TY  - JOUR
AU  - Gajica, Gordana
AU  - Šajnović, Aleksandra
AU  - Stojanović, Ksenija
AU  - Schwarzbauer, Jan
AU  - Kostić, Aleksandar
AU  - Jovančićević, Branimir
PY  - 2022
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4900
AB  - The molecular and isotopic composition of biomarkers in initial bitumen isolated from immature (0.41% Rr) oil shale samples (Aleksinac deposit) and liquid products obtained by pyrolysis in open (OS) and closed (CS) systems are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in liquid products is determined. The applicability of pyrolysis type, numerous biomarkers and carbon isotopic compositions (δ13C) of n-alkanes in liquid pyrolysates is established. Pyrolysis experiments were performed on two selected samples that showed high content of total organic carbon and hydrocarbon generation potential, but also certain variations in sources/depositional environment of organic matter (type I and mixed type I/II kerogen) within previous research of the oil shales sample set. The biomarker signatures were evaluated using gas chromatography-mass spectrometry (GC-MS) and δ13C of individual n-alkanes in bitumen and liquid pyrolysates. The molecular composition of liquid pyrolysates from the OS is very similar to those in initial bitumen, independently on kerogen type, confirming algal origin of organic matter (OM) deposited in lacustrine environment, even more apparently than results of initial bitumen. Therefore, OS can be useful for assessment of source and depositional environment of OM. Pyrolysis in the CS caused more intense thermal alterations, therefore the source fingerprints sometimes notably disappear. The liquid pyrolysates from the CS have the distributions of biomarkers similar to those in crude oils. The biomarker maturity parameters showed slightly higher values in the CS pyrolysate of mixed type I/II kerogen in relation to type I kerogen. δ13C of n-alkanes in liquid pyrolysates from the OS are isotopically lighter in comparison to bitumen, independently on kerogen type. Oppositely, in liquid pyrolysates from the CS, they become heavier than in bitumen, indicating the thermal influence on δ13C signatures, with more pronounced difference for type I kerogen.
PB  - Elsevier
T2  - Marine and Petroleum Geology
T1  - A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems)
VL  - 136
SP  - 105383
DO  - 10.1016/j.marpetgeo.2021.105383
ER  - 

@article{
author = "Gajica, Gordana and Šajnović, Aleksandra and Stojanović, Ksenija and Schwarzbauer, Jan and Kostić, Aleksandar and Jovančićević, Branimir",
year = "2022",
abstract = "The molecular and isotopic composition of biomarkers in initial bitumen isolated from immature (0.41% Rr) oil shale samples (Aleksinac deposit) and liquid products obtained by pyrolysis in open (OS) and closed (CS) systems are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in liquid products is determined. The applicability of pyrolysis type, numerous biomarkers and carbon isotopic compositions (δ13C) of n-alkanes in liquid pyrolysates is established. Pyrolysis experiments were performed on two selected samples that showed high content of total organic carbon and hydrocarbon generation potential, but also certain variations in sources/depositional environment of organic matter (type I and mixed type I/II kerogen) within previous research of the oil shales sample set. The biomarker signatures were evaluated using gas chromatography-mass spectrometry (GC-MS) and δ13C of individual n-alkanes in bitumen and liquid pyrolysates. The molecular composition of liquid pyrolysates from the OS is very similar to those in initial bitumen, independently on kerogen type, confirming algal origin of organic matter (OM) deposited in lacustrine environment, even more apparently than results of initial bitumen. Therefore, OS can be useful for assessment of source and depositional environment of OM. Pyrolysis in the CS caused more intense thermal alterations, therefore the source fingerprints sometimes notably disappear. The liquid pyrolysates from the CS have the distributions of biomarkers similar to those in crude oils. The biomarker maturity parameters showed slightly higher values in the CS pyrolysate of mixed type I/II kerogen in relation to type I kerogen. δ13C of n-alkanes in liquid pyrolysates from the OS are isotopically lighter in comparison to bitumen, independently on kerogen type. Oppositely, in liquid pyrolysates from the CS, they become heavier than in bitumen, indicating the thermal influence on δ13C signatures, with more pronounced difference for type I kerogen.",
publisher = "Elsevier",
journal = "Marine and Petroleum Geology",
title = "A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems)",
volume = "136",
pages = "105383",
doi = "10.1016/j.marpetgeo.2021.105383"
}

