Basic characteristics of beach facies limestones of Carboniferous Bashkirian period in northern Pre-Caspian Basin of Kazakhstan and their petroleum exploration implications

Abstract：The northern part of the Pre-Caspian Basin of Kazakhstan is rich in oil and gas, in which 39 oil and gas fields have been found. Lower Carboniferous and lower Permian strata constitute important oil and gas producing horizons. Recent exploration indicates that there exist lots of beach facies limestones of Middle Carboniferous Bashkirian stage, suggesting that the Middle Carboniferous strata may become a new exploration target. Based on the exploration data, this paper has made a detailed description of macroscopic and microscopic features of Bashkirian beach facies limestones, which will provide an important clue to future oil and gas exploration.