Table 8: Relationship between injected time of Cr³⁺/APP5 plugging agent and recovery efficiency.

Experimental scheme	Recovery efficiency (%)		The added value of recovery efficiency (%)
	Early water flooding	Subsequent water flooding	Compared with early water flooding
Water flooding 65%+0.3PV Cr3+/APP5 plugging agent+ Water flooding 98%	36.2	64.2	28
Water flooding 75%+0.3PV Cr3+/APP5 plugging agent+ Water flooding 98%	40.8	63.4	22.6
Water flooding 85%+0.3PV Cr3+/APP5 plugging agent+ Water flooding 98%	43.3	59.3	16
Water flooding 95%+0.3PV Cr3+/APP5 plugging agent+ Water flooding 98%	45.3	56.6	11.3