Research On The Sedimentary Microfacies Of Putaohua-? Oil Reservoir Of Gu693-Ao18 Well Area In South Gulong Area

Gulong Oilfield is located in Datong District,Daqing City,Heilongjiang Province,which is belong to the exploration and development block of the No.9 Oil Production Plant of Daqing Oilfield.As the oilfield entering the middle-ate stage of exploration and development,it is urgent to find various lithologic trap reservoirs and tectonic-lithologic composite trap reservoirs in the Gulongnan Sag.It was required taking the research on the sedimentary microfacies types,characteristics and sedimentary evolution laws of the target stratum in study area,which was in order to provide technical support for the next step to find remaining oil.Based on the previous studies,this paper took guidance by the high-resolution sequence stratigraphy,logging geology,continental sedimentology and river fine sedimentology,focused on the Gu 693-Ao 18 well area of the Putaohua-I oil reservoir which is in the south of the Gulong area,combined with core observation data,making full use of core,well loggingand other data to make the study of sedimentary microfacies characteristics and evolution laws,which had the great significance for oil and gas exploration in the study area.Taking the comprehensive utilization of core,well logging and other data,selected the standard layer,constructed isochronous stratigraphic framework,divided the stratigraphic division,the strata of the study area was divided into three sandstone groups,eight small layers,and ten sedimentary unit units.The delta front subfacies in the study area were further divided into 6 sedimentary microfacies such as subaqueous diversion channels,sand bars,sand sheets(subdivided into main sand sheets and non-main sand sheets),untabulated reservoirs and the bay mud between subaqueous distributary channels.,by means of provenance analysis and paleogeomorphology restoration.Combined with analysis of single well facies and connected well facies,it was judged that the lake level fluctuates frequently during the sedimentary period of the Putaohua-I group,and the lower sandstone group is in the stage of overall water regression.During the sedimentary periodthe of middle sandstone group,the northern source and the western provenance are simultaneously deposited in early phase,but the scale is small.With the time over,the sediments carried by the river began to deposit abundant in the study area,and a number of underwater distributary channel sand bodies wereoccured.During the upper sandstone group,the water was further deep,and the study area was in the outer front sedimentary environment.The transformation to the sand of the lake was stronger than that of the river,and the sediments are mostly sand sheet.The northern provenance was a long-distance source of gentle slope delta deposits.It had the characteristics of shallow water,sufficient supply of provenance,strong river energy and the ability to carry a large amount of debris.It played a controlling-role in the construction of the delta.Sand bodies are widely distributed from north to south,with subaqueous diversion channels in the north and sand bars in the south.