In the Shahejie Formation in the D oilfield area of the Laizhouwan Sag, Bohai Bay Basin, a mixed sedimentary structure of terrigenous clastic and carbonate rocks has developed. Scholars at home and abroad have performed much research on clastic and carbonate lithology identification. However, studies on lithology identification and reservoir characteristics of mixed siliciclastic-carbonate rocks in the study area have not been conducted thus far. Due to the complex logging response characteristics of mixed sedimentary rocks, it is difficult for conventional lithology identification methods to clearly reflect the lithological characteristics of mixed siliciclastic-carbonate rocks. In this study, the sensitivity of acoustic time difference, natural gamma ray, density, deep lateral resistivity and compensated neutron logging curves to each lithology was analysed using the conventional cross-plot method in the D oilfield. On this basis, a decision tree method is used to further screen and identify the lithology layer by layer, and the process and results of identifying a mixed lithology with logging curves are clearly reported. In addition, imaging logging and core data are used to verify the identified lithology, and a lithology identification template and technical method consisting of conventional logging cross plots, decision trees, imaging logging and core calibration are established to improve the accuracy of lithology identification of mixed rocks. Moreover, the influence of different lithologies on the reservoir characteristics in the study area is analysed.

中文翻译：

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渤海湾盆地莱州湾凹陷南部沙河街组下三段硅质碎屑-碳酸盐岩混合岩性识别及储层特征

渤海湾盆地莱州湾凹陷D油田区沙河街组发育陆源碎屑岩与碳酸盐岩混合沉积构造。国内外学者对碎屑岩和碳酸盐岩岩性识别进行了大量研究。但目前尚未开展研究区硅质碎屑-碳酸盐岩的岩性识别和储层特征研究。由于混合沉积岩测井响应特征复杂，常规岩性识别方法难以清晰反映硅质碎屑-碳酸盐岩混合岩的岩性特征。本研究中，声学时差、自然伽马射线、密度、在 D 油田，使用传统的交会图方法分析了每个岩性的深部侧向电阻率和补偿中子测井曲线。在此基础上，采用决策树方法进一步逐层筛选和识别岩性，清晰地报告了用测井曲线识别混合岩性的过程和结果。此外，利用成像测井和岩心数据对识别出的岩性进行验证，建立由常规测井交会图、决策树、成像测井和岩心标定组成的岩性识别模板和技术方法，提高混杂岩性识别的准确性。岩石。此外，分析了不同岩性对研究区储层特征的影响。