The Sedimentary Evolution and Response to Hydrocarbon Accumulation of Quantou and Qingshankou Formation in Songliao Basin

By studying the sedimentary evolution of Quantou and Qingshankou Formation in Songliao Basin,the characteristics of combination of oil genesis,reserves and caprocks and the rule of macroscopic distribution of oil and gas was denoted.The study of sedimentary geologic theory showed that Quantou Formation and Qingshankou Formation were a set of large-scale fluvial and shallow-water deltas created by lake upgrading and retrograding cycle of sedimentary formation.The sediment of Qingshankou formation was large-scale lake and delta.Short axis direction of the western source developed sublacustrine fan in Songliao Basion.The 1st member of Qingshankou Formation deposited oil shale and deep lake mudstone were the important source rocks and caprocks.The main reservoirs were large-scale delta complex,shallow-water delta and channel sand.Those sands had good physical property nearby oil sources,which extended to the lake basin center and inserted into the mature source rock or covered by the source rock,which was up genesis and down accumulating assemblage for Fuyang reservoir.The large delta is developed in the north-south long axis and the turbidite fan is developed in the short axis,which are major locations of reservoir distribution.The reservoir of Quantou Formation is mainly distributed in mesh river and shallow-water delta sand body in the central depression.