Mesoscale Assessment of CO₂ Storage Potential and Geological Suitability for Target Area Selection in the Sichuan Basin

Table 6

Index system for geological suitability assessment to select suitable targets for deep saline aquifer CO₂ storage.

Level one index	Weight	Level two index	Weight	Level three index	Weight	Good	General	Poor	Key veto factor
Reservoir conditions and storage potential	0.50	Characteristic of the best reservoir	0.60	Lithology	0.07	Clastic	Mix of clastic and carbonate	Carbonate
				Single layer thickness h/m	0.11	≥80	30 ≤ h < 80	10 ≤ h < 30	<10
				Sedimentary facies	0.36	River, delta	Turbidity, alluvial fan	Beach bar, reef
				Average porosity /%	0.20	≥15	10 ≤ < 15	5 ≤ < 10	<5
				Average permeability /mD	0.27	≥50	10 ≤ k < 50	1 ≤ k < 10	<1
		Storage potential	0.40	Storage potential per unit area G (10^4 t/km^2)	1.00	≥100	10 ≤ G < 100	<10
Geological safety	0.50	Characteristic of the main caprock	0.62	Lithology	0.30	Evaporites	Argillite	Shale and dense limestone
				Thickness h/m	0.53	≥100	50 ≤ h < 100	10 ≤ h < 50	<10
				Depth D/m	0.11	1000 ≤ D ≤ 2700	<1000	>2700
				Buffer caprock above the main caprock	0.06	Multiple sets	Single set	None
		Hydrodynamic conditions	0.24	Hydrodynamic conditions	1.00	Groundwater high-containment area	Groundwater containment area	Groundwater semicontainment area	Groundwater open area
		Seismic activity	0.14	Peak ground acceleration	0.50	<0.05 g	0.05 g, 0.10 g	0.15 g, 0.20 g, 0.30 g	≥0.40 g
				Development degree of fractures	0.50	Simple	Moderate	Complex	Within 25 km of active faults