Determination of Formation Time of Calcareous Cements in Marine Sandstone and Their Influence on Hydrocarbon Accumulation: A Case Study of the Carboniferous Donghe Sandstone in the Hadexun Oilfield, Tarim Basin

Figure 4

Typical characteristics of calcareous interlayers in the Hadexun Oilfield under a polarizing microscope with plane-polarized light and cross-polarized light.

(a) Oil-free sandstones, 5070.62 m, polarizing microscope with plane-polarized light, Well HD4

(b) Oil-free sandstones, 5070.62 m, polarizing microscope with cross-polarized light, Well HD4

(c) Oil-free sandstones, 5070.62 m, polarizing microscope with plane-polarized light, Well HD4

(d) Oil-free sandstones, 5070.62 m, polarizing microscope with cross-polarized light, Well HD4

(e) Oil-free sandstones, 5098.52 m, polarizing microscope with plane-polarized light, Well HD4

(f) Oil-free sandstones, 5098.52 m, polarizing microscope with cross-polarized light, Well HD4

(g) Oil-free sandstones, 5098.52 m, polarizing microscope with plane-polarized light, Well HD4

(h) Oil-free sandstones, 5098.52 m, polarizing microscope with cross-polarized light, Well HD4

(i) Oil-free sandstones, 5529.01 m, polarizing microscope with plane-polarized light, Well HD17

(j) Oil-free sandstones, 5529.01 m, polarizing microscope with cross-polarized light, Well HD17

(k) Oil-free sandstones, 5529.01 m, polarizing microscope with plane-polarized light, Well HD17

(l) Oil-free sandstones, 5529.01 m, polarizing microscope with cross-polarized light, Well HD17

(m) Oil-free sandstones, 5529.47 m, polarizing microscope with plane-polarized light, Well HD17

(n) Oil-free sandstones, 5529.47 m, polarizing microscope with cross-polarized light, Well HD47

(o) Oil-free sandstones, 5230.13 m, polarizing microscope with plane-polarized light, Well HD17

(p) Oil-bearing and oil-free sandstones, 5230.13 m, polarizing microscope with cross-polarized light, Well HD13