Research For Sedimentary Microfacies Of The Ⅱ、Ⅲ Sand Group Of The Third Member Of Hetaoyuan Formation In Du Po Oilfield

The Biyang sag is a sag shape one which the southern is deeper than the northern stacking in the Qinling Mountains orogenic belt.Small normal fault and nose structure mainly developed in the central deep concave area of the sag.It is the center of the main oil and gas reservoirs.The sag has high levels of reservoir exploration, and most of the oil field enter the secondary exploration phase,in order to keep the production stable, it is imminent to explore the subtle reservoir. The main research is the characteristics of the sedimentary microfacies of the paleogene Hetaoyuan three sections of the sub-section Ⅱ, Ⅲ sand set in the study area and its distribution and evolution,to clarify the relationship between sedimentary microfacies and oil-bearing propertyUsing mark layer method,according to the principle of sedimentary cycle establishes isochronous time stratigraphic framework of the Ⅱ-Ⅲ sand group of the third member of Hetaoyuan in the study area.It is divided into 3 layer and 21 layer, 45 layer,to make it more precise and reasonable.According to the well seismic research,the layer of Ⅱ-Ⅲ sand group develops well and preserves completely.Overall terrain is northwest higher than southeast. NE small normal faults that fault strike is mainly NEE and NE and nearly ES nose structure are developed.Based on studying the core multi-port coring wells,we found that the lithology of sand layer in this area is mainly quartz sandstone and feldspar quartz sandstone,and the rhythm type inside the compound type of rhythm is the most common one. The source mainly comes from the north delta of the ancient city.The thickness of sand body is smaller which 2m to 6m are more common, and the scale of development influenced by sedimentary microfacies. On the basis of core analysis, combining with the tectonic background and sedimentary evolution in the study area,using the logging facies and seismic facies research,gets the following results:there are developed two kinds of subfacies,delta front facies,prodelta mud and six kinds of microfacies,underwater distributary channel, sheet sand,underwater distributary interchannel,debouch bar,distal bar and prodelta mud in the Ⅱ-Ⅲ sand group of the third member of Hetaoyuan of the study area. The plane distribution features known from research area of sand sheet mostly patchy distribution,showing that has good interconnection in the plane.Reservoir heterogeneity research shows that reservoir heterogeneity is controlled by sedimentary microfacies,the Ⅱ-Ⅲ sand groups of the third member of Hetaoyuan heterogeneity are stronger in general.The underwater distributary channel microfacies of holes, seepage It was significantly higher than other microfacies.Through the reservoir heterogeneity and sand body plane distribution characteristics comprehensive research, the paper explore the relationship between oil-bearing and sedimentary microfacies,that study area of the Ⅱ-Ⅲ sand groups of the third member of Hetaoyuan heterogeneity underwater distributary channel and sheet sand slightly oily phase was significantly higher than other sedimentary microfacies.