测井资料用于盆地中火成岩岩性识别及岩相划分:以准噶尔盆地为例

Igneous lithology identification and lithofacies classification in the basin using logging data:Taking Junggar Basin as an example

以准噶尔盆地为例,建立火成岩的测井岩性识别和测井相划分的方法,运用火成岩岩石学理论和岩石物理学的技术方法,确立了火成岩岩性、岩相的测井分类标准。揭示了自然伽马测井、密度测井、ECS测井对火成岩化学成分的变化最为敏感,从基性到酸性火成岩的自然放射性强度逐渐增强,密度降低,金属元素含量减少,二氧化硅含量增加;火成岩的自然放射性、密度、电阻率对火成岩的结构变化有一定的反映,火山碎屑岩与同质的熔岩相比,自然放射性、密度、电阻率测井值降低;补偿中子测井值对火成岩的蚀变程度反映最为敏感,密度、电阻率对火成岩的蚀变程度有一定的反映,且随着蚀变程度的增强,密度、电阻率测井值有降低的趋势。并用岩性敏感测井曲线制作了多维火成岩岩性识别图版、用成像测井制作了火成岩的结构与构造识别图版,用ECS测井区分岩石成分,用岩心资料进行验证,提出了常规测井+成像测井+ECS测井+岩心标定的火成岩岩性识别模式和技术方法,综合判定火成岩岩石的类型、成分、结构和构造,提高了复杂火成岩岩性识别的准确率。

Taking the Junggar Basin as an example, this paper proposed a method for logging lithology identification and logging facies classification of igneous rock. Using the theory of igneous rocks and the technique of rock physics, we have set up the logging classification standard for igneous rock lithology and lithofaeies, and revealed that the natural gamma ray logging, density logging, and ECS logging are the most sensitive logging methods to the variety of chemical components of igneous rock. We have observed that, from basic to acid igneous rock, the intensity of natural radioactivity is gradually growing, the density is reducing, the content of metal elements is reducing, and the silica content is growing. The structural change is partly reflected by natural radioactivity, density, resistivity of igneous rock. Compared with the homogeneous lava and pyroclastic rock, the intensity of radioactivity, the value of density, and the resistivity are degraded in magnitude. The most sensitive logging for igneous rock alteration degree is the compensated neutron logging, while the density and the resistivity also partly reflected the alteration degree. With the increase of the alteration degree, both the density value and the resistivity appear a tendency of declining. We have utilized the logging curves which are sensitive to lithology to make multidimensional igneous lithology identification chart. By using imaging logging, the texture and structure of igneous rock identification chart was made; the ECS logging was applied to distinguish the rock composition; and the methods were validated through the core data. A technique for igneous rock lithology recognition mode was proposed based on the conventional logging, imaging logging, ECS logging, and core calibration. Thus a way for comprehensive assessment of the type, composition, texture and structure of igneous rock has been built up; this method greatly enhances the identification accuracy for complicated igneous lithology.