1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. Exploration and Development Research Institute, Jilin Oil Field Company, PetroChina, Songyuan 138000, Jilin, China

According to the oil reservoir characteristics of Wuxing structural belt in Luxiang Fault Depression, Yitong Basin, this study proposed a model of identifying logging lithology and a method of defining reservoir effective thickness. Six types of rocks, including mudstone, siltstone, fine-grained sandstone, medium-grained sandstone, coarse-grained sandstone and sandy conglomerate, are recognized by comprehensive analysis of gamma ray (Jilin gamma), resistivity, interval transit time and spontaneous potential curve, and cross ploting of well logs for lithology determination. The backward-inference method is proposed under the circumstance of similar log curve characteristics. Integrating regional sedimentary facies distribution and log correlation with adjacent wells this method can distinguish fine-grained sandstone from pebbled sandstone. Moreover, the authors studied the reservoir effective thickness based on well log interpretation, built the models of porosities, permeabilities and oil saturation, summarized the lower limits of lithology, physical property and electrical property to calibrate the oil and water layers encountered in 39 wells in the study area and mapped the effective thickness and litho-facies of single sand layer.