Study On The Reservoir Geological Characteristics Of The Es3~z Formation Of Fu 111 Block In The Western Fulin Sag

The Fu 111 fault block is located in the Fulin sub-sag in the southeast of the Zhanhua Sag,Jiyang Depression.The oil reservoir in the middle Es3 of this fault block has entered a high water-cut development stage,with disordered inter-layer connections and unclear microstructure characteristics,A series of problems such as uncertain description of the spatial distribution of sedimentary microfacies and lack of pertinence in the description of reservoir parameters have hindered the adjustment of the remaining oil development plan in this fault block.In response to these problems,a comprehensive study of reservoir geology was carried out on the middle Es3 of the Fu 111 fault block by integrating core,logging,seismic and production data,and the following main results and understandings were obtained:（1）The stratigraphic framework of the middle subsection of Sha 3 in the Fu 111 fault block was Established.The middle Es3 sub-member was divided into 1 sand group(ES₃^Z1)and 2 sand group(ES₃^Z2).ES₃^Z1 is a positive rhythm sedimentary cycle as a whole,and the underlying ES₃^Z2 was dominated by reverse cycle sedimentation controlled by the front edge of braided channels.Among them,the ES₃^Z1 sand group can be divided into 4 small layers,and the ES₃^Z2 sand group can be divided into 6 small layers.（2）The microstructural features and sedimentary characteristics of the middle Es3submember were clarified.It is found that flexure,broken nose and terrace microstructures are relatively common in fault blocks,but on a small scale.It is determined that the ES₃^Z1 and ES₃^Z2 sand groups belong to the nearshore submarine fan deposits.The sand group 1 is mainly braided channel in the fan and the sand body is thick;the sand group 2 develops the microfacies of the fan-edge braided channel and the slump of the outer fan.The type of sedimentary microfacies is more complicated than that of the 1 sand group.The 3-4 small layers of sand bodies in the 1 sand group are distributed in series with braided channels in the fan.The 3-5 small sand bodies of the 2 sand group are larger in scale,and the other small sand bodies are smaller in scale.（3）The macro and micro reservoir characteristics of ES₃^Z1 and ES₃^Z2 sand groups were clarified.It is believed that the reservoirs of the two sand groups have mesoporous-medium permeability characteristics,but the physical properties of the 1 sand group are better than those of the 2 sand group.The braided channel in the fan of 2-4 small layers in the 1 sand group has the highest physical properties and is a section with high-quality reservoirs in the region.Only 4 small layers in the 2 sand group have good physical properties.The pore throat structure of the reservoir is dominated by large pore-medium throat type.The braided channel sand pore throat at the front edge of the fan is the largest,and the pore throat structure is the best,followed by the sand pore throat of the fan channel,and the outer fan sliding turbidity The sand body has the worst pore throat structure.（4）The reservoir types and fluid properties in the fault block were clarified.The oil reservoirs in the middle sub-member of Shahejie Formation are dominated by broken nose structure reservoirs and lithological updip pin-out reservoirs;crude oil has the characteristics of medium density,high viscosity,low sulfur,and high wax content,and the formation water is mainly Ca Cl₂ type,And there is an obvious positive correlation between crude oil density and viscosity.（5）The distribution characteristics of remaining oil in the middle of the third member of Shahejie Formation were revealed,and the favorable area distribution was determined by comprehensive evaluation of reservoir geology using fuzzy mathematics method.Among them,the remaining oil saturation of the 3rd and 4th layers of the 1 sand group is relatively high,and the remaining oil saturation of the 2nd sand group is lower overall,and only the remaining oil distribution of the 4 little layers reaches the level of the 3 and 4 little layers of the 1 sand group.Using fuzzy mathematics method,it can be judged that the two favorable areas of sand group 1 have higher evaluation value,and the evaluation value of sand group 2is low although there are three favorable areas.The braided channel in the fan and the edge of the front edge of the fan in the channel,local high points and the periphery of the fault are the current favorable areas for tapping the remaining oil.