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

Figure 4

Thin section analysis of the Keshen Block. (a) Semifilled tectonic fracture (Keshen 207 well: 6998.09 m). (b) Semifilled tectonic fracture (Keshen 207 well: 6998.56 m). (c) Microfracture (0.01-0.05 mm) (Keshen 202 well: 6797.55 m). (d) Microfracture (0.01 mm) (Keshen 202 well: 6797.82 m).

(a)

(b)

(c)

(d)