The results of the studies presented in this paper show the similarity and differences in the lithological and mineralogical composition of sediments from the different Miocene stratigraphic levels occurring in the sedimentary section of the different anticline structures located in the Shamakhy-Gobustan and Absheron oil-gas bearing regions of the South Caspian basin.
A significant difference in the lithology and mineralogical composition of these deposits is a result of the influx of sedimentary material from various sources, such as the Greater and Lesser Caucasus. The appearance of sandy horizons in the section of the Upper Maykop (Lower Miocene) and Chokrak (Middle Miocene) and their enrichment in quartz most likely indicate the participation of granite rocks in the geological structure of the provenance area during these geological intervals, which is also confirmed by the presence of disthene and staurolite in the mineralogical composition of these sediments. The muddy rocks of these stratigraphic intervals are also enriched in quartz.
The reservoir properties of the Miocene sediments of the western flank of the South Caspian depression were assessed based on the study of the outcrop and core samples of the exploration wells. It is shown that the rocks from the outcrops have better reservoir properties, which is the result of their weathering in the hypergenesis zone.
The rocks of III and I sandy horizons of the Maykop Suite (Lower Miocene) and the Chokrak stage of the south-west Gobustan area display the best potential for oil and gas accumulation. However, effective porosity of these sediments is significantly lower than total porosity and can be classified as weak.
The reservoir properties of these rocks noticeably decrease outside the south-western tectonic zone of the Shamakhy-Gobustan oil-gas region and can be considered as negative in the Northern Gobustan, very week in the Baku archipelago, and, possibly, in the Absheron oil-gas region. These conclusions can play an important role in assessment of oil-gas potential of the Miocene sediments of the western flank of the South Caspian basin.

 

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