The Study On Sedimentary Characteristics Of Lower The 4th Member Of Shahejie Formation-the 1st Member Of Kongdian Formation In Dongying Depression

The degree of research and exploration of lower the 4th Member of Shahejie Formation─the 1st Member of Kongdian Formation in Dongying depression is relatively low.In recent years the discovery of commercial oil and gas flow in fengshen3,fengshen2 as well as some others,demonstrate that great potential available in the lower part of the 4th Member of Shahejie Formation─the 1st Member of Kongdian Formation.Guided by sequence stratigraphy and sedimentology,based on the comprehensive application of seismic data,well logging data,drilling cores and other related analyzed data,the sequence stratigraphic framework of lower the 4th Member of Shahejie Formation─the 1st Member of Kongdian Formation in Dongying depression is built up. In view of the different characteristics of the formation,wavelet transfer was tentatively applied in the research to identify the sequence boundary and to divide the sequence stratigraphy units.Ac well logging wave is applied in the division of redbeds,Gr well logging wave is applied in the division of salt-gypsum rock.This paper divide lower the 4th Member of Shahejie Formation─the 1st Member of Kongdian Formation into 5 third-order sequences,of which sequence 1,2 and 3 correspond to lower,middle and upper parts of Member 1 of Kongdian Formation and sequence 4 and 5 correspond to the lower and upper part of the lower part of the 4th Member of Shahejie Formation.On the basis of the comprehensive analysis of the exploratory well data,along with the seismic data,the types and distribution of sedimentary systems of Dongying depression are studied within the vertical sequence.This paper argues that the main types of sedimentary facies in the lower part of the 4th Member of Shahejie Formation─the 1st Member of Kongdian Formation include salt lake,nearshore subaqueous fan, flood─overlake,overlakedelta,overlake─beach and bar system,alluvial fan,fan delta, delta,beach and bar systerm.The control factor,material source and formation environment are studied by the research of the lithologic characteristics,sedimentary tectonic characteristics,geochemical characteristics,profile characteristics and plane distribution characteristics as well as the analysis of palaeostructure,palaeoclimate and palaeosalinity of the area.The results show that the salts are continental source and come from the Cambrian and Ordovician systems of the surrounding uplifts.Along with the evolution of palaeolake,the depositional environment of salt-gypsum rock varies from"shallow water evaporate"to"deep water evaporate".On the basis of the research on the types and characteristics of sedimentary facies,by the means of the thickness and percentage of glutenite ,colour and type of rock and seismic facies,the regular pattern of sedimentary facies in each of the sequence is obtained.