对ΔlogR技术提出了改进, 以实测TOC与计算TOC之差的平方和为目标函数, 由岩心样品在一定范围内自由浮动进行拟合,结合实例建立ΔlogR技术的改进模型, 确定了模型的岩心样品最大浮动距离为0. 375m (岩屑样品最大浮动距离为0. 75m) 时最为合理,既保证了归位的彻底, 又不会造成数据过度归位使得数据失真. 改进ΔlogR技术在大民屯凹陷沙四下亚段油页岩有机质丰度非均质性评价中应用效果良好, 计算TOC与实测TOC值高度相关. 评价结果显示, 沙四下亚段下部油页岩有机质丰度表现为较强的非均质性;沙四下亚段中部沉积时期, 台地中央油页岩有机质丰度较低, 而台地边部油页岩发育较好. 沙四下亚段上部沉积时期水体加深, 油页岩有机质丰度最高, 其TOC平均值高达4. 3%.%Improved ΔlogR technology is presented and a predictive model is established. Taking the square of the differ-ence between measured TOC and calculated TOC as objective function, core samples in a certain range of freefloating are used to fit. Taking Well Shen352 as an example, an improved model of to ΔlogR is established. It is identified that the model is most reasonable when its maximum floating distance of core sampes is 0. 375m ( the maximum floating distance of debris samples is 0. 75m) , which ensures thorough homing and will not cause excessive homing data resulting in data dis-tortion. Through the application of improved ΔlogR method to organicheterogeneity evaluation of oil shale in submember of the fourth member of Shahejie Formation of Damintun sag, it is found that the improvedΔlogR method has good effect, and the calculated TOC and measured TOC are higherly correlated, of which the correlation coefficient R2 of the submember of the fourth member of Shahejie Formation inWell Shen166 is 0. 759, while that of Well An1 is up to 0. 8191. The predicted results show that the organic matter abundance at lower part of ( PS1) of the submember of the fourth member of Shahejie Formation has strong heterogeneity;the middle part ( PS2) has lower organic matter abundance in sedimentary period, be-cause the central platform is dry and hot, water evaporates and gets shallower, oxidation is enhanced, water gets more qui-et, and impact of terrestrial organic matter supply is limited. Platform edge water is deeper as compared to central plat-form, and terrestrial organic matter supply is adequate, so hydrocarbon source rocks develop well. Organic matter is the most abundant in at the top of ( PS3) of the submember of the fourth member of Shahejie Formation in sedimentary period, because it gets warm and humid in general, and the average TOC is up to 4. 3%.
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