Research Of Sedimentary Facies And Prediction On Favorable Reservoir Zone In Chang 9-10 Oil Formation Of Huangling Area

In this paper,using theory and technology of the high-resolution sequence stratigraphy,to carry out sequence stratigraphic framework and sedimentary facies of Chang 9 and Chang 10 oil formation in the Huangling area,Ordos Basin.Through literature research,field outcrop,core and well logging data comprehensive study established the high-resolution sequence stratigraphic framework,to identify the types of sedimentary facies,clear the reservoir sand body distribution characteristics,and forecasts the lithologic traps in favorable target area.Application of high resolution sequence stratigraphy research methods,Chang 9and Chang 10 oil formation are divided for two long-term cycles,followed by bottom-up named as LSC1 and LSC2 sequence,and the long-term cycle is divided into four medium-term base level cycles,respectively as MSC1-1,MSC1-2 in LSC1and MSC2-1,MSC2-2 in LSC2 and through the combination of the medium-term cycles,10~2,10~1,9~2 and 9~1 sand group is calculated.The sequence stratigraphic framework of Chang 9-Chang 10 oil reservoir is established by means of connecting well formation,and the distribution characteristics of sequence strata are defined.Through field outcrop and drilling/logging analysis,with the study of sedimentary facies sequence stratigraphic framework,recognized delta facies and lacustrine facies sedimentary facies of Chang 9-Chang 10 oil formation in Huangling area,delta front,delta plain and shallow lake 3 kinds of sedimentary subfacies,and clear underwater distributary channel,mouth bar and sheet sand as the main sand body.In the sequence stratigraphic framework of control,with well logging data for research,drawn to sand group unit of the sand body distribution maps,clear Chang 9-10 sequence stratigraphic deposition within the framework of the facies distribution and evolution characteristics.The 10~2 period of the development of delta front subfacies deposition,accounting for the majority of the region.With the gradual increase of the datum,the area of the lake area becomes larger,the size of the delta front is contracted in the 10~1 period.After entering the Chang 9 oil formation period,base level continues to rise,increase the area of shallow lake subfacies,delta front subfacies shrink further,shore line move forward east and north direction.Considering the sequence stratigraphic position,structural map,the distribution of sand body,have been found oil and gas bearing system,trap type and other factors,identifying favorable oil-bearing layer is 9~1 sand group,the favorable sedimentary microfacies type are underwater distributary channel,mouth bar and sheet sand,types of favorable traps mainly lithologic traps;through the comprehensive analysis of sedimentary facies,tectonic,capacity predicted five favorable area.