The dark shale rich in organic matter in the middle and lower parts of Member 3(Es

3

)and the upper part of Member 4(Es

4

)of the Shahejie Formation are the source rocks in the Boxing sag of the Dongying depression.The measured geologic reserves are mainly discovered in the sandstones of the Es

3

and Es

4

.Based on a reconstruction of thermal history of the sag

the researchers simulated the source rock thermal maturation history and hydrocarbon generation

migration and accumulation histories.The findings are listed as the following:①There are at least two periods of hydrocarbon generation and expulsion with the first period lasting from 30Ma to 25Ma and the second ranging from 16Ma to 0Ma.of the second period

the most important time is from 5Ma(the end of deposition of the Guantao Formation)to the present

during which large amount of oil were generated and distributed the way we see today

and the major source rocks are supposed to be still generating oil at pre-sent;②The amount of oil generated and accumulated in the Es

4

member is significantly bigger than those in the Es

3

member

indicating the hydrocarbon generation and expulsion process of the main source rocks controlled the vertical crude oil distribution to a certain extent.③Seven favorable oil plays are identified near the main source rocks according to the simulation.Although the gentle slope in the Boxing sag is located in the lower oil-potential area and is favorable for oil migration and accumulation

the maturity of source rocks at the slope area is low and the oil migration from the lower area is blocked by the Boxing fault zone

resulting in the relatively small amount of oil accumulated in the slope.