The ramp zone of the petroliferous basin is a favorable area for hydrocarbon accumulation.To identify the distribution of oil and gas in the ramp zones of various kinds is of great significance for oil and gas exploration.Taking the Bohai Bay Basin as an example

we divided its ramps into three types

namely the simple type

transitional type and complex type

based on the basement geometry of the ramps under the impact of tectonic zonation.The simple type of ramp zone is characterized by weak tectonic activity and one-way dipping basement geometry with a small dip; structural-litho-logic and lithologic reservoirs are dominant in this type

and its hydrocarbon enrichment concentrates in one single layer and most hydrocarbons accumulate in early periods with a typical "line-styled" hydrocarbon distribution.The transitional type features stronger tectonic movement and the two-way dipping basement geometry

and the structural and structural-lithologic reservoirs are dominant in this type

with a small number of stratigraphic reservoirs.Hydrocarbons enrich in multiple layers through migration along faults and sand body

resulting in a ladder-shaped reservoir distribution.While the complex ramp zone features strong tectonic activity and three-way dipping basement geometry.The structural and structu-ral-lithologic reservoirs are dominant

with a large number of stratigraphic reservoirs.The hydrocarbons enrich in multiple layers

leading to a "comb-shaped" reservoir distribution.