Damage Mechanism of Oil-Based Drilling Fluid Flow in Seepage Channels for Fractured Tight Sandstone Gas Reservoirs

Table 3

XRD analysis of clay mineral content in the Keshen Block.

Core number	Absolute content of clay minerals (%)	Relative content of clay minerals (%)				Interlayer ratio (%S)
		Illite	Illite/montmorillonite	Kaolinite	Chlorite
ks2-2-8-61	4.9	52.6	8.3	0.0	39.1	15.0
ks2-2-8-67	2.3	53.4	6.6	0.0	40.0	15.0
ks2-2-8-72	6.2	66.0	8.7	0.0	25.3	15.0
ks2-2-8-84	3.0	58.2	3.1	0.0	38.7	10.0
ks2-2-14-131	3.3	57.0	14.3	0.0	28.7	15.0
ks8-114	6.0	66.4	11.7	0.0	21.8	15.0
ks207-90	6.0	53.3	14.4	0.0	32.3	15.0
ks208-104	8.5	53.9	18.3	0.0	27.9	15.0