae i Pinaceae. Taloženje i humifikacija organske supstance lignita odvijali su se u slatkovodnoj, neutralnoj do slabo kiseloj sredini. Uzimajući u obzir da se stvaranje lignita u ležištu Drmno odigravalo u isto vreme, pretpostavljeno je da klimatski faktor nije mogao značajnije uticati na sastav organske supstance. Razlike u sastavu macerala i biomarkera u ispitivanim lignitima posledica su kolebanja nivoa vodenog stuba u sredini taloženja usled sezonskih promena u količini padavina. Ovo kolebanje vodenog stuba uzrokovalo je promene kako u sastavu paleovegetacije, tako i u redoks potencijalu sredine taloženja (od anoksične do blago oksične). Dijagentske promene organske supstance odvijale su se uz intenzivnu mikrobnu aktivnost, dok je termička degradacija bila gotovo beznačajna.",
publisher = "Serbian Chemical Soc, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "Drmno lignite field (Kostolac Basin, Serbia): origin and palaeoenvironmental implications from petrological and organic geochemical studies, Ligniti ležišta Drmno (basen Kostolac) - poreklo i paleouslovi stvaranja na osnovu petrografskih i organsko-geohemijskih istraživanja",
volume = "77",
number = "8",
pages = "1109-1127",
doi = "10.2298/JSC111126017S"
}

Stojanović, K. A., Životić, D. R., Šajnović, A., Cvetković, O., Nytoft, H. P.,& Scheeder, G.. (2012). Drmno lignite field (Kostolac Basin, Serbia): origin and palaeoenvironmental implications from petrological and organic geochemical studies. in Journal of the Serbian Chemical Society
Serbian Chemical Soc, Belgrade., 77(8), 1109-1127.
https://doi.org/10.2298/JSC111126017S

Stojanović KA, Životić DR, Šajnović A, Cvetković O, Nytoft HP, Scheeder G. Drmno lignite field (Kostolac Basin, Serbia): origin and palaeoenvironmental implications from petrological and organic geochemical studies. in Journal of the Serbian Chemical Society. 2012;77(8):1109-1127.
doi:10.2298/JSC111126017S .

Stojanović, Ksenija A., Životić, Dragana R., Šajnović, Aleksandra, Cvetković, Olga, Nytoft, Hans Peter, Scheeder, Georg, "Drmno lignite field (Kostolac Basin, Serbia): origin and palaeoenvironmental implications from petrological and organic geochemical studies" in Journal of the Serbian Chemical Society, 77, no. 8 (2012):1109-1127,
https://doi.org/10.2298/JSC111126017S . .

TY  - JOUR
AU  - Mrkic, Sanja
AU  - Stojanović, Ksenija A.
AU  - Kostić, Aleksandar Ž.
AU  - Nytoft, Hans Peter
AU  - Šajnović, Aleksandra
PY  - 2011
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1173
AB  - The origin, depositional environment and maturity of petroleum source rocks were determined via conventional whole rock and biomarker analysis of samples from wells in the Banat Depression, where the most important Serbian oil and gas fields are located. The organic matter (OM) in organic-rich upper Tertiary siltstones and marls consists predominantly of Type II kerogen. Numerous biomarker parameters indicated mixed algal-terrestrial OM, related to a brackish or freshwater environment, whose salinity decreased from Middle to Upper Miocene. The OM was deposited under variable redox conditions, reducing to sub-oxic. The wells in the Banat Depression experienced variable high rates of rapid heating, providing an opportunity for examining the applicability of different thermal indicators in a hyperthermal basin. Rock-Eval and numerous biomarker parameters indicate that the main stage of oil generation begins at ca. 130 degrees C and vitrinite reflectance (Rc) ca. 0.63% and reaches a maximum at ca. 145-150 degrees C and Rc ca. 0.72-0.75%, while the late stage of oil generation starts at ca. 155 degrees C and ca. Rc 0.78%, which corresponds, depending on geothermal gradient, to relative depths of 2100-2300 m, 2600-2900 m and 3050-3100 m, respectively. The naphthalene and phenanthrene maturity parameters proved to be less applicable than the biomarker ratios, particularly in the early to moderate maturation range. The newly proposed parameter C(14a)-homo-26-nor-17 alpha(H)-hopane/C(30)hopane (C(30)HH/C(30)H) proved applicable to a wide range of maturity. (C) 2011 Elsevier Ltd. All rights reserved.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Organic Geochemistry
T1  - Organic geochemistry of Miocene source rocks from the Banat Depression (SE Pannonian Basin, Serbia)
VL  - 42
IS  - 6
SP  - 655
EP  - 677
DO  - 10.1016/j.orggeochem.2011.03.025
ER  - 

