The Mesozoic reservoirs of the Zhenjing area on the southwestern edge of the Ordos Basin feature in large tightness

low permeability

low abundance and large reserves. They possess huge exploration potentials which have been evidenced by several highyield wells penetrating these reservoirs. The Zhenjing area now has become one of the main areas for reserve replacement of SINOPEC. Through the analysis of source rocks

physical properties of reservoirs

trap features

diagenesis and characteristics of mudstone compaction

it is believed that tectonism resulted in the changes of diagenetic paths and overpressure distribution

and hereby the variaty of reservoir types. As a result

the Mesozoic hydrocarbon accumulation mechanism varies distinctively in different layers. In this paper

dynamic mechanisms of hydrocarbon accumulation in the Yan'an and Yanchang formations are classified into three types

namely the indigeneous highpressure enclosed type

the indegeneous lowpressure semienclosed type

and the distal normalpressure open type. For the indigeneous highpressure enclosed type

exploration should be focused on searching for highlyefficient reservoirs

while for the indegeneous lowpressure semienclosed type

clastic paleoweathering crust should be the focus of exploration. As for the distal normalpressure open type

the major exploration targets are differential compaction anticlines associated with paleogeomorphology. 