Research Article
Characteristics and Origin of Methane Adsorption Capacity of Marine, Transitional, and Lacustrine Shales in Sichuan Basin, China
Table 1
Characteristics of shale in different formation in the Sichuan Basin.
| | Deposition type | Formation | Number of samples | Organic matter type | TOC (%) | Ro (%) | Quartz (%) | Feldspar (%) | Carbonate minerals (%) | Clay minerals (%) |
| | Lacustrine shale | Ziliujing Formation | 13 | Mainly type II1 and II2, partly type III | 0.7–3.9
2.1 | 1.6–1.8
1.7 | 15.3–78.8
25.3 | 4.2–23.4
8.2 | 1.3–38.6
22.4 | 21.6–78.1
44.1 | | Xujiahe Formation | 17 | Mainly type II1 and II2, partly type III | 0.7–5.9
2.2 | 1.2–1.5
1.3 | 12.1–53.0
35.9 | 0.4–6.3
3.9 | 0.6–67.0
14.2 | 15.1–57.3
46.0 | | Transitional shale | Longtan Formation | 35 | Mainly type III, followed by II2 | 0.5–13.0
4.8 | 1.3–2.0
1.6 | 10.9–71.7
28.9 | 2.0–24.8
11.6 | 2.3–86.6
21.3 | 5.1–77.8
38.2 | | Marine shale | Longmaxi Formation | 52 | Mainly type I, part II1 | 0.4–5.6
1.8 | 2.1–2.9
2.4 | 28.7–76.3
42.2 | 4.2–19.3
9.8 | 8.3–33.3
16.7 | 26.7–53.0
31.3 | | Qiongzhusi Formation | 25 | Mainly I, II1 type | 0.9–9.9
4.5 | 3.2–3.6
3.3 | 26.2–70.6
44.1 | 3.5–26.1
10.3 | 2.5–16.5
12.1 | 23.8–54.5
33.6 |
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