The characteristics of carrier system and its relationship with the distribution of middle-shallow hydrocarbon pools in the He-31 block of the Xianhe oilfield in the Dongying Sag show that faults and sandbodies dominate the hydrocarbon carrier system in the block.The distribution of sandbodies and faults is not the only factor that control hydrocarbon enrichment in the study area.The spatial and temporal configurations of faults and sandbodies also control the effectiveness of carrier system

thus determine the formation and occurrence of the oil reservoirs in the middle-shallow layers(especially the Es

1

).The second-order faults and later induced faults are important to hydrocarbon migration.At the same time

the sandbodies well connected with these faults are the main destination of hydrocarbon migration.