| The clastic rocks buried deeply are complex and heterogeneous, especially for the low-porosity and low-permeability 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. |
