Table 1.

Assessment of the recovery rate of permeability of steel cores.

experiments	weighting agent	core	pressure difference of flow-back (MPa)	recovery rate (%)	permeability before damage (10−3 µm2)	permeability after damage (10−3 µm2)
without acid dissolution	standard barite	1	0.01	90.56	1.2145	1.0999
		2	0.01	91.68	0.9678	0.8879
	submicron barite	1	0.01	93.45	0.8745	0.8172
		2	0.01	94.03	0.8642	0.8126
	superfine manganese ore	1	0.01	96.24	1.1156	1.0737
		2	0.01	95.38	0.6574	0.627
	standard barite + superfine manganese ore	1	0.01	92.14	0.7687	0.7083
		2	0.01	92.54	0.9382	0.8682
with acid dissolution	standard barite	1	0	93.65	0.7885	0.7384
		2	0	95.36	0.9853	0.9396
	submicron barite	1	0	97.12	0.7712	0.749
		2	0	95.14	0.9631	0.9163
	superfine manganese ore	1	0	99.93	0.8954	0.8948
		2	0	102.14	0.9375	0.9576
	standard barite + superfine manganese ore	1	0	95.36	0.8979	0.8562
		2	0	98.47	0.9937	0.9785