Controls of sedimentary microfacies on litholigic oil pools in the Changling depression,southern Songliao Basin:An example from the Qingshankou Formation in the Yaoyingtai region

The integration of cores and well logs shows that the lacustrine and delta deposits are widely developed in the Qingshankou Formation in the Yaoyingtai region,Changling depression,southern Songliao Basin.The lacustrine facies consists of littoral and shallow lacustrine subfacies composed of mud beach,mixed beach and sandy beach bar microfacies.The delta facies is built up of delta plain subfacies and delta front subfacies.The delta plain subfacies may be subdivided into distributary channel and interdistributary bay microfacies,whereas the delta front subfacies include subaqueous distributary channel,subaqueous interdistributary bay,channel mouth bar,sheet sands and distal bar microfacies.The channel mouth bar,subaqueous distributary channel and beach bar sandstones are considered as the key areas due to good reservoir potential and hydrocarbon potential.The sedimentary microfacies cited above have significant controls on the distribution of the lithologic oil pools in the study area.The prolific zones are represented by the mobile belts of the lake strandline.