Study On Sedimentary Microfacies Of Fuyu Reservoir And Its Controlling Effect On Reservoir In Miaoxi Area,Songliao Basin

In view of the characteristics of rapid change of sedimentary facies,multiple types and scattered distribution of sand bodies in the Miaoxi area of Songliao Basin,the Fuyu reservoir in the Miaoxi area is divided into 13 small layers by making full use of previous research results,core and well logging data,and the isochronous stratigraphic framework in the study area is established.Based on the data of core,logging,logging and previous research results,the Fuyu reservoir in Miaoxi area is identified as a river controlled delta depositional system.In the isochronous stratigraphic framework,two subfacies and 11 microfacies are identified,and the logging facies model is established.The sedimentary period of FⅠ4-FⅣ13 was delta plain subfacies in the study area,and the sedimentary microfacies were mainly two kinds of distributary channel,and the overflowed bank sand and natural dike were relatively developed on both sides of the channel.The sedimentary microfacies of FⅠ1-FⅠ3 were delta front subfacies.The sedimentary microfacies of FⅠ1-FⅠ3 were mainly subfacies of subaqueous distributary channels.In general,the Fuyu reservoir is in the continuous water intake interval,and it mainly goes through three stages of change.Through the analysis of the microfacies plan of single well facies,connected well facies and each small layer,the sedimentary models of "river controlled lobe" and "river controlled zonal body" of Fuyu reservoir are established.The physical characteristics of Fuyu reservoir in the study area are low-ultra-low porosity and low-ultra-low permeability.The rock types are mainly lithic feldspar sandstone,followed by feldspar lithic sandstone,including a small part of quartz sandstone and lithic sandstone.The composition of interstitial material is mainly argillaceous complex,followed by carbonate.The reservoir pores are complex and diverse,the primary intergranular pores are the most developed,and the ingranular and intergranular dissolved pores are more developed.The main laryngeal types are variable section pore larynx,constricted partial larynx and curved sheet larynx.According to mercury injection curve,combined with lithology,physical property,micro-pore and other characteristics,the classification standard of the Miaoxi area reservoir is determined.The reservoir is divided into three categories: Ⅰ,Ⅱand Ⅲ,and the Ⅱ reservoir is subdivided into Ⅱa,Ⅱb and Ⅱc.The influence of sedimentary micro-relative characteristics on reservoir characteristics is manifested in three aspects: physical property,micro-porosity and reservoir distribution.The control effect of sedimentary micro-relative physical property is the most significant,which has a certain control effect on the micro-pore structure of reservoir and has an obvious control effect on the distribution of reservoir.There are three types of superimposed sand bodies:cutting superimposed sand bodies,superimposed sand bodies and separated sand bodies.Sedimentary evolution controls vertical superimposed sand bodies,thus controlling the development of reservoirs.The reservoir type of the cut and stack sand body is class Ⅰ or Class Ⅱa,the superimposed sand body is class Ⅱa or class Ⅱb,and the separated sand body is class Ⅱb or class Ⅱc.On the plane,Class Ⅰ reservoirs are generally distributed in a small range,Class Ⅱ reservoirs are widely distributed,and class Ⅲ reservoirs are mainly located at the river channel edge.Vertically,the high quality reservoirs in the sedimentary period of FⅡ7,FⅢ8-FⅢ9,FⅣ11-FⅣ13 are widely distributed and have good development potential.