Genesis and organic geochemical characteristics of oil shale in eastern Azerbaijan

Abstract

The paper presents a study on genesis and organic geochemical characteristics of oil shales, occurred in different tectonic zones of Eastern Azerbaijan. Lithostratigraphic properties of oil shale containing sediments, evolutionary dynamics and structural types of organic matter were studied. In terms of paleogeography, it was defined that the formation of oil shales in examined regions, are associated with an almost identical sedimentation conditions (in shallow freshwater and silty pools-lagoons). The organic matter of the oil shales is mainly consist of phytoplankton (algae) and zooplanktons (fish larvae etc.). Connected with orogenic phases, the formation of oil shale, coal and oil in southeastern slope of the Greater Caucasus links their similar genetic properties. Thermal analysis of oil shale revealed that when organic matter loses the most part of its weight at a higher temperature (≥400 °C) corresponds to aliphatic, but at lower temperatures (≥200 °C) aromatic structures. Pyrolysis of oil shale samples showed that in the initial stage (500-550 °C), excluding the amount of gas, bitumen and pyrolytic water were increased. Increasing the temperature up to 800-850 °C leads to the conversion of higher molecular hydrocarbons into lower, and formation of gases and coke residues. The gradual increase in temperature ends with carbonization of kerogen. An abrupt change in the yielding of bitumen is mainly observed at a temperature of 400 °C. Thermal analysis and pyrolysis of oil shale samples, taken from different studied regions allow making conclusion that some of their kerogens is fully matured.

Geochemical proxies of the gryphon breccia of mud volcanoes in East Azerbaijan: regularities in the distribution of chemical elements and spatial characteristics of sedimentation

“…This idea is consistent with the conclusion made in [9]. Thus, this literature shows that pyroclastic sediments brought into the paleobasin play a decisive role in the formation of Middle Eocene and Diatom oil shales [11] rich in organic matter (on average about 20 %) in Central and Southern Gobustan. The analysis of major oxides shows that the spatial position of the paleobasin of deposits belonging to the breccias of 12 mud volcanoes is completely different.…”

Deep fluids and their role in hydrocarbon migration and oil deposit formation exemplified by supercritical СO2

“…The biogenic source of petroleum hydrocarbons is predominantly aquatic organic matter, both in the case of traditional deposits and shale oil (Aliyev et al . 2018; Wang et al . 2020).…”

“…The degree of maturity of organic matter in oil shale is not always inferior to DOM (Aliyev et al . 2018). Oil shale includes only rock in which the concentration of organic matter usually exceeds 20 %.…”