The Study On Sedimentary Facies And Sand Body Prediction Of The Second Member Of Liushagang Formation In The Eastern Part Of Wushi Depression

Wushi Depression is a secondary sag of Beibu Gulf Basin,located in the northwest of Middle Depression in Beibu Gulf Basin,drilling and more than 30,and the main oil-bearing formation is the second member of Liushagang Formation.Current calculation proved reserves of nearly 40 million square in Wushi Depression,has a broad prospect of oil and gas exploration.However,the issues of the sedimentary microfacies types,distribution and evolution and distribution characteristics of sand body has no more detailed research,that encumbered the further exploration and development in this area.To solve above problems,this paper comprehensive use of geological,well logging and seismic data,etc.to analysis the study area.On the basis of identifying the types of sedimentary facies,the fine sand body distribution range and its distribution rule was summarized.And using constrained sparse pulse inversion method to the study area to predict the sand body distribution range.Using geostatistical inversion method to key research area of sand body flat profile sculpture,predict the favorable sand body distribution.In all,paper obtained the following results:1?Using Milankovitch cycles theory,using the GR curve trend of spectrum analysis technology,combined with the single well sequence division and seismic sequence interface,divided the sequence of study area,the east wushi depression total in the study area is divided into four complete sequence,respectively is: SQ1,SQ2,SQ3 and SQ4.And stablishing the sequence stratigraphic framework,discuss the formation development characteristics in the study area.2?In rock-logging-seism method to identify sedimentary types,on the basis of seismic attribute fitting sand ratio method is used to determine sedimentary microfacies distribution in the study area.Clarify a sequence development characteristics of sedimentary facies,clear quicksand port group of secondary sedimentation are mainly delta front deposition and to go.As a whole can be divided into four microfacies: subsea distributary channel deposit(nterdistributary bay deposit),sheet sand,beach bar,argillaceous shallow lake-deep lake deposits.3?The application of sedimentary facies distribution as a guide,combined with the feature of seismic section the reflection axis.To clear the six types of sand body section distribution rule in this area,and summarize all kinds of sand bodies:(1)the content source channel sand body;(2)the source direction of regressive sheet sand body;(3)the source direction of trangressive sheet sand body;(4)crosscut source direction sheet sand body;(5)crosscut source direction channel sand body and(6)crosscut source direction trangressive sand body.4?The CSSI inversion method for analyzing seismic inversion the target strata in the study area.Based on the analysis of the degree of inversion results,flat with inversion results of the study area as a whole to predict the sand body distribution range.And to determine the central north part of WS16-9 and WS17-2 wellblock on sand body prediction research area.5?the geostatistical inversion method is adopted to focus on the study area distribution of favorable sand body prediction,the key strata for SQ2 and SQ3,a total of six groups of sand carving plane and profile.Sand and analyze each group on the types and distribution characteristics of sand body was summarized.