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. 2021 Jul 1;6(27):17584–17598. doi: 10.1021/acsomega.1c02103

Figure 9.

Figure 9

Microscopic characteristics of the Ch-6 sandstones in the WJY area, Ordos Basin. (a) Original intergranular pores (yellow arrow); the brown chlorite coatings on the surface of the grains after being soaked by oil (green arrow); Well F11, 2368.33 m, plane-polarized light (PPL). (b) Grains exhibit a linear contact due to compaction (blue arrow), and some of them have microcracks (yellow arrow); Well Y83, 2492.42 m, PPL. (c) Plastic deformation of mica fragments due to compaction, which are in close contact with the rigid grains (yellow arrow); Well H35, 2515.63 m, PPL. (d) Intergranular pores (green arrow) and feldspar dissolved pores (blue arrow) are cemented by ferrocalcite; Well H307, 2736.84 m, PPL; (e) Intergranular pores are cemented by ferrocalcite (yellow arrow); Well H315, 2580.75 m, PPL. (f) Secondary growth on the surface of terrigenous quartz grains (yellow arrow); Well H306, 2739.40 m, PPL. (g) Authigenic quartz with a good crystal morphology in dissolution pores (yellow arrow); Well Y76, 2379.90 m, SEM. (h) Microcrystalline chlorites, which grow vertically on the surface of the grains in the intergranular pore, form coatings on the surface of the grains (yellow arrow); Well F11, 2369.17 m, PPL. (i) Chlorite with the crystalline morphology of a petaline shape on the surface of the grains (yellow arrow); Well Y28, 2423.00 m, SEM. (j) Kaolinite in feldspar dissolved pores (yellow arrow); Well C335, 2303.36 m, PPL. (k) Authigenic kaolinite grains with accordion morphologies occur in pore spaces (yellow arrow); Well Y28, 2442.78 m, SEM. (l) Illite occurs as pore bridges with the crystalline morphology of a needlelike and hairy structure (yellow arrow); Well Y76, 2385.80 m, SEM. (m) Feldspar dissolved pores (yellow arrow) and moldic pores (red arrow); Well Y76, 2338.63 m, PPL. (n) Intergranular pores (green arrow) and debris dissolved pores (yellow arrow); Well C335, 2303.36 m, PPL. (o) Feldspar grains are dissolved (yellow arrow) and authigenic kaolinite is developed in the dissolved pores (red arrow); Well Y28, 2448.23 m, SEM.