Structural Interpretation of the Qingdong Area in Bohai Bay Basin from Shipborne Gravity Data

The Qingdong area, located in Bohai bay basin, was suspected good exploration prospects. In order to study tectonic features and find out favourable petroleum prospects in the area, the gravity data at a scale of 1:50,000 were interpreted. This paper, through data processing and synthetic interpretation of the high-precision gravity data in the area, discusses characteristics of the gravity field and their geological implications, determines the fault system, analyses features of the main strata, divides structure units and predicts favourable petroleum zones. The results showed that the faults controlled the development of the Mesozoic and Cenozoic strata and the distribution of local structures in this area. The study revealed that the Qingtuozi uplift and the Kendong uplift in the north were formed in Mesozoic, and the Qingdong depression in the middle was the rift basin in Mesozoic and Cenozoic. Thicker strata in Mesozoic and Cenozoic developed in the Dongying depression and the Qingdong depression, so there is abundant hydrocarbon in these two depressions, and then the Guangligang rise-in-sag and the Qingdong rise-in-sag developed in the center in these two depressions are also favorable places for prospecting