Experimental Study on Enhanced Oil Recovery by Nitrogen-Water Alternative Injection in Reservoir with Natural Fractures

Table 4

Summary of orthogonal experimental design results.

No.	Gas-water slug ratio	Injection velocity; (mL/min)	Injection volume in one cycle; (PV)	Gas injection volume in one cycle; (PV)	Water injection volume in one cycle; (PV)	Oil recovery; (%)
1	0.5 : 1	0.6	0.5	0.17	0.33	24.15
2	0.5 : 1	0.4	1	0.33	0.67	24.75
3	0.5 : 1	0.2	2	0.67	1.33	26.09
4	0.5 : 1	0.1	5	1.67	3.33	22.68
5	1 : 1	0.6	1	0.50	0.50	24.82
6	1 : 1	0.4	0.5	0.25	0.25	25.43
7	1 : 1	0.2	5	2.50	2.50	22.34
8	1 : 1	0.1	2	1.00	1.00	26.15
9	2 : 1	0.6	2	1.33	0.67	23.34
10	2 : 1	0.4	5	3.33	1.67	22.27
11	2 : 1	0.2	0.5	0.33	0.17	26.22
12	2 : 1	0.1	1	0.67	0.33	26.35
13	4 : 1	0.6	5	4.00	1.00	21.14
14	4 : 1	0.4	2	1.60	0.40	23.14
15	4 : 1	0.2	1	0.80	0.20	23.48
16	4 : 1	0.1	0.5	0.40	0.10	22.74