Abstract: The Bohai Bay Basin is bordered by the Jiaoliao uplift in the east, the Taihangshan uplift in the west, and limited by the Luxi uplift and the Yanshan fold belt in the north and south respectively. Overall, the basin is in the shape of an irregular rhombus, with an area of about 20×104 km2. The valley basin is a large-scale (residual) basin superimposed by a Cenozoic fracture on a pre-Cenozoic craton basin, where a large number of buried hills are developed. However, basic geological research on the buried hills in Bohai Sea has been understudied, which results in scarce publicly-accessible petrological data, and consequently, repeated petrological work. In view of this, our study collected 204 Archean buried-hill metamorphic granite sections and their overlying glutenite rock sections of Paleogene Kongdian Formation in Bozhong Sag, Bohai Bay Basin. They were then divided into two parts, 61 granite sections and 143 clastic sections. It is revealed that the deep buried hill reservoir in the Bozhong 19-6 (i.e., BZ19-6) structural belt is a pan-buried hill reservoir system composed of the main body of Archean buried hill metamorphic granite and an overlying Paleogene Kongdian Formation glutenite, which formed a multi-layered reservoir structure consisting of glutenite pore zone, buried hill weathering crust dissolution fracture zone, and inner fracture zone tight zone, with complex reservoir genes and diverse reservoir types. The dataset records the sampling location, stratigraphic age, and name of the rock thin sections. The granite part shows that the buried hill mineral assemblage is dominated by dark minerals such as quartz, feldspar, and a small amount of biotite, and it also records the fracture period, filling type, and hole ratio. The clastic rock part records the composition of Kongdian Formation glutenite and the content of its miscellaneous base. A systematic study of the microscopic rock thin sections reveals a differential development of fractures caused by lithologic changes in the BZ19-6 reservoir system in the buried hills, and the impact of lithologic fluid on reservoir corrosion transformation, which provides basic petrographic data for further exploration of oil and gas in the buried hills of Bohai Sea.
Keywords: Bohai Bay Basin; buried hill; granite; glutenite