@article{
author = "Mrkic, Sanja and Stojanović, Ksenija A. and Kostić, Aleksandar Ž. and Nytoft, Hans Peter and Šajnović, Aleksandra",
year = "2011",
abstract = "The origin, depositional environment and maturity of petroleum source rocks were determined via conventional whole rock and biomarker analysis of samples from wells in the Banat Depression, where the most important Serbian oil and gas fields are located. The organic matter (OM) in organic-rich upper Tertiary siltstones and marls consists predominantly of Type II kerogen. Numerous biomarker parameters indicated mixed algal-terrestrial OM, related to a brackish or freshwater environment, whose salinity decreased from Middle to Upper Miocene. The OM was deposited under variable redox conditions, reducing to sub-oxic. The wells in the Banat Depression experienced variable high rates of rapid heating, providing an opportunity for examining the applicability of different thermal indicators in a hyperthermal basin. Rock-Eval and numerous biomarker parameters indicate that the main stage of oil generation begins at ca. 130 degrees C and vitrinite reflectance (Rc) ca. 0.63% and reaches a maximum at ca. 145-150 degrees C and Rc ca. 0.72-0.75%, while the late stage of oil generation starts at ca. 155 degrees C and ca. Rc 0.78%, which corresponds, depending on geothermal gradient, to relative depths of 2100-2300 m, 2600-2900 m and 3050-3100 m, respectively. The naphthalene and phenanthrene maturity parameters proved to be less applicable than the biomarker ratios, particularly in the early to moderate maturation range. The newly proposed parameter C(14a)-homo-26-nor-17 alpha(H)-hopane/C(30)hopane (C(30)HH/C(30)H) proved applicable to a wide range of maturity. (C) 2011 Elsevier Ltd. All rights reserved.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Organic Geochemistry",
title = "Organic geochemistry of Miocene source rocks from the Banat Depression (SE Pannonian Basin, Serbia)",
volume = "42",
number = "6",
pages = "655-677",
doi = "10.1016/j.orggeochem.2011.03.025"
}

Mrkic, S., Stojanović, K. A., Kostić, A. Ž., Nytoft, H. P.,& Šajnović, A.. (2011). Organic geochemistry of Miocene source rocks from the Banat Depression (SE Pannonian Basin, Serbia). in Organic Geochemistry
Pergamon-Elsevier Science Ltd, Oxford., 42(6), 655-677.
https://doi.org/10.1016/j.orggeochem.2011.03.025

Mrkic S, Stojanović KA, Kostić AŽ, Nytoft HP, Šajnović A. Organic geochemistry of Miocene source rocks from the Banat Depression (SE Pannonian Basin, Serbia). in Organic Geochemistry. 2011;42(6):655-677.
doi:10.1016/j.orggeochem.2011.03.025 .

Mrkic, Sanja, Stojanović, Ksenija A., Kostić, Aleksandar Ž., Nytoft, Hans Peter, Šajnović, Aleksandra, "Organic geochemistry of Miocene source rocks from the Banat Depression (SE Pannonian Basin, Serbia)" in Organic Geochemistry, 42, no. 6 (2011):655-677,
https://doi.org/10.1016/j.orggeochem.2011.03.025 . .

