Reservoir Sensitivity Analysis of Tight Sandstone and Its Controlling Factors: A Case Study from Chang 4+5 to Chang 6 Reservoirs in N 212 Well Block of Nanniwan Oilfield, Ordos Basin

Figure 5

Microstructural characteristics of the Chang 4+5 and Chang 6 reservoirs in the N 212 well block in Nanniwan Oilfield. Ch = chlorite; Q = quartz; I/S = illite/smectite; I = illite. (a) Chlorite can be seen at the edge of the particles, Chang 4+5, well N 212, 691.69 m; (b) chlorite and secondary quartz filling the intergranular pore, Chang 6, well N 212, 773.70 m; (c) illite and illite/smectite filling the intergranular pores, Chang 4+5, well N 212, 691.69 m; (d) secondary quartz, chlorite, and illite filling them intergranular pores, Chang 4+5, well N 212, 702.39 m.