Abstract:

The oil layers in the Carboniferous Kalashayi Formation (K) in the Tahe oilfield mainly occur in the interbedded sandstones and mudstones of K3 and K4 members. Based on the variability and cyclicity of resistivity and Gamma ray logs caused by calcareous contents in mudstones,K3 and K4 members were subdivided,from top to bottom,into five reservoir units:Ⅰ,Ⅱ,Ⅲ,Ⅳ and Ⅴ.The thickness of each unit ranges from 80 m to 100 m and the boundaries of each unit were calibrated to the same event on well-tie seismic profile,thus being isochronal.Most of the oil and gas layers appear laterally as separated lenticular sandbodies for their thin single layer(2～5 m)and channel microfacies.The pools are mainly controlled by structural traps,distribution of lenticular sandbodies and faults seated in the Cambrian and Ordovician source rocks.

Key words: stratigraphic characteristics, subzone correlation, Kalashayi Formation, pool type, Tahe oilfield