Reservoir Sensitivity Analysis of Tight Sandstone and Its Controlling Factors: A Case Study from Chang 4+5 to Chang 6 Reservoirs in N 212 Well Block of Nanniwan Oilfield, Ordos Basin

Table 6

Statistics of dynamic core flow tests for alkali sensitivity of samples from Chang 4+5 and Chang 6 reservoirs of N 212 well block.

Sample number	Depth (m)	Stratum	Lc (cm)	Dc (cm)	Kg (×10^-3 μm^2)	Φ (%)	(×10^-3 μm^2)	Critical pH	after alkalization (×10^-3 μm^2)	(%)		Rank
S2	692.59	Chang 4+5	3.97	2.49	0.0417	9.60	0.00538	8.5	0.00284	47.0	0.472	Moderate-weak
S5	702.39		3.84	2.50	0.688	9.38	0.00616	8.5	0.00409	33.6	0.336	Moderate-weak
S31	767.00	Chang 6	3.93	2.50	0.0302	5.23	0.00127	8.5	0.000669	47.3	0.473	Moderate-weak
S38	778.92		3.79	2.49	0.191	8.34	0.0166	8.5	0.00850	48.8	0.488	Moderate-weak
S40	791.77		3.83	2.50	0.262	9.03	0.0811	8.5	0.0440	45.7	0.457	Moderate-weak
S41	760.99		3.85	2.49	0.326	9.78	0.0806	8.5	0.0449	44.3	0.433	Moderate-weak