Research Article

Numerical Simulation Study of Pore-Throat Evolution of Upper Paleozoic in Ordos Basin, China

Table 4

Porosity evolution of different diagenetic stage (average/data range).

Diagenetic stageType of diagenesisHe 8 Member in Sulige areaShan 2 Member in Yulin area
Quartz sandstone and lithic quartz sandstoneQuartz sandstone

Original porosity (%)33/24-3634/28-38
Early diagenesisCompactionDecrease 62%Decrease 55%
CementationDecrease 1%Decrease 1%
Porosity at the end of Triassic (%)12.2/8.9-12.614.9/12.3-16.7
A stage of late diagenesisSiliceous cement (Ι)Decrease 5%Decrease 10%
DissolutionIncrease15%Increase 6%
Siliceous cement (ΙΙ)0%Decrease 4%
Clay cementDecrease 18%Decrease 12%
Porosity in early cretaceous (%)9.2/6.7-10.88.2/6.7-9.1
B stage of late diagenesisCarbonate cementDecrease 5%Decrease 3%
Carbonate dissolutionIncrease 1%Increase 1%
Porosity in present (%)8.3/5.9-9.17.5/6.2-8.4