Official Journal of the Asia Oceania Geosciences Society (AOGS)
Table 3 The evaluation scheme of exploitation potential for shale gas reservoirs
Evaluation index | Reservoir grade | |||
|---|---|---|---|---|
Non-economic | Class I | Class II | Class III | |
TOC (%) |  < 0.5 |  > 2.0 | 1.0–2.0 | 0.5–1.0 |
Ro (%) |  < 1.0 or > 4.0 | 2.0–3.5 | 1.0–2.0 | 3.5–4.0 |
Brittle mineral content (%) |  < 15 |  > 40 | 40–30 | 30–15 |
Clay mineral content (%) |  > 40 |  < 20 | 20–30 | 30–40 |
Thickness (m) |  < 30 |  > 200 | 100–200 | 30–100 |
Burial depth (m) |  < 1000 | 1000–3000 | 3000–4500 |  > 4500 |
Geological structural conditions | Extremely complex, close to erosion area or deep fault | Simple | Relatively complex | Complex |
Pressure coefficient |  < 1.0 |  > 2.0 | 1.5–2.0 | 1.0–1.5 |
Gas content (cm3/g) |  < 1.0 |  > 2.0 | 1.5–2.0 | 1.0–1.5 |