Pore Preservation and Failure Mechanism of Sinian Dengying Formation Carbonate Reservoirs: A Case Study of Two Ultradeep Wells in the Sichuan Basin, Western China

Figure 4

Chart of pore and filling mineral morphology of the CS well #1 Z₂dn⁴ member. (a) Bitumen is displayed as a patchy filling, and the contracted interval cracks of bitumen are mostly visible (sample depth is 8,161.07 m); (b) semifilling of bitumen in intergranular solution pores (sample depth is 8,154.39 m); (c) bitumen filling in recrystallised dolomite intergranular solution pores, where bitumen morphology is annular and attached to the cave wall (sample depth is 8,157.79 m); (d) and (e) diagram of principal component analysis of minerals; (f) bitumen in the solution pores is attached to the wall of the hole in a ring shape, and the morphology of bitumen is complete. Two contracted interval cracks are visible (sample depth is 8,159.62 m); (g) and (h) analysis of the main mineral components in (d).