Study On The Sedimentary And Reservoir Characteristics Of Es4scx Formation In The Western Of Northern Dongying Depression

The sands-conglomerate body reservoirs on the steep slope zone of the faulted lake basin are currently the focus of exploration and development.Sands-conglomerate body has the characteristics of fast deposition,large sedimentary thickness,and unstable lateral distribution.The reservoir has complex internal structures,large phase transitions,and heterogeneity.Problems such as strong nature have severely constrained the process of exploration and development.In this paper,sands-conglomerate body in the upper part under the northern part of the Dongying depression is taken as the research object.The comprehensive use of seismic,logging,logging,core,ordinary thin section analysis,casting thin section analysis,etc,systematically study the internal structure,genetic types and distribution rules of sands-conglomerate body,reservoir characteristics and development rules.Through the study of the relationship between the crushed conglomerate and the change of lake level of Es4 scx Formation,the genetic type of sands-conglomerate body has a “binary structure” in the vertical direction,ie,the early episodic tectonic activity and the gradual deepening of the water body were controlled.The development of the regressive offshore submarine fan,the late structural stability,and the gradual shallowing of the water control the formation of the fan-shaped fan delta.Inshore subaqueous fans are dominated by gravity flow and develop massive block formations;at the top of the fan delta,traction flow plays a major role in the development of grain sequence bedding and wavy layers.The sand-conglomerate bodies reservoirs are low porosity and low permeability,and the reservoir space is dominated by intergranular residual pores,cracks and intergranular dissolved pores.The fan delta reservoirs are distributed in layers.The reservoirs are mainly developed in the middle of subaqueous distributary channel,estuary dams and far sand dams.The near-shore subaqueous fans are characterized by mixed accumulation.Only a small amount of dissolved pores are developed in the middle fan braided channel,and the overall physical properties are poor.The formation of favorable conglomerate reservoirs in the study area has benefited from: dominant petrofacies such as fine sandstone,pebbly sandstone and fine conglomerate;dominant sedimentary microfacies such as the nearshore submarine fan channel front and fan delta underwater distributary channel The development of abnormal high-porosity zones is widespread.