Impact of Differential Densification on the Pore Structure of Tight Gas Sandstone: Evidence from the Permian Shihezi and Shanxi Formations, Eastern Sulige Gas Field, Ordos Basin, China
Table 1
Summary of thin section point count data by lithologic mode () indicating detrital and authigenic components for samples of differential mode.
Samples
Detrital components
Features of sandstone
Features of sandstone
Mode
Number of samples
Monocrystalline quartz
Polycrystalline quartz
Chert
K-feldspar
Plagioclase
Lithic fragments
Percentage of rigid lithic fragment (%)
Percentage of plastic lithic fragment (%)
Matrix
Clay
Carbonates
Siliceous
Sandstone grain size
Development position (B: braided river; M: meandering river)
Igneous rock
Metamorphic rock
Sedimentary rock
Chlorite
Illite
Kaolinite
Calcite
Fe-calcite
Siderite
Quartz overgrowth
Authigenic quartz
1
52.7
3.9
2.0
1.8
2.0
3.2
9.8
13.6
40.5
59.5
3.5
0
2.2
0
3.9
0.3
1.0
0
0
Fine
Middle-upper part of channel bar and channel lag sandbody (B), lower-middle part of point bar and crevasse splay sandbody (M)
Std. dev.
5.6
0.9
1.0
0.8
1.0
2.9
4.2
7.6
1.4
0.0
2.3
0.0
0.3
0.2
0.2
0.0
0
2
53.5
3.0
2.4
4.8
2.3
2.8
8.5
16.6
72.0
28.0
1.3
0.3
1.6
0.4
0.5
0.1
1.1
0.8
0
Meso—coarse
Middle part of channel bar and channel lag sandbody (B), middle-upper part of point bar and channel lag (M)
Std. dev.
6.6
1.0
1.2
1.4
1.5
2.6
3.4
3.6
1.1
0.5
0.5
0.0
0.3
0.0
0.6
0.3
0
3
53.0
2.1
3.0
3.3
3.0
1.8
10.1
13.6
78.5
21.5
4.0
2.9
1.0
1.1
0.1
0.0
0.3
0.3
0.4
Meso—coarse
Lower-middle part of channel bar and channel lag sandbody (B)
Std. dev.
6.1
1.0
0.7
2.1
1.7
1.2
3.8
4.0
2.1
0.3
0.0
0.3
0.0
0.0
0.0
0.1
0.4
4
61.8
1.5
2.4
2.3
1.8
3.3
9.7
11.7
75.2
24.8
1.1
0.2
0.6
0.0
0.1
0.0
0.0
3.4
0.1
Fine—meso
Lower part of point bar and middle-upper of crevasse splay sandbody (M)
Std. dev.
8.3
0.7
0.9
0.6
0.8
1.5
2.6
4.4
0.4
0.0
0.3
0.0
0.0
0.0
0.0
1.0
0
5
51.3
1.7
1.8
2.4
4.2
2.8
5.9
12.7
70.2
29.8
1.6
0.0
0.0
0.0
14.6
0.3
0.5
0.2
0
Fine—meso
Upper and lower part of sandbody that contact with thick-layer mudstone
Std. dev.
7.6
1.2
0.9
1.5
1.2
1.7
3.7
4.9
0.5
0.0
0.0
0.0
3.0
0.0
0.3
0.0
0
6
52.4
1.0
3.2
2.6
4.3
1.8
11.6
12.6
68.6
31.4
1.6
2.6
0.5
0.3
0.2
0.0
0.2
0.6
4.5
Meso—coarse
Lower part of point bar and channel lag sandbody, upper part of crevasse splay sandbody (M)
Std. dev.
10.5
0.2
0.7
2.0
0.8
1.2
6.5
8.2
1.1
0.5
0.4
0.3
0.0
0.0
0.0
0.5
2.3
7
55.3
1.5
1.3
3.9
5.1
1.6
6.4
11.2
69.6
30.4
1.6
0.1
1.4
1.6
0.7
6.1
0.3
1.7
0.2
Fine—meso
Upper part of point bar sandbody (M), small-scale channel bar (B) and point bar (M) sandbody contact with mudstone
Std. dev.
2.5
0.7
0.6
2.3
2.4
1.5
3.1
6.6
0.4
0.0
0.6
0.7
1.0
2.3
0.6
0.7
0.3
8
58.5
1.2
2.1
5.7
4.6
2.7
4.5
12.1
76.3
23.7
1.3
0.2
1.0
2.6
0.4
0.5
0.4
1.9
0.3
Meso—coarse
Middle part of point bar and channel lag (M) channel bar (B) sandbody
