Application of Principal Component Analysis to Diagenetic Facies Division of Lake Gravity Flow Sandstone Reservoirs in Dongying Depression of Bohai Bay Basin, China

The gravity flow sedimentation of lakes is characterized by diversity and can vary greatly on a small spatial scale, leading to extremely complex diagenesis. This complexity makes it difficult to accurately classify them using conventional diagenetic methods. This paper focuses on the study of gravity flow sedimentary units in the Dongying, the diagenetic facies were classified into five different types by using a novel principal component analysis method. Based on this, the diagenetic evolution of rocks was characterized, and the reservoir quality influence factors were clarified. First, detailed characterizations were conducted on the compositional characteristics of the two main reservoir types (feldspathic sandstone and lithic feldspathic sandstone), along with their diagenetic processes, including compaction, cementation, dissolution, and metasomatism. Then, the diagenetic control factors of gravity flow sandstone were clarified. It was found that the compaction and cementation had the greatest impact on rock porosity, had the presence of a large amount of clay cement leading to pore deterioration. Finally, a principal component analysis model was used to identify five types of diagenetic facies in the study area and characterize their distribution patterns, providing evidence for a deeper understanding of the sedimentary evolutionary sequence.