渤海海域沙一二段湖相混积岩储层测井分类与识别

Logging Classification and Recognition of Lacustrine Mixed Sedimentary Reservoirs in First and Second Members of Shahejie Formation in Bohai Sea

渤海海域沙一二段广泛发育混积岩储层,岩石种类复杂多样,识别困难.在大量岩心、壁心、薄片和全岩分析标定基础上,结合生产实践,提出成分-结构二级分类的混积岩测井分类方法并系统总结2个大类6个亚类10余种混积岩储层测井响应特征,采用箱型图法优选混积岩成分和结构敏感曲线并确定其区分界限.研究结果表明成分-结构二级分类方法不但利于岩性测井识别而且对储层品质也具有较好的区分效果;中子和光电吸收截面指数对岩石成分识别敏感性较高,而自然伽马、电阻率以及中子对岩石结构识别敏感性较高;建立的成分-结构二级解释流程可实现湖相混积岩储层岩石成分和结构的识别,具有简单、高效、准确的特点.该方法在实践中取的良好的应用效果,为复杂岩性识别及储层评价分类提供了思路,在渤海海域沙一二段及其他地区相似地质背景下湖相混积岩储层岩性识别中具有较好的应用前景.

Mixed sedimentary reservoirs are widely developed in the first and second members of the Shahejie Formation in Bohai Sea,which is difficult to be identified the complex and diverse rock types.Based on the analysis of a large number of cores,sidewall cores,thin sections and whole rocks analysis,in this paper it systematically summarizes the logging characteristics of more than 10 kinds of mixed sedimentary reservoirs in six subclasses of two major types,and discusses the sensitivity of various conventional logging curves to the"composition"and"structure"of mixed sedimentary reservoir.The results show that the composition-structure two-level classification method not only has a good distinguishing effect on lithology identification but also on the quality of mixed sedimentary reservoir.Neutron and photoelectric absorption cross-section indexes are more sensitive to rock composition identification,while natural gamma,resistivity and neutron are more sensitive to rock structure identification.The logging identification method of mixed sedimentary reservoir based on composition-structure classification is simple,efficient and accurate,and has good application effect in practice.It provides insights into complex lithology identification and reservoir evaluation and classification,and has good application prospects in the lithologic identification of lacustrine migmatite reservoir in the first and second members of Shahejie Formation in Bohai Sea area and other areas under the similar geological background.