Applications of well logs to the division of stratigraphic base-level cycles

The Bonan Oil Field located in the Jiyang depression, Shandong is the greatest oil field of low permeability in the depression. The oil-bearing rock series are mostly made up of the second and third members of the Paleogene Shahejie Formation in the Bonan oil field, of which 0-9 sandstone beds in the middle and upper parts of the third member have been well documented, and may be divided into hierarchical stratigraphic base-level cycles by using apparent resistivity curves. The interfaces between these base-level cycles are consistent with those divided by increasing limits of accommodation. The findings in this study may provide an important basis for the prediction of the distribution of reservoirs, especially the highly permeable reservoirs.