Gajica, G., Šajnović, A., Stojanović, K., Schwarzbauer, J., Kostić, A.,& Jovančićević, B.. (2022). A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems). in Marine and Petroleum Geology
Elsevier., 136, 105383.
https://doi.org/10.1016/j.marpetgeo.2021.105383

Gajica G, Šajnović A, Stojanović K, Schwarzbauer J, Kostić A, Jovančićević B. A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems). in Marine and Petroleum Geology. 2022;136:105383.
doi:10.1016/j.marpetgeo.2021.105383 .

Gajica, Gordana, Šajnović, Aleksandra, Stojanović, Ksenija, Schwarzbauer, Jan, Kostić, Aleksandar, Jovančićević, Branimir, "A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems)" in Marine and Petroleum Geology, 136 (2022):105383,
https://doi.org/10.1016/j.marpetgeo.2021.105383 . .

TY  - JOUR
AU  - Gajica, Gordana
AU  - Šajnović, Aleksandra
AU  - Stojanović, Ksenija
AU  - Schwarzbauer, Jan
AU  - Kostić, Aleksandar
AU  - Jovančićević, Branimir
PY  - 2022
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/5233
AB  - The molecular and isotopic composition of biomarkers in initial bitumen isolated from immature (0.41% Rr) oil shale samples (Aleksinac deposit) and liquid products obtained by pyrolysis in open (OS) and closed (CS) systems are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in liquid products is determined. The applicability of pyrolysis type, numerous biomarkers and carbon isotopic compositions (δ13C) of n-alkanes in liquid pyrolysates is established. Pyrolysis experiments were performed on two selected samples that showed high content of total organic carbon and hydrocarbon generation potential, but also certain variations in sources/depositional environment of organic matter (type I and mixed type I/II kerogen) within previous research of the oil shales sample set. The biomarker signatures were evaluated using gas chromatography-mass spectrometry (GC-MS) and δ13C of individual n-alkanes in bitumen and liquid pyrolysates. The molecular composition of liquid pyrolysates from the OS is very similar to those in initial bitumen, independently on kerogen type, confirming algal origin of organic matter (OM) deposited in lacustrine environment, even more apparently than results of initial bitumen. Therefore, OS can be useful for assessment of source and depositional environment of OM. Pyrolysis in the CS caused more intense thermal alterations, therefore the source fingerprints sometimes notably disappear. The liquid pyrolysates from the CS have the distributions of biomarkers similar to those in crude oils. The biomarker maturity parameters showed slightly higher values in the CS pyrolysate of mixed type I/II kerogen in relation to type I kerogen. δ13C of n-alkanes in liquid pyrolysates from the OS are isotopically lighter in comparison to bitumen, independently on kerogen type. Oppositely, in liquid pyrolysates from the CS, they become heavier than in bitumen, indicating the thermal influence on δ13C signatures, with more pronounced difference for type I kerogen.
PB  - Elsevier
T2  - Marine and Petroleum Geology
T1  - A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems)
VL  - 136
SP  - 105383
DO  - 10.1016/j.marpetgeo.2021.105383
ER  - 

