Sedimentary Characteristics Of Shallow Water Delta In Qian246-Rang70 Block,Southern Songliao Basin

The K₁q⁴ in Qian246-Rang70 block,southern Songliao Basin is taken as an object of study in this paper,according to sedimentology,high-resolution sequence stratigraphy and multiple sedimentology analysis methods,based on the full use of cores,well logging,seismic data,laboratory analysis and previous study results,etc.This study gives an analysis of the stratigraphic division and correlation,sedimentary microfacies characteristics,the evolution of shallow water delta and finally establishes its sedimentary model.The region is characterized by steady paleotectonic,gentle paleotopography,suitable paleoclimate and shallow paleobathymetry,it has abundant provenance from the southwestern Tongyu-Baokang drainage.These features match with the sedimentary environment of large-scale shallow water delta.On the foundation of core observation and description,the sedimentary facies marks are distinguished and electrofacies model is established.The target layer corresponds to the rising half cycle of long-term base level cycle,which is further classified into four middle-term base level cycles and 13 short-term base level cycles,develops shallow water delta plain and delta front,with eight microfacies including distributary channels,interdistributary area,crevasse splay,overbank sand,underwater distributary channel,underwater interdistributary bay,front sheet-like sand and mouth bar.Single well facies,well-to-well facies and plane distribution of sedimentary facies are analyzed,besides,the geology knowledge database is developed,to calculate the width,thickness,and the ratio of width and thickness of underwater distributary channel sand body.Finally,the sedimentary facies evolution and model are conducted.