Diagenetic Facies and Their Controls on the Quality of Tight Sandstone Reservoirs: A Case Study from the Upper Paleozoic Gas Reservoir in the Eastern Ordos Basin, North China

Table 2

Comparison of porosity evolution of sandstones of diagenetic facies.

Diagenetic facies	Original porosity (%)	Compacted porosity (%)		Cemented porosity (%)		Dissolution increases porosity (%)	Present porosity (%)	Permeability (×10^-3 μm^2)
		Loss	Remaining	Loss	Remaining
A	36.0	15.4	20.6	11.9	8.7	0.3	9.0	0. 60
B	35.6	17.6	18.0	13.8	4.2	3.6	7.8	0.40
C	34.9	18.1	16.8	13.8	3.0	3.7	6.7	0.25
D	34.4	16.1	18.3	15.5	2.8	3.8	6.6	0.25
E	34.4	16.4	18.0	16.1	1.9	1.7	3.6	0.09
F	34.2	18.9	15.3	13.7	1.6	1.9	3.5	0.09
Average	34.9	17.1	17.8	14.1	3.7	2.5	6.2	0.21