ON THE DISTRIBUTION OF THE TURBIDITE TYPE RESERVOIRS IN PRODUCTIVE SERIES WITHIN SOUTH CASPIAN DEEPWATER STRUCTURES

Ch. M. Khalifa-zade
Azerbaijan State Oil Academy

Well-known turbidite reservoirs are widespread in Miocene, Pliocene structures within gulf trench basins described by number researchers from the USA.

Recently we became witnesses on the wide spreading of the turbidite reservoirs within eastern passive margin of Brazil platform.

Primary concerning spreading of turbidite sandy system in productive series (Lower Pliocene) in South Caspian has been brought out by us on the base studying micro-textures of rocks and layers from outcrops in Apsheronian Peninsula and Lower Kurenion depression beside corn of deep exploration wells from areas Azery , Chirag, Gunashly and so on as well are studied. In further we are used additional materials-time sections and results of seismic stratigraphy data for prokes presenting (available) in productive series turbidite sandy systems. That's why described commercial hydrocarbon accumulation discovered in deepwater Structure Shakh-deniz highlighted turbidite sandstones in Balakchany swit as a new genetic reservoir type.

In this context, previously described in Balakhany suit turbidite sandstones and siltstones may be high oil-gas potential in deep-water structures within South Caspian Hence, it is evident, that hydrocarbon potential in deepwater Structures of South Caspian have to be associated with sandy turbidite systems, localized in homogenous pelagic shale formation.

Continental slope of Balakhany basin is southeast off folded line Structures -Gunashly, Chirag, Azery, Kapaz on the west if comprises southeastern termination of Baku archipelago based on new seismic and sedimentological data. We assume, that deepwater structures as Tagiyev, Absheron and Rasul-zade are located within paleoslope of Balakhany basin. Their paleobasin floor abyssal plane was located south and southeast of paleoslope, where just revealed deepwater structures Babek, Absheron and Vezirov. Namely, in this part of the Balachary basin is expected widespread sandy turbidite system among homogenous shale formations. Such type reservoirs can be found in coarse-grained middle to fine-grained sandstone and shale siltstones facies.

It is supposed that accumulated at about 1500-2000m depths where bottom water remains unsaturated by Ca -Mg carbonates, because of low temperature condition.

Hence, sandy turbidite system reservoirs should have poorly cemented by carbonates and normal porosity and permeability, that's why we suggested there to be a commercial quality reservoirs.

However, it is not excluded that, their carbonate content might be increased because of diagenesis process. Our calculations indicate that sandy turbidite reservoirs thickness is expected to be in the range of 10 to 50 m and most likely they expected to be iterated recurrently within deepwater sandy-shale formation.