Study On Sedimentary Microfacies And Single Sand Body Of The 4th Member Of Quantou Formation In Liangjing Oilfields In Jilin Province

As the old continental oilfield enters the stage of high water cut,the conventional reservoir research based on the accuracy of small layer is difficult to meet the needs of oilfield production,so it is urgent to refine the degree of geological research,and the focus of reservoir research is deepened from the basic unit of small layer to the basic unit of single sand body.This paper takes the 4th Member of Quan Formation in Liangjing Oilfields,Jilin Province as an example,and carries out research on sedimentary microfacies and single sand body under the guidance of theories of sedimentary petrology and development geology.Based on the distribution of sedimentary microfacies and single sand body characterization,the influence on remaining oil distribution is analyzed.The study shows that the fourth member of Liangjing Oilfields can be divided into 4 sand groups and 12 small layers,and isochronous stratigraphic framework is established under the control of regional marker layer.In the sedimentary background of Songliao Basin,two subfacies,delta plain and delta front,were developed in the study area based on core observation description and facies marker analysis.In the delta plain subfacies,distributary channel,natural levee,overbank sand and intertributary bay were identified.The delta front subfacies identifies four types of sedimentary microfacies: underwater distributary channel,mouth bar,underwater natural levee and underwater intertributary bay.On the basis of the study of sedimentary facies,the configuration interface of compound superimposed sand body is identified and studied.The genesis of compound superimposed sand body and six kinds of superimposed combination types are analyzed.The combination types of channel and channel sand body are isolated channel sand body,cut superimposed channel sand body and superimposed channel sand body.The combination types of channel and other sand bodies include distributary channel-mouth bar combination,channel-natural levee combination and channel-natural levee-overbank sand combination.Lateral and vertical accretion layers in sand body are identified and quantitatively characterized.The vertical and lateral identification marks are used to divide the single sand body,analyze the overlapping relationship between the single sand body,and study the distribution characteristics of the single sand body.Based on the above research,the influence of sedimentary microfacies and single sand body on remaining oil distribution is summarized,and the remaining oil prediction area is divided.