The clastic rocks buried deeply are complex and heterogeneous, especially for the low-porosity and lowpermeability rocks, and how to find and characterize the relatively high quality parts of the reservoir is worth exploring. In our case the drilling core is relatively limited, so the electrical image logging with a high resolution of longitudinal layering becomes valuable. In the study of the Paleogene Wenchang Formation reservoir in Structure HZ25-7, Zhujiangkou Basin, 14 types of lithofacies were divided by identification of lithology, grain size and bedding structure according to cores and resistivity images. And 6 lithofacies sequences were described in the two types of channel units, including branch channel of delta-plain and distributary channel of delta-front, which revealing the vertical heterogeneity of reservoir. According to the porosity and permeability of core samples, together with the conventional logging and electrical image logging calibrated by the core, the reservoir can be effctively evaluated on lithofacies units. In the same diagenetic background, particle size and bedding have obvious control effect on reservoir properties. From coarse to fine, the reservoir properties gradually deteriorated; from trough-like interlaced bedding to plate-like interlaced bedding, and then to massive bedding, the reservoir properties gradually get worse. The favorable lithologicfacies in Wenchang Formation developed in the upper part of the river unit with coarse particle and staggered bedding.%针对深层系储层勘探评价中遇到的岩性复杂、物性变化大的难题,以珠江口盆地HZ25-7构造古近系文昌组低孔低渗储层为例,利用电成像测井纵向分层的高分辨率优势,在宏观岩性识别和沉积层理构造解释的基础上,以微尺度的岩性相为单元,共划分出14种岩性相类型,分析了目的层段2种河道单元内部的岩性相组合序列,揭示了储层纵向上的非均质性特征.根据岩心物性分析并刻度常规测井和电成像测井,对各类岩性相单元开展物性评价.结果表明,在相同的成岩作用背景下,粒度和沉积层理构造对物性有明显控制作用:随着粒度由粗变细,层理构造由槽状交错层理、板状交错层理到块状层理,储层物性逐渐变差.在文昌组寻找优质储层,应以河道单元中上部岩性较粗且交错层理发育的高能沉积岩性相单元为主要目标.
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