Feldspar Dissolution and Its Influence on Reservoirs: A Case Study of the Lower Triassic Baikouquan Formation in the Northwest Margin of the Junggar Basin, China

Figure 6

Thin section images of the Baikouquan Formation. (a) Plane-polarized light (PPL) images showing orthoclase dissolution with well-developed chlorite and well-preserved original pores; (b) PPL images showing that the intergranular pores are filled with illite in some reservoirs, and only a small amount of the pore is preserved; (c) cathodoluminescence images showing two phases of calcium cement filling the pores, and a small amount of the calcite is dissolved; (d): PPL images showing the developed dissolution pores in the tuffaceous rocks; (e) PPL images showing that calcite cementation is developed in the dissolution pores of the feldspars; and (f) cross-polarized images showing the illite-smectite mixed-layer clay filling pores in some reservoirs. Chl: chlorite film; Sty: stylolite; Pri: primary pore; Pert: perthite; Orth: orthoclase; I/S: illite-smectite mixed-layer clays; Shri: shrinkage; AQ: authigenic quartz; Cal: calcite cement; F: Feldspar; InterD: interparticle dissolution pores; IntraD: intraparticle dissolution pores; Tuff: tuffaceous; Diss: dissolution pores; K: kaolinite; I: illite.

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