Geochemical characteristics of the organic matter of the Jurassic sediments of the southern regions of Western Siberia

UDK: 553.98.061.17
DOI: 10.24887/0028-2448-2021-5-50-53
Key words: Rock Eval method, Bazhenov formation, Tyumen formation, organic carbon content
Authors: K.I. Dаntsova (Gubkin University, RF, Moscow), K.O. Iskaziyev (Gubkin University, RF, Moscow), S.F. Khafizov (Gubkin University, RF, Moscow)

The results of the interpretation of pyrolytic studies of the Jurassic deposits of the Uvat group of deposits (West Siberian oil and gas province) are presented. A detailed study is due to the significant prospect of their oil and gas potential. The content of organic carbon, the stages of thermal maturity, the type of kerogen and the generation potential for the parent rocks are determined. An attempt was made to identify the patterns of changes in the catagenetic transformation of the organic matter scattered in the rocks of the studied layers. Due to the history of the sedimentation basin, the western part is more submerged than the eastern part. The location of the studied areas has a north-west - south-east trend, which is obviously controlled by a system of deep faults. The issue of oil typification is important in exploration work. The oils in the areas under consideration are deposited in reservoirs of different ages, which is why it is important to determine which oil source strata they were generated by. The correlation between oil and the organic matter of the proposed oil source strata can be proved only on the basis of the regularities of the distribution of hydrocarbons at the molecular level. In addition to geological methods, a complex of chemical-bituminological studies was used for each area to identify oil-source rocks of different categories (with different oil-and-gas-source potential and different degrees of catagenetic transformation). It included the determination of the content of organic carbon and bitumoids in the rock, gas-liquid chromatography, chromatography-mass spectrometry, determination of the elemental composition of bitumoids and kerogen, and Rock-Eval pyrolysis. To determine the type of kerogen and its position relative to the zones of oil and gas formation, the Van Crevelen diagram in the coordinates of the atomic ratios of the elemental composition of kerogen and its modification for pyrolytic data were used.

References

1. Peters K.E., Walters C.C., Moldowan J.M., The Biomarker guide, V. 1. Biomarkers and isotopes in the environment and human history, United Kingdom at the Cambridge University Press, 2005, V. 1.

2. Tissot B.P., Welte D.H., Petroleum formation and occurrence, Springer-Verlag Telos, 1984, 699 p.

3. Bordyug E.V., Geneticheskie tipy neftey produktivnykh otlozheniy yugo-vostochnoy chasti Zapadnoy Sibiri (Genetic types of oils in productive deposits of the southeastern part of Western Siberia): thesis of candidate of geological and mineralogical science, Moscow, 2012.

4. Dantsova K.I., Khafizov S.F., Geological and geochemical studies of the southern regions of the West Siberian oil and gas province (In Russ.), Conference Proceedings, Geomodel 2020, Sep 2020, V. 2020, p.1 – 5, DOI: https://doi.org/10.3997/2214-4609.202050053.

5. Krasnoyarova N.A., Geokhimiya organicheskogo veshchestva nizhney yury Zapadnoy Sibiri (Geochemistry of organic matter of the Lower Jurassic): thesis of candidate of geological and mineralogical science, Tomsk, 2007.

6. Komkov I.K., Mozhegova S.V., Dakhnova M.V., Dolmatova I.V., Organic matter geochemistry and the assessment of hydrocarbon migration from the Mid-Jurassic source rocks within Karabashskaya area (In Russ.), Geologiya nefti i gaza, 2016, no. 6, pp. 79–86.

7. Fomin A.N., Kontorovich A.E. Krasavchikov V.O., Katagenez organicheskogo veshchestva i perspektivy neftegazonosnosti yurskikh, triasovykh i paleozoyskikh otlozheniy severnykh rayonov Zapadno-Sibirskogo megabasseyna (In Russ.), Geologiya i geofizika, 2001, no. 11-12, pp. 1875-1887.

8. Gordadze G.N., Giruts M.V., Koshelev V.N., Application of organic geochemistry methods for exploration and development of oil fields (In Russ.), Burenie i neft', 2020, no. 1, pp. 32-39.

