Supervisor: Associate Professor Gasham Zeynalov
Keywords:
petroleum system, deposition, reservoir, source rock, volcanogenic sediments
The Yevlakh-Aghjabedi basin is located within the Kura intermountain
mega basin, borders in the north-east with the Goychay-Saatli uplift zone, in
the south-west with the Lesser Caucasus foothill fault, in the north-west with
the Shamkir palaeo-uplift, and in the south-east through the Araz transverse
fault. The deepest place of this basin on the surface of the pre-Jurassic
crystalline basement is located between the lower reaches of the Tartar and
Khachinchay rivers.
In the northern-east part of the Yevlakh- Aghjabedi basin (Muradkhanly,
Zardab, Jafarli fields) Paleogene-Cretaceous volcanic rocks overlaid by
Neogene-Quaternary sedimentary deposits, are distributed over a wide
stratigraphic range [Yusifov & Aslanov, 2018].
THE 3
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The southwest part of the basin has a very complicated deep structure.
This region is characterized by the incompatibility of the structural plans of
the Mesozoic, Paleogene-Neogene and Pliocene deposits. This affects the
efficiency of the exploration of oil and gas fields.
Oil and gas reservoirs of the Yevlakh-Aghjabadi basin are associated
mainly with the Upper Cretaceous, Eocene, Maykopian (Oligocene-Lower
Miocene), and Chokrak (Upper Miocene) deposits. Commercial oil flows
were obtained from effusive (andesites, basalts, porphyrites) and carbonate
rocks of the Upper Cretaceous in the northeast part of the basin (Muradkhanly,
Zardab fields), and oil and gas accumulate on the open surface of effusive
rocks in the reservoir of complex type as fractures, caverns, etc. The
Muradkhanli oil field related to effusive volcanogenic rocks is currently under
development. Although oil and gas flows and manifestations were obtained
in some structures [Sovetlar, Borsunlu, etc.] from the fractured carbonate
rocks of the Upper Cretaceous, their commercial importance was not
revealed [Klosterman et all.,1997; Suleymanov et all, 2006; Kocharli, 2015].
The commercial oil content of the Eocene reservoir rocks belongs to the
Middle Eocene tuffogenic-clastic facies in the north-eastern part of the basin
in Muradkhanli, Jafarli, and Zardab fields. On the south-western part of the
basin, the oil content of Eocene deposits was found in Gazanbulag, Godakboz,
and Borsunlu fields.
The oil and gas content of the Maykopian strata is mostly observed in
the southwestern part of the basin. Oil fields were discovered in Naftalan,
Gazanbulag, Ajidara, and Tartar structures from sand-dominated horizons in
the lower section of the Maykopian suits. Also, small oil flows were also found
in the sand-rich layers, cracked dolomite, and marl layers of Chokrak
deposits in the Muradkhanli field.
In the section of the Upper Eocene, thick shale rocks are present in the
basin. In the most buried part of the basin - Sovetlar, Eastern Aghjabedi,
Shirvanly and other areas, the thickness of shale rocks increases up to 700
m. These rocks are considered high-potentially source rock for hydrocarbon
generation with rich in organic matter.
Carbonate rocks of the Lower Eocene also do not have enough
volumetric capacity and permeability for hydrocarbon accumulation. However,
the Lower Eocene impermeable formation is regionally developed seals for
Upper Cretaceous oil fields and these deposits having a thick shale layer
underneath with rich in organic matter are also potentially oil-generated rocks
for the Middle Eocene reservoirs.
Thus, the analysis of structural-tectonic and lithofacies criteria show that
Cretaceous, Eocene, Maiykopian, and Chokrak deposits have favorable
geological conditions for the formation of oil and gas fields in the Yevlakh-
Aghjabedi basin.
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