Abstract:

In order to understand the influence of pore evolution and diagenesis on sandstone and conglomerate reservoir petrophysical property of the third and fourth members of shahejie formation in yongbei area，reservoir rock property and diagenesis are studied by using the methods of core and rock tine section observation，electron microscope scanning and Xdiffraction analysis.It is revealed that cementation destroys the reservoir property and dissolution improves it.Compaction result in primary pore decreasing，on the other hand，high pressure result in mineral grain breaking，so physical properties of reservoirs are improved.The loss ratio of porosity from the cementation and filling is about 43.95%，and that from compaction is about 25.29%.The secondary pores account for a great proportion in the Es3-Es4 reservoirs.The mechanism of genesis includes thermal evolution of organic matter，experiment indicates that the thermal degradation makes kerogen produce a large amount of organic acid before it goes into the oil generation windows，eluviations at unconformities or fracture zones produce weathering crust secondary pores，the fluid thermal cycle convection leads to the formation of secondary pores.

Key words: reservoir, diagenesis, thermal evolution of organic matter, aching action, abnormal pressure, Dongying Sag