Mechanism of Surfactant Enhancement of CO₂ Displacement Recovery in Interlayer Shale Oil Reservoirs

Table 4

Displacement effect of parallel rock samples under different DFV.

(a) CO₂

No.	Occurrence	Relative content ratio after saturated crude oil/%	Flow volume/PV	RDC/%
1	Free oil	49.95	5	66.26
			20	63.11
	Adsorbed oil	33.64	5	12.90
			20	16.61
	Organic matter	4.55	5	2.39
			20	2.06
2	Free oil	62.40	5	91.77
			20	79.64
	Adsorbed oil	29.59	5	0.93
			20	10.50
	Organic matter	3.26	5	2.17
			20	0.37
3	Free oil	40.51	5	57.50
			20	58.17
	Adsorbed oil	50.71	5	15.87
			20	30.87
	Organic matter	6.03	5	1.55
			20	0.63

(b) Surfactant + CO₂

No.	Occurrence	Relative content ratio after saturated crude oil/%	Flow volume/PV	RDC/%
4	Free oil	51.69	5 PV	76.60
			20 PV	70.21
	Adsorbed oil	33.33	5 PV	3.06
			20 PV	11.51
	Organic matter	3.68	5 PV	0.35
			20 PV	0.48
5	Free oil	61.82	5 PV	83.33
			20 PV	74.79
	Adsorbed oil	28.35	5 PV	4.82
			20 PV	14.63
	Organic matter	4.09	5 PV	0.07
			20 PV	1.62
6	Free oil	40.67	5 PV	79.00
			20 PV	78.71
	Adsorbed oil	53.21	5 PV	11.86
			20 PV	13.07
	Organic matter	5.98	5 PV	3.63
			20 PV	5.83