Lithofacies and reservoirs in sequence stratigraphic framework of Lower Palaeozoic carbonate, offshore Bohai Bay Basin, eastern China.

A set of marine carbonates was deposited in the Palaeozoic of the North China Craton, which is the dominant sequence for buried hill hydrocarbon exploration. This study focuses on the lithofacies and reservoirs developed in the sequence. Based on the data of cores, thin sections, drilling, and logging, the characteristics of the sequence stratigraphic framework and its control on lithofacies and reservoirs of the Lower Palaeozoic buried hills in the offshore Bohai Bay Basin are discussed. The results show that there developed 4 second‐order sequences and 21 third‐order sequences in the study area. Due to the deep burial depth, the dolomite is more likely to form high‐quality reservoirs than limestone in the study area, and we define the dolomitic tidal flat‐dominant sequences as 'favorable reservoir sequences'. There developed unconformity‐related reservoirs and inner reservoirs in the buried hill, and the 'favourable reservoir sequences' present obvious control on both reservoirs, showing: (i) 'favourable reservoir sequences' and weathering interface control on the scale of the unconformity‐related reservoir jointly, and (ii) the inner reservoirs developed within 'favourable reservoir sequences' as well, and the top and bottom of the high‐frequency sequences are the predominant areas for the bedding karst reservoir distribution. [ABSTRACT FROM AUTHOR]