The structure of oil deposits of the Bashkirian stage within low-amplitude uplifts of the eastern side of the Melekess depression

Abstract

The Bashkirian deposits of low-amplitude uplifts of the eastern side of the Melekess depression are currently considered as potentially oil-bearing objects. Despite the high level of regional OWC, which covers 2/3 of the the Bashkirian age section, industrial oil inflows were obtained on several structures. An analysis of the structure of oil-productive uplifts showed that up to two oil-bearing reservoir layers with a thickness of 2.0 to 8.0 m can be localized in them. Oil-bearing formations are confined to the roof of the sections of the Bashkirian stage. The upper layer abuts against dense clayed limestones of the Vereian horizon of the Moscovian stage, the lower layer is supported by the bottom waters of the modern OWC. Between them there is a dense bridge of dense carbonate rocks. The reservoir rocks are leached foraminiferal and algal-lumpy limestones, packstones and grainstones, formed at the stage of transgressive development of the epicontinental marine sedimentation basin of the Bashkirian age. Pseudobrecciated and microgranular mudstone formed at the stage of regression of the Bashkirian epicontinental paleobasin are dense cap rock. Reservoir rocks are characterized by porosity at the level of 10-15%, permeability - from 0.062 to 0.195 µm2 rocks.