东海西湖凹陷少井区中深层薄砂体识别及潜力分析

Identification and potential analysis of thin sand bodies in middle and deep layers of few well blocks in Xihu Sag,East China Sea

东海西湖凹陷钻井少、储层埋深大、井资料匮乏,制约着薄砂体的识别刻画。本文基于地震资料,通过应用地震沉积学和储层构型技术,采用90°相位转换、等时地层切片方法和“层次分析、模式拟合”的构型思路,有效识别出海上埋深3500 m左右薄砂体平面展布形态和纵向叠置关系,建立了沉积演化模式。结果表明,薄砂体所处河道类型在不同沉积时期分别呈高弯度型、低弯度型和顺直型,发育时期地形较平坦,水流方向整体自北向南。高弯度曲流河河道宽0.20~0.26 km,发育多个边滩,边滩长1.30~3.58 km,宽0.78~2.00 km;低弯度河道宽0.40~1.00 km,砂岩厚度7~11 m,宽厚比60∶1~100∶1;顺直型河道宽0.21~0.65 km,砂岩厚度7~10 m,宽厚比30∶1~65∶1,被泥质夹层分隔的砂体和边滩砂体均为有利的调整目标。

The identification and characterization of thin sand bodies in Xihu sag of the East China Sea are restricted by less drilling,large reservoir depth and lack of well data.Based on seismic data,by applying seismic sedimentology and reservoir configuration technology,with the use of 90°phase conversion,isochronous stratigraphic slicing method and"analytic hierarchy process,model fitting"configuration idea,the plane distribution shape and vertical superimposition relationship of thin sand bodies with buried depth of about 3500 m are effectively identified,and the sedimentary evolution model is established.The results show the channel types of thin sand bodies are high curvature type,low curvature type and straight type in different sedimentary periods,and the topography is relatively flat in the development period,and the water flow direction is from north to south as a whole.The channel width of high curvature meandering river is 0.20~0.26 km,which is developed with multiple banks,with the length of 1.30~3.58 km and width of 0.78~2.00 km,while the width of low curvature channel is 0.40~1.00 km,and the thickness of sandstone is 7~11 m.The width thickness ratio is 60∶1~100∶1;straight river channel width is 0.21~0.65 km,the sandstone thickness is 7~10 m,and the width thickness ratio is 30∶1~65∶1.The sand body separated by argillaceous interlayer and the beach sand bodies are favorable adjustment targets.