Architecture and Sequence Stratigraphy of Neogene Fluvial Systems in the Laizhouwan Depression, Bohai Bay Basin

Abstract

Summary The study area is located in the Laizhouwan Depression, south Bohai Bay Basin, China. The Depression has undergone extensive exploration, and most of the production is from fluvial sandstone reservoirs of the Guantao Formation, Neogene. Most of the fluvial deposits in the Guantao Formation of Bohai Bay Basin are consist of conglormerated sandstone with fining-upward sequence, which can be characterized with high-resolution sequence of base-level fall and rise model. These features show a sedimentary evolution from braided river to meandering river. Unlike most areas, the oil-bearing formation of the study area shows a complex litholigcial sequence with “fining-corsening-fining” feature. Previous sequence model fails to provide us predictions relating to variations in fluvial style, and there is currently no proper model to solve this problem. This article offers an effective sequence-stratigraphic model based on accommodation generation and sediment discharge to analyze the change in fluvial styles and interpret the depositional architecture of fluvial sedimentation. Variations in fluvial style and reservoir sand bodies dimensions have a considerable affect on oil migration and accumulation, and this research might be of assistance in planning further exploration in the Laizhouwan Depression and elsewhere.