Diagenetic Heterogeneity of Deep Sandstones and Its Relationship to Oil Emplacement: A Case Study from the Middle Jurassic Toutunhe Formation in the Fukang Sag, Central Junggar Basin (NW China)

Figure 9

SEM images of sandstones. (a) Sample 4515 m, well D-7: calcite composed mostly of anhedral calcite crystals. (b) Sample 4514.65 m, well D-7: calcite filling pore in patches. (c) Sample 4548.6 m, well D-8: secondary porosity created by complete dissolution of a detrital grain and authigenic albite growing over chlorite coats. Note that relict chlorite coats remain. (d) Sample 4837.5 m, well D-1: analcime and authigenic albite growing over illite/smectite clays. (e) Sample 3970.9 m, well D-6: analcime associated with illite/smectite clays. (f) Sample 5510.9 m, well D-3: anhydrite growing over authigenic albite. (g) Sample 3970.9 m, well D-6: quartz overgrowth. (h) Sample 5299.52 m, well D-1: pyrite filling intergranular pores. Cement: calcite (Cal), chlorite coat (Chl-c), analcime (Anl), anhydrite (Adr), quartz overgrowth (Qtz-o), albite (Ab), and pyrite (Py).

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)