Study On Diagenesis And Disgenetic Faceis Of Yingcheng Formation In Longfengshan Sub-sag,Songliao Basin

with recent years' exploration Longfengshan Sub-sag has been a new exploratory area of the Changling Fault depression.Due to the development of sandstone and conglomerate,the effective reservoir is thin and trapped in thick layers of tight sandstone and conglomerate,which results inrapid change of effective reservoir and strong heterogeneity,which restricts the next step of development.Therefore,studying how to use diagenetic facies to predict effective reservoirs is an important task for the effective development of the Longfengshan Sub-sug.On the basis of analyzing the petrologic characteristics of Yinghceng Formation in Longfengshan Sub-sag,combined with core observation a series of analysis technology,thin section identification,SEM,XRD and other analysis technology,the diagenesis of Yingcheng Formation are discussed and the stage of diagenesis are divied.However,the diagenetic facies areset up by the main diagenetic mineral features and diagenetic events.The physical characteristics of the diagenetic facies are analyzed by the petrophysical test and analysis.Then,according to the logging date to establish the discriminant function of diagenetic facies.Thus,the comprehensive judging standard are set up to recognize the digenetic face.According to the zonal feature of the diagenetic facies in space,to predict the favorable reservoir distribution zone.The above research shows that the Yingcheng Formation in the Longfengshan Sub-sug is a typical tight sandstone reservoir and undergoes complex diagenetic evolution during sedimentation,including compaction,cementation,and dissolution,including compaction,clay mineral cementation,and carbonate cementation is the main cause of the decrease of reservoir physical properties.The dissolution of feldspar and unstablerock debris and the dissolution of hollandite have improved the physical properties of the reservoir.The reservoir is mainly in the stage of diagenesis.Then,parameters such as compaction,dissolution,calcareous cementation laumontite cementation,chlorite rim,and siliceous cementation were extracted.The Yingcheng Formation in the Longfengshan Sub-sug was divided into six diagenetic phases which were(1)the strongly-compacted weakly carbonate-cement weakly dissolution facies,(2)the weakly-compacted weakly coabonate-cement strongly dissolution facies,(3)the weakly-compacted weakly carbonate-cement weakly dissolution facies,(4)the weakly-compacted chlorite siliceous-cement weakly dissolution facies,(5)the weakly-compacted chlorite carbonate-cement weakly dissolution facies,(6)the weakly-compacted chlorite laumonite-cement strongly dissolution facies.Among them,The properties of the weakly-compacted weakly coabonate-cement strongly dissolution facies and the weakly-compacted chlorite laumonite-cement strongly dissolution facies are the best.The properties of the weakly-compacted weakly carbonate-cement weakly dissolution facies and the weakly-compacted chlorite siliceous-cement weakly dissolution facies are secondary,while the properties of the strongly-compacted weakly carbonate-cement weakly dissolution facies and the weakly-compacted chlorite carbonate-cement weakly dissolution facies are the worst.The weakly-compacted chlorite laumonite-cement strongly dissolution facies mainly developed in the northern part of the study area.The acidic water intrusion late formed a large number of dissolved pores,and the connectivity was good.It is the “sweet spot” area for the next exploration and development.