Abstract: The diagenesis, reservoir characteristics and príncipal factors effecting the reservoir properties have been studied for Shasj member of Tertiary in Yonganzhen Oilfield, based on the data of seismic, well logging and deposition, etc., from which the classification and prediction of prospective areas for exploration has been made. It is concluded that Class Ⅰ reservoir was mainly distributed at the mid—fan channels; Class Ⅱ at the front and within channels as well as the fan margin ,Class Ⅲ at the fan bottom. The contemporaneous fault was one of the most important factors effecting the reservoir properties.

Key words: Yonganzhen oilfield, Shasi member, Reservoir property, Diagertesis, Secondary porosity, Heterogeneity