砂砾岩体沉积期次划分及其与物性的关系——以东营凹陷北部陡坡带Y920区块沙四上亚段为例

砂砾岩体储层岩性复杂、非均质性强，且扇体多期叠置，沉积期次划分困难。以东营凹陷北部陡坡带Y920区块沙四上亚段砂砾岩体为研究对象，建立以岩心、FMI图像为基础，以测井信息小波变换技术为核心，以三维地震为约束的砂砾岩扇体沉积期次划分方法。基于岩心、FMI图像可直观识别沉积期次界面，进而标定常规测井资料；经测井信息小波变换后表现出周期性振荡特征的小波系数曲线可反映沉积界面响应特征，结合功率谱筛选尺度因子，可定量对单井沉积期次进行划分；通过井-震结合，实现全区域期次界面的等时对比，将Y920区块砂砾岩体划分为8个沉积期次。沉积期次的发育控制着沉积相及岩性的分布，与物性展布也密切相关。研究结果表明，研究区块地层自下而上（8至1沉积期次）表现出退积沉积初始阶段（扇根—扇中）沉积期次中上部物性较好，沉积中间阶段（扇中）整个沉积期次物性均较好，而沉积末期阶段（扇中—扇端）沉积期次中下部物性较好，进而统计单井各期次有效储层的厚度，分期次刻画有效储层平面展布特征，发现3，4，5沉积期次的西北部为Y920区块有利储层展布范围。研究结果为东营凹陷北部陡坡带砂砾岩体油藏的精细勘探开发提供了依据。

Division of sedimentary cycle of sandy conglomerate body and its relationship with physical properties: a case study from the upper submenber of the fourth member of Shahejie Formation in Y920 block of northern steep slope zone in Dongying Sag

The sandy conglomerate reservoirs have complex lithology and strong heterogeneity,and the fan bodies are stacked in multiple stages,making it difficult to divide the sedimentary cycle. Based on core and FMI images, with the well logging information wavelet transform technology as the core,and with 3D seismic as the constraint,the method of sedimentary cycle division of sandy conglomerate fan body was established by taking the upper submenber of the fourth member of Shahejie Formation in Y920 block of the northern steep slope zone in Dongying Sag as the research object. Based on core and FMI images,the interface of sedimentary cycle can be identified intuitively,and then conventional logging data can be calibrated. The wavelet coefficient curve showing oscillation characteristics after the wavelet transform of logging information can reflect the response characteristics of the sedimentary interface,and the sedimentary period of a single well can be divided quantitatively by combining the scale factor of power spectrum screening. Through the well-seismic combination,the isochronic comparison of the cycle interfaces in the entire region was achieved,and the sandy conglomerate body in Y920 block was divided into 8 sedimentary cycles. The development of the sedimentary cycle controls the distribution of sedimentary facies and lithology,which is also closely related to the distribution of physical properties. The results show that the strata in the study area show good physical properties in the middle and upper part of sedimentary cycle in the initial stage of retrograde deposition(root-middle fan)from the bottom to the top(8 to 1 sedimentary cycle),and the strata show good physical properties in the entire sedimentary cycle of the intermediate deposition stage(middle fan)and the middle and lower parts of sedimentary cycle in the final deposition stage(middle-bottom fan). Furthermore,the thickness of the effective reservoirs in each cycle of a single well was counted,and the planar distribution characteristics of the effective reservoirs were described in cycles. It is found that the northwest of 3,4 and 5 sedimentary cycles is the favorable reservoir distribution range of Y920 block. The research results provide a basis for fine exploration and development of sandy conglomerate reservoirs in the northern steep slope zone of Dongying Sag.