TY  - JOUR
AU  - Šolević-Knudsen, Tatjana
AU  - Stojanović, Ksenija A.
AU  - Bojesen-Koefoed, J.
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
AU  - Vitorović, Dragomir K.
PY  - 2008
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/920
AB  - Twenty five crude oil samples from Velebit oil-gas field (SE Pannonian Basin, Serbia) were investigated in order to define the depositional environment, lithology, thermal maturity and depth of burial of the corresponding source rocks. Saturated biomarkers (n-alkanes, isoprenoids, steranes and triterpanes) were determined using gas chromatography (GC) and gas chromatography-mass spectrometry-mass spectrometry (GC MS-MS). Source and maturity parameters were calculated from the distribution and abundance of biomarker compounds and principal component analysis (PCA) was used to interpret their relationships. The Velebit crude oils were generated from siliciclastic source rocks containing a mixture of terrestrial and marine organic matter that was deposited under a predominantly reducing environment, probably in the distal marine portion of a delta. Maturation parameters indicated significant thermal maturity corresponding to peak oil generation. Age-diagnostic biomarker ratios suggest that the source of Velebit oils may be Upper Cretaceous, older than most oils in the Pannonian Basin, which are generated from Tertiary sources. These source rocks are thought to be at a present-day depth of approximately 3000 m, within or in close proximity to, the oil field. (c) 2007 Elsevier Ltd. All rights reserved.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Organic Geochemistry
T1  - Origin of oils in the Velebit oil-gas field, SE Pannonian Basin, Serbia - Source rocks characterization based on biological marker distributions
VL  - 39
IS  - 1
SP  - 118
EP  - 134
DO  - 10.1016/j.orggeochem.2007.09.003
ER  - 

@article{
author = "Šolević-Knudsen, Tatjana and Stojanović, Ksenija A. and Bojesen-Koefoed, J. and Nytoft, Hans Peter and Jovančićević, Branimir and Vitorović, Dragomir K.",
year = "2008",
abstract = "Twenty five crude oil samples from Velebit oil-gas field (SE Pannonian Basin, Serbia) were investigated in order to define the depositional environment, lithology, thermal maturity and depth of burial of the corresponding source rocks. Saturated biomarkers (n-alkanes, isoprenoids, steranes and triterpanes) were determined using gas chromatography (GC) and gas chromatography-mass spectrometry-mass spectrometry (GC MS-MS). Source and maturity parameters were calculated from the distribution and abundance of biomarker compounds and principal component analysis (PCA) was used to interpret their relationships. The Velebit crude oils were generated from siliciclastic source rocks containing a mixture of terrestrial and marine organic matter that was deposited under a predominantly reducing environment, probably in the distal marine portion of a delta. Maturation parameters indicated significant thermal maturity corresponding to peak oil generation. Age-diagnostic biomarker ratios suggest that the source of Velebit oils may be Upper Cretaceous, older than most oils in the Pannonian Basin, which are generated from Tertiary sources. These source rocks are thought to be at a present-day depth of approximately 3000 m, within or in close proximity to, the oil field. (c) 2007 Elsevier Ltd. All rights reserved.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Organic Geochemistry",
title = "Origin of oils in the Velebit oil-gas field, SE Pannonian Basin, Serbia - Source rocks characterization based on biological marker distributions",
volume = "39",
number = "1",
pages = "118-134",
doi = "10.1016/j.orggeochem.2007.09.003"
}

Šolević-Knudsen, T., Stojanović, K. A., Bojesen-Koefoed, J., Nytoft, H. P., Jovančićević, B.,& Vitorović, D. K.. (2008). Origin of oils in the Velebit oil-gas field, SE Pannonian Basin, Serbia - Source rocks characterization based on biological marker distributions. in Organic Geochemistry
Pergamon-Elsevier Science Ltd, Oxford., 39(1), 118-134.
https://doi.org/10.1016/j.orggeochem.2007.09.003

Šolević-Knudsen T, Stojanović KA, Bojesen-Koefoed J, Nytoft HP, Jovančićević B, Vitorović DK. Origin of oils in the Velebit oil-gas field, SE Pannonian Basin, Serbia - Source rocks characterization based on biological marker distributions. in Organic Geochemistry. 2008;39(1):118-134.
doi:10.1016/j.orggeochem.2007.09.003 .

Šolević-Knudsen, Tatjana, Stojanović, Ksenija A., Bojesen-Koefoed, J., Nytoft, Hans Peter, Jovančićević, Branimir, Vitorović, Dragomir K., "Origin of oils in the Velebit oil-gas field, SE Pannonian Basin, Serbia - Source rocks characterization based on biological marker distributions" in Organic Geochemistry, 39, no. 1 (2008):118-134,
https://doi.org/10.1016/j.orggeochem.2007.09.003 . .