Difference of Microfeatures among Diagenetic Facies in Tight Sandstone Reservoirs of the Triassic Yanchang Formation in the Midwestern Region, Ordos Basin

Figure 5

NMR T₂ spectrum distribution of different diagenetic facies. Note: the blue area is the movable pore space corresponding to the relaxation time greater than the T₂ cut-off value, the pink area is the movable pore space corresponding to the relaxation time less than the T₂ cut-off value, and the dashed line is the T₂ cut-off value. (a) Residual chlorite-membrane intergranular-pore diagenetic facies, H393, 2247.3 m. (b) Feldspar dissolution diagenetic facies, H185, 226.5 m. (c) Clay mineral cemented microporous diagenetic facies, A296, 2197.6 m. (d) Carbonate cemented tight diagenetic facies, H26, 2199.9 m.

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