Fluvial Reservoir Architecture Characterization Of The Ng?² Oil Layer In The 2^nd Fault Block Of Liu Guanzhuang Area In Dagang Oilfield

The 2^nd fault block in the study area is located in the ascending plate of the Yangerzhuang fault,which is a lithologic structural reservoir with very active edge and bottom water.Although the predecessors have recognized that the study area is fluvial deposits but less on reservoir architecture research and distribution characteristics of braided sandbodies,which is not conducive to the later development adjustment of the oilfield.Therefore,in order to further provide a more reasonable geological basis for the later well location deployment and development plan of the 2^ndfault block.Based on the core data,logging data,seismic data and development dynamic data of the study area,under the guidance of reservoir sedimentology theory,this paper conducts a comprehensive study on the sedimentary microfacies,sand body distribution,interlayer characteristics and sand body configuration characteristics in the study area,analyzes the influence of configuration on sand body connectivity,and establishes the river reservoir configuration model.The achievements and understandings of this paper are as follows:1.The Ng ?² Oil Layer in the 2^nd fault block is braided river sedimentary facies as a whole,developing braided channel and channel bar microfacies,and less developing flood plain deposition.The channel bar is characterized by medium-high amplitude box in logging curve,and the braided channel is mainly medium-low amplitude funnel.The stacking patterns of sand body of Ng ?² in the profile are top flat bottom concave multi-layer type and lateral shearing type.In the plane,the average thickness of sand body of Ng ?²-1 layer is thicker than that of Ng ?²-2 layer.2.The study area develops mud interlayer and physical interlayer.The mud interlayer is mainly composed of mudstone and silty mudstone.The logging response GR increased obviously,and the return range was more than 1/2;Microelectrode decrease obviously.The physical interlayer is mainly siltstone,and the logging curve is mainly manifested as:the natural gamma return amplitude is greater than 1/2;The natural potential value has an increasing trend,but the value is lower than that of mud interlayer;Microelectrode decreases;The acoustic time difference increases.3.The sedimentary architecture interface is divided into several levels:level 5 is the composite sand body;level 6 is the single-stage river sedimentary body,level 7 is the single braided stream belt/composite channel bar,level 8 is the single channel bar,level 9 is the vertical accretion body/gully/silting layer/retention sediment at the bottom of the channel/channel filling sand.4.Through the statistical analysis of the length-width ratio and area ratio of the channel bar,channel and gully in the modern Yarlung Zangbo River,the results show that the gully area developed in the Yarlung Zangbo River has a good positive correlation with the channel bar area.The gully area and the channel bar area are about 1:9,and the gully width and the channel bar width are about 1:8.2.The measurement results of braided river in Liuguanzhuang area show that the ratio of length to width of channel bar is about 2.8,and the ratio of average width of braided river channel to width of channel bar is 1:3.3,showing the characteristics of“wide beach and narrow channel”.The developed gully area and the channel bar area are about 1:5.According to the position and period of the deposition layer and gully development,the deposition layer can be divided into three combination modes,(1)silting layer is widely distributed;(2)The gully channel exists in isolation;(3)Gully channel cutting silt layer.