Characterization And Main Controlling Factors Of Submarine Fan Of 1st Member Of Huangliu Formation In Dongfang X Area,Yinggehai Basin

The submarine fan in the first member of Huangliu Formation in Dongfang X area,in Yinggehai Basin,belongs to gravity flow deposition.The previous studies on sedimentary micro-facies of submarine fan are not unified and the main controlling factors need to be studied further.The sedimentary model was focused on regional deposition,it's too large scale of spatiotemporal evolution to show the evolution law.The research in this paper is helpful to improve the sedimentary model of the submarine fan.The research object of the paper is the submarine fan in the first member of Huangliu Formation.Under the guidance of the theory of sequence stratigraphy,seismic sedimentology,petrology,logging geology and so on.Based on drilling core,well logging data,3D seismic data,and existing research results,the spatiotemporal evolution process of the submarine fan and its key controlling factors of the two problems are studied.The sedimentary characteristics of the submarine fan were performed for the classification of sedimentary micro-facies,evolution laws of submarine fan,the genesis mechanism and main controlling factors.At the last part,the sedimentary model was summed up.The main understanding and conclusions are as follows:The characteristics of trace fossils and the abundance of foraminiferal fossils indicate that the sedimentary environment of the gravity flow belongs to the outer neritic environment.Most of the sedimentary structures were deposited from gravity flow and some of it were under tidal influence.It indicates that the submarine fan of the first member of Huangliu Formation belongs to the gravity flow deposits,and is partly affected by tidal action.Combining with the seismic micro-facies,characters of well-logging and core analysis,four types of sedimentary micro-facies are identified,including restrictive lobes,restrictive channels,channel-levee complexes and non-restrictive lobes.The non-restrictive lobes can be subdivided into the proximal lobes and distal lobes.Analyses of spatiotemporal evolution characteristics of sedimentary system from two aspects of vertical evolution and plane evolution show a clear laws.At the early stage of the gravity flow,restrictive lobes and restrictive channels were developed,and at the late stage,non-restrictive lobes and channel-levee were developed.Variable gradient caused the gravity flow to transform from the supercritical flow to the subcritical flow.And the hydraulic jump caused the gravity flow to erode the underlying strata,resulting in the increase of the thickness of the proximal lobes.Restrictive Channel-Restrictive Lobes-Channel-Levee-Non-restrictive Lobes,that is a unique sedimentary model of the submarine fan in the first member of Huangliu Formation,has been summed up lastly.