Buried hills of Archaeozoic

Paleozoic and Mesozoic Eras developed well in the west part of Dongying Depression. Affected by Tanlu fault activities

the buried-hills took the form of zonal distribulion

thus forming NW- and NE- strike buried-hill structural zones. The Cenozoic Shahejie and Kongdian Formations

the Mesozioc and the Permo-Carboniferous Systems are the main source rocks of the buried-hill oil pools. The reservoir rocks are Archaeozoic metamorphic rocks and Lower Paleozoic carbonate rocks. The cap rocks are the strata of Permo-Carboniferous

Tertiary and Lower Jurassic. The pools could be divided into hill-top type and inside hill type.Hydrocarbon pools are basically distributed close to fractural belts near source rocks

and non hydrocarbon gases usually migrated along deep rift

the pathways in volcano to form non hydrocarbon gas pools in proper buried-hill traps.