Reservoir Architecture Of The First Member Of Funing Formation In Wei 5 Fault Block

The reservoir of the first segment of Fu'ning formation in Wei 5 fault block is the main type of delta front sandbody,and it is a heavy oil reservoir mainly composed of fine sand and siltstone.Due to the lack of accurate understanding of reservoir in the early stage of development,the contradiction of reservoir development is gradually exposed as the oil field entering the development stage of high(medium to high)water cut,and these problems restrict the later development work.To solve these problems,this paper takes the guidance of high-resolution sequence stratigraphy and sedimentary petrology as the guidance,combined with core,logging and dynamic data.Based on the comparison,the stratigraphic framework is further refined.Based on delta-front the sedimentation model and law,the sedimentary system and microfacies characteristics of the study area are clarified.On the basis of fine microfacies study,the characteristics of the delta-front reservoir architecture units split are determined,and the architecture pattern of E1f1 in Wei 5 fault block is established.The main results are as follows:High-resolution sequence stratigraphy framework has been built after basal-level cycling analysis.Based on the results of previous stratigraphic correlation,4 additional auxiliary marker beds have been identified,which are located at the top of E1f11-5,E1f11-7,E1f11-10 and E1f11-13.Based on the identification of basal-level cycling structure and its superimposed characteristics,the study area is divided into 1 long-term cycles,6 medium-term base level cycles,17 short-term base level cycles and 31 ultra short-term base level cycles,and 17 small layers were further subdivided into 31 monolayers.The major reservoir of the research area is divided into monolayers for the first time.Based on the analysis of lithology,structure and the sedimentary background of the study area,the sedimentary micro facies of the research area are studied.the research target layer develops mainly delta-front,and there are many types of microfacies and complex space superposition relationships in the reservoir.Comprehensive application of core and log data,we identify 5 sedimentary microfacies:mouth bar,bar edge,submerged distributary channel,sheet sand and interdistributary bay.There are 4 types of micro facies distribution in the plane:submerged distributary channel-mouth bar,mouth bar-beach sand,a series of contiguous mouth bar and sheet sand deposition.In vertical direction,the overall level of the relative lake is declining,and the characteristics of the whole cycle are counter cycle,forming the deposition of the front and inner front of the delta.The reservoir architecture of the study area is analyzed in detail with the guidance of the sedimentary patterns.According to Miall's architecture unit division scheme,the 6 level classification scheme of the sedimentary architecture in the study area is determined.The main research object is the four-level architecture unit mouth bar.In the vertical direction,3 kinds of vertical stacking methods independent type,superposition type and cascade type are identified.In the lateral direction,5 kinds of architecture unit interstitching patterns:mouth bar-mouth bar,mouth bar-bar edge-mouth bar,mouth bar-interdistributary bay mud-mouth bar,mouth bar-distributary channel,mouth bar-beach sand-mouth bar.In this paper,the focus of this study is to identify the single mouth bar unit inside a series of contiguous mouth bar,and summing up 4 identification marks of the single architecture unit.From the analysis of the horizontal and longitudinal architecture unit distribution diagram,it is concluded that the architecture unit of the whole study area is the pattern of split plate.