International scientific journal

ISSN: 2663-0419 (electronic version)

ISSN: 2218-8754 (print version)

International scientific journal

ISSN: 2663-0419 (electronic version)

ISSN: 2218-8754 (print version)

SCImago Journal & Country Rank

Izotope and geochemical properties of oils of fields of the South Caspian basin eastern flank (Western Turkmenistan)

Huseynov D.A., Feyzullayev A.A.

Institute of Geology and Geophysics of Azerbaijan National Academy of Sciences, 119, H.Javid Ave., Baku, AZ1143, Azerbaijan:,


The paper deals with results of the performed isotopic-geochemical and chromato-mass-spectrometric analyses of oils from 14 fields located in shelf and onshore of the south flank (Turkmenian sector) of the South-Caspian basin (SCB). These oil fields are corresponded to the anticlinal structures of three tectonic zones: Pribalkhanian zone of uplifts (Jdanov, LAM banks, Cheleken, West Cheleken, Kotur-Tepe, Barsa-Gelmes, Burun, Komsomolskaya, Kumdag), Kizilkum trough (Erdekli) and Gograndag-Okarem (Korpeje, S. Kamishlija, Ag-Patlaukh) zones of uplifts. The low prystane-phytane (Pr/Ph) ratios (1.17-1.63 in oils and 1.45-2.08 in condensates), predominance of the low molecular alkanes in the general series of alkanes’ distribution (С31:С19=0.08:0.63), the prevalence of the even alkanes over the uneven ones in unweathered oils as well as the clear naphthenic nature of oils (naphthenic index = 1.9-6.7) testify to mainly marine nature of the initial organic matter (OM). The isotopic composition of oil carbon also points to that. The clear tendency of isotopic lightening of oils is observed in the eastern direction, from shelf fields towards the onshore fields. According to the physical-chemical properties, the oils from single fields located in the various structural zones and the production targets within one field differ significantly. Oils and condensates have very low degree of maturity; calculated by biomarker data in vitrinite equivalent (Ro,%) they make 0.55-0.65% and 0.62-0.75% accordingly. The oil generation mainly from diatom organic matter of clayey sediments of marine delta is sub-stantiated. Moreover, the summary contribution of the Middle- and Upper Miocene complex into oil formation is higher than of the Paleogene-Lower Miocene one; the oil and condensate maturity is low. The supply of structures with hydrocarbons in the shelf of the east flank of the SCB took place as from kitchen areas located within the SCB (Kizilkum trough) and from sources in the Middle Caspian (Kelkor trough).

Keywords: oil, organic matter, isotopic-geochemical analysis, biomarkers, maturity, South-Caspian basin, Turkmenian sector



Bagir-zadeh F.M., Burakovski L.A., Babayev F.R. Geochemistry of oils and gases of Absheron-Pribalkhanian trough. Nedra. Moscow, 1974, 285 p. (in Russian).

Bagir-zadeh F.M., Babayev F.R. Distribution of n-alkanes and hydrocarbons of the isoprenoid structure in oils of the off-shore fields in Azerbaijan. Oil and gas geology, No. 1, 1988, pp. 43-45 (in Russian).

Chung H.U., Rooney M.A., Toon M.B., Claypool G.E. Carbon isotope composition of marine oils. The American Association of Petroleum Geologists Bulletin, V. 76, No. 7, 1992, pр.1000-1007.

Feyzullayev A.A., Huseynov D.A., Tagiyev M.А.F. Oil source rocks and geochemistry of hydrocarbons in South Caspian basin. In book: South Caspian basin: geology, geophysics and gas content. Nafta-Press. Baku, 2004, pp. 286-321.

Guliyev I.S., Feyzullayev A.A., Huseynov D.A. Isotopic composition of oil carbon of the South-Caspian megadepression. Azerbaijan Oil Industry, No. 6, 1999, pp. 3-13 (in Russian).

Guliyev I.S., Feyzullayev A.A., Huseynov D.A. Oil maturity of reservoirs of the different age in the South-Caspian megadepression. Oil and gas geology, No. 3, 2000, pp. 41-50 (in Russian).

Guliyev I.S., Feyzullayev A.A., Huseynov D.A. Isotopic compo-sition of hydrocarbon fluids’ carbon in the South-Caspian megadepression. Geochemistry, No. 3, 2001, pp. 271-278 (in Russian).

Guliyev I., Feyzullayev A., Huseynov D. Isotope-geochemical prognosis of the stratigraphic origin of the oil seepage source in the South, Caspian Basin. AAPG’s Inaugural Regional International Conference, Istanbul, 2000.

Guliyev I.S., Feyzullayev, A.A., Huseynov D.A. Isotope geochemistry of oils from fields and mud volcanoes in the South Caspian Basin, Azerbaijan. Petroleum Geoscience, V.7, 2001, pp. 201-209.

Gurgey K. Correlation, alteration, and origin of hydrocarbons in the GCA, Bahar, and Gum Adasi fields, western South Caspian Basin: geochemical and multivariate statistical assessments. Marine and Petroleum Geology, V. 20, No. 10, 2003, pp.1119-1139.

Kamyanov V.F., Dragunskaya V.S., Yurchenko A.N., Solodkov V.K. Geochemistry of oils, condensates and gases in Turkmenia. Proceedings of Academy of Sciences of Turkmenian SSR. Series of physical-technical, chemical and geological sciences, No. 2, 1974, pp. 38-41 (in Russian).

Katz K.J., Richards D., Long D., Lawrence W. A new look at the components of the petroleum system of the South Caspian Basin. Journal of Petroleum Science and Engineering, V. 28, 2000, pp.161-182.

Sofer Z. Stable carbon isotope composition of crude oils: Application to source depositional environments and petroleum alteration. The American Association of Petroleum Geologists Bulletin, V. 68, No. 1, 1984, pp. 31-49.

Solodkov V.K., Kamyanov V.F., Dragunskaya V.S. Isoprenoid hydrocarbons in depths and condensates of the West Turkmenia. Proceedings of Academy of Sciences of Turkmenian SSR. Series of physical-technical, chemical and geological sciences, No. 1, 1974, pp. 76-88 (in Russian).

Starobinets I.S. Geochemical characteristics of oils, gases and bituminous formations in Turkmenian SSR in connection with issues of oil content. In collection: Prospects of oil-and-gas content and direction of exploration activities in the west regions of the Middle Asia. Gostoptekhizdat. Moscow, 1969, pp. 162-167 (in Russian).

DOI: 10.33677/ggianas20190200027