Study Of Sedimentary Microfacies And Geologic Modeling Of Chang 8₂ Reservoir In The East Of Jiyuan Area,Changqing Oilfields

Based on plenty of collected data and conclusions of previous researches,and in terms of core,well logging data,dynamic production data and analysis of testing data,combined with theories and methods of Sequence Stratigraphy,Sedimentology,Reservoir Characterization and Geologic Modeling,this paper makes a comprehensive analysis of types and features of sedimentary facies of Chang 8₂ in the east of Jiyuan area of Changqing oilfields,and establishes three-D geologic models of Chang 8₂ in Di231-57 well zones.On the basis of characteristics of sedimentary cycles,fine stratigraphic classification and correlation and pervious dimidiate classification plan,Chang 8₂reservoir is divided into four sublayers.They are Chang 8₂^2-2,Chang 8₂^2-1,Chang 8₂^1-2and Chang 8₂^1-1 from bottom to the top.The provenance derives from northeast of the study area in the period of Chang 8₂.Source rocks are mainly metamorphic rocks,neutral to acid volcanic rocks and a few older sedimentary rocks.In the stage of Chang8₂,the study area primarily develops river-dominated shallow water delta front subfacies,including subaqueous distributary channel microfacies,under water natural levee facies and tributary bay microfacies.Moreover,Due to the flat terrain of the study district,the water is shallow and the lacustrine level varies quickly.Consequently,subaqueous distributary channels divert frequently,leading to the expansive growth of sandbody.On account of plane and sectional evolution laws of four sublayers of Chang 8₂ oil reservoir in the study area,accompanied by sedimentary evolution features of Ordos Basin,this paper makes an appropriate sedimentary model conformed to Chang 8₂reservoir.Research indicates that in the sedimentary stage of Chang 8₂²,the lake expanses,while in that of Chang 8₂¹,the water level deepens fast.The thickness and sedimentary scope of sandbody reduce obviously.To conclude,Chang 8₂ oil reservoir in the research area experiences a water transgressing sedimentary process.Using basic approaches and procedures of reservoir modeling,reservoir model is made in the Petrel platform.The model suggests that multi-period reservoir sandbodies of Chang 8₂ overlap reciprocally and Chang 8₂ reservoir presents serious heterogeneity.