The diagenesis of Tertiary sandstone reservoirs in Huanghua Depression varied obviously with the increase of buried depth and it should belong to normal buried diagenesis. Thecharacteristics and evolution degrees of the reservoir porosity differ differently with theburied depth of the reservoirs

and based on this

the reservoir porosity could be classified into three zones: 1. shallow zone with the buried depth less than 2 200 m and primary porosityplaying the main part; 2. transitional zone with buried depth between 2 200-3 000 m and secondary porosity occupying 30%-50% ; 3. deep zone with buried depth greater than 3 000 mand secondary porosity occupying the main part. It is suggested that the boundary betweeneogenetic A and B stages should be in 2 200-2 500 m depth;the boundary between early andlate diagenetic stages should be at 3 000 m depth. The study results show that the diagenesisis controlled by buried depth

the pore evolution is controlled by diagenesis. Sedimentary environment has less influence on reservoirs beyond certain depth.