@article{
author = "Gajica, Gordana and Šajnović, Aleksandra and Stojanović, Ksenija and Schwarzbauer, Jan and Kostić, Aleksandar and Jovančićević, Branimir",
year = "2022",
abstract = "The molecular and isotopic composition of biomarkers in initial bitumen isolated from immature (0.41% Rr) oil shale samples (Aleksinac deposit) and liquid products obtained by pyrolysis in open (OS) and closed (CS) systems are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in liquid products is determined. The applicability of pyrolysis type, numerous biomarkers and carbon isotopic compositions (δ13C) of n-alkanes in liquid pyrolysates is established. Pyrolysis experiments were performed on two selected samples that showed high content of total organic carbon and hydrocarbon generation potential, but also certain variations in sources/depositional environment of organic matter (type I and mixed type I/II kerogen) within previous research of the oil shales sample set. The biomarker signatures were evaluated using gas chromatography-mass spectrometry (GC-MS) and δ13C of individual n-alkanes in bitumen and liquid pyrolysates. The molecular composition of liquid pyrolysates from the OS is very similar to those in initial bitumen, independently on kerogen type, confirming algal origin of organic matter (OM) deposited in lacustrine environment, even more apparently than results of initial bitumen. Therefore, OS can be useful for assessment of source and depositional environment of OM. Pyrolysis in the CS caused more intense thermal alterations, therefore the source fingerprints sometimes notably disappear. The liquid pyrolysates from the CS have the distributions of biomarkers similar to those in crude oils. The biomarker maturity parameters showed slightly higher values in the CS pyrolysate of mixed type I/II kerogen in relation to type I kerogen. δ13C of n-alkanes in liquid pyrolysates from the OS are isotopically lighter in comparison to bitumen, independently on kerogen type. Oppositely, in liquid pyrolysates from the CS, they become heavier than in bitumen, indicating the thermal influence on δ13C signatures, with more pronounced difference for type I kerogen.",
publisher = "Elsevier",
journal = "Marine and Petroleum Geology",
title = "A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems)",
volume = "136",
pages = "105383",
doi = "10.1016/j.marpetgeo.2021.105383"
}

Gajica, G., Šajnović, A., Stojanović, K., Schwarzbauer, J., Kostić, A.,& Jovančićević, B.. (2022). A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems). in Marine and Petroleum Geology
Elsevier., 136, 105383.
https://doi.org/10.1016/j.marpetgeo.2021.105383

Gajica G, Šajnović A, Stojanović K, Schwarzbauer J, Kostić A, Jovančićević B. A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems). in Marine and Petroleum Geology. 2022;136:105383.
doi:10.1016/j.marpetgeo.2021.105383 .

Gajica, Gordana, Šajnović, Aleksandra, Stojanović, Ksenija, Schwarzbauer, Jan, Kostić, Aleksandar, Jovančićević, Branimir, "A comparative study of the molecular and isotopic composition of biomarkers in immature oil shale (Aleksinac deposit, Serbia) and its liquid pyrolysis products (open and closed systems)" in Marine and Petroleum Geology, 136 (2022):105383,
https://doi.org/10.1016/j.marpetgeo.2021.105383 . .

TY  - JOUR
AU  - Gajica, Gordana
AU  - Šajnović, Aleksandra
AU  - Stojanović, Ksenija
AU  - Kostić, Aleksandar
AU  - Slipper, Ian
AU  - Antonijević, Milan D.
AU  - Nytoft, Hans Peter
AU  - Jovančićević, Branimir
PY  - 2017
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2162
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 and Kostić, Aleksandar and Slipper, Ian and Antonijević, Milan D. 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., Kostić, A., Slipper, I., Antonijević, M. D., 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 K, Kostić A, Slipper I, Antonijević MD, 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, Kostić, Aleksandar, Slipper, Ian, Antonijević, Milan D., 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  - Mrkić, Sanja
AU  - Stojanović, Ksenija
AU  - Kostić, Aleksandar
AU  - Nytoft, Hans Peter
AU  - Šajnović, Aleksandra
PY  - 2011
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/789
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.
PB  - Oxford : Pergamon-Elsevier Science Ltd
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 = "Mrkić, Sanja and Stojanović, Ksenija and Kostić, Aleksandar 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.",
publisher = "Oxford : Pergamon-Elsevier Science Ltd",
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"
}

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

Mrkić S, Stojanović K, Kostić A, 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 .

Mrkić, Sanja, Stojanović, Ksenija, Kostić, Aleksandar, 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 . .