Crude oils of Shengtuo oilfield in Dongying depression can be divided into 4 groups.Group 1 is mature oil sourced from the lower 3

rd

member of Eogene Shahezhen Fm

which is distributed mainly in Ninghai and western Tuo-1 block.Group 2 is mature oil sourced from the upper 4

th

member of Shahezhen Fm

which is distributed mainly in Tuo-2 block

Tuo-3 block and the eastern part of Tuo-1 block.It is the major crude oil group in Shengtuo area.Group 3 is mixed oils sourced from the lower 3

rd

member and the upper 4

th

member of Shahezhen Fm

with a restricted distribution.Group 4 is low-mature oil generated from source rocks with high gammacerane in the lower 3

rd

member of Shahezhen Fm in Minfeng sag during low maturity period

which are distributed only on the northern side of Shengbei fault.Hydrocarbons that have been generated from the source rocks in the lower 3rd member of Shahezhen Fm in Lijin sag may migrate upward along Tuo 94 fault and are accumulated in the western part of Tuo-1 block and Ninghai area from both the eastern and western charging points.Hydrocarbons that have been generated from the source rocks in the upper 4

th

member of Shahezhen Fm in Lijin sag may migrate upward along Tuo 94 fault and are accumulated in the eastern part of Tuo-1 block.The 8

th

sandstone units in Tuo 2 and 3 blocks have experienced two oil and gas charging stages from the source rocks in the upper 4

th

member of Shahezhen Fm.The early reservoiring occurs at the end of deposition of Dongying Fm

and the oil and gas have accumulated mainly in the sandstone reservoirs below the 8

th

sandstone unit(including the 8

th

sandstone unit itself) in the upper 3

rd

member of Shahezhen Fm.The late reservoiring occurs during the deposition of Minghuazhen Fm

and the oil and gas have accumulated mainly in the sandstone reservoirs above the 8

th

sandstone unit(including the 8

th

sandstone unit itself) in the 2

nd

member of Shahezhen Fm and Dongying Fm.The early migration has been charged from Shenbei fault

while the late migration has been charged from the northern part of the S-N trending fault.