Seismic Geomorphology Study Of Paleogene To Neogene In Liaodongdong Area,Bohai Bay Basin,China

Taking the Paleogene~Neogene in Liaodongdong area of Bohai Bay Basin as an example,based on the two and three dimensional seismic data,a small amount of drilling and logging and core data,the study of seismic geomorphology has been carried out.The three order sequence stratigraphic framework is established,the paleogeomorphology of the main sequence interface is restored in the sequence framework,and the background of paleogeomorphology and paleo-drainage-system of the study area are clearly defined.Under the control of third-order sequence strata framework,palaeo-geomorphology,paleo-drainage-system of region,the sequence stratigraphy,sedimentary system,palaeogeomorphology and paleo-drainage-system in the key area of the 3D area are studied meticulously,the sedimentary characteristics and evolution history of the fluvial-delta systems are analyzed,and the lithologic trap is predicted by the way of seismic geomorphology.According to the data of drilling and logging and the characteristic of seismic reflection termination,the lower number of Guantao Formation to Minghuazhen Formation is divided into 4 three-order sequences and 8 system tracts,the strata model of the Guantao formation is onlap type and the lower number of Minghuazhen formation is characterized by weak overlying strata in the study area,which is put forward by drilling,logging and seismic information.Tectonic and climate factors are the main factors controlling the sequence development of different grades in the area,which control the development patterns of the sequences.Under the control of isochronous sequence framework,the residual stratum thickness,true thickness and original sedimentary thickness of the Paleogene~Neogene in the Liaodongdong area were restored.The paleogomorphology of the depositional area and denudation area was restored by the impression method,increasing the overall understanding of the source to sink.Based on the paleogeomorphology restoration,paleo-drainage-system was reconstructed and interpreted,providing scientific basis for provenance analysis and sand body prediction.Under the control of high precision sequence stratigraphic framework and restoration of paleogeomorphology and paleo-drainage-system,seismic geomorphology studies have been carried out in the key areas of the Neogene Guantao Formation and the lower number of Minghuazhen Formation.Firstly,the feasibility of predicting lithology by seismic data is analyzed.Then,according to the geological characteristics of the study area,the isochronous problem of the stratigraphic section is analyzed,and a stratal slicing method suitable for the study area is established.Finally,the typical stratal slices in different periods are explained and the history of their sedimentary evolution is analyzed.The main types of lithologic traps of the Neogene in Liaodongdong area are sandstone updip pinch out trap,sandstone lens trap,stratigraphic overlying trap and structural lithologic trap.Under the control of seismic geomorphology and drilling and logging data,using the method of seismic geomorphology analysis,the dynamic superposition method is adopted for the analysis of favorable sand bodies developed in different periods,and the structural factors are fully considered,and the lithologic trap prediction is carried out on the main target layers in the key area of the study area.