NMR Experimental Study on Dynamic Process of Pore Structure and Damage Mechanism of Sandstones with Different Grain Sizes under Acid Erosion

Table 3

NMR spectrum area and rate of change in each group of sandstone with soaking time.

Group	Sample no.	NMR spectrum area							Change rate of spectrum area (%)
		0 d	10 d	20 d	30 d	40 d	50 d	60 d	0–10 d	10–20 d	20–30 d	30–40 d	40–50 d	50–60 d
B	N-1	1412	1464	1566	1679	1745	1817	1835	3.68	6.97	7.22	3.93	4.13	0.99
	N-2	1432	1487	1576	1683	1756	1824	1849	3.84	5.99	6.79	4.34	3.87	1.37
	N-3	1649	1710	1797	1905	1972	2035	2043	3.70	5.09	6.01	3.52	3.19	0.39
	Average value	1498	1554	1646	1756	1824	1892	1909	3.74	6.01	6.67	3.93	3.73	0.92
C	N-4	2028	2272	2504	2711	2903	2966	3028	12.03	10.21	8.27	7.08	2.17	2.09
	N-5	2341	2592	2829	3016	3238	3301	3374	10.72	9.14	6.61	7.36	1.95	2.21
	N-6	2238	2478	2703	2887	3069	3135	3203	10.72	9.08	6.81	6.30	2.15	2.17
	Average value	2202	2447	2679	2871	3070	3134	3202	11.16	9.48	7.23	6.92	2.09	2.16
D	N-7	3175	3630	4009	4289	4364	4423	4438	14.33	10.44	6.98	1.75	1.35	0.34
	N-8	3320	3804	4192	4458	4528	4572	4603	14.58	10.20	6.35	1.57	0.97	0.68
	N-9	3184	3670	4074	4331	4405	4431	4486	15.26	11.01	6.31	1.71	0.59	1.24
	Average value	3226	3701	4092	4359	4432	4475	4509	14.72	10.55	6.55	1.68	0.97	0.75