Seven intermediate term stratigraphic base level circles and the corresponding seven stratigraphic sequences could be distingushed in Upper Jurassic in Ludong Sag

Kailu Basin.The intermediate term stratigraphic circles could be divided into two long-term circles correesponding to the basin's subsiding and fault-depressing stages.The high-resolution stratigraphic correlation framework of the sag could be established based on the principle of the stratigraphic circle correlation.It is suggested that the base level circles bear close relation to source-reservior-cap rock assemblage.The huge thick mudstone section deposited at the turning position from uprising to subsiding of the base-level is the main hydrocarbon source rock and favourable reginal cap rock.The sandbodies formed during the uprising and subsiding periods are the main reservoir bodies.What's more

the assemblages formed during uprising period are usually of the type with source rock in the up part and reservoirs below

or self-generation and self-reservoiring type;that formed during subsiding period usually belong to the type of source rock below reservoirs.It is proposed that the first kind of assemblages are more favourable.