A Detailed Study On The Interstition And Interlayer Of Sa Ⅱ Oil Formation In The First Block Of Northeast Lamadian Oilfield

Lamadian oilfield is in the development state of ultra-high water cut,and Saltu reservoir is confronted with the problems of small remaining recoverable reserves and complicated distribution of remaining oil.Because the development degree and distribution characteristics of interlayer in reservoir have significant influence and control on the percolation capacity of reservoir and the distribution law of remaining oil,it is of great significance to study the type,cause,identification criteria and distribution characteristics of interlayer in this area for late reservoir development and oil and gas production.This thesis takes the Sa Ⅱ oil formation in the first area of northeast Lamadian Oilfield as the research object.According to the geological characteristics of this area,guided by stratigraphy and sedimentary characteristics,the logging facies model of Sa Ⅱ oil formation is established through fine stratigraphic division and correlation,combined with the basic geological data such as core,well logging and drilling,and the plane distribution characteristics of its sedimentary microfacies are analyzed.Based on the standardized logging data,the electrical and physical characteristics of the strata under different genetic conditions are analyzed,and the qualitative and quantitative identification criteria are established for each type of interlayer,based on which the distribution characteristics of interlayers are analyzed.The study says:(1)Based on the petroelectric characteristics and marker correlation method,Sa Ⅱreservoir group is divided into 6 sandstone groups,10 small beds and 20 sedimentary units.(2)On the basis of fine stratigraphic subdivision and correlation,core observation and geological data analysis show that the Saertu oil formation in the first area of northeast is a delta facies sedimentary environment,including 1 sedimentary facies,2 sedimentary subfacies and 10 sedimentary microfacies.Thus,a sedimentary microfacies-logging facies model which can be applied to the whole area is established.(3)According to their genesis,the interbeds developed in Sa Ⅱ oil formation can be divided into argillaceous interbeds,physical interbeds and calcareous interbeds.Argillaceous interbeds and physical interbeds are mainly formed by sedimentation,while calcareous interbeds are mainly formed by diagenesis.(4)The sensitivity logs of SP,GR,AC and other types of interlayers were selected,and the qualitative and quantitative identification criteria of the three types of interlayers were established by using the grey correlation theory and crossgraph method,and verified by the core observation results,so as to realize the effective identification of interlayers in the study area.(5)Using geostatistics and other methods,the statistics of the parameters of interlayers and interlayers show that the interlayers of Sa Ⅱ oil formation are mainly located in the place where the sandstone is not developed.The more developed the sandstone is,the lower the drilling rate of small interlayer,and there is no sporadic distribution of interlayers.The interlayer is relatively developed,and the distribution frequency of interlayer is positively correlated with the distribution density.(6)Based on the Miall configuration interface theory,the interlayer of Sa Ⅱ oil formation can be divided into three levels: small interlayer,interlayer of single sand body and interlayer of single sand body.According to the analysis of interlayer distribution by connecting well profile,three sets of small interval layers with large thickness are developed in Sa Ⅱ oil formation,which are stratified and stable distribution with strong continuity.The interlayer between single sand bodies is locally developed and small in scale,and its continuity is poor compared with that of small interlayer.The interlayer in the single sand body is sporadically distributed,with small development scale,poor stability and low profile tracking.