9. Shimanskiy V.K., Shapiro A.I., Vasil'eva V.F. et al., Features of the composition of bitumoids of dispersed organic matter mudstones of Mesozoic deposits in the south of Western Siberia (In Russ.), Neftegazovaya geologiya. Teoriya i praktika, 2006, V. 1, URL: http://www.ngp.ni/rub/1/09.pdf

The results of the interpretation of pyrolytic studies of the Jurassic deposits of the Uvat group of deposits (West Siberian oil and gas province) are presented. A detailed study is due to the significant prospect of their oil and gas potential. The content of organic carbon, the stages of thermal maturity, the type of kerogen and the generation potential for the parent rocks are determined. An attempt was made to identify the patterns of changes in the catagenetic transformation of the organic matter scattered in the rocks of the studied layers. Due to the history of the sedimentation basin, the western part is more submerged than the eastern part. The location of the studied areas has a north-west - south-east trend, which is obviously controlled by a system of deep faults. The issue of oil typification is important in exploration work. The oils in the areas under consideration are deposited in reservoirs of different ages, which is why it is important to determine which oil source strata they were generated by. The correlation between oil and the organic matter of the proposed oil source strata can be proved only on the basis of the regularities of the distribution of hydrocarbons at the molecular level. In addition to geological methods, a complex of chemical-bituminological studies was used for each area to identify oil-source rocks of different categories (with different oil-and-gas-source potential and different degrees of catagenetic transformation). It included the determination of the content of organic carbon and bitumoids in the rock, gas-liquid chromatography, chromatography-mass spectrometry, determination of the elemental composition of bitumoids and kerogen, and Rock-Eval pyrolysis. To determine the type of kerogen and its position relative to the zones of oil and gas formation, the Van Crevelen diagram in the coordinates of the atomic ratios of the elemental composition of kerogen and its modification for pyrolytic data were used.

References

1. Peters K.E., Walters C.C., Moldowan J.M., The Biomarker guide, V. 1. Biomarkers and isotopes in the environment and human history, United Kingdom at the Cambridge University Press, 2005, V. 1.

2. Tissot B.P., Welte D.H., Petroleum formation and occurrence, Springer-Verlag Telos, 1984, 699 p.

3. Bordyug E.V., Geneticheskie tipy neftey produktivnykh otlozheniy yugo-vostochnoy chasti Zapadnoy Sibiri (Genetic types of oils in productive deposits of the southeastern part of Western Siberia): thesis of candidate of geological and mineralogical science, Moscow, 2012.

4. Dantsova K.I., Khafizov S.F., Geological and geochemical studies of the southern regions of the West Siberian oil and gas province (In Russ.), Conference Proceedings, Geomodel 2020, Sep 2020, V. 2020, p.1 – 5, DOI: https://doi.org/10.3997/2214-4609.202050053.

5. Krasnoyarova N.A., Geokhimiya organicheskogo veshchestva nizhney yury Zapadnoy Sibiri (Geochemistry of organic matter of the Lower Jurassic): thesis of candidate of geological and mineralogical science, Tomsk, 2007.

6. Komkov I.K., Mozhegova S.V., Dakhnova M.V., Dolmatova I.V., Organic matter geochemistry and the assessment of hydrocarbon migration from the Mid-Jurassic source rocks within Karabashskaya area (In Russ.), Geologiya nefti i gaza, 2016, no. 6, pp. 79–86.

7. Fomin A.N., Kontorovich A.E. Krasavchikov V.O., Katagenez organicheskogo veshchestva i perspektivy neftegazonosnosti yurskikh, triasovykh i paleozoyskikh otlozheniy severnykh rayonov Zapadno-Sibirskogo megabasseyna (In Russ.), Geologiya i geofizika, 2001, no. 11-12, pp. 1875-1887.

8. Gordadze G.N., Giruts M.V., Koshelev V.N., Application of organic geochemistry methods for exploration and development of oil fields (In Russ.), Burenie i neft', 2020, no. 1, pp. 32-39.

9. Shimanskiy V.K., Shapiro A.I., Vasil'eva V.F. et al., Features of the composition of bitumoids of dispersed organic matter mudstones of Mesozoic deposits in the south of Western Siberia (In Russ.), Neftegazovaya geologiya. Teoriya i praktika, 2006, V. 1, URL: http://www.ngp.ni/rub/1/09.pdf


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