Experimental Study on the Effect of Long-Term Water Injection on Micropore Structure of Ultralow Permeability Sandstone Reservoir

Table 6

Comparison of matrix minerals and clays between initial state and after-LTWF state.

Core		C9-1	C9-2	C11-1	C11-2
Type		Unimodality		Bimodality
State		Initial	After	Initial	After
Matrix minerals (%)	Quartz	36.2	36.6	32.5	32.8
	K-feldspar	5.7	6	9.4	9.6
	Plagioclase	41.1	40.9	40.2	39.8
	Calcite	0.7	0.6	0.9	1.1
	Total	83.7	84.1	83	83.3
Clays (%)	Illite/smectite mixed layer	2.8	2.4	2	1.8
	Illite	2.3	1.7	1.7	1.5
	Chlorite	11.2	11.8	13.3	13.4
	Total	16.3	15.9	17	16.7