Study On Sedimentary Microfacies Of Tengger Formation In J45 Fault Block Of Baorao Oilfield

The Lower Cretaceous Series Tengger Formation is the most important oil-bearing formation in the Jiergalangtu Sag of the Erlian Basin,which has important research value and economic value.The J45 fault block of Baorao Oilfield is located in the Baorao Tectonic Belt in the middle of Jiergalangtu Sag of Erlian Basin,which is one of the main fault blocks of Baorao Oilfield.The sedimentary microfacies were studied in order to understand the distribution of oil and water and to improve oil recovery.In this paper,based on the background analysis of regional sedimentary evolution,using the sequence stratigraphy,sedimentary geology,petroleum geology,logging geology theory as the instruction,we take full advantage of core,logging,logging and seismic data,established the closed framework profile to fine divide and contrast the strata in the study area and to clarify the stratigraphic distribution characteristics of the study aera.;Then,based on the coring well core observation and description,the micro chip data analysis,combined with the logging curve characteristics,we identified the sedimentary facies marks of the researching area,and in combination with regional sedimentary background,the background of tectonic evolution,we determined the sedimentary system,divided the sedimentary facies types and cleared the development characteristics of each sedimentary microfacies by dot(single well)to line(well tie)to surface(plane distribution)research,and analyzed the sedimentary microfacies plane distribution and vertical evolution characteristics;Finally,by drawing the cross section of the composite sand body and the horizontal distribution chart of the sand body,and analyzing the horizontal,vertical and plane distribution of sand bodies in the study area,the distribution characteristics of sand bodies in Tengger Formation of J45 Fault Block in Baorao Oilfield were studied.Based on the principle of "sedimentary cycle as the main line,marker layer control,adjacent well similarity comparison and well seismic combination",this paper divides the Tengger Formation of J45 Fault Block in Baorao Oilfield into 11 sand formations and 50 small layers.The sedimentary facies study shows that a braided delta sedimentary system has been formed in the study area,which is mainly composed of braided delta front subfacies,and can be further divided into five microfacies: underwater distributary channel,main body of sand bar,inner edge of dam,outer edge of dam and distributary bay.The first and second stages of Tenger Formation are the process of one water retreat and one water advance.The overall thickness of sand body in the study area is large,the plane distribution is northwest-southeast,underwater distributary channel sand body development is the best,thickness of single layer is large and connectivity is good.The plane shows multi-branch strip distribution.The main sand development area of the sand bar is large,plane shape is irregular oval.The thickness of the inner edge of the dam and the outer edge of the dam is relatively thin in a ring belt around.As dominant facies,the main microfacies of underwater distributary channel and sand bar are favorable reservoirs for future exploration and development,and can be used as key research and development objects.