Characteristics and types of fine-grained sedimentary rocks lithofacies in semi-deep and deep lacustrine, Dongying Sag

Key words:  Dongying Sag  semi-deep and deep lacustrine  fine-grained sedimentary rock  lithofacies  log response

Abstract:

Combining detailed description of core, thin sections identification, analysis of whole rock X-ray diffraction and scanning electron microscopy technologies, this study sets up a lithofacies classification scheme that is suitable for the fine-grained sedimentary rock in the 3rd and 4th members of Shahejie Formation in the west part of Dongying area. The analyses are based on the direct reflection of lithofacies differences and integrating various factors such as mineral composition, sedimentary structure, organic matter abundance, color and other foreign matters. The results show that there are nine types of lithofacies, and six major types, which can be further divided into 11 sub-types according to their organic content. This study mainly focuses on the five types of facies which are relatively developed, such as organic-rich laminated limestone, organic-rich calcareous interbedded limestone, organic-contained fine-grained mixed sedimentary rocks, organic-lean massive clay stone and organic-rich laminated clay stone. The differences in macroscopic characteristics, microscopic characteristics, log responses and sedimentary microfacies are analyzed. The lateral distribution of lithofacies is shown to reflect the differences in semi-deep and deep lacustrine.