Quantitative Study On Interlayer Of Braided River Reservoir In High Water Cut Oilfield Of DQ

High water cut oil fields are currently in the stage of decreasing production by water injection.At present,most of the discussion on the distribution of remaining oil is concentrated on the combined sand bodies,and the research inside the sand bodies is not enough.Most of the studies on the interior of braided river sand bodies are semi-quantitative descriptions of hyperplasia and interlayers.Therefore,advancing the study of interlayer to quantitative descriptions is an important basis for refinement of remaining oil research.The braided river sand body of PI2 is divided into PI21,PI22 and PI23,which is composed of multi-stage central beach dam.The core and logging data show that the study area has developed muddy interlayers,physical interlayers and calcareous interlayers.The accuracy of interlayer type identification can be improved by SVM in combination with parameters such as GR,AC et,al.Based on the 4-level configuration interface,the precise study of the 3-level configuration interlayer is carried out.The study includes interlayer formation mechanism,shape,length,width,thickness,position and frequency.The interlayer was formed by the flood event,the vertical deposition of fine sediments on the central beach dam.The center of the interlayer is high and flat,sloping to all sides,and the inclination angle is generally less than 3°.The average length,width and thickness of the interlayer are 385 m,188m and 0.1-0.4m,and the length and width show a good linear relationship.The bigger the A/S ratio,the bigger the interlayer.The frequency of P12 interlayer is about 0.39,and the frequency of P122 is the most about 0.4.The quantitative study of interlayer characteristics is an important basis to advance the study of residual oil distribution.The remaining oil in the interlayer was further studied by quantitative description of the interlayer.The control effect of the type,frequency,thickness,upper and lower position,development position and shape of the interlayer on the remaining oil was analyzed.The control effect of argillaceous interlayer on remaining oil is greater than that of physical interlayer.When the interlayer frequency is less than 0.7,the remaining oil distribution is mainly controlled by the location of the interlayer.while the interlayer frequency is > 0.7,the saturation of the remaining oil increases with the interlayer frequency.Residual oil saturation is positively correlated with interlayer thickness.The remaining oil saturation of the lower part of the interlayer is greater than that of the upper part.A/S ratio is larger,and the remaining oil is more enriched.Large and continuous interlayers have a higher degree of control over the remaining oil.Based on SVM and F-score weight analysis,frequency interlayer rate is the most critical factor to control the remaining oil.Quantitative interlayer study explored the relationship between interlayer characteristics and remaining oil,and improved the configuration-based distribution model of remaining oil,which is crucial for the study of remaining oil.